LTE from A-Z
Technology and Concepts of
the 4G 3GPP Standard
INACON GmbH
Kriegsstrasse 154
76133 Karlsruhe
Germany
www.inacon.com
e-mail: inacon@inacon.de
Cover design by Stefan Kohler
© 1999 - 2009 INACON GmbH
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Foreword of the Publisher:
Dear Reader:
Note that this book is primarily a training document because the primary business of
INACON GmbH is the training and consulting market for mobile communications. As
such, we are proud to providing high-end training courses to many clients worldwide,
among them operators like Cingular, Mobilkom Austria, SWISSCOM, T-MOBILE or
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SONY-ERICSSON, MOTOROLA, NOKIA-SIEMENS and RIM.
INACON GmbH is not one of the old-fashioned publishers. With respect to time-tomarket, form-factor, homogenous quality over all books and most importantly with
respect to after-sales support, INACON GmbH is moving into a new direction.
Therefore, INACON GmbH does not leave you alone with your issues and this book
but we offer you to contact the author directly through e-mail (inacon@inacon.de), if
you have any questions. All our authors are employees of INACON GmbH and all of
them are proven experts in their area with usually many years of practical
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The most important assets and features of the book in front of you are:
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Extreme degree of detailed information about a certain technology.
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Extensive and detailed index to allow instant access to information
about virtually every parameter, timer and detail of this technology.
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Incorporation of several practical exercises.
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If applicable, incorporation of examples from our practical field
experiences and real life recordings.
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References to the respective standards and recommendations on
virtually every page.
Finally, we again like to congratulate you to the purchase of this book and we like to
wish you success in using it during your daily work.
Sincerely,
Gunnar Heine / President & CEO of INACON GmbH
Table of Content
Table of Content
Principles and Motivation of LTE............................................1
1.1 Mobile Radio: Comparison between 3G and 4G..................2
1.1.1 Performance and Mobility Management related Issues..............2
1.1.2 Architecture related Issues..........................................................4
1.1.3 Procedure and Radio related Issues...........................................6
1.2 Requirements on LTE............................................................8
1.2.1 General Requirements................................................................8
1.2.1.1 Support of Enhanced Quadruple Play Services............................10
1.2.1.2 Very High Data Rates @ flexible bandwidth deployment ((1.25) 5 –
20 MHz).....................................................................................................10
1.2.1.3 AIPN and PS services only............................................................10
1.2.2 Important Characteristics of LTE Physical Layer.......................12
1.2.2.1 General Physical Layer Characteristics.........................................12
1.2.2.1.1 OFDM ..................................................................................12
1.2.2.1.2 Scalable Bandwidth..............................................................13
1.2.2.1.3 Smart Antenna Technology..................................................14
1.2.2.1.4 Fast scheduling and AMC.....................................................14
1.2.2.1.5 No Soft(er) handover............................................................14
1.2.3.2 OFDM/OFDMA..............................................................................16
1.2.3.2.1 Traditional narrowband communication................................16
1.2.3.2.2 Problems for wideband signals.............................................17
1.2.3.2.3 OFDM...................................................................................17
1.2.3.2.4 OFDM and OFDMA..............................................................17
1.2.3.2.5 LTE and OFDM.....................................................................17
1.2.3.3 Smart Antenna Technology in LTE................................................18
1.2.3.3.1 Categorization of Smart Antenna Technologies...................18
1.2.3.3.1.1 SISO.............................................................................18
1.2.3.3.1.2 SIMO............................................................................18
1.2.3.3.1.3 MISO............................................................................19
1.2.3.3.1.4 MIMO...........................................................................19
1.2.3.3.2 Multiple Input Multiple Output (MIMO)..................................20
1.2.3.3.2.1 Multiple carrier technology...........................................21
1.2.3.3.2.2 MIMO...........................................................................21
1.2.3.3.3 Adaptive Antenna Systems (AAS)........................................22
1.2.3.3.3.1 Signal generation.........................................................23
1.2.3.3.3.2 Constructive superimposition at the intended receiver 23
1.2.3.3.3.3 Destructive superimposition at the not intended receiver
.......................................................................................................23
1.2.3.3.3.4 Generation of signals for multiple UE’s........................23
1.2.3.4 Macro Diversity exploitation by SFN..............................................24
1.2.3.4.1 Requirements for MBMS services........................................24
1.2.3.4.2 MBMS operation with a SFN.................................................24
1.2.3.4.3 SFN for point to point services..............................................25
1.2.3.5 The Frequency Bands Intended for LTE.......................................26
1.2.3.5.1 Exclusive usage....................................................................27
1.2.3.5.2 Refarming.............................................................................27
1.2.3.5.3 Licensed operation................................................................27
1.2.3.5.4 Unlicensed operation............................................................27
1.2.3.6 Flexible Bandwidths, Parameters..................................................28
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and will be prosecuted to the full extent of German and international laws. Version Number 2.030
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LTE from A-Z
1.2.3.6.1 Fixed subcarrier separation..................................................28
1.2.3.6.2 Usage of carriers in the middle of the bandwidth for PBCH
and synchronization signals.................................................................29
1.2.3.6.3 Deployment Scenarios..........................................................30
1.2.4 Important Characteristics of the LTE Layer 2 and 3..................32
1.2.4.1 Support of the new LTE L1............................................................32
1.2.4.2 Simple IP centric protocols supporting AIPN.................................32
1.2.4.3 Support of various inter RAT handovers (GSM, UTRA, etc.)........33
1.3 LTE and System Architecture Evolution (SAE)..................34
1.3.1 Overview...................................................................................34
1.3.1.1 Missing RNC..................................................................................34
1.3.1.2 Interconnected eNB’s....................................................................35
1.3.1.3 Separate entities for user plane and control plane in the EPC......36
1.3.1.4 Combined Serving Gateway and MME.........................................36
1.3.1.5 Combined Serving and PDN Gateways........................................36
1.3.1.6 S1-flex...........................................................................................36
1.3.1.7 Used legacy elements...................................................................36
1.3.1.8 Roaming case................................................................................36
1.3.1.9 Direct Tunnel.................................................................................36
1.3.1.10 EPS, EPC, E-UTRAN & LTE, SAE..............................................36
1.3.2 The eNB....................................................................................38
1.3.2.1 Selection of MME at attachment....................................................39
1.3.2.2 Scheduling of paging messages....................................................39
1.3.2.3 Routing of user plane data to Serving GW....................................40
1.3.2.4 PDCP.............................................................................................40
1.3.2.5 RRM/RRC......................................................................................40
1.3.2.6 RLC...............................................................................................40
1.3.2.7 MAC...............................................................................................40
1.3.2.8 Complete L1 functionality..............................................................40
1.3.3 The MME...................................................................................42
1.3.3.1 NAS signalling...............................................................................42
1.3.3.2 Inter CN node signaling (3GPP networks).....................................42
1.3.3.3 Security management....................................................................42
1.3.4 The Serving GW........................................................................44
1.3.4.1 Termination of U-plane packets for paging reasons......................44
1.3.4.2 Support of UE mobility anchoring by switching U-plane during inter
eNB handover............................................................................................44
1.3.4.3 Transport Packet Marking According to QCI.................................45
1.3.4.4 Mobility anchoring for inter-3GPP mobility....................................45
1.3.4.5 Packet routing and forwarding.......................................................45
1.3.4.6 Charging support...........................................................................45
1.3.4.7 Lawful interception.........................................................................45
1.3.5 The PDN GW............................................................................46
1.3.5.1 Termination towards of PDN’s.......................................................46
1.3.5.2 Policy enforcement........................................................................46
1.3.5.3 Charging support...........................................................................46
1.3.5.4 DHCPv4 and DHCPv6 functions...................................................47
1.3.6 Identifiers of the UE and the Network Elements........................48
1.3.6.1 PLMN ID........................................................................................50
1.3.6.2 EPS Bearer ID...............................................................................50
1.3.6.3 MMEI.............................................................................................50
1.3.6.4 GUMMEI........................................................................................50
1.3.6.5 Physical Cell ID.............................................................................50
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and will be prosecuted to the full extent of German and international laws. Version Number 2.030
Table of Content
1.3.6.6 eNB/cell ID.....................................................................................50
1.3.6.7 TAI.................................................................................................50
1.3.6.8 C-RNTI..........................................................................................50
1.3.6.9 RA-RNTI........................................................................................50
1.3.6.10 SI-RNTI........................................................................................50
1.3.6.11 P-RNTI.........................................................................................50
1.3.6.12 Random Value.............................................................................50
1.3.6.13 IMSI, S-TMSI, and IMEI...............................................................52
1.3.6.14 GUTI............................................................................................52
1.3.6.15 eNB S1-AP UE ID and MME S1-AP UE ID.................................52
1.4 The E-UTRAN Protocol Stack..............................................54
1.4.1 Control Plane Protocol Stack....................................................54
1.4.1.1 Air Interface protocols....................................................................55
1.4.1.2 NAS protocols................................................................................56
1.4.2 User Plane Protocol Stack........................................................58
1.4.2.1 Air Interface protocols....................................................................58
1.4.2.2 S1 protocol....................................................................................58
1.4.3 X2 Interface Control Plane Protocol Stack................................60
1.4.4 X2 User Plane Protocol Stack...................................................62
1.5 Overview Channels of E-UTRAN.........................................64
1.5.1 Channel Types..........................................................................64
1.5.1.1 Logical Channels...........................................................................64
1.5.1.2 Transport Channels.......................................................................64
1.5.1.3 Physical Channels.........................................................................65
1.5.2 Logical Channels of E-UTRAN..................................................66
1.5.2.1 BCCH............................................................................................66
1.5.2.2 PCCH............................................................................................66
1.5.2.3 CCCH............................................................................................66
1.5.2.4 MCCH............................................................................................66
1.5.2.5 DCCH............................................................................................67
1.5.2.6 DTCH.............................................................................................67
1.5.2.7 MTCH............................................................................................67
1.5.3 Transport Channels of E-UTRAN..............................................68
1.5.3.1 RACH............................................................................................68
1.5.3.2 UL-SCH.........................................................................................68
1.5.3.3 BCH...............................................................................................68
1.5.3.4 PCH...............................................................................................68
1.5.3.5 MCH..............................................................................................69
1.5.3.6 DL-SCH.........................................................................................69
1.5.4 Physical Channels of E-UTRAN................................................70
1.5.4.1 PBCH.............................................................................................70
1.5.4.2 PDCCH..........................................................................................70
1.5.4.3 PCFICH.........................................................................................71
1.5.4.4 PUCCH..........................................................................................71
1.5.4.5 PRACH..........................................................................................71
1.5.4.6 PHICH...........................................................................................72
1.5.4.7 PDSCH..........................................................................................72
1.5.4.8 PMCH............................................................................................72
1.5.4.9 PUSCH..........................................................................................72
1.5.4.10 Downlink reference signal...........................................................72
1.5.4.11 Primary and secondary synchronization signal...........................72
1.5.4.12 Uplink reference signal or UL pilot symbol..................................72
1.5.4.13 Uplink sounding signal.................................................................72
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and will be prosecuted to the full extent of German and international laws. Version Number 2.030
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LTE from A-Z
1.5.4.14 Random Access Preamble..........................................................72
1.5.5 Mapping of Channels in E-UTRAN............................................74
1.6 Key Development Trends manifested in LTE.....................76
1.6.1 Mapping of User Plane Packets to the Resources....................76
1.6.1.1 Method 1: Fast resource allocation on optimum resources...........77
1.6.1.2 Method 2: Slow resource allocation on suboptimum resources....78
1.6.1.3 GSM..............................................................................................78
1.6.1.4 WCDMA.........................................................................................78
1.6.1.5 HSPA.............................................................................................78
1.6.1.6 LTE................................................................................................78
1.6.1.7 General trend.................................................................................78
1.6.2 All IP Network and Simple Packet Service Driven Protocols.....80
1.6.2.1 Reduced User Plane Latency........................................................82
1.6.2.1 Reduced Control Plane Latency....................................................84
1.7 LTE Key Feature Summary..................................................86
1.7.1 Air Interface Technology...........................................................86
1.7.2 System Architecture..................................................................87
1.7.3 Service Aspects........................................................................87
Key Technologies of the LTE Physical Layer......................89
2.1 Introduction OFDM Technology..........................................90
2.1.1 Impact of Orthogonality in the Frequency Domain – 3 Steps....90
2.1.2 Practical Exercise: Physical Basics of OFDM / OFDMA...........96
2.1.3 Practical Exercise: Scaling of OFDM / OFDMA-Systems..........98
2.1.4 The In-Phase – Quadrature (I/Q) Presentation.......................100
2.1.5 OFDM / OFDMA and IFFT......................................................102
2.1.5.1 Considering the Discrete Oscillator Array Option........................103
2.1.5.2 Details of the IFFT Option...........................................................103
2.1.5.3 Why is it called F a s t Fourier Transformation?..........................103
2.1.6 Modulation Scheme Overview.................................................104
2.1.8 Tackling Inter-Symbol Interference (ISI)..................................108
2.1.8.1 Introduction..................................................................................108
2.1.8.1.1 Delay Spread......................................................................108
2.1.8.2 Cyclic Prefix.................................................................................110
2.1.8.2.1 Variable Duration and other Assets of the Cyclic Prefix.....111
2.1.8.2.2 Cyclic Prefix in OFDMA in LTE...........................................111
2.1.9 Layout of a Typical OFDM System..........................................112
2.1.9.1 Remarks on the Brick Wall Image...............................................113
2.1.9.2 Subchannelization ......................................................................113
2.1.9.3 Pilot Subcarriers..........................................................................113
2.1.9.4 Null Subcarriers...........................................................................113
2.2 Introduction to MIMO Technology....................................114
2.2.1 The Basics: Signal Fading Physics between TX and RX........114
2.2.2 Multiplexing Dimensions.........................................................116
2.2.2 Multiplexing Dimensions.........................................................118
2.2.3 The Multipath Dimension........................................................120
2.2.6 MIMO General Operation........................................................122
The Physical Layer of E-UTRAN..........................................125
3.1 The Use of OFDM/OFDMA in LTE.....................................126
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and will be prosecuted to the full extent of German and international laws. Version Number 2.030
Table of Content
3.1.1 Frame Structure......................................................................126
3.1.1.1 The generic frame structure........................................................126
3.1.1.2 The downlink slots.......................................................................127
3.1.1.3 The uplink slots............................................................................127
3.1.1.4 The frame structure type 2..........................................................127
3.1.2 LTE Parameters......................................................................128
3.1.2.1 The normal configuration.............................................................128
3.1.2.2 The extended configuration with 15 kHz subcarrier separation...128
3.1.2.3 The extended configuration with 7.5 kHz subcarrier separation..129
3.1.2 Resource Element and Resource Block Definition..................130
3.1.2.1 Definition Resource Element.......................................................130
3.1.2.2 Definition Resource Block...........................................................130
3.1.2.3 Definition Subframe.....................................................................130
3.1.2.4 Number of resource blocks in a given bandwidth........................131
3.1.3 Choice of the UL Transmission Scheme (UL Data Symbols only)
.........................................................................................................132
3.1.3.1 What would happen if OFDM would be used in the UL...............133
3.1.3.2 SC-FDMA is used for the UL.......................................................133
3.1.4 FDD and TDD Operation in E-UTRAN....................................134
3.1.4.1 Reciprocity...................................................................................134
3.1.4.1.1 Reciprocity of the mobile radio channel..............................134
3.1.4.1.2 Speed of scheduling decisions...........................................135
3.1.4.2 UL / DL Asymmetry and Others...................................................136
3.1.4.2.1 UL/DL symmetry.................................................................136
3.1.4.2.2 Interference scenarios........................................................136
3.1.4.2.3 TRX architecture.................................................................137
3.1.4.2.4 Deployment in a given frequency band...............................137
3.1.4.3 Summary FDD vs. TDD...............................................................138
3.2 The DL Physical Channels and their Frame Structures. .140
3.2.1 Allocation of DL Physical Channels to Resource Elements... .140
3.2.1.1 Not used subcarriers...................................................................142
3.2.1.2 Primary Synchronization Signal...................................................142
3.2.1.3 Secondary Synchronization Signal..............................................142
3.2.1.4 Pilot or Reference Signal.............................................................142
3.2.1.5 PBCH...........................................................................................142
3.2.1.6 PCFICH.......................................................................................142
3.2.1.7 PHICH.........................................................................................142
3.2.1.8 PDCCH........................................................................................142
3.2.1.9 PDSCH (and PMCH)...................................................................142
3.2.2 System Information on PBCH and PDSCH.............................144
3.2.2.1 Split of the BCH on the PBCH and the PDSCH..........................144
3.2.3 PCFICH, PDCCH, and PHICH................................................146
3.2.3.1 The PCFICH................................................................................147
3.2.3.2 The PDCCH.................................................................................148
3.2.3.3 The PHICH..................................................................................148
3.2.4 The Downlink Processing Chain.............................................150
3.2.4.1 Encoded transport block bits.......................................................150
3.2.4.2 Scrambling...................................................................................150
3.2.4.3 Modulator.....................................................................................152
3.2.4.4 Layer Mapper..............................................................................152
3.2.4.5 Precoding....................................................................................152
3.2.4.6 OFDM signal generation..............................................................152
3.2.4.7 CP and IFFT................................................................................152
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and will be prosecuted to the full extent of German and international laws. Version Number 2.030
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LTE from A-Z
3.3 The UL Physical Channels and their Frame Structures. .154
3.3.1 Overview UL Physical Channels (RRC_CONNECTED).........154
3.3.1.1 Scheduling Request (SR) on the PUCCH...................................154
3.3.1.2 Small amount of L1 information on the PUCCH..........................155
3.3.1.3 Big amount of L1 information on the PUSCH..............................155
3.3.1.4 L1 information on the PUSCH multiplexed with the TrCH data...155
3.3.1.5 Sounding reference symbols PUSCH resources.........................155
3.3.2 Overview PUCCH...................................................................156
3.3.3 PUCCH Mapping for ACK/NACK only and Scheduling Request
.........................................................................................................158
3.3.3.1 Usage of Zadoff-Chu sequences.................................................158
3.3.3.2 Spreading of repeated data Zadoff-Chu symbols........................160
3.3.3.3 Spreading of reference Zadoff-Chu symbols...............................160
3.3.3.3 PUCCH Format 1........................................................................160
3.3.3.4 PUCCH Formats 1a and 1b.........................................................160
3.3.3.5 Shortened PUCCH Formats 1a and 1b.......................................160
3.3.3.6 Multiple access of the PUCCH....................................................160
3.3.4 Shared usage of Resources with CAZAC Sequences............162
3.3.4.1 Zadoff-Chu sequences are CAZAC sequences..........................163
3.3.4.2 Separation of different UE’s with cyclic shifted Zadoff-Chu
sequences...............................................................................................163
3.3.5.1 PUCCH Format 2........................................................................164
3.3.5.2 PUCCH Formats 2a and 2b.........................................................165
3.3.6 The Uplink Processing Chain..................................................166
3.3.6.1 Transport block bits.....................................................................166
3.3.6.2 Scrambling...................................................................................166
3.3.6.3 Modulator.....................................................................................166
3.3.6.4 DFT pre-coder.............................................................................166
3.3.6.5 Demultiplexing of signals other than data....................................167
3.3.6.6 Resource element mapper..........................................................167
3.3.6.7 IFFT.............................................................................................167
3.3.6.7 CP................................................................................................167
3.4 Overview all Physical Channels........................................168
3.4.1 Special usage of the 6 RB around the DC carrier...................169
3.4.2 Multiplexing of the PCFICH, PDCCH and the PDSCH/PMCH in
the normal DL subframe...................................................................170
3.4.3 Sounding reference signal.......................................................170
3.4.4 Modulation of the physical channels.......................................170
3.4.5 Channel coding.......................................................................170
3.5 Physical Layer Procedures...............................................172
3.5.1 Timing Advance Control..........................................................174
3.5.1.1 Principle.......................................................................................174
3.5.1.2 Procedure....................................................................................178
3.5.1.2.1 TA while the UE is not synchronized to the eNB................178
3.5.1.2.2 TA while the UE is synchronized to the eNB......................179
3.5.2 Channel Estimation DL...........................................................180
3.5.2.1 Channel Estimation Principle of LTE...........................................180
3.5.2.1.1 The description of the mobile radio channel.......................180
3.5.2.1.2 Coping with a frequency selective mobile radio channel....182
3.5.2.2 Channel Estimation Downlink......................................................184
3.5.2.2.1 Normal configuration with 4 TX antennas...........................184
3.5.2.2.2 Normal configuration with less than 4 TX antennas...........185
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and will be prosecuted to the full extent of German and international laws. Version Number 2.030
Table of Content
3.5.2.2.3 Extended configuration with 15 kHz subcarrier spacing.....185
3.5.2.2.4 Extended configuration with 15 kHz subcarrier spacing for
MBSFN..............................................................................................185
3.5.2.2.5 Extended configuration with 7.5 kHz subcarrier spacing for
MBSFN..............................................................................................185
3.5.3 Power Control Principle (PUSCH)...........................................186
3.5.4.1 The Transmission Diversity Problem...........................................188
3.5.4.1.1 Receive diversity.................................................................188
3.5.4.1.2 Unsuccessful transmit diversity...........................................189
3.5.4.2 AAS in LTE............................................................................190
3.5.4.2.1 Practical Exercise: Draw the Antenna Diagram of AAS......192
3.5.4.3 CDD.............................................................................................194
3.5.4.3.1 Delay diversity.....................................................................194
3.5.4.3.2 Cyclic delay diversity...........................................................194
3.5.4.3.3 Cyclic delay diversity and MIMO.........................................195
3.5.4.4 SFBC...........................................................................................196
3.5.4.4.1 Space Frequency Block Codes...........................................197
3.5.4.4.2 Space Time Block Codes....................................................197
3.5.4.5 MIMO...........................................................................................198
3.5.4.5.1 MIMO and AAS combined = multiple rank beamforming....199
3.5.4.5.2 When MIMO fails................................................................199
3.5.4.6 The Codebook.............................................................................200
3.5.4.6.1 Optimum beamforming weights..........................................201
3.5.4.6.2 Signaling of sub-optimum beamforming weights................201
3.5.5 Initial Cell Search ...................................................................202
3.5.5.1 Primary and Secondary Synchronization Signals........................202
3.5.5.2 Procedure....................................................................................204
3.5.6 Random Access......................................................................206
3.5.6.1 PRACH Structure Format 0.........................................................206
3.5.6.2 Random Access Procedure.........................................................208
3.5.7 Inter Cell Interference Mitigation.............................................210
3.5.7.1 Traditional frequency reuse in LTE..............................................210
3.5.7.1.1 Frequency reuse bigger than 1...........................................211
3.5.7.1.2 Frequency reuse 1 with low initial load...............................211
3.5.7.1.3 Frequency reuse 1 strongly increased load........................211
3.5.7.1.4 Frequency reuse 1 after “the party”....................................211
3.5.7.2 Fractional Frequency Reuse with Intercell Interference
Coordination............................................................................................212
3.6 UE Classes..........................................................................214
3.6.1 Overview.................................................................................214
3.6.1.1 Classes 1-4..................................................................................214
3.6.1.2 UE class 5...................................................................................215
3.6.2 Calculation of the DL Peak Throughput for LTE UE Class 5...216
The Higher Layers of E-UTRAN...........................................219
4.1 Overview.............................................................................220
4.1.1 E-UTRAN Architecture Control Plane.....................................220
4.1.2 E-UTRAN Architecture User Plane.........................................222
4.2 Features of MAC.................................................................224
4.2.1 Overview.................................................................................224
4.2.1.1 Data transfer logical channels ←→ transport channels..............224
4.2.1.2 Radio resource allocation............................................................224
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LTE from A-Z
4.2.2 MAC Random Access Procedure............................................226
4.2.2.1 Contention based random access procedure..............................226
4.2.2.2 Non-contention based random access procedure.......................227
4.2.3 Structure of MAC-PDU............................................................228
4.2.3.1 MAC control element...................................................................229
4.2.3.2 Normal MAC SDU.......................................................................229
4.2.4 MAC Control Elements............................................................230
4.2.4.1 Contention resolution ID..............................................................231
4.2.4.2 Timing Advance...........................................................................231
4.2.4.3 DRX.............................................................................................231
4.2.4.4 Padding.......................................................................................231
4.2.4.5 Short, long and truncated buffer status reports...........................231
4.3 Features of RLC.................................................................232
4.3.1 Overview.................................................................................232
4.3.1.1 Data transfer................................................................................232
4.3.1.2 Error detection and recovery.......................................................232
4.3.1.3 Reset...........................................................................................233
4.3.2 Structure of RLC PDU.............................................................234
4.3.3 Structure of RLC AM with PDCP PDU Segments...................236
4.4 Features of PDCP...............................................................238
4.4.1 Overview.................................................................................238
4.4.1.1 RoHC...........................................................................................238
4.4.1.2 Numbering of PDCP PDU’s.........................................................238
4.4.1.3 In-sequence delivery of PDU’s....................................................238
4.4.1.4 Duplicate deletion........................................................................238
4.4.1.5 Encryption....................................................................................239
4.4.1.6 Integrity Protection.......................................................................239
4.4.2 Structure of PDCP PDU..........................................................240
4.5 Features of RRC.................................................................242
4.5.1 Overview.................................................................................242
4.5.1.1 Transmission of broadcast information........................................243
4.5.1.2 Establish and maintain services..................................................243
4.5.1.3 QoS control..................................................................................243
4.5.1.4 Transfer of dedicated control information....................................243
4.5.2 State Characteristics of RRC..................................................244
4.5.2.1 RRC_IDLE...................................................................................244
4.5.2.2 RRC_CONNECTED....................................................................244
4.6 NAS Protocol States and Transitions...............................246
4.6.1 EMM-DEREGISTERED & ECM-IDLE.....................................246
4.6.2 EMM-REGISTERED & ECM-IDLE..........................................246
4.6.3 EMM-REGISTERED & ECM-CONNECTED...........................247
4.7 Mobility...............................................................................248
4.7.1 Mobility Management in the EMM-DEREGISTERED & ECMIDLE State........................................................................................248
4.7.2 Mobility Management in the EMM-REGISTERED & ECM-IDLE
State.................................................................................................250
4.7.3 Mobility Management in the EMM-REGISTERED & ECMCONNECTED State.........................................................................252
4.7.4 Inter RAT Mobility Management..............................................254
4.7.4.1 Cell Reselection (EMM-REGISTERED & ECM-IDLE).................255
4.7.4.2 Handover (EMM-REGISTERED & ECM-CONNECTED)............255
- viii -
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Table of Content
4.8 QoS in LTE..........................................................................256
4.8.1 Bearer Architecture.................................................................256
4.8.2 QoS Parameters.....................................................................258
4.8.2.1 ARP.............................................................................................259
4.8.2.2 Label............................................................................................259
4.8.2.3 GBR.............................................................................................259
4.8.2.4 MBR.............................................................................................259
4.8.2.5 AMBR..........................................................................................259
4.8.3 QoS Classes Identifier............................................................260
4.9 Security in LTE...................................................................262
Selected E-UTRAN Scenarios..............................................265
5.1 Initial Context Setup Procedure........................................266
5.2 Tracking Area Update........................................................268
5.1.1 Inter MME tracking area update..............................................268
5.1.2 Intra MME tracking area update..............................................269
5.3 PDP Context Establishment..............................................270
5.4 Intra MME Handover...........................................................274
5.4.1 Practical Exercise: Intra eNB Handover..................................278
5.5 Inter MME Handover...........................................................280
5.6 How a TCP/IP MTU is reaching the UE / the Internet.......284
5.6.1 TCP/IP layer............................................................................284
5.6.2 PDCP layer.............................................................................284
5.6.3 RLC layer................................................................................284
5.6.4 MAC layer...............................................................................285
5.6.5 PHY layer................................................................................285
Solutions for Practical Exercises........................................287
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LTE from A-Z
-x-
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Principles and Motivation of LTE
Chapter 1:
1
Principles and Motivation of LTE
Objectives
Some of your questions that will be answered during this session…
•
What is the difference in-between 3G and 4G?
•
What is LTE and why it is introduced in the first place?
•
What are the requirements for LTE and how do they differentiate from those
of UMTS?
•
What are the key characteristics of LTE’s (E-UTRAN’s) layer 1 and layer 2/3?
•
How the LTE and SAE (System Architecture Evolution) does evolved mobile
radio network look like?
•
How the protocol stacks of the E-UTRAN and its network elements look
like?
What key development trends are manifested in LTE?
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1.1 Mobile Radio: Comparison between 3G and 4G
1.1.1 Performance and Mobility Management related Issues
The objective of this section is to list the most important performance and
mobility management related differences between 3G and 4G mobile radio.
Key points of this section are:
1. 4G mobile radio will be strongly focusing on the provision of IP-based
bearer services. This will also require IP-based mobility management
mechanisms.
2. 4G mobile radio services will not be able to provide IP-based real-time
end-to-end services without QoS-aware IP backbone networks. This is an
important, yet usually unconsidered constraint.
-2-
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Room for your Notes
•
1
Abbreviations of this Section:
3G ...
3rd Generation ...
MOBIKE
IKEv2 Mobility and Multihoming
Protocol (RFC 4555)
4G
4th Generation ...
QoS
Quality of Service
GMM
GPRS Mobility Management
RAN
Radio Access Network
IKEv2
Internet Key Exchange protocol /
version 2 (RFC 4306)
RAT
Radio Access Technology (e.g.
GERAN, UTRAN, ...)
IP
Internet Protocol (RFC 791)
SIP
Session Initiation Protocol (RFC
3261)
MM
Mobility Management
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1.1.2 Architecture related Issues
The objective of this section is to list the most important architecture related
differences between 3G and 4G mobile radio.
Key points of this section are:
1. The independence between core and access network is the basic means
to provide for FMC.
2. Many 4G handsets will be multipurpose devices that are not limited to
mobile access networks. To a large degree, these handsets will have at least
the functionality of today’s PDA’s.
-4-
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Room for your Notes
•
1
Abbreviations of this Section:
3G ...
3rd Generation ...
IP
Internet Protocol (RFC 791)
4G
4th Generation ...
PDA
Personal Digital Assistant
FMC
Fixed Mobile Convergence
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1.1.3 Procedure and Radio related Issues
The objective of this section is to list the most important procedure and radio
related differences between 3G and 4G mobile radio.
Key points of this section are:
1. The most impressive increased spectral efficiency of 4G mobile radio.
2. The transition away from an access network specific protocol architecture
towards an IP-based architecture.
Spectral efficiency is not relating to the peak throughput directly but is giving
average usage of the spectrum in the cells. The true unit is bit/s/Hz/cell.
-6-
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Room for your Notes
•
1
Abbreviations of this Section:
3G ...
3rd Generation ...
SIP
Session Initiation Protocol (RFC
3261)
4G
4th Generation ...
UMTS
Universal Mobile Telecommunication
System
IP
Internet Protocol (RFC 791)
WCDMA
Wide-band Code Division Multiple
Access
OFDMA
Orthogonal Frequency Division
Multiple Access
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1.2 Requirements on LTE
1.2.1 General Requirements
The objective of this section is to provide the key requirements on LTE.
Key points of this section are that LTE is designed for AIPN and for PS
services only from the start and that the requirements are very similar to
those of WiMAX.
-8-
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Room for your Notes
•
1
Abbreviations of this Section:
AIPN
All IP Network
MHz
Mega Hertz (106 Hertz)
DL
Downlink
PS
Packet Switched
E-UTRAN Evolved UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
UL
Uplink
L1
Layer 1 (physical layer)
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
LTE
Long Term Evolution (of UMTS)
WiMAX
Worldwide Interoperability for
Microwave Access (IEEE 802.16)
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1.2.1.1 Support of Enhanced Quadruple Play Services
Quadruple play services have not only to be followed - also the (quality)
enhancements being standardized in 3GPP and the other standardization bodies
have to be followed, e.g. conversational QoS VoIP, fast gaming, enhanced MBMS
etc. For the UE Mobility speeds of up to 250 km/h should be supported. In a special
case implementation up to 500 km/h should be possible.
1.2.1.2 Very High Data Rates @ flexible bandwidth deployment ((1.25) 5 – 20
MHz)
Very high data rates are necessary in order to keep up with the fixed network
developments and the other 4G mobile radio standards. Flexible bandwidth is easing
the deployment because not everywhere the biggest bandwidth deployment is
reasonable or possible. It is open whether 1.25 MHz will be implemented. This is a
compatibility issue with LCR. LCR and 1.25 MHz apply for China.
1.2.1.3 AIPN and PS services only
The AIPN will make the infrastructure deployment a lot cheaper and easier. Naturally,
to use only PS services in an AIPN is the best choice. However, in order to have the
same high QoS standards as known from CS services, both the network architecture
and the latency requirements in the PS user plane need to be changed. As well an
efficient operation of PS service including fast wake up of the UE in RRC_IDLE mode
is requiring low latency times in the control plane as well.
[3GTR 25.912 (13.2, 13.3), 3GTR 25.814 (7.1.2.4.3), 3GTR 26.913 (5, 7.5), 3GTR
25.912 (7.1.1.4)]
Room for your Notes
- 10 -
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Room for your Notes
•
1
Abbreviations of this Section:
3GPP
Third Generation Partnership Project
(Collaboration between different
standardization organizations (e.g.
ARIB, ETSI) to define advanced
mobile communications standards,
responsible for UMTS)
MHz
Mega Hertz (106 Hertz)
3GTR
3rd Generation Technical Report
PS
Packet Switched
4G
4th Generation ...
QoS
Quality of Service
AIPN
All IP Network
RRC_ID
LE
RRC state
CS
Circuit Switched
UE
User Equipment
LCR
Low Chip Rate TDD
VoIP
Voice over IP
MBMS
Multimedia Broadcast / Multicast
Service
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1.2.2 Important Characteristics of LTE Physical Layer
1.2.2.1 General Physical Layer Characteristics
The objectives of this section are to list the key characteristics of the physical
layer and to provide understanding about how they relate to the
requirements on LTE.
Key point of this section is that the LTE layer 1 is dominated by flexibility in
all aspects.
1.2.2.1.1 OFDM
OFDM is enabling an efficient and low complexity usage of high data rate
transmission in a frequency selective channel. In a broadband single carrier system
AMC is the less efficient the more bandwidth is used.
[3GTR 25.912 (7.1, 7.2), 3GTR 25.912 (5.8, 6.6)]
- 12 -
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1.2.2.1.2 Scalable Bandwidth
It is for further study what operating bandwidths are used for TDD below 5 MHz 1.6
and 3.2 MHz will not be used for FDD.
1
[3GTS 36.101 (4.5.2)]
Room for your Notes
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
MIMO
Multiple In / Multiple Out (antenna
system)
3GTS
3rd Generation Technical
Specification
OFDM
Orthogonal Frequency Division
Multiplexing
AAS
Adaptive Antenna Systems
OFDMA
Orthogonal Frequency Division
Multiple Access
AMC
Adaptive Modulation and Coding
SC-FDMA Single Carrier Frequency Division
Multiple Access
DL
Downlink
TDD
Time Division Duplex
E-UTRAN Evolved UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
UE
User Equipment
FDD
Frequency Division Duplex
UL
Uplink
LTE
Long Term Evolution (of UMTS)
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
MBMS
Multimedia Broadcast / Multicast
Service
eNB
Enhanced Node B
MHz
Mega Hertz (106 Hertz)
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1.2.2.1.3 Smart Antenna Technology
Especially MIMO Technologies and SDMA (beam forming) technology have to be
mentioned here. These technologies are allowing reuse of the transmission capacity
of the given radio channel several times and are the preconditions for very high data
rates.
[3GTR 25.912 (5.3.3, 5.3.4)]
1.2.2.1.4 Fast scheduling and AMC
As known from HSPA, LTE will also perform fast scheduling and HARQ. The
difference with respect to HSPA will be that these processes run much faster. LTE
offers a HARQ RTT of only 5 ms. AMC will be used for both UL and DL with more
variants of modulation schemes than HSPA. In contrast to HSPA a shared channel is
used in the UL.
[3GTR 25.912 (7.1.2)]
1.2.2.1.5 No Soft(er) handover
Since there will be no RNC’s, currently no soft handover will be used for LTE. Instead
of the soft handover the eNB’s coordinate their interference amongst each other. In
order to reach the same benefits as the missing soft handover this interference
coordination will be utilized in a self organizing network such that the interference
amongst the eNB’s is kept at a minimum.
[3GTR 25.912 (7.1.1.4, 11.2.5)]
Room for your Notes
- 14 -
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Room for your Notes
•
1
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
MIMO
Multiple In / Multiple Out (antenna
system)
AMC
Adaptive Modulation and Coding
RNC
Radio Network Controller
DL
Downlink
RTT
Round Trip Time
HARQ
Hybrid ARQ
SDMA
Space Division Multiple Access
HSPA
High Speed Packet Access (operation UL
of HSDPA and HSUPA)
Uplink
LTE
Long Term Evolution (of UMTS)
Enhanced Node B
eNB
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1.2.3.2 OFDM/OFDMA
The objective of this section is to show how OFDM technology is combining
the benefits of narrowband systems with the benefits of wideband systems
by means of orthogonal frequency multiplexing technology.
Key point of this section is that OFDM is combining the advantages of
narrowband systems – simple receiver – with the advantage of wideband
systems – high
1.2.3.2.1 Traditional narrowband communication
All mobile radio signals experience distortions at the boundaries of their symbols.
This is due various delayed versions of the transmitted signal that are received with
different delays and are thus overlapping at the symbol boundaries.
The nature of traditional narrowband communication is that the symbols are very long
compared to the distortion zone in-between their symbols. In the useful time of the
received symbol the modulated content of the symbol can be demodulated. The
advantage of this scheme is that no complex equalizer is needed in order to detect
these narrowband signals
- 16 -
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1.2.3.2.2 Problems for wideband signals
Unfortunately this scheme cannot be used for wideband signals directly since then
the symbol duration is limited by the maximum expected length of the distortion zone.
1
1.2.3.2.3 OFDM
OFDM is a wideband system using many orthogonal narrowband carries in order to
perform a simple receive processing on each of these carriers. Orthogonality is
achieved by means of having an equal distance in-between the individual carriers.
This frequency spacing is the inverse useful symbol duration. Thus OFDM can allow
for both a wideband signal for high data rate transmission and an easy detection
mechanism. In the picture Orthogonality can be seen by the fact that at the position
of the main lobe of each subcarriers spectrum there is a zero crossing of the other
subcarriers’ spectra.
1.2.3.2.4 OFDM and OFDMA
Both OFDM and OFDMA are using OFDM technology. The difference is:
OFDMA
The OFDMA transmitter is mapping signals dedicated to more than one receiver on
the OFDM carriers.
OFDM
OFDM alone is using all the transmitted carriers for a single receiver.
1.2.3.2.5 LTE and OFDM
LTE is using OFDMA technology in the DL and single carrier technology in the UL.
However the UL signals look like OFDM signals. This method is allowing an easy
equalization in the frequency domain before the UL signals are demodulated in the
time domain.
[3GTR 25.912 (7.1, 7.2)]
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
OFDM
Orthogonal Frequency Division
Multiplexing
DL
Downlink
OFDMA
Orthogonal Frequency Division
Multiple Access
LTE
Long Term Evolution (of UMTS)
UL
Uplink
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1.2.3.3 Smart Antenna Technology in LTE
1.2.3.3.1 Categorization of Smart Antenna Technologies
The objective of this section is to clarify the different terms which are used in
the context of multiple antenna techniques
Key point of this section is that the terms “single in / out” or “multiple-in / out”
have to be interpreted from the perspective of the channel between TX and
RX. Therefore, a system with two RX-antennas and one TX-antenna is a
SIMO
Image Description
•
The image illustrates a system which consists of a transmitter (TX) and a receiver
(RX).
•
Both, transmitter and receiver may deploy one or multiple antennas to send
information into the channel or to receive information from that channel.
•
Depending on the number of antennas, the different configurations SISO, MISO,
SIMO and MIMO have to be distinguished
1.2.3.3.1.1 SISO
SISO-systems do not really belong in this section but need to be mentioned for
completeness. SISO-systems deploy only one TX- and one RX-antenna which
excludes them from the group of “multiple antennas” techniques with their enhanced
capabilities.
1.2.3.3.1.2 SIMO
•
- 18 -
SIMO-systems have been around for quite some time. SIMO-systems apply
receive diversity schemes and typically soft decision and maximum ratio
combining (MRC) to counteract poor multipath conditions at a single antenna.
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•
One important implementation example for a receive diversity scheme is the
GSM-uplink receive diversity: The MS uses a single TX-antenna but typically, the
BS has two receive antennas
1
1.2.3.3.1.3 MISO
•
The opposite cases to the aforementioned one are MISO-systems. Two or more
TX-antennas are used to apply transmit diversity schemes towards a single RXantenna. One important implementation example for a transmit diversity scheme
is Space-Time-Coding (STC) which will be represented in a later section.
•
Another example are beamforming techniques which will also be elaborated in
more detail in a later section.
1.2.3.3.1.4 MIMO
MIMO-systems are characterized by deploying both: Two or more TX-antennas and
two or more RX-antennas.
MIMO-systems may or may not incorporate the receive and transmit diversity
schemes of SIMO- and MISO-systems, respectively.
Room for your Notes
•
Abbreviations of this Section:
BS
Base Station (IEEE 802.16)
RX
Receive
GSM
Global System for Mobile
Communication
SIMO
Single In / Multiple Out (antenna
system)
MIMO
Multiple In / Multiple Out (antenna
system)
SISO
Single In / Single Out (antenna
system)
MISO
Multiple In / Single Out (antenna
system)
STC
Space Time Coding
MRC
Maximum Ratio Combining
TX
Transmit
MS
Mobile Station
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1.2.3.3.2 Multiple Input Multiple Output (MIMO)
The objective of this section to visualize the key features of MIMO
technology in a very simple way.
Key points of this section are the efficiency of MIMO comes with the expense
of equalization:
1. that MIMO is enabling a multiplication of the data rate possible on the same radio
frequency
2. that this increase comes at the expense of additional complexity.
Image Description
•
- 20 -
This picture is showing a comparison of multiple carrier technology with MIMO
technology
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•
Green and red bits are symbolizing the two data streams at the transmitter.
•
The pipes are symbolizing the mobile radio channels of the two carriers.
•
The buckets are symbolizing the output of the initial detector at the receiver.
•
The two guys are conveying the key messages.
1
1.2.3.3.2.1 Multiple carrier technology
For the multiple carrier transmission scheme the input data need first to be separated
to two data streams. Each of the data streams could be able to completely occupy
the individual carrier. Each of the shown two carriers is treated individually as if only
one carrier would be transmitted. Multiple carrier technology is known for a very long
time even though the digital signal processing is very simple the challenge of multiple
carrier technology lies in the RF. This is why these days not that much multiple
carrier technology is implemented (except for OFDM systems of course).
1.2.3.3.2.2 MIMO
MIMO is as well using a serial to parallel converter in order to create separate data
streams. The difference here is that not multiple carriers but multiple antennas are
used in TX and RX in order to create more max. throughput or signals for more
users. With e.g. N antennas for TX and N antennas for RX (N x N) the data rate could
be enhanced by N times. Since each receive antenna is receiving the signals from
both transmitters in the general case the mobile radio channel is mixing up the two
data streams. This means that the receiver has to separate these mixed data
streams from each other. Since N data streams have to be separated the receiver
has to receive N different versions of the N data stream signals. This is why N
receive antennas are needed. This data separation might add quite significant effort
in the receiver’s digital signal processing. Since with MIMO now the data rate on a
single carrier is multiplied, it becomes very tempting for 4G to implement MIMO
nevertheless.
MIMO add a new dimension to mobile radio: Instead of frequency space is used.
•
Abbreviations of this Section:
4G
4th Generation ...
RF
Radio Frequency
MIMO
Multiple In / Multiple Out (antenna
system)
RX
Receive
OFDM
Orthogonal Frequency Division
Multiplexing
TX
Transmit
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1.2.3.3.3 Adaptive Antenna Systems (AAS)
The objective of this section to show key features and key benefits of AAS.
Key point of this section is that AAS is both improving the signal quality and
is reducing the interference in the system by means of weighing various TX
antennas’ signals with different antenna weights.
Image Description
- 22 -
•
The top half of the picture is showing the generation of the signal for UE 1 in an
AAS scenario with two antennas.
•
The lower half of the picture is showing how the signal for UE 1 is perceived by
UE 2.
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1.2.3.3.3.1 Signal generation
In the upper part the physical setup the signal generation is shown. At first the user
signal is created as if there were no AAS.
Then the signal is copied two times (once for each antenna) and is then multiplied
with a user dependent weighing factor for each antenna. In the case of this picture
the two weighing factors are both 1. In an AAS system the antennas are usually very
close together: Typically half the wave length is chosen in order to perform
beamforming.
1
1.2.3.3.3.2 Constructive superimposition at the intended receiver
In the picture the weighing coefficients are chosen in a way that the two antennas
radio signals are superimposing constructively at the position of the UE. One benefit
of the AAS is that the TX energy is bundled in the direction of the UE’s the signal is
intended for.
For realistic AAS more than 2 antennas are situated in a line (linear antenna array) or
on a circle (circular antenna array).
1.2.3.3.3.3 Destructive superimposition at the not intended receiver
UE2 is located below the two antennas. Here the signal of antenna 1 has traveled
exactly half a wavelength longer than the signal of antenna 2. This has the
consequence that it always has a phase shift of 180 degrees compared with the
signal of antenna 2.
This leads to a complete destruction of the two antennas signals. Here the benefit of
AAS of interference reduction is shown very well.
What would happen once one of the two antennas is switched off?
How to achieve that that the AAS is radiating the signal towards UE2?
1.2.3.3.3.4 Generation of signals for multiple UE’s
Each UE will have its own signal generated with its own weighing factors. After the
weighing process for each UE the signals are added up before they reach the TX
antennas. This feature is very important for AAS’s application in modern mobile radio
systems where multiple signals for multiple UE’s are transmitted on the individual
radio carrier.
Room for your Note
•
Abbreviations of this Section:
AAS
Adaptive Antenna Systems
TX
Transmit
UE
User Equipment
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1.2.3.4 Macro Diversity exploitation by SFN
The objective of this section is to illustrate how the SFN basically works.
Key point of this section is that SFN transmitting the same signals
synchronously by multiple eNB’s in order to provide macro diversity.
Image Description
•
This picture is comparing SFN with a choir: The core network is the conductor,
the eNB’s are the choir members, and the UE’s are the audience.
1.2.3.4.1 Requirements for MBMS services
Since the signals for MBMS are multicast it is difficult to direct or tune them to the
individual UE’s mobile radio channels. They have to be broadcast. Even though here
MIMO is applicable many other methods like power control, AAS, etc. cannot be
applied. This is why it would be very advantageous if some kind of macro diversity
could be exploited in order to enhance the quality of MBMS to a similar level as for
the point to point services.
1.2.3.4.2 MBMS operation with a SFN
Like in a choir the core network is distributing the same piece of data to a multitude of
eNB’s. The eNB’s are drawn as choir members. In a choir all the members have to
sing synchronously and with the same voice. In an OFDM system SFN can be
applied easily provided that all the eNB’s are synchronized and that they are
transmitting exactly the same bits on exactly the same subcarriers. Then the UE’s
cannot distinguish whether the signal is coming from one or from several eNB’s and
macro diversity is exploited automatically.
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This benefit, however, comes at a price: Like the conductor does with the choir, the
mobile radio network needs to coordinate precisely within the eNB’s.
1
1.2.3.4.3 SFN for point to point services
Imagine an individual person is listening to a choir presentation alone. Then the ticket
would be quite expensive. In the same way the aforementioned coordination
overhead is limiting the use of SFN for point to point services. Features like soft
handover are not intended by LTE – especially this can be seen from the network
architecture.
[3GTR 25.912 (7.1.1.4, 13.9)]
Room for your Notes
•
Abbreviations of this Section:
AAS
Adaptive Antenna Systems
OFDM
Orthogonal Frequency Division
Multiplexing
LTE
Long Term Evolution (of UMTS)
SFN
Single Frequency Network
MBMS
Multimedia Broadcast / Multicast
Service
UE
User Equipment
MIMO
Multiple In / Multiple Out (antenna
system)
eNB
Enhanced Node B
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1.2.3.5 The Frequency Bands Intended for LTE
The objective of this section is to show how LTE will use the available
frequency bands.
Key point of this section is that LTE and UTRA compete for the same
frequency bands.
Table Description
These tables are showing the frequency bands foreseen for FDD and TDD. On
purpose they are identical to the frequency bands for UMTS - UTRA.
Since of the frequency bands are also foreseen for other standards e.g. band 7 and
12 might/will also be used for WiMAX, LTE is both competing with other standards
and with UTRA about the frequency bands.
•
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Obviously 6 bits will be used for signaling of the frequency bands later on. Thus
the lower 32 band numbers are used for FDD and the higher 32 band numbers are
used for TDD bands. There is a work item to introduce LTE in the 3.5 GHz band.
1
[3GTS 36.101 (5.2)]
Possibly the following options can be used for the frequency allocation by the country
individual regulators and operators:
1.2.3.5.1 Exclusive usage
Here the regulator decides to mandate a certain mobile radio standard to be used on
this frequency (band), e.g. LTE. These days usually this decision is left up to the
operators owning this frequency.
1.2.3.5.2 Refarming
The frequency band is previously operated with another standard e.g. UTRA and the
operator decides to use LTE instead. Also both systems LTE and UMTS might be
operated in the operators band. Here they will use different carriers.
Another possibility is the license for this frequency band is running out and the
regulator is allocating a new operator to this frequency band.
1.2.3.5.3 Licensed operation
A frequency band is given to an operator and this operator decides how it is used.
1.2.3.5.4 Unlicensed operation
A frequency band is not belonging to anybody and everybody can use it provided the
rules set by the regulator are adhered to. Handovers will be difficult in this scenario.
In any case unlicensed bands do not allow for a mobile radio operation as known
from the licensed bands.
What is the maximum width of the consecutive bands an operator might get?
WiMAX is aiming to use the 3.5 GHz bands as well. This indicates that higher
frequency will also be an option for LTE as well.
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
TDD
Time Division Duplex
DL
Downlink
UL
Uplink
FDD
Frequency Division Duplex
UMTS
Universal Mobile Telecommunication
System
GHz
Giga Hertz (109 Hertz)
UTRA
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access
LTE
Long Term Evolution (of UMTS)
WiMAX
Worldwide Interoperability for
Microwave Access (IEEE 802.16)
MHz
Mega Hertz (106 Hertz)
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1.2.3.6 Flexible Bandwidths, Parameters
The objectives of this section are
- to show how the bandwidth of both the network and the terminal can be
used flexibly
- to list what deployment scenarios are resulting from this flexibility to show
where to find the SCH and the BCH to enable the UE to log on the cell.
Key point of this section is there are many constraints to deploy LTE at its
full capability – using 20 MHz.
Image Description
•
On the left hand side of this picture the different applicable bandwidths of LTE are
shown. Unlike for UTRAN there is no fixed bandwidth intended to be applied in
the whole network. Instead there is a set of 4 bandwidths to choose from.
On the right hand side the basic trade-offs of the application scenarios are
visualized.
Now the problem arises that regardless of the chosen bandwidth in the network every
UE – regardless its capability restrictions (not only bandwidth) - should be able to use
that cell and should be able to camp on this cell. This is achieved by two measures:
•
1.2.3.6.1 Fixed subcarrier separation
The subcarrier separation is fixed either to 15 kHz (normal configuration) or to 7.5
kHz (extended configuration for lower UE mobility and broadcast-like operation). This
is resulting for a different amount of used carriers for each of the 4 bandwidths. Due
to the fixed subcarrier separation all the UE’s can use at least a subset of the
subcarriers regardless how big their bandwidths is.
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1.2.3.6.2 Usage of carriers in the middle of the bandwidth for PBCH and
synchronization signals
In the middle of the bandwidth always the same number of consecutive carriers is
used for carrying PBCH and primary/secondary synchronization signals. This is
enabling the UE’s to synchronize on the cells and to read the PBCH in the middle of
the subcarrier range. Of course the UE is not in need to tune its subcarriers always to
the middle. Once it gets assigned other subcarriers it does not need to read the
PBCH and will tune to the sub-carriers assigned. Since the same frequency bands as
UTRA are used, the center frequency of the cells can vary to any center frequency in
the well-known 200 kHz grid.
[3GTR 25.912 (10.1), 3GTR 25.813 (9.1.1), 3GTR 25.814 (7.1.1, 7.1.2.4.3)]
1
In any case the RF front end of any UE has to support 20 MHz bandwidth. This is
a tough constraint for the implementation of the UE.
Room for your Notes
•
Abbreviations of this Section:
3GPP
Third Generation Partnership Project
(Collaboration between different
standardization organizations (e.g.
ARIB, ETSI) to define advanced
mobile communications standards,
responsible for UMTS)
UE
User Equipment
3GTR
3rd Generation Technical Report
UTRA
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access
LTE
Long Term Evolution (of UMTS)
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
MHz
Mega Hertz (106 Hertz)
kHz
Kilo Hertz (103 Hertz)
PBCH
Physical Broadcast Channel
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1.2.3.6.3 Deployment Scenarios
The right hand side of the picture is showing the application scenarios of LTE.
Reviewing the size of the FDD and TDD frequency bands foreseen for LTE and the
current allocation of these frequency bands to the operators, it is less likely that an
operator gets allocated a consecutive band of 20 MHz. Even if it gets this bandwidth
it is likely that it only has 20 MHz - then at a given location the operator can only use
a single 20 MHz carrier. This is imposing some restrictions on the usage of LTE at is
full capability. It is more likely that 20 MHz bandwidth can be used
1. The smaller the cells are.
Pico cells usually are well shielded from the surrounding macro cells and thus
can be used at 20 MHz bandwidth without a penalty in the surrounding macro
cells.
2. The higher the carrier frequency becomes
Since there is not that much opportunity in the bands noted in the tables above,
the operators might need to wait to deploy LTE at its full capability in frequency
bands having a higher carrier frequency than e.g. 3 GHz and are not assigned
yet. These bands are broader than the bands listed above. Unfortunately due to
the constraints of the radio propagation these bands only allow for less mobility
and less range.
LTE needs a bandwidth of 20 MHz in order to provide the peak data rates of 100
Mbit/s in the downlink and 50 Mbit/s in the uplink.
Room for your Notes
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Room for your Notes
•
1
Abbreviations of this Section:
FDD
Frequency Division Duplex
MHz
Mega Hertz (106 Hertz)
GHz
Giga Hertz (109 Hertz)
TDD
Time Division Duplex
LTE
Long Term Evolution (of UMTS)
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1.2.4 Important Characteristics of the LTE Layer 2 and 3
The objective of this section is to illustrate the key differences of the LTE
layer 2 and 3 compared to the legacy UMTS systems.
Key point of this section is the simplification of layer 2 and layer 3 in LTE
goes that far that the RNC has been removed.
1.2.4.1 Support of the new LTE L1
Nothing to add to what is stated in the image.
1.2.4.2 Simple IP centric protocols supporting AIPN
The consequent tuning towards simple protocols suitable for an AIPN is involving
quite radical changes such as removal of the RNC, an eNB covering L1/2/3
completely, and the abandoning of the soft handover concept. The concept of selforganizing networks will replace the soft handover. There are only 2 RRC states in
LTE.
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1.2.4.3 Support of various inter RAT handovers (GSM, UTRA, etc.)
Nothing to add to what is stated in the image.
1
[3GTR 25.912 (8, 9.1, 9.3)]
Room for your Notes
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
MM
Mobility Management
AIPN
All IP Network
RAT
Radio Access Technology (e.g.
GERAN, UTRAN, ...)
GSM
Global System for Mobile
Communication
RNC
Radio Network Controller
HO
Handover
RRC
Radio Resource Control
IP
Internet Protocol (RFC 791)
SM
Session Management (3GTS 23.060,
3GTS 24.008)
L1
Layer 1 (physical layer)
UMTS
Universal Mobile Telecommunication
System
L2
Layer 2 (data link layer)
UTRA
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access
LTE
Long Term Evolution (of UMTS)
eNB
Enhanced Node B
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1.3 LTE and System Architecture Evolution (SAE)
1.3.1 Overview
The objective of this section is to give an overview of the LTE radio access
network elements and the new SAE EPC network elements.
Key point of this section that LTE is going together with very significant
changes in the core as well.
Image Description
• In the picture the LTE and SAE network is shown.
Here the radical change in the network architecture becomes obvious.
1.3.1.1 Missing RNC
Since a RNC would have obstructed short latency times and a high quality of service
it has been removed and its functionality is now distributed in-between EPC and eNB.
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1.3.1.2 Interconnected eNB’s
The X2 interface is interconnecting the eNB’s. One might think that the X2 interface is
like the Iur interface. Even though the inter eNB handovers are negotiated using the
X2 interface during the handover it is only transferring the data in the buffer from the
source eNB to the target eNB. Continuous payload exchange and a soft handover
are not foreseen. Instead the inter cell interference coordination for a self-organizing
network is done on the X2 interface.
1
Room for your Notes
•
Abbreviations of this Section:
E-UTRAN Evolved UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
PCRF
Policy Control and Charging Rules
Function (3GTS 23.203) (Rel. 7
onwards)
EPC
Evolved Packet Core (3GTS 23.401)
(Rel. 8 onwards)
PDN
Packet Data Network
EPS
Evolved Packet System
PS
Packet Switched
GERAN
GSM EDGE Radio Access Network
PSTN
Public Switched Telephone Network
GGSN
Gateway GPRS Support Node
RNC
Radio Network Controller
GW
Gateway
SAE
System Architecture Evolution
HSS
Home Subscriber Server (3GTS
23.002). HSS replaces the HLR with
3GPP Rel. 5
SGSN
Serving GPRS Support Node
IMS
Internet Protocol Multimedia Core
SGi
Network Subsystem (Rel. 5 onwards)
Reference Point in LTE
LTE
Long Term Evolution (of UMTS)
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
MME
Mobility Management Entity (3GTS
23.401) (Rel. 8 onwards)
eNB
Enhanced Node B
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1.3.1.3 Separate entities for user plane and control plane in the EPC
Like in the UTRAN in the CS domain now also the EPC is separating control plane
and user plane.
1.3.1.4 Combined Serving Gateway and MME
Optionally the Serving Gateway and the MME can be united in one entity. Then the
S11 interface need not to be implemented.
1.3.1.5 Combined Serving and PDN Gateways
Optionally the Serving Gateway and the PDN Gateway can be united in one entity.
Then the S5 interface needs not to be implemented.
1.3.1.6 S1-flex
Like the Iu-flex feature in UMTS there is a S1-flex feature in SAE. With this feature
the eNB’s can be connected to different MME’s and Serving Gateways also including
the core networks of other operators using the regarded E-UTRAN as well.
1.3.1.7 Used legacy elements
The SGSN, HSS, and the network elements right of the PDN Gateway are legacy
elements. The PCRF is a R7 core network element.
1.3.1.8 Roaming case
In the roaming case the VPLMN is connecting to the HSS, PDN Gateway, PCRF,
IMS, PDN, etc. of the HPLMN.
1.3.1.9 Direct Tunnel
The optional S12 is used between UTRAN and Serving GW for user plane tunneling
when a Direct Tunnel is established.
1.3.1.10 EPS, EPC, E-UTRAN & LTE, SAE
The names LTE and SAE describe standardization processes for the RAN and the
core network respectively. They are more of marketing nature soon they will
disappear from the specifications. E-UTRAN, EPC, and EPS are official
standardization terms in the specifications and describe the RAN, the core and the
unity of RAN and core respectively.
[3GTS 23.203 (6.2.1), 3GTS 23.401, 3GTR 25.912 (9)]
Room for your Notes
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Room for your Notes
•
1
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
LTE
Long Term Evolution (of UMTS)
3GTS
3rd Generation Technical
Specification
MME
Mobility Management Entity (3GTS
23.401) (Rel. 8 onwards)
CS
Circuit Switched
PCRF
Policy Control and Charging Rules
Function (3GTS 23.203) (Rel. 7
onwards)
E-UTRAN Evolved UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
PDN
Packet Data Network
eNB
Enhanced Node B
RAN
Radio Access Network
EPC
Evolved Packet Core (3GTS 23.401)
(Rel. 8 onwards)
SAE
System Architecture Evolution
EPS
Evolved Packet System
SGSN
Serving GPRS Support Node
GW
Gateway
UMTS
Universal Mobile Telecommunication
System
HPLMN
Home Public Land Mobile radio
Network
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
HSS
Home Subscriber Server (3GTS
23.002). HSS replaces the HLR with
3GPP Rel. 5
VPLMN
Visited Public Land Mobile radio
Network
IMS
Internet Protocol Multimedia Core
Network Subsystem (Rel. 5 onwards)
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1.3.2 The eNB
The objective of this section is to provide the key functions of the eNB.
Key point of this section is that the eNB is having most of the functions of the
RNC in a UTRAN network.
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1.3.2.1 Selection of MME at attachment
Since there is the S1-flex feature more than one MME can be connected to the same
eNB. The eNB select which MME it connects the UE to according to the load
situation and the operator the UE belongs to.
1
1.3.2.2 Scheduling of paging messages
Once the UE is in the idle state there are neither location areas nor routing areas but
tracking areas. Then the UE needs to be paged on TA level. The TA is having a
function like the URA but is also replacing LA and RA.
Room for your Notes
•
Abbreviations of this Section:
AM
Acknowledged Mode operation
RNC
Radio Network Controller
DL
Downlink
RRC
Radio Resource Control
GW
Gateway
RRM
Radio Resource Management
IP
Internet Protocol (RFC 791)
SAE
System Architecture Evolution
L1
Layer 1 (physical layer)
TA
Tracking Area
LA
Location Area
TM
Transparent Mode operation
MAC
Medium Access Control
UE
User Equipment
MME
Mobility Management Entity (3GTS
23.401) (Rel. 8 onwards)
UL
Uplink
PDCP
Packet Data Convergence Protocol
UM
Unacknowledged Mode operation
PDU
Protocol Data Unit or Packet Data
Unit
URA
UTRAN Registration Area
RA
Routing Area
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
RLC
Radio Link Control
eNB
Enhanced Node B
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1.3.2.3 Routing of user plane data to Serving GW
It is for further study which node is establishing the user plane tunnel and whether it
is established at RRC establishment.
1.3.2.4 PDCP
Please note here that PDCP is used for both control and user plane. In UTRAN there
is no PDCP in the control plane.
1.3.2.5 RRM/RRC
The RRC is issuing commands executing the decisions of the RRM.
1.3.2.6 RLC
Since L1 RLC and MAC are in the eNB there is the possibility to adapt the RLC-PDU
size flexibly to the transport block size in MAC.
1.3.2.7 MAC
Nothing to add to what is stated in the image.
1.3.2.8 Complete L1 functionality
See layer 1 sections.
[3GTS 36.300 (4.1), 3GTR 25.912 (9)]
Room for your Notes
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Room for your Notes
•
1
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
PDU
Protocol Data Unit or Packet Data
Unit
3GTS
3rd Generation Technical
Specification
RLC
Radio Link Control
GW
Gateway
RRC
Radio Resource Control
L1
Layer 1 (physical layer)
RRM
Radio Resource Management
MAC
Medium Access Control
SAE
System Architecture Evolution
ISDN
Integrated Services Digital Network
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
PDCP
Packet Data Convergence Protocol
eNB
Enhanced Node B
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1.3.3 The MME
The objective of this section is to provide the key functions of the mobility
management entity.
Key points of this section are that the SGSN is separated in user plane entity
and control plane entity and that the MME is performing all control plane
activities representing the EPC towards the E-UTRAN.
1.3.3.1 NAS signalling
Once the UE is idle but stays registered the MME keeps the context of the UE in
order to allow for a fast reconnection.
1.3.3.2 Inter CN node signaling (3GPP networks)
The MME is interconnecting to the SGSN and the HSS as well as to the Serving GW
and it has the responsibility to select the right code network nodes – especially in a
handover situation.
1.3.3.3 Security management
Nothing to add to what is stated in the image.
[3GTS 23.401 (4.4.2), 3GTS 36.300 (4.1)]
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Room for your Notes
•
1
Abbreviations of this Section:
3GPP
Third Generation Partnership Project
(Collaboration between different
standardization organizations (e.g.
ARIB, ETSI) to define advanced
mobile communications standards,
responsible for UMTS)
MME
Mobility Management Entity (3GTS
23.401) (Rel. 8 onwards)
3GTS
3rd Generation Technical
Specification
NAS
Non-Access-Stratum
CN
Core Network
SAE
System Architecture Evolution
EPC
Evolved Packet Core (3GTS 23.401)
(Rel. 8 onwards)
SGSN
Serving GPRS Support Node
GW
Gateway
UE
User Equipment
HSS
Home Subscriber Server (3GTS
23.002). HSS replaces the HLR with
3GPP Rel. 5
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
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1.3.4 The Serving GW
The objective of this section is to provide the key functions of the Serving
GW.
Key point of this section is that the Serving GW is performing all user plane
activities representing the EPC towards the E-UTRAN.
1.3.4.1 Termination of U-plane packets for paging reasons
Once data is arriving in the downlink and the UE is in EMM-REGISTERED & ECMIDLE then the Serving Gateway is initiating the paging procedure before forwarding
the data packets further.
1.3.4.2 Support of UE mobility anchoring by switching U-plane during inter eNB
handover
At any time each UE has just one Serving GW. Once the UE does not leave the zone
of the Serving GW the Serving GW stays the same (anchoring).
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1.3.4.3 Transport Packet Marking According to QCI
The marking of the packets is helping the eNB to reinforce the right QoS.
1
1.3.4.4 Mobility anchoring for inter-3GPP mobility
It terminates the S4 interface towards the SGSN for 2G/3G traffic.
1.3.4.5 Packet routing and forwarding
In handover situations involving different code network entities the packets need to
be forward to the target Serving GW before the handover is complete.
1.3.4.6 Charging support
Nothing to be added to what is stated above.
1.3.4.7 Lawful interception
The Serving GW has to support tapping the user plane for lawful interception
purposes.
[3GTS 23.401 (4.4.3.2), 3GTS 36.300 (4.1)]
•
Abbreviations of this Section:
3GPP
Third Generation Partnership
Project (Collaboration between
different standardization
organizations (e.g. ARIB, ETSI)
to define advanced mobile
communications standards,
responsible for UMTS)
SAE
System Architecture Evolution
3GTS
3rd Generation Technical
Specification
SGSN
Serving GPRS Support Node
EMMEnhanced Mobility Management
REGISTERED state for non active packet
& ECM-IDLE transmission
UE
User Equipment
EPC
Evolved Packet Core (3GTS
23.401) (Rel. 8 onwards)
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
GW
Gateway
eNB
Enhanced Node B
QCI
QoS Classes Identifier
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1.3.5 The PDN GW
The objective of this section is to provide the key functions of the Packet
Data Network GW.
Key point of this section is that the PDN GW’s difference to the Serving GW
is that this PDN GW is directed towards the PDN, IMS, PSTN and service
related core network entities, whereas the Serving GW has a clear direction
towards the E-UTRAN.
1.3.5.1 Termination towards of PDN’s
If the UE using more than one PDN it may use more than one PDN GW. Once the
UE connects to a PDN GW for a service then it stays connected to this PDN GW as
long as the service is consumed.
1.3.5.2 Policy enforcement
Nothing to add to what is stated in the image.
1.3.5.3 Charging support
For users visiting the network the charging policies may be downloaded from its
home PLMN.
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1.3.5.4 DHCPv4 and DHCPv6 functions
The PDN GW will provide the IP addresses to the UE’s.
1
[3GTR 23.882 (7.2.2), 3GTS 23.401 (4.4.3.3), 3GTS 36.300 (4.1)]
Room for your Notes
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
PLMN
Public Land Mobile Network
3GTS
3rd Generation Technical
Specification
PSTN
Public Switched Telephone Network
DHCPv4
Dynamic Host Configuration Protocol
Version 4 (RFC 2131)
QCI
QoS Classes Identifier
DHCPv6
Dynamic Host Configuration Protocol
Version 6 (RFC 3315)
SGi
Reference Point in LTE
GW
Gateway
UE
User Equipment
IMS
Internet Protocol Multimedia Core
UTRAN
Network Subsystem (Rel. 5 onwards)
PDN
Packet Data Network
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
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1.3.6 Identifiers of the UE and the Network Elements
The objective of this section is to provide a list of the most relevant ID’s in
the LTE RAN and in the SAE network and to emphasize the importance of
the ID’s for a packet centric protocol stack.
Key point of this section is that the ID concept of LTE is very close to UMTS
even though some ID’s have changed.
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Room for your Notes
•
1
Abbreviations of this Section:
C-RNTI
Cell Radio Network Temporary
Identifier
MNC
Mobile Network Code
E-UTRAN Evolved UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
PLMN
Public Land Mobile Network
eNB
Enhanced Node B
P-RNTI
Paging - Radio Network Temporary
Identifier
EPS
Evolved Packet Switched
RA-RNTI
Random Access - Radio Network
Temporary Identifier
GUMMEI
Global Unique MME Identity
RAN
Radio Access Network
GUTI
Global Unique Terminal Identity
S-TMSI
SAE Temporary Mobile Subscriber
Identity
ID
Identity
S1-AP
S1 Application Part
IMEI
International Mobile Equipment
Identity
SAE
System Architecture Evolution
IMSI
International Mobile Subscriber
Identity
SI-RNTI
System Information - Radio Network
Temporary Identifier
LTE
Long Term Evolution (of UMTS)
TAC
Tracking Area Code
M-TMSI
MME - Temporary Mobile Subscriber
Identity
TAI
Timing Advance Index
MCC
Mobile Country Code
TMSI
Temporary Mobile Subscriber
Identity
MME
Mobility Management Entity (3GTS
23.401) (Rel. 8 onwards)
UE
User Equipment
MMEC
MME Code
UMTS
Universal Mobile Telecommunication
System
MMEGI
MME Group Identity
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
MMEI
MME Identity
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1.3.6.1 PLMN ID
Like in UTRAN multiple operators can share the same E-UTRAN. Consequently
more than 1 PLMN ID (MCC + MNC) can be signaled.
1.3.6.2 EPS Bearer ID
An EPS bearer ID uniquely identifies an EPS bearer for one UE accessing via EUTRAN.
1.3.6.3 MMEI
The MMEI provides a unique ID for identifying the MME during RRC connection
establishment. It is constructed using the MMEGI identifying the group of MME’s and
the MMEC being the code of the MME within these groups.
1.3.6.4 GUMMEI
The GUMMEI is the global unique ID if the MME it is adding MCC and MNC to the
MMEI.
1.3.6.5 Physical Cell ID
This ID is related to the choice of the primary and secondary synchronization signals
and scrambling codes of the cell.
1.3.6.6 eNB/cell ID
The exact definition of the eNB or cell ID is for further study at the point of time this
training manual has been written. The eNB ID might be used in order to identify the
old eNB after handover for better handover handling. The cell ID will also be used in
the cell update procedure.
1.3.6.7 TAI
Each cell can be allocated only to one TAI – even though the TAI of different cells
belonging to the same eNB can be different. The TAI is replacing both URA ID, LAI,
and RAI. Similar as the LAI the TAI is constructed using MCC, MNC, and TAC.
1.3.6.8 C-RNTI
The C-RNTI is identifying the RRC connection uniquely on cell level. It is replacing
the H-RNTI for HSDPA and the E-RNTI for HSUPA.
1.3.6.9 RA-RNTI
The RA-RNTI is used during some transient states, the UE is temporarily identified
with a random value for contention resolution purposes.
1.3.6.10 SI-RNTI
The SI-RNTI is used in order to identity paging groups on the BCCH mapped on the
DL-SCH.
1.3.6.11 P-RNTI
The P-RNTI is used in order to identity paging groups on the PCH mapped on the
PDSCH.
1.3.6.12 Random Value
During random access the UE is using a random ID for contention resolution.
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•
Abbreviations of this Section
1
BCCH
Broadcast Control Channel
MMEI
MME Identity
C-RNTI
Cell Radio Network Temporary
Identifier
MNC
Mobile Network Code
DL-SCH
Downlink Shared Channel
P-RNTI
Paging - Radio Network Temporary
Identifier
E-RNTI
E-DCH Radio Network Temporary
Identifier (3GTS 25.401)
PCH
Paging Channel
E-UTRAN Evolved UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
PDSCH
Physical Downlink Shared Channel
eNB
Enhanced Node B
PLMN
Public Land Mobile Network
EPS
Evolved Packet System
RA-RNTI
Random Access - Radio Network
Temporary Identifier
GUMMEI
Global Unique MME Identity
RAI
Routing Area Identification
H-RNTI
HS-DSCH Radio Network Transaction
Identifier (3GTS 25.331, 25.433)
RRC
Radio Resource Control
HSDPA
High Speed Downlink Packet Access
(3GTS 25.301, 25.308, 25.401,
3GTR 25.848)
SCH
Synchronization Channel
HSUPA
High Speed Uplink Packet Access
(3GTS 25.301, 25.309, 25.401,
3GTR 25.896)
SI-RNTI
System Information - Radio Network
Temporary Identifier
ID
Identity
TAC
Tracking Area Code
LAI
Location Area Identification (LAI =
MCC + MNC + LAC)
TAI
Timing Advance Index
MCC
Mobile Country Code
UE
User Equipment
MME
Mobility Management Entity (3GTS
23.401) (Rel. 8 onwards)
URA
UTRAN Registration Area
MMEC
MME Code
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
MMEGI
MME Group Identity
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1.3.6.13 IMSI, S-TMSI, and IMEI
Used as in 3GPP 2G and 3G. S-TMSI is using the M-TMSI which is identifying the
UE in the MME. The S-TMSI is replacing TMSI and P-TMSI in 2G and 3G networks.
IMSI and IMEI are used as in UTRAN.
1.3.6.14 GUTI
The GUTI is a temporary ID. It is used to support subscriber identity confidentiality,
and, in the shortened S-TMSI form, to enable more efficient radio signaling
procedures (e.g. paging and Service Request).
1.3.6.15 eNB S1-AP UE ID and MME S1-AP UE ID
The eNB S1-AP UE ID and MME S1-AP UE ID are temporary ID’s which are
identifying the UE in the S1-MME in the eNB or MME respectively.
[3GTS 23.401 (5.2), 3GTR 25.813 (5.6), 3GTS 36.300 (8)]
Room for your Notes
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Room for your Notes
•
1
Abbreviations of this Section
3GPP
Third Generation Partnership Project
(Collaboration between different
standardization organizations (e.g.
ARIB, ETSI) to define advanced
mobile communications standards,
responsible for UMTS)
M-TMSI
MME - Temporary Mobile Subscriber
Identity
3GTR
3rd Generation Technical Report
MME
Mobility Management Entity (3GTS
23.401) (Rel. 8 onwards)
3GTS
3rd Generation Technical
Specification
P-TMSI
Packet TMSI
eNB
Enhanced Node B
S-TMSI
SAE Temporary Mobile Subscriber
Identity
GUTI
Global Unique Terminal Identity
S1-AP
S1 Application Part
ID
Identity
TMSI
Temporary Mobile Subscriber
Identity
IMEI
International Mobile Equipment
Identity
UE
User Equipment
IMSI
International Mobile Subscriber
Identity
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
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1.4 The E-UTRAN Protocol Stack
1.4.1 Control Plane Protocol Stack
The objective of this section is to visualize the control plane protocol stack of
the various network elements and interfaces of LTE.
Key point of this section is the control plane protocol stack structure of LTE
is combining the AIPN protocol stack and the air-interface protocol stack of
UMTS.
Image Description
• This picture is showing the control plane protocol stack of E-UTRAN.
More or less the control plane is exhibiting the same structure as the protocols known
from UTRAN with an AIPN.
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1.4.1.1 Air Interface protocols
Even though the individual protocol layer may differ significantly due to the new air
interface, names and structure are retained from UTRAN. Here also the RRM is
shown which is determining the configurations and channel settings transmitted in the
RRC messages. What is new here is the allocation of protocol entities on the network
elements. In particular the eNB has now a complete set of L2 and L3 protocols. Since
the NAS and the AS messaging will be ciphered the PDCP protocol has also been
introduced for the control plane in LTE. Since all the transport channels are shared
the scheduler in the eNB has to be implemented with special care.
1
There is a similar concept like in UTRAN for SRB’s but details are not specified
yet.
•
Abbreviations of this Section:
AIPN
All IP Network
RLC
Radio Link Control
AS
Access Stratum (UMTS)
RRC
Radio Resource Control
E-UTRAN Evolved UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
RRM
Radio Resource Management
IP
Internet Protocol (RFC 791)
S1-AP
S1 Application Part
L2
Layer 2 (data link layer)
SCTP
Stream Control Transmission
Protocol (RFC 2960)
L3
Layer 3 (network layer)
SDH
Synchronous Digital Hierarchy
LTE
Long Term Evolution (of UMTS)
SRB
Signaling Radio Bearer
MAC
Medium Access Control
TrCH
Transport Channel (UMTS)
MME
Mobility Management Entity (3GTS
23.401) (Rel. 8 onwards)
UMTS
Universal Mobile Telecommunication
System
NAS
Non-Access-Stratum
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
PDCP
Packet Data Convergence Protocol
eNB
Enhanced Node B
PDH
Plesiochronous Digital Hierarchy
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Since it will be discussed later on, the RRM is shown in the picture. This is not a
protocol entity which is in need to be standardized e.g. like the RRC. This is more
a group of tasks which have to be included in the eNB in order to make it perform
well. The RRM is using the protocols to work in a smart way. How to use the
protocols smartly is not in need to be specified in the standards. A powerful RRM
is essential for a good implementation.
1.4.1.2 NAS protocols
For the NAS protocols there are no details defined yet. The author is expecting
that there will be SM and EMM protocol entities here.
The name S1-AP is preliminary at this point in time and might change in future
[3GTS 36.300 (4.3.2, 19)]
Room for your Notes
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Room for your Notes
•
1
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
RRM
Radio Resource Management
EMM
Evolved Mobility Management
S1-AP
S1 Application Part
NAS
Non-Access-Stratum
SM
Session Management (3GTS 23.060,
3GTS 24.008)
RRC
Radio Resource Control
eNB
Enhanced Node B
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1.4.2 User Plane Protocol Stack
The objective of this section is to visualize the user plane protocol stack of
the various network elements and interfaces of LTE.
Key point of this section is the user plane protocol stack structure of LTE is
combining the AIPN protocol stack and the air-interface protocol stack of
UMTS.
Image Description
• This picture is showing the user plane protocol stack of E-UTRAN.
Again there is a big similarity with the protocols known from UTRAN with an AIPN.
1.4.2.1 Air Interface protocols
For the air interface protocols the same naming conventions and presumably also the
internal structure of UTRAN is reused. There again there is the possibility of AM, UM
and TM for the RLC data. This means in RLC-AM there is like in HSPA both an ARQ
loop on RLC level and an HARQ loop on MAC and L1 level. The RLC PDU size will
be variable. The PDP is terminated in the PDN/internet.
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1.4.2.2 S1 protocol
Physical layer, data link layer, and IP are typical protocol entities known from the
AIPN already. Like in UTRAN there is the GTP-U creating a shared tunnel for the
user data in the EPC.
[3GTS 36.300 (4.3.1, 19)]
•
1
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
PDN
Packet Data Network
AIPN
All IP Network
PDP
Packet Data Protocol
AM
Acknowledged Mode operation
PDSCH
Physical Downlink Shared Channel
ARQ
Automatic Repeat Request
PDU
Protocol Data Unit or Packet Data
Unit
DL
Downlink
PUSCH
Physical Uplink Shared Channel
DL-SCH
Downlink Shared Channel
RLC
Radio Link Control
EPC
Evolved Packet Core (3GTS 23.401)
(Rel. 8 onwards)
SAE
System Architecture Evolution
GTP
GPRS Tunneling Protocol (3GTS
29.060)
SDH
Synchronous Digital Hierarchy
GTP-U
GTP User Plane
SI
Service Indicator
GW
Gateway
TM
Transparent Mode operation
HARQ
Hybrid ARQ
UDP
User Datagram Protocol (RFC 768)
HSPA
High Speed Packet Access (operation UL
of HSDPA and HSUPA)
Uplink
IP
Internet Protocol (RFC 791)
UL-SCH
Uplink Shared Channel
L1
Layer 1 (physical layer)
UM
Unacknowledged Mode operation
LTE
Long Term Evolution (of UMTS)
UMTS
Universal Mobile Telecommunication
System
MAC
Message Authentication Code
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
PDCP
Packet Data Convergence Protocol
eNB
Enhanced Node B
PDH
Plesiochronous Digital Hierarchy
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1.4.3 X2 Interface Control Plane Protocol Stack
The objective of this section is to visualize the control plane protocol stack of
the X2 interface in LTE.
Key point of this section is that the control plane of the X2 interface is mainly
dealing with inference coordination for the self-organizing network and RRM
issues.
Image Description
This picture is showing the control plane protocol stack of the X2 interface.
Physical layer, data link layer, IP and SCTP are typical protocol entities known from
the AIPN already. The X2-AP is executing the commands from RRM, e.g. for
handover and for interference coordination in the self organizing network.
The X2 interface is a virtual interface. Physically it will connect via a router in the
core.
[3GTS 36.300 (20)]
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Room for your Notes
•
1
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
RRM
Radio Resource Management
AIPN
All IP Network
SCTP
Stream Control Transmission
Protocol (RFC 2960)
Ethernet
Layer 2 Protocol for IP (IEEE 802.3)
SDH
Synchronous Digital Hierarchy
IP
Internet Protocol (RFC 791)
X2-AP
X2 Application Part
LTE
Long Term Evolution (of UMTS)
eNB
Enhanced Node B
PDH
Plesiochronous Digital Hierarchy
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1.4.4 X2 User Plane Protocol Stack
The objective of this section is to visualize the user plane protocol stack of
the X2 interface of LTE.
Key point of this section is that the user plane of the X2 interface is used to
forward data from one eNB to the other but that this is only for a short time
during handover.
Image Description
• This picture is showing the user plane protocol stack of the X2 interface.
Physical layer, data link layer, and IP are typical protocol entities known from the
AIPN already. The X2 interfaces user plane is used for data forwarding during the
handover procedure. Once the source eNB still has data in its buffer it will forward it
to the target eNB. Unlike procedures on the Iur this data forwarding is only short
term. No semi permanent data forwarding is intended.
Like for the transmission in-between core network elements and the RAN the GTP-U
is taking care of the transmission in-between the eNB’s.
[3GTS 36.300 (4.3.1, 19, 20)]
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Room for your Notes
•
1
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
MAC
Message Authentication Code
AIPN
All IP Network
PDH
Plesiochronous Digital Hierarchy
AM
Acknowledged Mode operation
PDN
Packet Data Network
ARQ
Automatic Repeat Request
PDP
Packet Data Protocol
EPC
Evolved Packet Core (3GTS 23.401)
(Rel. 8 onwards)
RAN
Radio Access Network
GTP
GPRS Tunneling Protocol (3GTS
29.060)
RLC
Radio Link Control
GTP-U
GTP User Plane
SDH
Synchronous Digital Hierarchy
IP
Internet Protocol (RFC 791)
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
LTE
Long Term Evolution (of UMTS)
eNB
Enhanced Node B
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1.5 Overview Channels of E-UTRAN
1.5.1 Channel Types
The objective of this section is to show that physical channels, transport
channels, and logical channels are defined according to the same guidelines
as in UTRAN.
Key point of this section is that the LTE has the same concept about logical,
transport, and physical channels as UTRAN.
Image Description
•
This graph shows part of the Radio Interface Protocol Architecture of E-UTRA
and the different channel types defined for signal exchange between the different
protocol layers.
1.5.1.1 Logical Channels
The interface between RLC and MAC is called Logical Channel. There are several
different Logical Channel types.
The type of data that is transferred defines each Logical Channel type. This data can
be either control or user data.
1.5.1.2 Transport Channels
The interface between MAC and the Physical Layer is denoted as Transport
Channel.
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Transport Channels are services offered by layer 1 to the higher layers for data
transfer over the air interface.
Transport Channels define how and with which characteristics data is transferred by
the physical layer.
1
Transport Channels are required to allow service multiplexing and to enable the use
of variable bit rate transmission.
1.5.1.3 Physical Channels
Physical Channels are used to finally transmit the data over the air interface.
Physical Channels define the exact physical characteristics of the radio channel
(frequency, subcarrier ...)
Room for your Notes
•
Abbreviations of this Section:
DTCH
Dedicated Traffic Channel
RLC
Radio Link Control
E-UTRA
Evolved UMTS Terrestrial Radio
Access
UL-SCH
Uplink Shared Channel
LTE
Long Term Evolution (of UMTS)
UTRA
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access
MAC
Medium Access Control
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
PUSCH
Physical Uplink Shared Channel
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1.5.2 Logical Channels of E-UTRAN
The objective of this section is to give an overview of the logical channels
being defined for LTE uplink and LTE downlink.
Key point of this section is that except for very few exemptions the logical
channels are the same as in UTRAN.
Image Description
•
This picture shows the different logical channels used in E-UTRA. It categorizes
them in control channels and traffic channels.
1.5.2.1 BCCH
Nothing to add to what is stated in the image.
1.5.2.2 PCCH
Nothing to add to what is stated in the image.
1.5.2.3 CCCH
Here it has to be mentioned that the FACH and the RACH as signaling carrying
transport channel do not exist in E-UTRAN and that all the UE specific signaling is
handled on the shared channels as well.
1.5.2.4 MCCH
Transmits MBMS control information.
It is for further study whether MBMS scheduling is done by layer 1 signaling (like the
HSPA control channels).
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1.5.2.5 DCCH
This channel is present only once an RRC connection has been established
(RRC_CONNECTED state). Usage as in UTRAN.
1
1.5.2.6 DTCH
Nothing to add to what is stated in the image.
1.5.2.7 MTCH
This point to multipoint channel is used for MBMS service.
[3GTS 36.300 (6.1.2)]
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
LTE
Long Term Evolution (of UMTS)
BCCH
Broadcast Control Channel
MBMS
Multimedia Broadcast / Multicast
Service
CCCH
Common Control Channel
MCCH
MBMS point-to-multipoint Control
Channel
CCH
Control Channel
MTCH
MBMS point-to-multipoint Traffic
Channel
DCCH
Dedicated Control Channel
PCCH
Paging Control Channel
DL
Downlink
RRC
Radio Resource Control
DTCH
Dedicated Traffic Channel
RRC_CON RRC state in E-UTRA
NECTED
E-UTRA
Evolved UMTS Terrestrial Radio
Access
UE
User Equipment
FACH
Forward Access Channel (UMTS
Transport Channel)
UTRA
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access
HSPA
High Speed Packet Access (operation UTRAN
of HSDPA and HSUPA)
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
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1.5.3 Transport Channels of E-UTRAN
The objective of this section is to give an overview of the transport channels
being defined for LTE.
Key point of this section is that the transport channel concept in LTE is
focusing on shared channels. There are no dedicated transport channels.
Image Description
•
his picture shows the different transport channels used in E-UTRA.
1.5.3.1 RACH
Transmits very limited control information only. In UTRAN it can also carry short user
packages. As in UTRAN collisions can happen.
1.5.3.2 UL-SCH
Recourses are allocated dynamically or semi statically. HARQ and beamforming are
applied (does not exist in UTRAN).
1.5.3.3 BCH
Only fixed transport format is used. Is transmitted over complete coverage area of the
cell but is only containing the most basic system information. The other system
information is transmitted on the DL-SCH.
1.5.3.4 PCH
Is mapped dynamically on physical channels (different from UTRAN).
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1.5.3.5 MCH
Is transmitted for the complete cell. It supports SFN combining during transmission
on multiple cells. The MCH does not exist in UTRAN.
1
1.5.3.6 DL-SCH
Recourses are allocated dynamically or semi statically. HARQ and beamforming are
applied (as in HSDPA).
[3GTS 36.300 (5.3)]
Room for your Notes
•
Abbreviations of this Section
3GTS
3rd Generation Technical
Specification
PCH
Paging Channel
BCH
Broadcast Channel
RACH
Random Access Channel
DL
Downlink
SFN
Single Frequency Network
DL-SCH
Downlink Shared Channel
TrCH
Transport Channel (UMTS)
E-UTRA
Evolved UMTS Terrestrial Radio
Access
UL
Uplink
HARQ
Hybrid ARQ
UL-SCH
Uplink Shared Channel
HSDPA
High Speed Downlink Packet Access
(3GTS 25.301, 25.308, 25.401,
3GTR 25.848)
UTRA
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access
LTE
Long Term Evolution (of UMTS)
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
MCH
Multicast Channel
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1.5.4 Physical Channels of E-UTRAN
The objective of this section is to give an overview of the physical channels
being defined for LTE.
Key point of this section is that the physical channel concept is very similar
to HSPA but with the difference that it is symmetric in uplink and downlink.
Image Description
•
This picture shows the different physical channels and physical signals used in EUTRA.
1.5.4.1 PBCH
The PBCH is using QPSK modulation and is using always the 72 subcarriers (shared
with other physical channels) around the DC carrier. It carries only the MIB.
1.5.4.2 PDCCH
The PDCCH is transporting the transport format, resource allocation and the HARQ
information for the PCH, UL-SCH, and the DL-SCH. As well power control
information for the UL is transmitted.
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1.5.4.3 PCFICH
The PCFICH is transmitting the size of the PDCCH.
1
1.5.4.4 PUCCH
The PUCCH is formed by two consecutive resource blocks with frequency hopping at
the slot boundary. It contains CQI (in case of MIMO this is also containing the MIMO
related feedback), the ACK/NACK (1 bit for HARQ) and the scheduling requests for
the coordination of coming UL transmissions.
1.5.4.5 PRACH
The PRACH is only comprising the random access preamble and it is occupying 72
subcarriers of bandwidth in the frequency domain. Once the random access is
successful the random access message is transmitted on the UL-SCH.
All control channels have QPSK modulation (the PUCCH can use BPSK) and - like in
HSPA - the timing of the transport blocks and the corresponding ACK/NACK is fixed
such that signaling load is saved.
•
Abbreviations of this Section:
ACK
Acknowledgement
PBCH
Physical Broadcast Channel
BCH
Broadcast Channel
PCFICH
Physical Control Format Indicator
Channel
BPSK
Binary or Bipolar Phase Shift Keying
PCH
Paging Channel
CQI
Channel Quality Indicator
PDCCH
Physical Downlink Control Channel
DC
Direct Current
PDSCH
Physical Downlink Shared Channel
DL
Downlink
PHICH
Physical HARQ Acknowledgement
Indicator Channel
DL-SCH
Downlink Shared Channel
PMCH
Physical Multicast Channel
E-UTRA
Evolved UMTS Terrestrial Radio
Access
PRACH
Physical Random Access Channel
EUTRAN
Evolved UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
PUCCH
Physical Uplink Control Channel
HARQ
Hybrid ARQ
PUSCH
Physical Uplink Shared Channel
HSPA
High Speed Packet Access (operation
of HSDPA and HSUPA)
QPSK
Quadrature Phase Shift Keying
LTE
Long Term Evolution (of UMTS)
SCH
Synchronization Channel
MIB
Master Information Block
UL
Uplink
MIMO
Multiple In / Multiple Out (antenna
system)
UL-SCH
Uplink Shared Channel
NACK
Negative Acknowledgement
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1.5.4.6 PHICH
The PHICH is used to acknowledge UL transmissions.
1.5.4.7 PDSCH
The PDSCH is carrying the DL payload. It is using AMC with QPSK, 16-QAM, and
64-QAM. It is intended to be used with smart antenna technologies like MIMO.
1.5.4.8 PMCH
The PMCH is carrying the DL multicast payload in case of multiple cell transmission.
It can be used like the PDSCH but is transmitted with only 1 antenna. This might be
an antenna only used for MBMS and only be used for SFN.
1.5.4.9 PUSCH
The PUSCH is carrying the UL payload in the LTE system it is using AMC with
QPSK, 16-QAM, and optionally 64-QAM. It is intended to be used with smart antenna
technologies like MIMO.
1.5.4.10 Downlink reference signal
The downlink reference signal is located on selected subcarriers on selected OFDM
symbols of a downlink slot.
1.5.4.11 Primary and secondary synchronization signal
The synchronization signal is identifying 168 cell ID groups of 3 group members
each.
1.5.4.12 Uplink reference signal or UL pilot symbol
The uplink reference signal is located on the 4th SC-FDMA symbol block of an UL
slot of the PUSCH. The PUCCH can have 2 or 3 uplink reference signals. The
reference signal is a cyclically extended Zadoff-Chu sequence. It is used as a
reference for the equalization of UL signals in the frequency domain.
1.5.4.13 Uplink sounding signal
The uplink sounding signal is transmitted on the last symbol of the PUSCH. It is
requested by the eNB in order to access the mobile radio channel quality and the
timing of the UE’s UL transmissions.
1.5.4.14 Random Access Preamble
The random access preamble is part of the PRACH and is again generated with a
Zadoff-Chu sequence. These Zadoff-Chu sequences have a zero correlation zone
with eases the processing of different random access bursts received together.
[3GTS 36.211 (5, 6), 3GTS 36.300 (5.1, 5.2, 5.3.1)]
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Room for your Notes
•
1
Abbreviations of this Section:
16-QAM
16 symbols Quadrature Amplitude
Modulation
PHICH
Physical HARQ Acknowledgement
Indicator Channel
3GTS
3rd Generation Technical
Specification
PMCH
Physical Multicast Channel
64-QAM
64 symbols Quadrature Amplitude
Modulation
PRACH
Physical Random Access Channel
AMC
Adaptive Modulation and Coding
PUCCH
Physical Uplink Control Channel
DL
Downlink
PUSCH
Physical Uplink Shared Channel
FDMA
Frequency Division Multiple Access
QPSK
Quadrature Phase Shift Keying
ID
Identity
SC-FDMA Single Carrier Frequency Division
Multiple Access
LTE
Long Term Evolution (of UMTS)
SFN
Single Frequency Network
MBMS
Multimedia Broadcast / Multicast
Service
UE
User Equipment
MIMO
Multiple In / Multiple Out (antenna
system)
UL
Uplink
OFDM
Orthogonal Frequency Division
Multiplexing
eNB
Enhanced Node B
PDSCH
Physical Downlink Shared Channel
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1.5.5 Mapping of Channels in E-UTRAN
The objective of this section is to visualize the mapping amongst the different
channel types in LTE.
Key point of this section is that the LTE channel mapping is a lot simpler
than in UTRAN.
Image Description
This picture shows how the different channel types in E-UTRA are mapped on
each other.
It is worth to highlight the following mappings:
Since the RACH is carrying only limited control information no logical channel is
mapped on this transport channel. Consequently mostly the MAC is driving the
activities on the RACH.
Like in HSPA no transport channel is mapped on the PUCCH, the PCFICH, the
PHICH, and the PDCCH. This shows that also in LTE the scheduling HARQ, etc.
is a procedure very close to the physical layer which is expressed by the
physical layer signaling approach used here.
The PBCH is always transmitted in the middle of the LTE carrier.
•
[3GTS 36.300 (5.3.1, 6.1.3)]
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Room for your Notes
•
1
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
PBCH
Physical Broadcast Channel
BCCH
Broadcast Control Channel
PCCH
Paging Control Channel
BCH
Broadcast Channel
PCFICH
Physical Control Format Indicator
Channel
CCCH
Common Control Channel
PCH
Paging Channel
DCCH
Dedicated Control Channel
PDCCH
Physical Downlink Control Channel
DL
Downlink
PDSCH
Physical Downlink Shared Channel
DL-SCH
Downlink Shared Channel
PHICH
Physical HARQ Acknowledgement
Indicator Channel
DTCH
Dedicated Traffic Channel
PMCH
Physical Multicast Channel
E-UTRA
Evolved UMTS Terrestrial Radio
Access
PRACH
Packet Random Access Channel
HARQ
Hybrid ARQ
PUCCH
Physical Uplink Control Channel
HSPA
High Speed Packet Access (operation PUSCH
of HSDPA and HSUPA)
Physical Uplink Shared Channel
L1
Layer 1 (physical layer)
RACH
Random Access Channel
LTE
Long Term Evolution (of UMTS)
UL
Uplink
MAC
Medium Access Control
UL-SCH
Uplink Shared Channel
MCCH
MBMS point-to-multipoint Control
Channel
UTRA
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access
MCH
Multicast Channel
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
MTCH
MBMS point-to-multipoint Traffic
Channel
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1.6 Key Development Trends manifested in LTE
1.6.1 Mapping of User Plane Packets to the Resources
The objective of this section is to describe the changes of the resource
scheduling strategies from UMTS over HSPA to LTE.
Key point of this section is that today’s standards combine resource
allocation strategies with diversity.
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Image Description
•
With the introduction of digital signal processing technology the mobile radio
systems have been enabled to play with the degrees of freedom offered by the
mobile radio channel and the setup of the network: time, frequency, and space. In
particular the bad fading characteristics have been combated by means of one or
more diversity schemes. In general there are two ways how to do that
1
1.6.1.1 Method 1: Fast resource allocation on optimum resources
Here always the best instantaneous selection (time, frequency, and space) of
resources is chosen.
This means a combination of choosing the best time, the best frequency and the best
space properties for transmission of the data packet in order to have the best
possible throughput. Since for early mobile radio systems this is needing too much
signaling and these systems are not able to schedule their transmissions very fast
this method is not used e.g. for GSM. Another problem is that for a moving UE the
optimum configuration is changing faster than it can be traced or faster than it can be
signaled. This is why the second approach is also very important.
Room for your Notes
•
Abbreviations of this Section:
GSM
Global System for Mobile
Communication
UE
HSPA
High Speed Packet Access (operation UMTS
of HSDPA and HSUPA)
Universal Mobile Telecommunication
System
LTE
Long Term Evolution (of UMTS)
Wide-band Code Division Multiple
Access
WCDMA
User Equipment
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1.6.1.2 Method 2: Slow resource allocation on suboptimum resources
Here, the resources are spread on a wide range of time, frequency, or space.
This exploits that in some regions there is good quality and in some other regions
there is bad quality. Since the resources are spread on both kinds of regions the
effect of the bad regions is averaged and not critical any more. This scheme is
working always more or less good but of course is only providing a throughput being
of average size only.
In the following some examples are given of how the resource allocation is optimized
in well-known mobile radio systems:
1.6.1.3 GSM
In GSM for speech transmission each interleaving frame is extending over a time of
37 ms using 8 different bursts such that the different instantaneous quality of the 8
bursts used is averaging out. As well GSM is applying frequency hopping such that
also the quality of up to 8 different carrier frequencies in the interleaving frame can
average out.
1.6.1.4 WCDMA
WCDMA is spreading its resources on a wideband carrier and is exploiting frequency
diversity by means of spreading. As well time diversity is exploited e.g. by means of a
20 ms TTI for speech services. However only the low performing second scheme can
be used for WCDMA
1.6.1.5 HSPA
In HSPA the TTI’s are that short (2 ms) and the signaling is that fast that the first
scheme can be applied for the first time on the time dimension. The UE’s might only
be scheduled to use the resources on the carrier once the quality is very good - once
the quality is bad other UE’s might be scheduled on the resources. It has to be
mentioned that these methods is requiring a bidirectional signaling: One direction for
the scheduling and another direction for the feedback (quality and ACK/NACK).Since
still spreading is used the second method is applied on the frequency dimension.
Optionally beamforming is using also the first method on the space dimension: by
means of radiating the signal only to the direction of the UE.
1.6.1.6 LTE
In LTE there is now the possibility to use the first method for both the time and the
frequency dimension. Once the transmission is both restricted to the subcarriers
having the best quality at the time instants with the best quality as well, a very high
throughput can be achieved. Again bidirectional signaling might is required. MIMO
and beamforming are applied on the space dimension. Also the second method can
be deployed in the frequency dimension, e.g. by applying frequency hopping.
1.6.1.7 General trend
The general trend being visible is that for modern mobile radio systems it is possible
to select the best configuration for the resources very fast and even follow changing
mobile radio conditions: best frequency at the best time and using the best antenna
configuration. The tuning in this respect is becoming more and more precise with the
advance of mobile radio standards and the duration of the allocated data packets is
getting shorter and shorter in order to track a changing mobile radio channel faster.
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Room for your Notes
•
1
Abbreviations of this Section:
ACK
Acknowledgement
NACK
Negative Acknowledgement
GSM
Global System for Mobile
Communication
TTI
Transmission Time Interval
HSPA
High Speed Packet Access (operation UE
of HSDPA and HSUPA)
User Equipment
LTE
Long Term Evolution (of UMTS)
Wide-band Code Division Multiple
Access
MIMO
Multiple In / Multiple Out (antenna
system)
WCDMA
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1.6.2 All IP Network and Simple Packet Service Driven Protocols
The objectives of this section are to highlight the benefits of the packet
service driven protocols, and to show these lead to a new network
architecture tailored to the all IP network (AIPN).
Key point of this section is that the simplified network architecture of LTE
leads to a reduced latency.
Image Description
This picture is visualizing the latency of a messages traveling through the UTRAN
and the E-UTRAN. The longer the line the longer the latency will be.
In UTRAN an AIPN has been introduced step by step and at the same time PS
services have gained more and more momentum within 3GPP. However, still the
basic structure of the GSM network is used. The Node B’s are connected to RNC’s
and the RNC’s are connected to the core network. This is still like BTS, BSC und
Core in GSM. Since this structure is best suited for CS services which are routed
rather stationary in-between the network elements the structure is leading to the
rather complex protocol for the PS services where the allocation of the resources is
not fixed and shared.
•
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In the picture a message is running through many network entities and their various
algorithms – especially to pass them in and out of the network elements is very timeconsuming and disadvantageous for the latency of the user plane and the latency of
the control plane.
This is one of the reasons why the RNC is not present in LTE. The result is that the
protocols are simplifying a lot and that the latency is reduced significantly by means
of having less algorithms and processing stages involved.
Effectively the trend toward an AIPN and all PS services is dictating a very
revolutionary change in the network architecture: The missing RNC in LTE.
1
Room for your Notes
•
Abbreviations of this Section:
3GPP
Third Generation Partnership Project
(Collaboration between different
standardization organizations (e.g.
ARIB, ETSI) to define advanced
mobile communications standards,
responsible for UMTS)
MME
Mobility Management Entity (3GTS
23.401) (Rel. 8 onwards)
AIPN
All IP Network
PS
Packet Switched
BSC
Base Station Controller
RNC
Radio Network Controller
BTS
Base Transceiver Station
SAE
System Architecture Evolution
CS
Circuit Switched
SGSN
Serving GPRS Support Node
GSM
Global System for Mobile
Communication
UMTS
Universal Mobile Telecommunication
System
GW
Gateway
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
IP
Internet Protocol (RFC 791)
eNB
Enhanced Node B
LTE
Long Term Evolution (of UMTS)
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1.6.2.1 Reduced User Plane Latency
The objective of this section is to visualize how the tight latency
requirements of the physical layer are allowing the use of all QoS classes of
the PS services.
Key point of this section is that reduced user plane latency allows for HSPAlike HARQ and the application of all QoS traffic classes.
Image Description
This picture is showing the composition of the LTE user plane latency and how it
is relating it to the QoS requirements.
The user plane latency time for a good and reliable packet transmission has been
one of the blocking points which have delayed an introduction of Streaming and
Conversational QoS PS services.
Since no CS services are intended in LTE, the user plane latency has to be
significantly improved.
The top part of the picture is showing the chain of processing steps leading to the
user plane latency. The chain of events is starting with data arriving in the Serving
GW and is ending with data arriving in the application running on the UE.
It can be seen that the processing times inside the network elements and on the
interfaces are dimensioned to be very short.
•
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This is possible because the Serving GW is directly connected to the eNB. In case of
a failure to transmit a packet on the Uu interface, retransmissions using HARQ are
adding another 5 ms each to the user plane latency.
As shown in the middle part of the picture the duration of a single transmission (basic
user plane latency) and the time duration for possible retransmissions using HARQ
have to be smaller the maximum user plane delay tolerated by the QoS profile.
Assuming a BLER of 30 % the average user plane latency of LTE then is ranging
from 6.3 to 20.9 ms. This is a very short user plane latency. Once a RTT for HARQ of
e.g. 12 ms is assumed it becomes clear that for HSPA only one retransmission could
be tolerated for a high QoS service. Only then the Uu latency for the first
transmission and the following retransmission can stay below the 20 ms interleaving
frame duration of CS voice transmission. This would lead to a quite low performance.
However with LTE the Uu latency is below 20 ms even if the voice packets are
retransmitted 2 times. This is demonstrating very well that with LTE there is the
possibility to achieve an even higher QoS than possible with UMTS CS services.
1
[3GTR 25.912 (13.3), 3GTS 36.213]
Question No 1: Once the BLER for a signal transmission is 30 %, what is the
residual BLER after 3 transmissions? Once for speech services a residual BLER of
1 % is aimed at what would be the BLER for a single transmission?
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
QoS
Quality of Service
BLER
Block Error Rate
RTT
Round Trip Time
CS
Circuit Switched
SAE
System Architecture Evolution
GW
Gateway
TTI
Transmission Time Interval
HARQ
Hybrid ARQ
UE
User Equipment
HSPA
High Speed Packet Access (operation UMTS
of HSDPA and HSUPA)
Universal Mobile Telecommunication
System
LTE
Long Term Evolution (of UMTS)
Enhanced Node B
PS
Packet Switched
eNB
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1.6.2.1 Reduced Control Plane Latency
The objective of this section is to demonstrate how the reduced control plane
latency is allowing for a reduced protocol complexity.
Key point of this section is that reduced control plane latencies lead to
dramatically simplified layer 3 protocols - not vice versa.
Image Description
This picture is showing the RRC states of LTE and UTRAN and the necessary
transition times in-between them.
In LTE the transition times in-between the RRC states are required to be 50 ms or
less and from the detached state to the active state there is the requirement of 100
ms control plane latency.
•
[3GTR 25.913 (6.2.1)]
These latency times are very short compared to those of UTRAN because LTE is
aiming to keep the UE’s in a dormant state (like URA_PCH) with the benefit of having
a low resource consumption on air and a low battery power consumption whilst
having also a very fast reactivation of the UE once some data is to be transferred
again.
For UMTS the transition time in-between the various RRC states are shown in the
lower part of the picture. These times are taken from a 3GTR about the possible
future improvement of the protocols and are not even implemented yet.
[3GTR 25.815 (5)]
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As it can be seen these times are a lot longer than the LTE requirement of 50 ms.
The result of the LTE feasibility study shows that the transition time from the EMMREGISTERED & ECM-IDLE to the EMM-REGISTERED & ECM-CONNECTED state
can be done in only 56-96 ms. This is already involving the RRC connection
establishment with the MME. Since the time is significantly smaller than any UTRAN
transition to the CELL_DCH state the 5 RRC states in UTRAN reduce to just 2 states
in LTE. In LTE the CELL_FACH state does not make any sense any more and the
RRC_IDLE, the URA_PCH, and the CELL_PCH states’ functions are taken by the
EMM-REGISTERED & ECM-IDLE state. This is leading to a very significant reduction
of the protocol complexity and is well suited for the packet services as well: For a
packet transmission there are also two possibilities only: Either packets are
transmitted or the transmitter is idle and is not transmitting any packets.
1
[3GTR 36.300 (A.2)]
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
RRC
Radio Resource Control
CELL_DCH
RRC Dedicated State
RRC_CON
NECTED
RRC state in E-UTRA
CELL_FACH
RRC FACH State in UTRA
RRC_IDLE RRC state
CELL_PCH
RRC PCH State in UTRA
UE
User Equipment
EMMEnhanced Mobility Management
REGISTERED state for active packet
& ECMtransmission
CONNECTED
UMTS
Universal Mobile Telecommunication
System
EMMEnhanced Mobility Management
REGISTERED state for non active packet
& ECM-IDLE transmission
URA_PCH
RRC URA State in UTRA
LTE
Long Term Evolution (of UMTS)
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
MME
Mobility Management Entity
(3GTS 23.401) (Rel. 8 onwards)
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LTE from A-Z
1.7 LTE Key Feature Summary
The objective of this section is to summarize the key features of LTE.
Key point of this section is both air interface, system architecture, and
services change dramatically with LTE.
1.7.1 Air Interface Technology
The changes in the air interface technology cause that LTE is not compatible to
legacy UMTS / HSPA+ UE’s. CDMA technology has been replaced with OFDM (SCFDMA). Also the SFN operation is new for LTE. The data rates are at least double as
high than for HSPA+. The data rates given are the max possible data rates for UL
and DL. Like HSPA+ LTE is using MIMO, too.
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Principles and Motivation of LTE
1.7.2 System Architecture
For LTE all the standardization activities worked towards an AIPN from the start. This
brings quite revolutionary changes such has to omit the RNC and to create a new
EPC.
1
1.7.3 Service Aspects
The choice of only relying on PS services from the start and not to implement any CS
services is leading to a quite challenging task on protocol stack level. At the
beginning of the UMTS process PS services have just been some best effort
services. Now PS has to comply to the same – if not tougher – requirements as for
the legacy CS services. This challenge has been met with a very low user plane and
a very low control plane latency.
Room for your Notes
•
Abbreviations of this Section:
AIPN
All IP Network
MIMO
Multiple In / Multiple Out (antenna
system)
CDMA
Code Division Multiple Access
OFDM
Orthogonal Frequency Division
Multiplexing
CS
Circuit Switched
PS
Packet Switched
DL
Downlink
RNC
Radio Network Controller
EPC
Evolved Packet Core (3GTS 23.401)
(Rel. 8 onwards)
SC-FDMA Single Carrier Frequency Division
Multiple Access
FDMA
Frequency Division Multiple Access
SFN
HSPA
High Speed Packet Access (operation UE
of HSDPA and HSUPA)
User Equipment
HSPA+
Enhanced High Speed Packet Access
(operation of enhanced HSDPA and
enhanced HSUPA)
UL
Uplink
LTE
Long Term Evolution (of UMTS)
UMTS
Universal Mobile Telecommunication
System
Single Frequency Network
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LTE from A-Z
Lessons Learned / Conclusions:
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Key Technologies of the LTE Physical Layer
Chapter 2:
Key Technologies of the LTE Physical Layer
2
Objectives
Some of your questions that will be answered during this session…
•
What is OFDM and how does it differ from OFDMA?
•
How does IFFT relate to OFDM?
•
What is a cyclic prefix, why can it differ in duration and what is it used for?
•
How MIMO is applied in order to multiply the throughput compared to
systems with a single antenna?
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2.1 Introduction OFDM Technology
2.1.1 Impact of Orthogonality in the Frequency Domain – 3 Steps
2
The objectives of this section are to provide a 3D-view of sine waves and to
pave the way to understand orthogonality.
Image Description
•
The image illustrates 3 different sine waves on 3 different frequencies.
•
The image provides two different perspectives: in the upper left part (cylinder) the
image presents the time domain while in the lower right part the frequency
domain is highlighted.
In the OFDM-terminology, the 3 different frequencies are usually called subcarriers
or tones.
Provided their carrier frequency is different not modulated carriers can always be
perfectly separated.
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Room for your Notes
2
•
Abbreviations of this Section:
OFDM
Orthogonal Frequency Division
Multiplexing
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2.1.1 Impact of Orthogonality in the Frequency Domain – 3 Steps
2
The objective of this section is to illustrate what happens to three nonorthogonal frequencies if they are modulated.
If frequencies are non-orthogonal, they need to be sufficiently spaced apart
from each other to minimize the inter-frequency interference.
Image Description
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•
The image continues the presentation from the previous section. However, in this
section, the three non-orthogonal frequencies are modulated with some
baseband signal.
•
The impact becomes visible in the frequency domain: Modulation cause
sidebands with decreasing amplitude, yet inter-frequency interference cannot be
avoided.
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Room for your Notes
2
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2.1.1 Impact of Orthogonality in the Frequency Domain – 3 Steps
2
The objective of this section is to illustrate how orthogonality is achieved in
case of FDM.
Key point is that orthogonal frequencies are integer multiples of a base
frequency. The orthogonality therefore relates to the distance among the
different frequencies f1, f2, f3 and f(n).
Image Description
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•
The image illustrates the already known cylinder.
•
In this case, the distance between the frequencies f1, f2 and f3 is chosen in a way
that it is always an integer multiple of the base frequency f1.
•
Example: If f1 = 10 kHz, then f2 = 20 kHz, f3 = and 30 kHz and so on.
•
The most important property of selecting the distance among the different carriers
like this is that in case of modulation, the zero crossings of the side bands
coincide with the center frequencies.
•
Therefore there is no interference between these center frequencies and the side
bands of the other carrier frequencies.
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Room for your Notes
2
•
Abbreviations of this Section:
FDM
Frequency Division Multiplexing
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2.1.2 Practical Exercise: Physical Basics of OFDM / OFDMA
2
The objective of this section is to familiarize the students with the operation
of OFDM-systems.
Image Description
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•
The image illustrates an OFDM transmitter which uses three subcarriers and
BPSK-modulation on all subcarriers.
•
The input bit rate is 6 bit/s which means that the duration of a single bit at the
input equals 166.67 ms.
•
On the right hand side the image illustrates the resulting OFDM-wave which
represents the sum of the three subcarriers.
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Your tasks:
1. Assign the different bits 1 through 6 to the 3 subcarriers.
2. Use color pencils to draw the signal waves for the 6 bits into the respective
parts of the OFDM-modulator, using BPSK-modulation.
2
3. What is the duration of a single bit (symbol) within the OFDM-modulator?
Answer: The duration equals T(b) = _______ s
4. What does this mean for the smallest frequency f(0)?
Answer: Subcarrier 0 uses a frequency f(0) = _______ = ________
5. … and what does it mean for the f between the subcarriers?
Answer: Δf = _______ = ________
Room for your Notes
•
Abbreviations of this Section:
BPSK
Binary or Bipolar Phase Shift Keying
OFDM
Orthogonal Frequency Division
Multiplexing
OFDMA
Orthogonal Frequency Division
Multiple Access
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2.1.3 Practical Exercise: Scaling of OFDM / OFDMA-Systems
2
The objective of this section is to guide the students through basic scaling
and dimensioning issues of OFDM-systems.
Image Description
•
- 98 -
The image illustrates two options on how to scale an OFDM-system in case of
variable bandwidth situations.
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•
The upper part uses fix subcarrier spacing and simply applies more subcarriers if
more bandwidth is available.
•
The second part uses the opposite approach: ‘n = 5’ and the subcarrier spacing
varies with the available bandwidth
•
The third part uses a constant overall bandwidth and varies the number of
subcarriers. This will keep the throughput the same.
•
The lower part uses different modulation schemes on the subcarriers.
2
Your tasks:
•
1.
Which option (1 - 4) do you suggest and prefer in a mobile
environment? Explain your choice in detail.
2.
What is a safe subcarrier spacing in case of LTE?
Abbreviations of this Section:
BW
Bandwidth
OFDMA
Orthogonal Frequency Division
Multiple Access
LTE
Long Term Evolution (of UMTS)
WiMAX
Worldwide Interoperability for
Microwave Access (IEEE 802.16)
OFDM
Orthogonal Frequency Division
Multiplexing
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2.1.4 The In-Phase – Quadrature (I/Q) Presentation
2
The objective of this section is to show how sine-waves can be expressed by
complex numbers in the I / Q plane.
Key point of this section is that amplitude and phase of any sine-wave can
be expressed by a complex number.
Image description
•
This picture is showing that the superimposition of a sinus and a cosine is
creating any other sine wave of different amplitude and phase.
•
On the left side the complex expression of this superimposition is shown.
The expression of base band signals in the complex notation is very common. Any
sine-wave with arbitrary amplitude and phase can be expressed as the liner
superimposition of a sine-wave and a cosine-wave.
Note that the complex superimposition works based on the signals (phase and
amplitude) being modulated on the carrier frequency of the radio carrier.
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Room for your Notes
2
•
Abbreviations of this Section:
There are no abbreviations in this section.
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2.1.5 OFDM / OFDMA and IFFT
2
The objective of this section is to illustrate how IFFT maps so perfectly to the
requirements of an OFDM system.
Key point of this section is that IFFT provides nothing else but the digital
recipe to produce perfectly orthogonal sine waves and to burn the formula
into silicon.
Image Description
•
The image illustrates two implementation options.
•
The upper option 1 is analog and operates by producing the single orthogonal
subcarriers within an oscillator array.
•
Option 2 goes a different way and applies the IFFT formula within the yellow box.
The most important asset of this IFFT-formula is the factor ‘k’ that inherently
provides harmonic, orthogonal frequencies.
Please note that in both cases, the resulting S(t) is a baseband signal that needs
to be mapped to the respective RF-carrier frequency.
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2.1.5.1 Considering the Discrete Oscillator Array Option
This option is unrealistic for large scale deployments as it scales very poorly and
since it is very expensive to implement.
2.1.5.2 Details of the IFFT Option
•
The illustrated formula may be real numbered only (sin) or complex numbered
(sin + cos).
•
The number of samples S(t) over one symbol duration T(b) depends on the
highest OFDM frequency which is k x f(0).
•
According to Nyquist, we therefore need 2 x k x f(0) different samples S(t) per
symbol period T(b) to provide for an error-free signal processing.
•
Obviously, for each sample S(t(x)), all different k-values need to be applied.
•
We provided the aforementioned details to illustrate the enormous processing
power that is required for OFDM.
2
2.1.5.3 Why is it called F a s t Fourier Transformation?
•
The difference between fast and regular Fourier transformation is that fast Fourier
transformation uses a special algorithm for the fast calculation of the single
values of a Fourier series.
•
This algorithm was officially published in 1965 but was applied already by Carl
Friedrich Gauss in 1805.
•
Obviously, this algorithm is also optimal for chip based calculations. The only
disadvantage of FFT is that the FFT-size = N needs to be a 2 k value (e.g. 64, 128,
256, 512, 1024 …) for best efficiency. Values like N = 66, 214 or similar are
therefore less efficient.
Room for your Notes
•
Abbreviations of this Section:
FFT
Fast Fourier Transformation
OFDMA
Orthogonal Frequency Division
Multiple Access
IFFT
Inverse Fast Fourier Transformation
RF
Radio Frequency
OFDM
Orthogonal Frequency Division
Multiplexing
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2.1.6 Modulation Scheme Overview
2
The objective of this section is to illustrate the basic modulation schemes
which are used by the LTE implementation.
Key point of this section is that higher order modulation schemes require a
better CINR because their decision space between adjacent symbols is
smaller.
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Image Description
•
The image illustrates the I/Q-plane view of the three modulation schemes which
are supported by the LTE - implementation.
•
Each dot stands for a separate symbol and its position is used to convey the
respective number of bits.
2
Room for your Notes
•
Abbreviations of this Section:
16-QAM
16 symbols Quadrature Amplitude
Modulation
LTE
Long Term Evolution (of UMTS)
64-QAM
64 symbols Quadrature Amplitude
Modulation
QPSK
Quadrature Phase Shift Keying
CINR
Carrier to Interference and Noise
Ratio
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2.1.7 Using different Modulation Schemes on Different Subcarriers
2
The objective of this section is to illustrate the inherent capability of IFFT to
mimic different modulation schemes on different subcarriers.
Key point of this section is that commercial OFDM/OFDMA-systems do not
use coefficients ‘0’ to ‘n’ but rather ‘-n/2’ to ‘(n/2-1)’ with the DC-subcarrier
being positioned at the center carrier frequency.
Image Description
- 106 -
•
The image illustrates at the top the already introduced formula for complex
numbered IFFT.
•
In this example, only three subcarriers shall be considered.
•
The so called DC-subcarrier always generates a zero output (see image). This
rule also applies in commercial OFDM-implementations.
•
On subcarrier 1 (k = 1), QPSK shall be applied with a bit value of ‘10’ to be
transmitted.
•
On subcarrier 2 (k = 2), 16-QAM shall be applied with a bit value of ‘0001’ to be
transmitted.
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As the right part of the image illustrates, every combined phase and amplitude
digital modulation system represents its different symbol values simply by applying
different coefficients a(k(t)) and b(k(t)) to the sine and cosine parts.
2
Room for your Notes
•
Abbreviations of this Section:
16-QAM
16 symbols Quadrature Amplitude
Modulation
OFDM
Orthogonal Frequency Division
Multiplexing
DC
Direct Current
OFDMA
Orthogonal Frequency Division
Multiple Access
IFFT
Inverse Fast Fourier Transformation
QPSK
Quadrature Phase Shift Keying
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2.1.8 Tackling Inter-Symbol Interference (ISI)
2.1.8.1 Introduction
2
The objectives of this section are to illustrate how multipath causes intersymbol interferences and which means exist to tackle this interference.
Key point of this section is that there are basically two means to cope with
ISI: Either to increase the time between two successive symbols or to
calculate the impact of ISI for each symbol (equalization).
Image Description
• The red sine wave represents the transmitted signal at the transmitter.
All the grey sine waves are attenuated and time shifted copies which are perceived
by and at the receiver.
• As illustrated, these copies spread into the following symbol and interfere with it.
You may compare this ISI with the water that the car in front of you spills on your
windshield while it is raining and if you are too close.
2.1.8.1.1 Delay Spread
- 108 -
•
The delay spread represents the maximum delay which needs to be considered.
•
Its value depends mostly on the RF-frequency in use, on the relative speed of
transmitter and receiver and on the type of terrain
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One well known example is GSM with an RF-frequency of 900 MHz, a symbol
duration of 3.692 µs and a maximum speed of 250 km/h. The delay spread to be
coped with by technical implementations is 5 symbol periods (app. 18 µs).
•
In a GSM-system equalizers are used to calculate the impact of the ISI caused by
the preceding 4 symbols on the current symbol.
•
This equalization is a complex process and needs to be done independently for
each burst.
•
However, the alternative to wait long enough between two successive symbols in
GSM is obviously no option considering the enormous delay spread of 18 µs
compared to a symbol duration of just 3.69 µs.
2
However, this is very different in an OFDM-system with its inherently long symbol
durations.
Room for your Notes
•
Abbreviations of this Section:
GSM
Global System for Mobile
Communication
OFDM
Orthogonal Frequency Division
Multiplexing
ISI
Inter-Symbol Interference
RF
Radio Frequency
MHz
6
Mega Hertz (10 Hertz)
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2.1.8.2 Cyclic Prefix
2
The objective of this section is to introduce the cyclic prefix which is placed
in front of each symbol to cope with the ISI from the previous symbol.
Key points of this section are:
1. OFDM can cope without equalization because the inherently long symbol
durations allow for the option to insert a cyclic prefix in the first place.
2. The “squeezing in” of the cyclic prefix between two successive OFDMsymbols obviously degrades the system performance by the respective
percentages (e.g. N(CP) = 5 - 20 % of N).
3. The operation in lower RF-frequency ranges tendentiously requires larger
N(CP) T(sample) -values because of the probability of more paths and
therefore higher delay spread.
The useful symbol time T(b) is therefore only 80-95 % of the overall OFDMA
symbol time.
- 110 -
•
Image Description
•
The image illustrates an OFDM-symbol and its preceding and succeeding
neighbors.
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•
The cyclic prefix represents the final part of the OFDM-symbol that is simply
copied and placed at the front of the same OFDM-symbol.
•
Note how smooth and without sharp edge the cyclic prefix attaches to the
beginning of the indicated symbol period.
•
This is clear considering that the OFDM-wave consists of the aggregation of a
number of phase consistent (n x 2π) pure sine waves (upper right part of the
image).
2
2.1.8.2.1 Variable Duration and other Assets of the Cyclic Prefix
•
The aforementioned smooth edge is due to the phase and amplitude consistency.
•
All contributing sine waves of the OFDM-symbol are phase consistent which
means that they all begin and end at n x 2π. Consequentially, there is no phase
or amplitude shift at the edge between cyclic prefix and OFDM-symbol.
•
In LTE, N(CP) is variable (e.g. 1/20 – 1/5 of N) to provide for the compensation of
different delay spread durations at different frequencies.
•
Frequently, people ask why no pure sine is used for the cyclic prefix. Taking the
previous explanations on this page into account, a pure sine wave as cyclic prefix
would interfere with the contiguous OFDM-symbol because of the phase shift that
occurs between them.
•
Opposed to a pure sine wave, the OFDM-wave is identical and even phase
consistent between the cyclic prefix and the contiguous OFDM-symbol.
2.1.8.2.2 Cyclic Prefix in OFDMA in LTE
•
The specification mandates adjustable cyclic prefix values of 6 % and 20 % of the
OFDMA symbol to be supported by all implementations.
Room for your Notes
•
Abbreviations of this Section
ISI
Inter-Symbol Interference
OFDMA
Orthogonal Frequency Division
Multiple Access
LTE
Long Term Evolution (of UMTS)
RF
Radio Frequency
OFDM
Orthogonal Frequency Division
Multiplexing
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2.1.9 Layout of a Typical OFDM System
2
The objectives of this section are to illustrate the typical “brick wall image” of
any OFDM/OFDMA-implementation to the student and to indicate the
specific settings of the OFDM-physical layer.
Key points of this section are:
1. OFDM uses all the subcarriers for a single user.
2. OFDMA used different subcarriers for different users.
3. There are three types of subcarriers: Data, Pilot and Null.
- 112 -
•
Image Description
•
The image illustrates the most important assets of any OFDM-system
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2.1.9.1 Remarks on the Brick Wall Image
•
Important to recognize are the two guard bands at the outer edges of the OFDMsignal.
•
The related guard band subcarriers remain unused (no RF-Transmission). This
helps to avoid interferences with adjacent bands.
•
This leaves us with only less than N subcarriers of data transmission of which one
is occupied by the DC-subcarrier at the center carrier frequency.
•
So there are only less than N subcarriers left. Taking into account the subcarriers
reserved for pilot signals, even less subcarriers are left for data transmission.
2
2.1.9.2 Subchannelization
•
These N-X subcarriers may be subchannelized to support multiple users during
one OFDM-symbol (OFDMA).
•
Or all subcarriers are allocated to a single user during the OFDM Symbol duration
(OFDM).
2.1.9.3 Pilot Subcarriers
•
In general, pilot subcarriers are evenly distributed along the subcarriers.
•
Pilot subcarriers transmit a predefined bit pattern and allow the receiver the
detection of frequency selective channel distortions.
•
The detection of these distortion patterns is required also for the channel
estimation of the frequency adjacent data subcarriers.
Note the fix position of the pilot subcarriers the picture. In fact the position of the
pilot subcarriers is variable and they may not occur in the same position in the
different OFDM symbols.
2.1.9.4 Null Subcarriers
•
In addition to data and pilot subcarriers there are also null subcarriers without any
transmission.
•
These null subcarriers are the DC-subcarrier and subcarriers within the guard
bands. They are not transmitted.
•
Abbreviations of this Section:
DC
Direct Current
OFDMA
Orthogonal Frequency Division
Multiple Access
MHz
Mega Hertz (106 Hertz)
RF
Radio Frequency
OFDM
Orthogonal Frequency Division
Multiplexing
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2.2 Introduction to MIMO Technology
2.2.1 The Basics: Signal Fading Physics between TX and RX
2
The objectives of this section are to illustrate the different physical principles
resulting in fading of the mobile radio channel.
Key point of this section is that all the effects are resulting in the
superposition of different radio paths at the receivers antenna. This is
causing the fading.
[3GTR 25.876]
On its way from sender to destination, any electromagnetic wave may encounter the
illustrated types of signal distortions. It depends on the terrain whether one or some
of these signal distortion types are dominant or simply not there. Example: Satellite
transmissions are not affected by obstacles and therefore suffer the least.
• Scattering
When the electromagnetic wave hits an obstacle which dimension is close to the
wavelength of that wavelength then scattering happens: Scattering causes the
original wave to be split into multiple parts of which each takes its own route.
Compare this to a water hose that is directed at a smaller stone. The one water beam
is scattered in all directions.
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• Refraction
Refraction occurs when an electromagnetic wave changes the media in which it
propagates. Example: When regular light moves on from the media air into the media
water it is affected by refraction. We can see this refraction for instance by putting a
stick into the water. The stick seems to have a buckling. That is, the direction of the
electromagnetic wave changes.
2
• Reflection
The most well known signal distortion is reflection. Reflection means that
electromagnetic wave hits an obstacle which dimension is well beyond its
wavelength. In such case, reflections occur. Reflections represent copies of the
original electromagnetic wave that take a different path. Reflections occur again and
again on a single wave and are pre-dominantly responsible for multipath effects.
• Diffraction
Diffraction is a mixture of scattering and reflections. It occurs when electromagnetic
waves run through holes which have a dimension of approximately the wavelength of
this electromagnetic wave. Reflections and scattering cause a mixture of signal
annulations (when (+) and (–) meet) and signal amplifications (when (+) and (+) or (-)
and (-) meet) because of multipath effects.
Room for your Notes
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
RX
Receive
TX
Transmit
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2.2.2 Multiplexing Dimensions
2
The objective of this section is to indicate the four legacy multiplexing
dimensions that are used in today’s mobile communication. This section
continues in the next section.
Key point of this section is that there seems to be yet another multiplexing
dimension in addition to SDMA, TDMA, FDMA and CDMA.
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Room for your Notes
2
•
Abbreviations of this Section:
CDMA
Code Division Multiple Access
SDMA
Space Division Multiple Access
FDMA
Frequency Division Multiple Access
TDMA
Time Division Multiple Access
GSM
Global System for Mobile
Communication
TV
Television
IS
Interim Standard (ANSI Standard)
UTRA
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access
IS-95
Interim Standard - 95 (Qualcomm
CDMA)
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2.2.2 Multiplexing Dimensions
2
The objective of this section is to indicate the four legacy multiplexing
dimensions that are used in today’s mobile communication. This section
continues from the previous section.
Key point of this section is that there seems to be yet another multiplexing
dimension in addition to SDMA, TDMA, FDMA and CDMA.
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Room for your Notes
2
•
Abbreviations of this Section:
CDMA
Code Division Multiple Access
SDMA
Space Division Multiple Access
FDMA
Frequency Division Multiple Access
TDMA
Time Division Multiple Access
IS
Interim Standard (ANSI Standard)
TV
Television
IS-95
Interim Standard - 95 (Qualcomm
CDMA)
UTRA
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access
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2.2.3 The Multipath Dimension
2
The objectives of this section are to illustrate the radio propagation of
different antennas of the same base station.
Key point of this section is that even though the antenna of a base station
are quite close to each other the radio paths can differ than much that their
multiple path profile is different.
⇒ Multipath is caused by the various fading events (Scattering, Reflection,
Diffraction and Refraction) that the signal is exposed to on its way from
transmitter to receiver due to the various obstacles on this way.
⇒ Multipath and fading cause the original signal to arrive at the receive antenna
in different versions. Each version is due to scattering, reflection, diffraction
and refraction differently phased, timed and attenuated.
⇒ As illustrated in the figure, two transmit antennas, sufficiently spaced apart
from each other, will each cause a unique and independent reception pattern
(ó fingerprint) at the receive antenna.
⇒ Technically speaking, the relative positions of antennas TX 1 ó RX 1 and TX
2 ó RX 1 allow for an uncorrelated multipath pattern at the receiver antenna
RX 1.
⇒ Depending on the distance between the antennas, one achieves microdiversity (distance between TX-antennas ≈ 0.5 wavelengths) or macrodiversity (distance between TX-antennas >> wavelength). MIMO only works
with macro diversity or polarization diversity approaches.
⇒ With micro-diversity, only fast fading issues can be tackled. Macro-diversity is
required to address also slow fading.
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Room for your Notes
2
•
Abbreviations of this Section:
RX
Receive
TX
Transmit
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2.2.6 MIMO General Operation
2
The objective of this section is to explain the principles of MIMO-systems.
Key point of this section is that MIMO-systems transmit different information
over the same resources, frequency and time but are differentiated by the
receiver through the specific multipath between each transmit antenna and
the receive antennas.
Image Description
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•
The illustrated example shows a 2 x TX and 2 x RX MIMO system for the two
cases that the transmitter and the receiver are connected by means of a cable
and that both of them are communicating with 2x2 antennas.
•
In case there are no cables used each RX antenna receives information from
each TX antenna. Sophisticated receivers need to separate the different transmit
antennas from each other, e.g. based on pilot bits.
•
MIMO systems therefore require sophisticated processing at the receiver side
and they require a unique multipath morphology between TX and RX.
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The larger the number of TX-antennas and RX-antennas, the higher the theoretical
throughput rate. The larger the number of RX-antennas, the better the diversity
decision at the receiver. For linear receivers like the LMMSE MIMO can increase
the max. throughput by the minimum of RX and TX antennas. E.g. once there are
3 TX and 2 RX antennas the max. throughput can be increased by 2 times.
2
In LoS condition MIMO can fail even though it usually works. In this case it is not
possible to separate the two data streams at the receiver. Once there is real
multiple path propagation (non LoS) the probability that MIMO works fine is higher.
Room for your Notes
•
Abbreviations of this Section:
LMMSE
Linear Minimum Mean Square Error
receiver
RX
Receive
LoS
Line of Sight
TX
Transmit
MIMO
Multiple In / Multiple Out (antenna
system)
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Lessons Learned / Conclusions:
2
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Chapter 3:
The Physical Layer of E-UTRAN
Objectives
Some of your questions that will be answered during this session…
•
How the physical frame structure is facilitating the use of a flexible
bandwidth allocation?
•
What is the structure of uplink and downlink physical channels in detail?
•
How do the digital signal processing chains of uplink and downlink look like
and what is their difference with respect to conventional mobile radio
systems?
•
How do the physical layer procedures of the air interface work?
•
How does LTE keep aligned in timing and transmission power?
•
What is the foundation of LTE’s antenna technology?
•
How do initial cell search and random access work?
•
How the throughput of the UE categories can be calculated?
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3.1 The Use of OFDM/OFDMA in LTE
3.1.1 Frame Structure
3
The objective of this section is to give an overview of the downlink frame
structure and the uplink frame structure of the LTE burst.
Key point of this section is that uplink and downlink are using essentially the
same frame structure only the DMA scheme is different.
Image description
•
This picture is giving both a view on the overall LTE frame structure and it is
showing the structure of the uplink and downlink slots.
3.1.1.1 The generic frame structure
The generic frame is consisting of 20 slots of 0.5 ms length each. Its length of 10 ms
is made up of 307200 sample periods of length T(sample). This means a sampling
frequency of 30.72 MHz which is corresponding to exactly 2048 carriers with 15 kHz
carrier spacing. Since this would lead to a bandwidth of 30 MHz it is obvious that not
all these 2048 subcarriers are indented to be used. Two slots constitute a subframe.
For FDD LTE this frame structure is applying for both UL and DL. For TDD LTE the
slots’ length is staying the same, too and subframe 0 and 5 are always downlink
subframes.
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3.1.1.2 The downlink slots
The downlink slots are containing 3, 6, or 7 OFDM symbols with N(CP) samples for
the cyclic prefix and N samples for the useful part of the OFDM symbol. The table
below the picture will give details of the possible configurations. Some OFDM
symbols are containing reference signals or pilots on some subcarriers.
3.1.1.3 The uplink slots
Even though the UL is not using OFDMA the UL signals also have a cyclic prefix.
Since no OFDM is applied the symbol in the middle is used as a pilot symbol or
reference symbol. Later this reference symbol will be used for channel estimation. In
different configurations 2 or 3 symbols can be used as a pilot.
3
3.1.1.4 The frame structure type 2
There is also frame structure type 2 which is not shown in this picture. It will be
compatible to LCR TDD frame structure. It is likely that this standard and the
alternative frame structure will be mainly used in mainland China. The alternative
frame structure is not treated closer in this book.
[3GTS 36.211 (4.1, 5.2, 6.2)]
Room for your Notes
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
MHz
Mega Hertz (106 Hertz)
CP
Cyclic Prefix
OFDM
Orthogonal Frequency Division
Multiplexing
DL
Downlink
OFDMA
Orthogonal Frequency Division
Multiple Access
DMA
Division Multiple Access
TDD
Time Division Duplex
FDD
Frequency Division Duplex
UL
Uplink
LCR
Low Chip Rate TDD
kHz
Kilo Hertz (103 Hertz)
LTE
Long Term Evolution (of UMTS)
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3.1.2 LTE Parameters
3
The objective of this section is to give an overview of the downlink frame
structure, the uplink frame structure, and the variable parameters of the LTE
burst.
Key point of this section is that uplink and downlink are using also the same
detailed parameters.
Table description
• This table is giving the LTE parameters for both the uplink and downlink slots.
There are 3 different configurations to parameterize the lengths of the different fields
in the slots and symbols. These configurations are relating to different deployment
scenarios of LTE. The UE has to identify which of these 3 configurations is used
during initial cell search by try and error.
3.1.2.1 The normal configuration
The normal configuration is using 7 symbols in each slot. Here the subcarrier spacing
is 15 kHz. The cyclic prefix of the first OFDM symbol is a bit longer in order to make 7
symbols fit exactly to 0.5 ms slot length. Since the guard period is rather short this
configuration is fitting for most deployments but for usage in tough conditions
(mountains, big cities) it is not suited. Once SFN is used in that section of the network
the cells should not be bigger then about 1-2 km because each 300 m difference in
distance of the UE to e.g. two base stations will add 1 s to the length of the channel
impulse response and thus to the length requirements for CP.
3.1.2.2 The extended configuration with 15 kHz subcarrier separation
The extended configuration with 15 kHz carrier separation is solving the problems
mentioned for the normal configuration. It can be well deployed for SFN and for hilly
terrain and in cities like in New York. With respect to the user density it usually does
not make much sense to create very big cells for pure mobile radio applications with
bidirectional services. Since the cyclic prefix is now making up for 20 % of the OFDM
symbol time, there is 20 % throughput loss for this case. This is the penalty to let the
OFDM system operated in harsh conditions.
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3.1.2.3 The extended configuration with 7.5 kHz subcarrier separation
The extended configuration exists for DL only. Here the subcarrier spacing is only 7.5
kHz and the cyclic prefix is twice a long as for the extended configuration with 15 kHz
subcarrier spacing. This is indicating quite well that this configuration is intended for
broadcast operation of e.g. TV programs.
[3GTS 36.211 (4.1, 5.2, 6.2)]
Room for your Notes
•
3
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
SFN
Single Frequency Network
CP
Cyclic Prefix
TV
Television
DL
Downlink
UE
User Equipment
LTE
Long Term Evolution (of UMTS)
kHz
Kilo Hertz (103 Hertz)
OFDM
Orthogonal Frequency Division
Multiplexing
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3.1.2 Resource Element and Resource Block Definition
3
The objective of this section to provide the definition of the downlink
resource elements and resource blocks within the OFDMA access scheme.
Key point of this section is that the resources can be distributed in form of
resource blocks of subcarriers and OFDMA/SC-FDMA symbols instead of
individual subcarriers and OFDM symbols.
Image description
•
The picture above is showing how the LTE carrier is split up in downlink resource
blocks.
3.1.2.1 Definition Resource Element
A resource element is a subcarrier on a OFDMA/SC-FDMA symbol.
3.1.2.2 Definition Resource Block
The resource blocks are bundles of 1 slot and 180 kHz bandwidth of either 12 x 15
kHz subcarriers or 24 x 7.5 kHz subcarriers (only DL). These resource elements or
subchannels can be assigned to the UE having the best performance on this
frequency and subchannel pair. This is of essential importance for a good scheduling
performance. It can be seen the DC carrier is not used (DL only) and that guard
bands of several carriers are not used in order to ease both the RF implementation
and the separation of different carriers, cells, and operators.
3.1.2.3 Definition Subframe
The resource blocks are grouped in two slots to form a subframe carrying the TTI. In
different slots of the same subframe the allocation to resource blocks can be
different. Frequency hopping might be applied a sub frame.
[3GTS 36.211 (5.2, 6.2)]
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The picture is showing a distribution of resources being consecutive. In LTE there
is also a distributed configuration of the resources possible (DL only).
3.1.2.4 Number of resource blocks in a given bandwidth
Due to the upper and lower guard bands only 25 resource blocks can be used per 5
MHz band. These resource blocks make up for 4.5 MHz carrier bandwidth.
Consequently there are 0.5 MHz guard bands. Once the band is 20 MHz wide this
ratio does not change. Only 100 resource blocks or 18 MHz can be used for the LTE
carrier.
3
Question No 2: Why the ratio of guard bands versus used bands goes not change
for bigger carriers? Why 0.5 MHz is not enough here always?
Room for your Notes
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
OFDM
Orthogonal Frequency Division
Multiplexing
DC
Direct Current
OFDMA
Orthogonal Frequency Division
Multiple Access
DL
Downlink
RF
Radio Frequency
LTE
Long Term Evolution (of UMTS)
UE
User Equipment
MHz
Mega Hertz (106 Hertz)
kHz
Kilo Hertz (103 Hertz)
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3.1.3 Choice of the UL Transmission Scheme (UL Data Symbols
only)
3
The objective of this section is to provide the reasoning behind the decision
for SC-FDMA as the UL transmission technology.
Key point of this section is that SC-FDMA has been chosen because of the
reduced AM requirements on the power amplifier of the UE compared to
OFDM technology (cost reasons).
Image description
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•
The picture shows the distribution of 16-QAM modulation symbols on the OFDM
subcarriers and the resulting time signal for OFDMA technology being used in the
UL on the left hand side.
•
The picture shows the distribution of 16-QAM modulation symbols on the SCFDMA subsymbols and the resulting time signal for SC-FDMA technology being
used in the UL on the right hand side.
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3.1.3.1 What would happen if OFDM would be used in the UL
Once OFDM would be used in the UL there would be the same RB structure as in the
DL. Consequently multiple of 12 subcarriers would be used to map the UL bits of e.g.
16-QAM symbols on the subcarriers. Since all the subcarriers’ signals superimpose
on the time signal of the OFDM symbol, very severe AM would be the result. For high
data rate UE’s this AM would result in very expensive power amplifiers.
3.1.3.2 SC-FDMA is used for the UL
The advantage of a single carrier signal would be that the AM at the power amplifier
is mainly determined by the modulation alphabet and not additionally by the number
of subcarriers. Thus the AM and consequently also the power amplifiers price is
much more favorable than for OFDM signals. In order to enjoy still the benefit of low
processing power requirements of OFDM signals the SC- signal has been designed
to fit into the corset of the would be UL OFDM signal by means of the following
measures:
1. Choose the same amount of modulation symbols in the RB
2. Choose the same bandwidth occupied by the RB
3. Choose the same duration of SC-FDMA symbols (cluster of n x 12
modulation symbols)
4. Adding the same CP period as for an OFDM signal
5. Choosing the same sampling grid for the processed signals. (The
modulation symbols are interpolated to sampling grid.)
All these measures ensure that effectively the same subcarriers are used, that
orthogonality is kept amongst the subcarriers and that a similar way to process the
SC-FDMA symbols as for OFDM symbols is kept.
3
Please note that SC-FDMA is strictly speaking only applied for the payload data in
the UL. The L1 signaling channels, the pilots and the sounding reference symbols
are created in the frequency domain and they also have almost constant amplitude
in the time domain.
•
Abbreviations of this Section:
16-QAM
16 symbols Quadrature Amplitude
Modulation
OFDMA
Orthogonal Frequency Division
Multiple Access
AM
Amplitude Modulation
RB
Resource Block
CP
Cyclic Prefix
SC-FDMA Single Carrier Frequency Division
Multiple Access
DL
Downlink
UE
User Equipment
OFDM
Orthogonal Frequency Division
Multiplexing
UL
Uplink
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3.1.4 FDD and TDD Operation in E-UTRAN
3.1.4.1 Reciprocity
3
The objective of this section is to highlight the difference in reciprocity inbetween FDD and TDD.
Key point of this section is that in FDD UL and DL have different mobile radio
channels and in TDD whilst the mobile radio channel is the same for TDD.
Image description
The picture is showing the most important difference of FDD and TDD operation:
The channel reciprocity.
LTE can be operated both with the FDD and in the FDD mode. The generic frame
structure is used in both modes. However the characteristics of FDD and TDD lead to
very distinct differences in the system behavior of these modes. In the following the
main differences should be described.
•
3.1.4.1.1 Reciprocity of the mobile radio channel
In the TDD mode the mobile radio channel of UL and DL is the same. This means
that once the UE is having a low mobility the eNB can conclude from the behavior of
the UL signals how the downlink channel will behave. This is very beneficial for
beamforming and MIMO algorithms. Then the UE is not in need to transmit a CSI any
more in order to give the eNB hints how to do the beamforming in the downlink. For
FDD UL and DL are always different - only their long term behavior is the same.
However, this is not allowing for very powerful algorithms. This is why CSI’s are
needed especially for closed loop MIMO.
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3.1.4.1.2 Speed of scheduling decisions
Since in TDD the mobile radio channel is used for both DL and UL, UL and DL have
to follow one another. This means that the UE cannot transmit the CSI and the CQI
whilst it is receiving the DL signals. It as to wait until it is the turn of the UL and then
transmits its signaling. The same applies for the DL signaling which cannot take
place whilst the UL is to be transmitted. This is lowering the performance of the
scheduling algorithms. In FDD both UL and DL are transmitted simultaneously. This
is used in order to optimize the timing of the scheduling algorithms.
LTE is putting big emphasis on the FDD bands while for WiMAX TDD is the focus
of the work recently.
3
Room for your Notes
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
TDD
Time Division Duplex
CQI
Channel Quality Indicator
UE
User Equipment
CSI
Channel State Information
UL
Uplink
DL
Downlink
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
FDD
Frequency Division Duplex
WiMAX
Worldwide Interoperability for
Microwave Access (IEEE 802.16)
LTE
Long Term Evolution (of UMTS)
eNB
Enhanced Node B
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3.1.4.2 UL / DL Asymmetry and Others
3
The objectives of this section are to show how both FDD and TDD operation
is enabled with the frame structures of the pervious sections and to list the
special advantages and disadvantages of using TDD.
Key point of this section is that both FDD and TDD have their distinct
advantages and disadvantages.
Image description
•
The picture is showing the other very important differences of FDD and TDD
operation: The different UL / DL symmetry and the new interference scenarios in
TDD.
3.1.4.2.1 UL/DL symmetry
The FDD mode is using UL and DL in a symmetrical way. This means UL and DL use
the same portion of bandwidth. TDD can adjust a different amount of slots to the DL
than to the UL. This is allowing for asymmetrical usage of UL and DL resources for
asymmetrical UL/DL traffic.
3.1.4.2.2 Interference scenarios
Unfortunately the TDD advantage of the tunable UL/DL symmetry cannot be used
freely because of the interference situation. Once in FDD the interference is only
coming from eNB to UE and from UE to eNB and is thus following the ´normal signal
flow, the interference in TDD can also be eNB – eNB interference and UE – UE
interference. Since in-between two same network elements the mobile radio channel
can be very good there is a very high potential of strong interference once the once
cell is allocating UL to a slot and at the same time the neighbor cell is using DL.
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This interference situation is requiring to decouple the cells by means of radio
network planning or very effective interference coordination. In a macro deployment it
is very difficult to circumvent this problem.
3.1.4.2.3 TRX architecture
For TDD the TRX architecture is requiring a switch and FDD is using a filtering here.
The switch is in general smaller and cheaper then the filter architecture.
3.1.4.2.4 Deployment in a given frequency band
Of course it is easier to deploy a TDD system in a given frequency band. FDD always
needs a paired frequency band (one band for UL and another band for the DL). Thus
TDD can also fit in unoccupied niches of the overall spectrum. However, in some
case the interference problems described earlier will lead to challenging co-existence
problems with neighboring systems.
3
[3GTS 36.211 (4.1, 4.2)]
Room for your Notes
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
TDD
Time Division Duplex
CSI
Channel State Information
TRX
Transmitter / Receiver
DL
Downlink
UE
User Equipment
FDD
Frequency Division Duplex
UL
Uplink
LTE
Long Term Evolution (of UMTS)
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
MIMO
Multiple In / Multiple Out (antenna
system)
eNB
Enhanced Node B
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3.1.4.3 Summary FDD vs. TDD
3
The objective of this section the advantages of TDD and FDD discussed in
the previous 2 sections.
Key point of this section is that it depends on the deployment and service
what duplex mode might be more suitable than the other.
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Since the details are already discussed in the pervious sections only the conclusion
should be given here:
1. The usage of FDD and TDD in a given scenario should be well thought over.
2. It depends on what services / service mix the operator wants to offer and
what deployment is suitable for the operators business case whether this or
the other duplex mode is more favorable than the other.
Room for your Notes
•
3
Abbreviations of this Section:
DL
Downlink
TRX
Transmitter / Receiver
FDD
Frequency Division Duplex
UE
User Equipment
L1
Layer 1 (physical layer)
UL
Uplink
MBSFN
MBMS Single Frequency Network
eNB
Enhanced Node B
TDD
Time Division Duplex
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3.2 The DL Physical Channels and their Frame Structures
3.2.1 Allocation of DL Physical Channels to Resource Elements
3
The objective of this section is to show how the different DL physical
channels are mapped on the resource elements in their frame structures.
Key point of this section is that size and position of the DL physical channels
is highly flexible.
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Image description
•
The picture shows the allocation of the DL physical channels and signals on RB
and SC level.
•
The picture shows the allocation for the case that normal CP is configured, the
LTE carriers has only 6 RB’s, subchannel 0 is taken, that 3 OFDM symbols are
configured for L1 signaling, and that only 1 PHICH is configured.
The thick black lines are marking the boundaries of the RB and slots. They do not
represent unused subcarriers.
In the following the allocation of the physical channels and physical signals is
discussed according to their allocation priority. This means a physical channel or
physical signal can only assume described positions once this position has not been
claimed by physical channels and physical signals described before.
•
3
Room for your Notes
•
Abbreviations of this Section:
CP
Cyclic Prefix
PCFICH
Physical Control Format Indicator
Channel
DC
Direct Current
PDCCH
Physical Downlink Control Channel
DL
Downlink
PDSCH
Physical Downlink Shared Channel
L1
Layer 1 (physical layer)
PHICH
Physical HARQ Acknowledgement
Indicator Channel
LTE
Long Term Evolution (of UMTS)
RB
Resource Block
OFDM
Orthogonal Frequency Division
Multiplexing
SC
Subcarrier
PBCH
Physical Broadcast Channel
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3.2.1.1 Not used subcarriers
The DC subcarriers are never used in DL. They are also not counted in the subcarrier
numbering.
3
3.2.1.2 Primary Synchronization Signal
The Primary Synchronization Signal only exists on the last OFDM symbol on slots 0
and 10. In the other slots these OFDM symbols will be used for the PDSCH or
PMCH. Note that this signal is only existing on the 6 middle RB’s of the LTE carrier
and that the 5 outermost SC’s are reserved for this signal but not used.
3.2.1.3 Secondary Synchronization Signal
Here the last but one OFDM symbol on slots 0 and 10 is used. Apart from that the
same other rules apply as for the primary synchronization signal.
3.2.1.4 Pilot or Reference Signal
The reference signal is using subcarriers distributed in time and frequency in order to
access the mobile radio channel completely. Please note that in formal operation the
reference signal is belonging to the eNB and is not individual to the UE getting a
packet on the regarded RB’s. In this case the number of pilot subcarriers assigned is
varying with the number of antennas. It is also possible to assign the reference
signals individual to the UE’s in the case of plain beam forming.
3.2.1.5 PBCH
The PBCH is taking OFDM symbols in the middle 6 RB’s of the LTE carrier at the
beginning of slot 1. In the other RB’s and slots these symbols are claimed by the
PDSCH or the PMCH.
3.2.1.6 PCFICH
The PCFICH is indicating how many OFDM symbols of the subframe are allocated to
the PCFICH, the PHICH, and the PDCCH. This is only one PCFICH for subframe.
There are 4 group of 4 SC which are equally distributed on the complete LTE
subcarrier. The position of the PCFICH is depending on the cell ID and the bandwidth
of the LTE carrier.
3.2.1.7 PHICH
The PHICH is clustered in groups of 2 or 4. 12 SC’s (3 groups of 4 SC’s each) of the
PHICH group are distributed in the L1 signaling OFDM symbols of the subframe.
More than 1 PHICH group can be configured. The exact allocation rules are not clear
yet.
3.2.1.8 PDCCH
The PDCCH is using the SC’s and being not used by the PCFICH and the PHICH.
More than 1 PDCCH can be configured.
3.2.1.9 PDSCH (and PMCH)
All the remaining subcarriers and symbols can be used by the PDSCH or PMCH.
[3GTS 36.311 (6.3 - 6.9)]
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For all the control channels MIMO is not allowed and the PMCH. They might be
transmitted with a single antenna or use TX diversity (not the PMCH). Only the
PDSCH might be used with MIMO.
Question No 3: What is the reason for this restriction?
3
Room for your Notes
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
PCFICH
Physical Control Format Indicator
Channel
CP
Cyclic Prefix
PDCCH
Physical Downlink Control Channel
DC
Direct Current
PDSCH
Physical Downlink Shared Channel
DL
Downlink
PHICH
Physical HARQ Acknowledgement
Indicator Channel
ID
Identity
PMCH
Physical Multicast Channel
L1
Layer 1 (physical layer)
RB
Resource Block
LTE
Long Term Evolution (of UMTS)
SC
Subcarrier
OFDM
Orthogonal Frequency Division
Multiplexing
UE
User Equipment
PBCH
Physical Broadcast Channel
eNB
Enhanced Node B
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3.2.2 System Information on PBCH and PDSCH
3
The objective of this section is to show the structure of the PBCH and the
work split in between the PBCH and the PDSCH.
Key point of this section is that the PBCH is only carrying the MIB - other
system information messages are transmitted on the PDSCH.
Image description
•
The picture shows the distribution of system information MIB, SIB, and SU on the
different physical cannels carrying the BCH.
3.2.2.1 Split of the BCH on the PBCH and the PDSCH
The PBCH is just carrying very limited information. The term MIB is reused from
UMTS here. The MIB carries very basic information which is quite close to a physical
layer signaling. It also indicates with the SFN the presence of the most important SU
in the concerned frame. The MIB is transmitted very 40 ms.
Once the SU-1 is present it is located at a fixed position in the frame. It is repeated
every 80 ms and contains most important system information as cell and network
specific codes and ID’s. It is as well scheduling other SU’s, SB’s, and SIB’s.
In general the SU is containing more than one system information. It is grouping
system information having the same periodicity for their transmission and can be thus
transmitted together.
[3GTS 36.300 (7.4), 3GTS 36.331(5.1.1.2, 6.2.1)]
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Room for your Notes
3
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
PLMN
Public Land Mobile Network
BCH
Broadcast Channel
SB
Scheduling Block
DL
Downlink
SFN
System Frame Number
FFS
For Further Study
SIB
System Information Block
ID
Identity
SU
Scheduling Unit
MIB
Management Information Base
TA
Tracking Area
PBCH
Physical Broadcast Channel
TX
Transmit
PDSCH
Physical Downlink Shared Channel
UMTS
Universal Mobile Telecommunication
System
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3.2.3 PCFICH, PDCCH, and PHICH
3
The objective of this section is to show the structure of the PCFICH, the
PDCCH, and the PHICH.
Key point of this section is that with the physical control channels the
functions of the HS-SCCH, the E-AGCH, the E-RGCH and the E-HICH in
HSPA are followed.
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Image description
•
The picture shows what HSPA physical channels are replaced by the LTE
physical control channels and how the related information is transmitted.
3.2.3.1 The PCFICH
Since the PDCCH is sharing the RB with the PDSCH it has to be communicated how
much of the RB is taken for the PDCCH. This is done by the CFI’s transmitted on the
PCFICH. The PCFICH is using 16 data subcarriers of the first OFDM symbol of the
subframe. Their position is depending of cell ID and used bandwidth for the cell.
Since the size of the PDCCH is depending on the signaling needs there are 3
different CFI values possible. They are signaling whether the first 1, 2, or 3 OFDM
symbols are used of the subframe are used for the PDCCH. In case less then 10
RB's are used for the DL carrier the numbers are 2, 3, or 4.
•
3
Abbreviations of this Section:
ACK
Acknowledgement
MIMO
Multiple In / Multiple Out (antenna
system)
CFI
Control Format Indicator
NACK
Negative Acknowledgement
DCI
Downlink Control Indicator
OFDM
Orthogonal Frequency Division
Multiplexing
DL
Downlink
PC
Power Control
DPCCH
Dedicated Physical Control Channel
(UMTS Physical Channel)
PCFICH
Physical Control Format Indicator
Channel
E-AGCH
E-DCH Absolute Grant Channel
PDCCH
Physical Downlink Control Channel
E-HICH
E-DCH HARQ Acknowledgement
Indicator Channel (3GTS 25.211)
PDSCH
Physical Downlink Shared Channel
E-RGCH
E-DCH Relative Grant Channel (3GTS PHICH
25.211)
Physical HARQ Acknowledgement
Indicator Channel
HI
HARQ Indicator
RB
Resource Block
SIMO
Single In / Multiple Out (antenna
system)
HS-SCCH High Speed Shared Control Channel
(3GTS 25.211, 25.214)
HSPA
High Speed Packet Access (operation UE
of HSDPA and HSUPA)
User Equipment
ID
Identity
Uplink
LTE
Long Term Evolution (of UMTS)
UL
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LTE from A-Z
3.2.3.2 The PDCCH
The PDCCH is transmitting the information about the resource allocation, the HARQ
info, the transport format and implicitly the RNTI’s for the DL transmission. This has
been taken care of by the HS-SCCH in HSDPA. Due to the advanced antenna
technology there is also some additional information transmitted: the codebook entry
and the transmission rank of the following DL packet. Here it is specified how the TX
antenna system is used. This information is needed in order to detect the data packet
in the UE.
The PDCCH can also transmit the scheduling grant for the UL. Since no CDMA is
used in LTE here the explicit resources have to be granted. Multiple UE’s cannot
access the same subcarriers in an uncontrolled manner. In the UL it is possible to
choose also the TX antenna to use. The scheduling grant has been managed by the
E-AGCH and the E-RGCH in HSUPA.
It is also possible to perform UL power control with the PDCCH. In this sense the
PDCCH is also taking functions of the DPCCH of UMTS.
Since the PDCCH has a lot of functions and not all of them are used at the same time
it is obvious that the PDCCH is in need to be configured flexibly. The L1 signaling is
done with DCI. These DCI’s can have 10 formats following the different functions: 1
format for UL scheduling, 5 formats for DL scheduling (no MIMO), 2 formats for DL
scheduling (MIMO), and 2 formats for UL power control only.
3.2.3.3 The PHICH
Once the UE is transmitting data in the UL it will listen to the PHICH for the
acknowledgements. This function is taken over from the E-HICH in HSPA.
The several PHICH’s are forming a PHICH group using the same resource elements.
With this group depending on the CP configuration and MBSFN usage 1,2, or 3
OFDM symbols will be configured by higher layers. The PHICH’s are spread using
spreading factor of 2 or 4 depending on the CP configuration.
Each HI (ACK or NACK) is repetition encoded in order to have 3bits on the physical
layer
In order to prevent a hen and egg situation both the PCFICH and the PDCCH and
the PHICH are restricted to single antenna transmission and TX diversity with 2 or
4 antennas – MIMO is not allowed.
[3GTS 36.211 (6), 3GTS 36.212 (5.3.3, 5.3.4, 5.3.5)]
Room for your Notes
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Room for your Notes
3
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
HSUPA
High Speed Uplink Packet Access
(3GTS 25.301, 25.309, 25.401,
3GTR 25.896)
ACK
Acknowledgement
L1
Layer 1 (physical layer)
CDMA
Code Division Multiple Access
LTE
Negative Acknowledgement
CP
Cyclic Prefix
MBSFN
MBMS Single Frequency Network
DCI
Downlink Control Indicator
MIMO
Multiple In / Multiple Out (antenna
system)
DL
Downlink
NACK
Negative Acknowledgement
DPCCH
Dedicated Physical Control Channel
(UMTS Physical Channel)
OFDM
Orthogonal Frequency Division
Multiplexing
E-AGCH
E-DCH Absolute Grant Channel
PCFICH
Physical Control Format Indicator
Channel
E-HICH
E-DCH HARQ Acknowledgement
Indicator Channel (3GTS 25.211)
PDCCH
Physical Downlink Control Channel
E-RGCH
E-DCH Relative Grant Channel (3GTS PHICH
25.211)
Physical HARQ Acknowledgement
Indicator Channel
HARQ
Hybrid ARQ
TX
Transmit
HI
HARQ Indicator
UE
User Equipment
HS-SCCH High Speed Shared Control Channel
(3GTS 25.211, 25.214)
UL
Uplink
HSDPA
High Speed Downlink Packet Access
(3GTS 25.301, 25.308, 25.401,
3GTR 25.848)
UMTS
Universal Mobile Telecommunication
System
HSPA
High Speed Packet Access (operation
of HSDPA and HSUPA)
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3.2.4 The Downlink Processing Chain
3
The objective of this section is to illustrate the structure and use of the
downlink processing chain.
Key point of this section is that for of the processing is already associated
with the individual antennas.
Image description
•
This picture is showing the basic steps of the DL signal processing chain. In the
following the individual steps are described closer.
•
The path of the second TB is shown as a dotted line.
3.2.4.1 Encoded transport block bits
The encoded transport block bits are the input of the scrambler.
3.2.4.2 Scrambling
Scrambling is serving two purposes: Signal separation and signal randomization.
Scrambling is done by XORing the input bits with a PN scrambling code. In order to
ensure the separation of different signals in different cells different scrambling codes
are applied in different cells. The scrambling code is also necessary to randomize
long sequences of bits being the same (e.g. once a transport block is zero padded).
These sequences can evoke very severe AM in the signals to be transmitted. Without
a scrambler a very expensive RF would be required to deal with this AM.
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Room for your Notes
3
•
Abbreviations of this Section:
AM
Acknowledged Mode operation
MIMO
Multiple In / Multiple Out (antenna
system)
AM
Amplitude Modulation
OFDM
Orthogonal Frequency Division
Multiplexing
CDD
Cyclic Delay Diversity
PN
Pseudo Noise
CP
Cyclic Prefix
RF
Radio Frequency
DL
Downlink
TB
Transport Block
IFFT
Inverse Fast Fourier Transformation
TX
Transmit
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3.2.4.3 Modulator
In the next step the bits are used in order to create complex modulated symbols
according to the chosen modulation alphabet of this channel (QPSK, 16-QAM, 64QAM).
3
3.2.4.4 Layer Mapper
In the layer mapper these modulated symbols are then demultiplexed to the different
antennas. Form then on the modulated symbols are processed differently on different
antennas.
3.2.4.5 Precoding
In case smart antenna technology is applied the precoding is preparing the
modulated symbols to give optimum performance in the given antenna system. There
are several methods to do that: E.g. to apply beamforming coefficients in order to
ensure optimum SIR in the receiver or to use CDD which is randomizing the phases
of the transmitted signals – also for better quality in the receiver.
3.2.4.6 OFDM signal generation
For the OFDM signal generation the modulated and precoded symbols are finally
mapped on the subcarriers of the OFDM signal. Possibly also reference or pilot
symbols are inserted on selected carriers. In case of multiple antenna operation the
pilot symbols are inserted differently for the different antennas. Later on these
reference signals are allowing for channel estimation of the individual antennas’
CIR’s
3.2.4.7 CP and IFFT
The IFFT and the addition of the cyclic prefix are creating the final signal to be
transmitted on each antenna.
[3GTS 36.211 (6.3)]
Room for your Notes
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Room for your Notes
3
•
Abbreviations of this Section:
16-QAM
16 symbols Quadrature Amplitude
Modulation
CP
Cyclic Prefix
3GTS
3rd Generation Technical
Specification
IFFT
Inverse Fast Fourier Transformation
64-QAM
64 symbols Quadrature Amplitude
Modulation
OFDM
Orthogonal Frequency Division
Multiplexing
CDD
Cyclic Delay Diversity
QPSK
Quadrature Phase Shift Keying
CIR
Channel Impulse Response
SIR
Signal to Interference Ratio
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3.3 The UL Physical Channels and their Frame Structures
3.3.1 Overview UL Physical Channels (RRC_CONNECTED)
3
The objective of this section is to show the conditions for the usage of the UL
physical channels in RRC_CONNECTED mode.
Key points of this section are that the PUCCH only used once the PUSCH is
not transmitted and that the PUSCH is also carrying L1 signaling data.
Image description
•
The picture shows in the top part the conditions when the UL physical channels
are used how.
•
The picture shows in the bottom part what data is demultiplexed on the physical
channels.
3.3.1.1 Scheduling Request (SR) on the PUCCH
There are special SR resources on the PUCCH. Here the UE can request to be
scheduled UL data. In case an a DL transmission has to be acknowledged at the
same time this will happen on the same resource.
Otherwise the acknowledgement will be on the following resources:
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3.3.1.2 Small amount of L1 information on the PUCCH
A UE will get some UL resources assigned semi statically for the PUCCH for other
L1 signaling than SR. These resources can be used for acknowledging the DL TB’s,
for transmitting CQI, PMI, RI and other DL feedback information. Since it is not
transmitted once a PUSCH is transmitted it not not contain any further UL related
information.
3.3.1.3 Big amount of L1 information on the PUSCH
In case a lot of CQI, PMI, and RI have to be transmitted this L1 information is
transmitted on the PUSCH.
3
3.3.1.4 L1 information on the PUSCH multiplexed with the TrCH data
Since SC-FDMA is used only a single carrier signal is allowed which cannot be
ensured once the UE would transmit on both the PUSCH and the PUCCH.
Consequently, in case a PUSCH is transmitted for data it will also contain the L1
signaling which would elsewise have been transmitted on the PUCCH/PUSCH. Then
the PUCCH is not in need to be transmitted. The L1 signaling information is
distributed on the SC-FDMA symbols and follows the same modulation scheme as
the other PUSCH data.
3.3.1.5 Sounding reference symbols PUSCH resources
A similar issue is also valid for the transmission of the SRS. The SRS is used for a
detailed assessment of the mobile radio channel. With the SRS the eNB can decide
where best to allocate the UL resources and how the timing advance has to be set
for this UE. In order to keep the single carrier guideline it can only be transmitted
together with the PUSCH. Only 1 position is possible: the last symbol of the
subframe.
[3GTS 36.212 (5.4), 3GTS 36.212 (5.2.2.7), 3GTS 36.213 (7.2.2, 10)]
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
PUSCH
Physical Uplink Shared Channel
ACK
Acknowledgement
RI
Rank Indicator
CQI
Channel Quality Indicator
RRC_CO RRC state in E-UTRA
NNECTED
DL
Downlink
SC-FDMA Single Carrier Frequency Division
Multiple Access
eNB
Enhanced Node B
SR
Scheduling Request
FDMA
Frequency Division Multiple Access
SRS
Sounding Reference Symbol
HARQ
Hybrid ARQ
TB
Transport Block
L1
Layer 1 (physical layer)
TrCH
Transport Channel (UMTS)
NACK
Negative Acknowledgement
UE
User Equipment
PMI
Precoding Matrix Indicator
UL
Uplink
PUCCH
Physical Uplink Control Channel
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3.3.2 Overview PUCCH
3
The objective of this section is to show that both possible uplink physical
channels are using the same frame structure but that they differ how it is
used.
Key point of this section is that the PUCCH is combining the functions of the
HS-PDCCH and some functions of the E-DPCCH in HSPA.
Image description
• The picture compares the physical channels in HSPA with the PUCCH.
Since the PUCCH is not transmitted in presence of a PUSCH no L1 information
regarding the transmitted UL TB’s is transmitted in the PUCCH.
Like the PDCCH the PUCCH is tailored from the start to the use in LTE: This is why it
is combining the function^s of two HSPA channels. However the function is also
enhanced with respect to the HSPA usage. The information elements are grouped in
UCI’s.
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For example not only one bit ACK/NACK can be transmitted but also two. The reason
for this configuration is that the downlink can transmit two data streams with MIMO.
Each data stream has it own TB. In case 4x4 antennas are used in the DL the
number of TB’s stays with 2.
Next to the CQI other parameters are transmitted. Here codebook entries creating a
favorable receive performance in the UE’s receiver are transmitted as PMI as well as
the TX rank (how many parallel data streams the UE can take). This information is –
as in HSPA - not binding for the eNB. This is why the eNB has to transmit the chosen
codebook entry and the TX rank in the PDCCH as well.
Another function of the PUCCH is to transmit the scheduling request which is needed
in order to get UL resources assigned for transmission. This function corresponds
quite well to the Happy Bit in HSUPA.
There is a dilemma with the PUCCH: Not all the functions and transmitted information
is needed all the time this is why the PUCCH has 6 different format which are restring
the use of the PUCCH.
3
[3GTS 36.211 (5.4), 3GTS 36.300 (5.2.3)]
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
NACK
Negative Acknowledgement
ACK
Acknowledgement
PDCCH
Physical Downlink Control Channel
CQI
Channel Quality Indicator
PMI
Precoding Matrix Indicator
DL
Downlink
PUCCH
Physical Uplink Control Channel
E-DPCCH
Enhanced Uplink Dedicated Physical
Control Channel (3GTS 25.211)
PUSCH
Physical Uplink Shared Channel
HSDPCCH
High Speed Dedicated Physical
Control Channel (3GTS 25.211)
TB
Transport Block
HSPA
High Speed Packet Access (operation TX
of HSDPA and HSUPA)
Transmit
HSUPA
High Speed Uplink Packet Access
(3GTS 25.301, 25.309, 25.401,
3GTR 25.896)
UCI
Uplink Control Indicator
L1
Layer 1 (physical layer)
UE
User Equipment
LTE
Long Term Evolution (of UMTS)
UL
Uplink
MIMO
Multiple In / Multiple Out (antenna
system)
eNB
Enhanced Node B
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3.3.3 PUCCH Mapping for ACK/NACK only and Scheduling
Request
3
The objective of this section is to show how ACK’s, NACK’s and scheduling
requests are transmitted on the PUCCH with slot formats 1(x).
Key point of this section is that for these 5 formats both CDMA and cyclically
shifted Zadoff-Chu sequences are used to multiplex different UE’s to use the
same UL resources for the PUCCH.
Image description
•
The picture visualizes the different 1(x) formats of the PUCCH.
In the foreground the picture shown the normal CP configuration. Below the
second slot the extended CP configuration is shown.
Since the PUCCH is using a single RB and waste of resources needs to be
prevented, this single RB is in need to be shared in-between more than 1 UE. The
following 3 methods help to achieve this goal.
•
3.3.3.1 Usage of Zadoff-Chu sequences
There the 12 SC's on each SC-FDMA symbol are used in order to create a ZadoffChu sequence in the time domain. These symbols are modulated with information of
the PUCCH.
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These sequences process almost ideal autocorrelation properties such that different
UE can use the same sequence but with a different cyclic shift in the time domain.
Then these UE have almost orthogonal signals.
Room for your Notes
3
•
Abbreviations of this Section:
ACK
Acknowledgement
RB
Resource Block
CDMA
Code Division Multiple Access
SC
Subcarrier
CP
Cyclic Prefix
SC-FDMA Single Carrier Frequency Division
Multiple Access
FDMA
Frequency Division Multiple Access
UE
User Equipment
NACK
Negative Acknowledgement
UL
Uplink
PUCCH
Physical Uplink Control Channel
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3.3.3.2 Spreading of repeated data Zadoff-Chu symbols
In order to improve the protection the modulated Zadoff-Chu sequences are repeated
3 or 4 times. In order to increase the number of UE's sharing these resources a
spreading code overlays this repetition. Different UE's can then be separated by
different spreading codes.
3
3.3.3.3 Spreading of reference Zadoff-Chu symbols
2 or 3 reference Zadoff-Chu Symbols used for chanel estimation. These symbols are
modulated according to a spreading code of SF 2 or 3. In order to allow different UE's
to share these resources, again different spreading codes and cyclic shifts are
assigned to different UE's.
3.3.3.3 PUCCH Format 1
Format 1 is used to transmit SR's in absence of acknowledgements. It is not
modulated. The presence of a Zadoff-Chu sequence on a certain resource is
indicating a SR. This is why it can be combined with acknowledgements, but then it
would be format 1a or format 1b. Like all the format 1(x) formats there are 3
reference symbols for the normal CP and 2 reference symbols for the extended CP.
3.3.3.4 PUCCH Formats 1a and 1b
The difference with respect to format 1 is that these two formats are modulated in
order to convey an acknowledgement for 1 TB (1a) or and acknowledgement for 2
TB's (1b). In order to do so they are modulated with BPSK (1a) or with QPSK (1b).
3.3.3.5 Shortened PUCCH Formats 1a and 1b
These formats cut the last data symbol of the second slot in order to support the
transmission of a SRS at this position. This is not possible for the extended CP.
3.3.3.6 Multiple access of the PUCCH
In theory 12 cyclic shifts can be used for the Zadoff-Chu sequences. The SF codes
would allows for 4 different codes. However since there are only up to 3 symbols for
the reference signals the number of spreading codes is limited to the number of
reference symbols such that the theoretical maximum of simultaneous UE's would be
36 for the normal CP and 24 for the extended CP. Since this operation is vulnerable
to long channel impulse responses usually 6 instead of 12 cyclic shifts are used only.
This is reducing the amount of UE's to be served in parallel by 50 %.
Once the extended cyclic prefix is used for the UL there are 2 pilot symbols for a
slot only. Compared to the normal cyclic prefix 1 symbol is missing (6 instead of 7
symbols).
[3GTS 36.211 (5.4)]
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Room for your Notes
3
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
SR
Scheduling Request
BPSK
Binary or Bipolar Phase Shift Keying
SRS
Sounding Reference Symbol
CP
Cyclic Prefix
TB
Transport Block
PUCCH
Physical Uplink Control Channel
UE
User Equipment
SF
Spreading Factor
UL
Uplink
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3.3.4 Shared usage of Resources with CAZAC Sequences
3
The objective of this section is to show how resources can be shared with
CAZAC sequences (in LTE Zadoff-Chu sequences).
Key point of this section is that cyclic shifts combined with the good auto
correlation features of the Zadoff-Chu sequences are allowing have more
than one UE using the same physical resource.
Image description
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•
The top part of the picture visualizes the features which make Zadoff-Chu
sequences CAZAC sequences.
•
The bottom part of the picture shows how these features are used to allocate two
or more UE’s on the same physical resource.
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3.3.4.1 Zadoff-Chu sequences are CAZAC sequences
CAZAC means Constant Amplitude Zero Auto-Correlation. These features are
exhibited by Zadoff-Chu sequences being used in LTE. Consequently they have an
almost constant amplitude over the complete symbol duration and their
autocorrelation function is 1 at 0 and almost 0 everywhere else over the length of the
useful part of the SC-FDMA symbol.
3.3.4.2 Separation of different UE’s with cyclic shifted Zadoff-Chu sequences.
These features can be used in order to multiplex different UE’s using the same
subcarriers e.g. on the PUCCH. This is done by applying different cyclic shifts to
different UE’s. Please note that for the PUCCH there are 12 sub-symbols in the time
domain for each SC-FDMA symbol. In the picture the sequence of UE 2 is cyclically
shifted by 2 of these sub-symbols against the sequence of UE 1.
Once both UE’s are transmitting on the same RB their signals superimpose at the
eNB’s receiver.
Then the eNB can run the cyclical cross-correlation of UE 1’s not shifted basic
sequence with the received signal. Then there are correlation peaks corresponding to
the CIR and modulation of the two UE’s in different windows of the cross correlation
function. This output can either be used for channel estimation or for demodulation of
the PUCCH messages. Since the CIR of the UE has to fit inside the windows the
number of different UE’s which can be put on the same RB’s is limited by the
expected CIR length.
3
Since for the PUCCH only 1 RB is used the limited bandwidth is allowing only two
independent CIR samples to be measured in each of the 6 windows shown in the
picture. Hence 6 UE’s can be separated by means of the usage of Zadoff-Chu
sequences alone. For high data rate transmissions on the PUSCH more RB’s are
used and hence a more exact channel estimation is possible.
•
Abbreviations of this Section:
CAZAC
Constant Amplitude Zero
Autocorrelation Code
RB
Resource Block
CIR
Channel Impulse Response
RX
Receive
FDMA
Frequency Division Multiple Access
SC-FDMA Single Carrier Frequency Division
Multiple Access
LTE
Long Term Evolution (of UMTS)
UE
User Equipment
PUCCH
Physical Uplink Control Channel
eNB
Enhanced Node B
PUSCH
Physical Uplink Shared Channel
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3.3.5 PUCCH mapping of CQI and other information
3
The objective of this section is to show how CQI and other information are
transmitted on the PUCCH with format 2.
Key point of this section is by means of omitting the spreading and slot
repetition used for the formats 0-1 20 bits can be transported on the PUCCH.
Image description
•
The picture visualizes the procedure of mapping CQI and other information on the
subframe of the PUCCH.
•
In the foreground the picture shown the normal CP configuration. Below the
second slot the extended CP configuration is shown.
3.3.5.1 PUCCH Format 2
For the case that CQI and other information are in need to be transmitted more data
rate than 1-2 bit per subframe is needed.
This is why for format 2 on the PUCCH the individual Zadoff-Chu sequences are
modulated individually with the QPSK symbols and the repetition of the slot as well
as the spreading inside a slot are omitted. There is also no spreading for the pilots.
The advantage of this scheme is that still the UL resources can be shared by different
UE’s by means of applying different cyclic shifts on the Zadoff-Chu sequences of the
data symbols and on the Zadoff-Chu sequences of the pilot symbols.
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Please note that there are two pilot symbols for slot format 2. This leaves 5 symbols
per slot for the normal CP configuration. For the extended CP configuration there is
one symbol less. Consequently there is only 1 pilot symbols to keep 5 symbols per
slot for the extended CP configuration.
3.3.5.2 PUCCH Formats 2a and 2b
These formats allow to transmit an acknowledgement and a CQI together. Here the
first pilot symbol is modulated according to BPSK and QPSK modulation needed to
transmit 1 or 2 acknowledgements. Since there is only 1 reference symbol for the
extended CP configuration these formats are only applicable for the normal CP
configuration.
3
[3GTS 36.211 (5.4)]
Room for your Notes
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
QPSK
Quadrature Phase Shift Keying
CP
Cyclic Prefix
RB
Resource Block
CQI
Channel Quality Indicator
UE
User Equipment
PUCCH
Physical Uplink Control Channel
UL
Uplink
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3.3.6 The Uplink Processing Chain
3
The objective of this section is to illustrate the structure and use of the uplink
processing chain.
Key point of this section is beginning and end of the UL processing chain is
the same as for the DL processing chain.
Image description
•
As the picture above shows the UL signal processing chain is very similar to the
DL signal processing chain. With respect to the difference of OFDM and SCFDMA there are only few differences. In the following the individual stages are
revisited.
3.3.6.1 Transport block bits
There is no difference with respect to the DL signal processing.
3.3.6.2 Scrambling
There is no difference with respect to the DL signal processing.
3.3.6.3 Modulator
There is no difference with respect to the DL signal processing.
3.3.6.4 DFT pre-coder
According to the number of allocated subcarriers the sequence of modulated
symbols is segmented in block with the name number of symbols than the number of
sub carriers. Then each segment is undergoing a DFT.
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3.3.6.5 Demultiplexing of signals other than data
As explained before the pilots symbols, the PUCCH symbols, and the sounding
reference symbols (SRS) are created separately in the frequency domain and do not
follow the DFT. PUSCH, PUCCH, and SRS have their own power control and thus
their own scaling factor. The pilot symbols are following the scaling of their physical
channels. The PRACH is created different form the other physical channels and is
not discussed here.
3.3.6.6 Resource element mapper
According to the allocated subcarriers and the frequency hopping sequence the DFT
transformed symbols are allocated on the subcarriers.
3
3.3.6.7 IFFT
Here the modulated symbols are interpolated in the frequency domain. Some SCFDMA symbols are prepared to transmit reference or sounding signals. Sounding
signals are needed to test a wide range of UL spectrum. Once the eNB is receiving
them is has valuable information on which carriers inside the eNB’s receive band
there is a good opportunity to schedule the UE next.
3.3.6.7 CP
There is no difference with respect to the DL signal processing.
[3GTS 36.211 (5.3)]
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
PUCCH
Physical Uplink Control Channel
CP
Cyclic Prefix
PUSCH
Physical Uplink Shared Channel
DFT
Discrete Fourier Transformation
SC-FDMA Single Carrier Frequency Division
Multiple Access
DL
Downlink
SRS
Sounding Reference Symbol
IFFT
Inverse Fast Fourier Transformation
UE
User Equipment
OFDM
Orthogonal Frequency Division
Multiplexing
UL
Uplink
PRACH
Physical Random Access Channel
eNB
Enhanced Node B
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3.4 Overview all Physical Channels
3
The objective of this section is to give an overview of the structure and
channel coding of all physical channels.
Key point of this section is that especially in the DL several physical
channels are sharing the subframes.
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Table description
The upper section of the table is describing the DL physical channels and the DL
physical signals where as the lower half of the table is doing the same for the UL.
In the following the channels and signals are described closer which are not treated
in very much details in the other sections of this book.
•
3.4.1 Special usage of the 6 RB around the DC carrier
These RB’s are shared in-between all DL physical channels and physical signals. In
the first subframe the some symbols are dedicated to the PBCH. Please note here
that the 2 last symbols of the 1st and 10th slot are used by the primary and
secondary synchronization signal.
•
3
Abbreviations of this Section:
16-QAM
16 symbols Quadrature Amplitude
Modulation
PDSCH
Physical Downlink Shared Channel
64-QAM
64 symbols Quadrature Amplitude
Modulation
PHICH
Physical HARQ Acknowledgement
Indicator Channel
BCH
Broadcast Channel
PMCH
Physical Multicast Channel
BPSK
Binary or Bipolar Phase Shift Keying
PRACH
Physical Random Access Channel
CRC
Cyclic Redundancy Check
PUCCH
Physical Uplink Control Channel
DC
Direct Current
PUSCH
Physical Uplink Shared Channel
DL
Downlink
QPSK
Quadrature Phase Shift Keying
DL-SCH
Downlink Shared Channel
RACH
Random Access Channel
FFS
For Further Study
RB
Resource Block
L1
Layer 1 (physical layer)
RNTI
Radio Network Temporary Identifier
MCH
Multicast Channel
SC-FDMA Single Carrier Frequency Division
Multiple Access
OFDM
Orthogonal Frequency Division
Multiplexing
SCH
Synchronization Channel
OFDMA
Orthogonal Frequency Division
Multiple Access
TrCH
Transport Channel (UMTS)
PBCH
Physical Broadcast Channel
UL
Uplink
PCFICH
Physical Control Format Indicator
Channel
UL-SCH
Uplink Shared Channel
PCH
Paging Channel
XOR
Exclusive-Or Logical Combination
PDCCH
Physical Downlink Control Channel
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LTE from A-Z
3.4.2 Multiplexing of the PCFICH, PDCCH and the PDSCH/PMCH in the normal
DL subframe.
In the normal DL subframe the PDSCH is used together with the PCFICH and the
PDCCH. The first OFDM symbol is (partially) be used by the PCFICH. The PCFICH
is indicating how big the PDCCH will be: Whether it uses 1, 2, or 3 (+1 each number
in case of less than 10 RB's) first OFDM symbols of the DL sub frame. The remaining
symbols of the OFDM subframe are used by the PDSCH. The PMCH can be treated
in the same way as the PDSCH. The different is that it is used on one special
antenna port for SFN transmissions only.
The PRACH isexplained in a later section.
3.4.3 Sounding reference signal
The sounding reference signal is requested by the UE once it is in need to access the
UL channel in order to decide which resources to schedule to the regarded UE. Once
the UE is performing regular UL transmission there is no need to have this sounding
signal. This is why there will be a special procedure to schedule this signal to the UE.
The sounding signal may be mapped on the last symbol of an UL subframe and it will
likely be a broadband signal.
The PUCCH has been explained already in an earlier section.
3.4.4 Modulation of the physical channels
The PDSCH, PMCH and the PUSCH are carrying payload thus they are able to carry
QPSK, 16-QAM and 64-QAM. For the signaling channels mostly QPSK is used. The
PUCCH is the only exemption.
3.4.5 Channel coding
The PDSCH, PMCH and the PUSCH are using turbo coding like in HSPA. For the
signaling channels another approach than in UMTS has been taken. The signaling
channels are only carrying few bits compared to the payload carrying channels. With
the block sizes the tails bits for the convolutional encoding can take a significant
portion of the overall input of the channel encoder. This is why in LTE tailbiting
convolutional coding is used. This has the advantage that the tailbits are spared. As
some DL signaling channels in HSPA the PDCCH is using as well a 16 bit CRC
which is masked wit the 16 bit RNTI’s used for indication for which user the DL
signaling is intended for. The PDCCH may also indicate which TX antenna the UE is
supported to use (format 0). This will also be done using a CRC masking code.
Room for your Notes
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Room for your Notes
3
•
Abbreviations of this Section:
16-QAM
16 symbols Quadrature Amplitude
Modulation
PMCH
Physical Multicast Channel
64-QAM
64 symbols Quadrature Amplitude
Modulation
PRACH
Physical Random Access Channel
CRC
Cyclic Redundancy Check
PUCCH
Physical Uplink Control Channel
DL
Downlink
PUSCH
Physical Uplink Shared Channel
HSPA
High Speed Packet Access (operation QPSK
of HSDPA and HSUPA)
Quadrature Phase Shift Keying
LTE
Long Term Evolution (of UMTS)
RNTI
Radio Network Temporary Identifier
OFDM
Orthogonal Frequency Division
Multiplexing
SFN
Single Frequency Network
PCFICH
Physical Control Format Indicator
Channel
UE
User Equipment
PDCCH
Physical Downlink Control Channel
UL
Uplink
PDSCH
Physical Downlink Shared Channel
UMTS
Universal Mobile Telecommunication
System
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3.5 Physical Layer Procedures
3
The objective of this section is to give an overview of the following physical
layer procedures.
Timing advance control
Here the way how timing advance control is performed and the way possible timing
advance control commands are signaled should be covered.
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Channel estimation
Here the differences of UL and Downlink channel estimation should be tackled.
Especially how to achieve that individual channel estimation can be performed for the
individual transmit antennas.
Power control
Here the way how power control is performed and the way possible power control
commands are signaled should be covered.
MIMO
Here the details of how the signals are prepared for MIMO transmission should be
covered: the codebook, closed loop MIMO, and CDD. As well some background of
MIMO technology should be given in order to achieve understanding of the applied
methods.
3
Initial cell search
Here the detailed procedure of synchronizing on the primary synchronization signal,
secondary, synchronization signal, and finally on the BCH should be described.
Random access
Here the details of the random access procedure should be given.
Inter Cell Interference Mitigation
Here the way how the different cells are coordinating their interference in the network
is described.
[3GTS 36.211, 3GTS 36.213]
Room for your Notes
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
MIMO
Multiple In / Multiple Out (antenna
system)
BCH
Broadcast Channel
UL
Uplink
CDD
Cyclic Delay Diversity
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3.5.1 Timing Advance Control
3.5.1.1 Principle
3
The objectives of this section are to show the principle operation of timing
advance control in LTE and to state to what degree the time synchronization
by means of timing advance control is in need to be maintained.
Key point of this section is that since LTE is a TDMA system like GSM TA
like in GSM becomes necessary.
Image description
This picture is stating the basic synchronization requirements for OFDM and is
visualizing the behavior of the system in the synchronized and in the
unsynchronized case.
In UTRA the downlink signals are synchronized to a 256 chip grid whereas the uplink
signals are asynchronous amongst each other. This is a rather relaxed
synchronization requirement.
However in LTE, due to the special nature of the applied OFDM and SC-FDMA
technology even tougher synchronization requirements have to be followed.
•
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Like in GSM there is the TDMA structure to be followed. This is requiring that the UL
frames of all the UE’s are synchronized to the eNB’s timing grid.
As well the usage of OFDMA and SC-FDMA technology is implying that signals for
multiple UE’s are received or transmitted at the same time. In order to allow for a
good separation of the signals for the different UE’s this is requiring that the cyclic
prefixes are coinciding. For the downlink this is quite simple to implement because
the eNB is aligning the CP’s of the signals for the different UE’s automatically.
For the UL however this is more difficult to achieve. As shown in the picture once the
UE’s CP’s are not arriving in a synchronous manner in the eNB the distortions
caused by the changing symbol modulation in the CP interfere with the UE’s signals
on the neighboring carriers. This inference will make a successful detection
impossible.
Only once the SC-FDMA symbols are synchronized such that their CP’s are coinciding the interference is falling into the CP. Since the CP is not processed for the
detection process it is not harmful in the synchronized case.
3
Room for your Notes
•
Abbreviations of this Section:
CP
Cyclic Prefix
TA
Timing Advance
DL
Downlink
TDMA
Time Division Multiple Access
GSM
Global System for Mobile
Communication
UE
User Equipment
LTE
Long Term Evolution (of UMTS)
UL
Uplink
OFDM
Orthogonal Frequency Division
Multiplexing
UTRA
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access
OFDMA
Orthogonal Frequency Division
Multiple Access
eNB
Enhanced Node B
SC-FDMA Single Carrier Frequency Division
Multiple Access
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Like in GSM this synchronization is achieved by means of timing advance control.
The UE has to apply a timing advance which is shifting the gird of the UL timing
against the downlink grid of the DL at the UE. Since both the downlink needs a
propagation delay  to arrive at the UE’s position and the uplink needs a propagation
3
delay τ as well to arrive at the eNB the uplink timing grid has to advance twice to
propagation delay at the UE’s position to arrive in the eNB’s timing grid at the eNB’s
position.
The eNB is controlling the timing advance of the UE’s by means of timing advance
control commands. In general the average CIR profile is controlled since the control
algorithm is too slow to follow the instantaneous changes of the mobile radio
channels propagation delay. Since the CP can have a length of only about 5 s the
accuracy of the timing advance control has to be for sure better than 1 s. It has to
be highlighted here the timing advance inaccuracy is shortening the maximum length
of the channel impulse response tolerated by the system.
It is open until now whether the timing advance control is an open or closed loop, and
whether it is performed suing physical layer power control commands or using higher
layer commands.
[3GTR 25.814 (9.1.2.6)]
Room for your Notes
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Room for your Notes
3
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
GSM
Global System for Mobile
Communication
CIR
Channel Impulse Response
UE
User Equipment
CP
Cyclic Prefix
UL
Uplink
DL
Downlink
eNB
Enhanced Node B
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3.5.1.2 Procedure
3
The objectives of this section are to show how in detail the timing advance
control algorithms work.
Key point of this section is that the timing advance control is operating
differently for the unsynchronized and the synchronized state.
Image description
•
This picture is showing the operation of TA control as a flow chart in the
unsynchronized and in the synchronized state.
3.5.1.2.1 TA while the UE is not synchronized to the eNB
Once the UE is not synchronized the UE will send a random access preamble until it
gets a response from the network. After that the eNB will transmit a message with the
TA. The length of the TA message and the physical channel the TA message will be
transmitted is not clear now.
In any case the granularity of the TA is 0.52 μs. This is 16 T(sample) which would
correspond to the sampling grid of a 1.25 MHz carrier which is the smallest
bandwidth discussed for LTE so far. 0.52 μs is corresponding to a distance of 75 m.
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This TA update is transmitted on the DL-SCH using a special LCID in the MAC-PDU
header is reserved for the RACH message 2.
3.5.1.2.2 TA while the UE is synchronized to the eNB
Once the UE is in the synchronized state the eNB will listen to the physical channels
being transmitted by the UE. It is not clear which physical channel can be listened to:
PUCCH, PUSCH, or sounding signals. Once the UE has not transmitted something
after a given time the eNB will ask the UE to issue a sounding signal. With the
analysis of the sounding signal then the TA update can be determined.
Once of the key differences to GSM TA update is that a TA update will only be
performed once it is needed. This is typically the case every two seconds. Once the
eNB is recognizing that the UE is not very mobile it will not issue a new TA very
often. In case a TA update is needed the eNB will transmit a TA update relative to the
old timing advance possibly on the PDCCH. This TA update is transmitted on the DLSCH using a special LCID in the MAC-PDU header is reserved for timing advance
transmissions.
3
Once an UL signal with a bandwidth of 1080 kHz (72 subcarriers) or more is
transmitted the TA can be determined without interpolation techniques. Once the
bandwidth is reduced to e.g. 1 resource block (180 kHz) then the TA can only be
determined with a granularity comparable to GSM (5 s) and then interpolation
techniques will have to be applied to come to a better resolution. Some mobile
radio channels might then not support a reasonable TA performance any more.
[3GTR 25.814 (9.1.2.6), 3GTS 36.211 (8), 3GTS 36.213 (4.2.4), 3GTS 36.221
(6.2.1)]
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
PDU
Protocol Data Unit or Packet Data
Unit
3GTS
3rd Generation Technical
Specification
PUCCH
Physical Uplink Control Channel
DL
Downlink
PUSCH
Physical Uplink Shared Channel
DL-SCH
Downlink Shared Channel
RACH
Random Access Channel
GSM
Global System for Mobile
Communication
TA
Timing Advance
LCID
Logical Channel ID
UE
User Equipment
LTE
Long Term Evolution (of UMTS)
UL
Uplink
MAC
Medium Access Control
eNB
Enhanced Node B
MHz
Mega Hertz (106 Hertz)
kHz
Kilo Hertz (103 Hertz)
PDCCH
Physical Downlink Control Channel
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3.5.2 Channel Estimation DL
3.5.2.1 Channel Estimation Principle of LTE
3
The objective of this section is to show the background and the necessity of
channel estimation in LTE.
Key point of this section is that the mobile radio channel essentially behaves
the same in multiple dimensions: frequency and time (space).
Image description
3.5.2.1.1 The description of the mobile radio channel
In OFDMA technology the mobile radio system is dimensioned that the mobile radio
channel is flat on the individual subcarriers. This means that the mobile radio
channels influence can simply be described by means of a multiplication with a
complex number. This complex number is introducing distortions on the transmitted
data symbol i.e. the amplitude and the phase of the received symbols are different
than the amplitude and phase of the transmitted symbols.
Once the mobile radio channel is known then this distortion can be undone by means
of dividing by the estimated complex number.
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This picture is showing the basic behavior of the mobile radio channel. Since the
mobile radio channel is changing with time and also with frequency selectively, the
channel estimate is in need to cover these changes and also to provide a channel
estimates for data symbols on subcarriers where there are no reference or pilot
symbols transmitted.
Room for your Notes
3
•
Abbreviations of this Section:
CINR
Carrier to Interference and Noise
Ratio
OFDM
Orthogonal Frequency Division
Multiplexing
CIR
Channel Impulse Response
OFDMA
Orthogonal Frequency Division
Multiple Access
FFT
Fast Fourier Transformation
SC-FDMA Single Carrier Frequency Division
Multiple Access
IFFT
Inverse Fast Fourier Transformation
UE
LTE
Long Term Evolution (of UMTS)
User Equipment
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LTE from A-Z
3.5.2.1.2 Coping with a frequency selective mobile radio channel
At first the mobile radio channel is showing different behavior on different subcarrier.
This means that the phase shift and attenuation of the mobile radio channel is
different for different subcarriers. The background is that the CIR is creating a
frequency selective mobile ratio channel. The longer the CIR the more frequency
selectivity is created. The Fourier Transformation of the CIR is the subcarrier
spectrum. In order to space possible pilots or reference signals on the subcarriers
with the right spacing in-between each other the sampling theorem has to be
adhered to in the frequency domain. This means that the pilot subcarrier spacing has
to follow at least the following equation:
Δf(pilot)≤1/τ
With Δfpilot being the subcarrier spacing of the pilots and τ being the max. length of
the CIR (note that for SFN the CIR is lengthening due to the big difference of
distance of the eNB’s). Here the longer the CIR has to be expected the more dense
the pilot signals have to be spaced.
3.5.2.1.3 Coping with the time variance of the mobile radio channel
Secondly the mobile radio channel is changing with time. This is mainly cased by the
UE’s movements. Each movement is causing a small frequency shift being called
Doppler shift. The maximum Doppler frequency is proportional to the velocity of the
UE. In order to cover this, the pilots have also to be repeated from time to time in
order to follow the time variations of the mobile radio channels. Mathematical
speaking the inverse Fourier Transformation of the Doppler spectrum is giving the
behavior over time of the individual subcarriers. For the right spacing of the pilots in
time the following equation has to be adhered to in order to fulfill the sampling
theorem in the time domain:
Δt(pilot)≤1/(2 f(d, max))=c/(2 f(c) v)
With Δt(pilot) being the time spacing of consecutive pilot symbols, f(D, max) being the
maximum Doppler shift, c the speed of light v the velocity of the UE and f(c) the
carrier frequency.
Of course the time variance and frequency selectivity are working on the mobile radio
channels independently from each other.
Room for your Notes
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Room for your Notes
3
•
Abbreviations of this Section:
CIR
Channel Impulse Response
UE
User Equipment
SFN
Single Frequency Network
eNB
Enhanced Node B
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3.5.2.2 Channel Estimation Downlink
3
The objective of this section is to show how the reference symbols are
distributed in time and subcarrier space and how it is ensured that the
signals from different TX antennas can be separated in the downlink.
Key point of this section is that the special arrangement of the pilot symbols
is enabling the receiver to estimate the channel impulse response belonging
to the individual transmit antennas.
Image description
•
The picture is focusing on the 15 kHz sub carrier spacing and is showing how the
pilot subcarriers are distributed.
3.5.2.2.1 Normal configuration with 4 TX antennas
Here the pilot symbols have to enable the differentiation of 4 antennas. This is done
by means of having exclusively reserved positions of pilot symbols for the individual
antennas. If one antenna is transmitting on one subcarrier this subcarrier will not be
used by the other antenna neither for pilot symbols nor for data symbols.
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This has the advantage that no interference is coming from the other antennas for the
channel estimation of the regarded antenna.
The disadvantage obviously is that the throughput to be transmitted for each antenna
is suffering the more antennas are used.
For the 3rd and the 4th antenna the pilot symbols are less dense in the time domain,
because 4 antennas would lead to an extremely high data rate and this is only less
likely to successfully happening with a high UE mobility. So the UE speed to be
supported can be lower from the channel estimation point of view also.
3.5.2.2.2 Normal configuration with less than 4 TX antennas
If the above allocation would be used for less than 4 antennas (2 and 1 antenna)
there would be some positions which are never used. In order to gain throughout
these positions will be used for data symbols again.
3
3.5.2.2.3 Extended configuration with 15 kHz subcarrier spacing
Here the difference is that there are only 6 OFDM symbols instead of the 7 symbols
shown in the picture. The change here is that the symbols with the number 2 or 3 in
the normal configuration is omitted.
3.5.2.2.4 Extended configuration with 15 kHz subcarrier spacing for MBSFN
This configuration is used for MBMS transmission combined with SFN only. Here the
channel impulse responses can be very long. This is the reason why the pilots a
more dense in the frequency domain. Since the MBMS services are expected to be
associated with less mobility for the UE there are more OFDM symbols as for the
other configurations.
3.5.2.2.5 Extended configuration with 7.5 kHz subcarrier spacing for MBSFN
This configuration is existing only in the DL – thus for broadcast operation.
As shown in the lower part of the picture, optionally the channel impulse response
can be interpolated in-between the pilot symbols for equalizing the data symbols.
[3GTS 36.211 (6.10)]
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
SFN
Single Frequency Network
DL
Downlink
TX
Transmit
MBMS
Multimedia Broadcast / Multicast
Service
UE
User Equipment
MBSFN
MBMS Single Frequency Network
kHz
Kilo Hertz (103 Hertz)
OFDM
Orthogonal Frequency Division
Multiplexing
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3.5.3 Power Control Principle (PUSCH)
3
The objective of this section is to show the principle operation of UL power
control in LTE.
Key point of this section is that in LTE there is no clear distinction in-between
open loop and closed loop power control. It is rather a matter of
parameterization and implementation what scheme is followed.
Image description
• This picture is visualizing the most likely setup of power control.
Since the details of the PC standardization are not settled, this description is only of
preliminary nature.
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The PC mechanism will be a mixture in-between open loop and closed loop power
control. It will take both advantage of scheduling grants or corrections being sent on
PDCCH (closed loop power control) and adjustment of the TX power according to a
measured path loss in-between eNB and the UE (open loop power control). From
time to time the eNB will adjust the parameters for the PUSCH power control.
For a FDD system this scheme will result in a rather slow power control compared to
UMTS because
1. Since UL and DL are different the path loss has to be averaged in order
to get a reliable figure. This will make the algorithms slow.
2. Due to the packet nature of the complete traffic there will be a delay for
the UL transmissions needed for the eNB to correct the UL power and
the DL signals communicating the new power.
Since UL and DL are reciprocal in TDD it can be expected that PC control will
happen faster than in FDD. In TDD for slow UE mobility there is no averaging for the
path loss needed.
3
[3GTR 25.814 (7.1.2.5, 9.1.2.4), 3GTS 36.213 (5)]
Room for your Notes
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
PDCCH
Physical Downlink Control Channel
3GTS
3rd Generation Technical
Specification
TB
Transport Block
BCH
Broadcast Channel
TDD
Time Division Duplex
DL
Downlink
TX
Transmit
DL-SCH
Downlink Shared Channel
UE
User Equipment
FDD
Frequency Division Duplex
UL
Uplink
LTE
Long Term Evolution (of UMTS)
UMTS
Universal Mobile Telecommunication
System
MCS
Modulation and Coding Scheme
eNB
Enhanced Node B
PC
Power Control
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3.5.4 Antenna Processing
3.5.4.1 The Transmission Diversity Problem
3
The objective of this section is to show the essential problem to be solved for
successfully applying transmission diversity.
Key point of this section is the problem to be overcome by transmission
diversity is that uncontrolled superimposition of the signals in the mobile
radio channel leads to destructive superimposition at the receiver antennas.
Image description
•
The left side of the picture is showing the receive diversity case: one transmission
antenna is received by two receive antennas. It is shown how the mobile radio
channels are altering the pilot signals.
•
The right side of the picture is showing a bad example for transmit diversity: two
transmission antennas are received by a single receive antenna. It is shown how
the mobile radio channels are altering the pilot signals.
3.5.4.1.1 Receive diversity
With receive diversity the not modulated carrier (pilot) is altered in amplitude and
rotated differently by the two mobile radio channels. Since two signals are arriving at
the receiver the receiver can rotate them back and add them up such that they
superimpose constructively in the receiver. Here the receiver has to control about the
superimposition. This controlled superimposition is also called maximum ration
combining.
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3.5.4.1.2 Unsuccessful transmit diversity
Once the transmitter is just plainly transmitting the same signal on two antennas,
there are two mobile radio channels towards the same receive antenna. Once this
scheme would be applied the receiver would not know how the mobile radio channels
have alerted the amplitude and rotated the phase. The data subcarrier will arrive with
an uncontrolled superimposition created at the received antenna. Here it is not
possible for the receiver to intervene. This random superimposition is of same nature
as the fading in the fading channel. Effectively this scheme would create very
unpleasant fast fading even for a LoS channel.
3
Consequently the key problem with transmit diversity is how to deal with the
controlled superimposition on the mobile radio channel.
Room for your Notes
•
Abbreviations of this Section:
RX
Recieve
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3.5.4.2 AAS in LTE
3
The objective of this section is to how the transmission diversity problem is
solved by AAS.
Key point of this section is that the UE is measuring the responses of the
mobile radio channel and is informing the eNB. Then the eNB can exploit
this knowledge.
Image description
•
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The picture is showing the AAS case: two transmission antennas are received by
one receive antenna. It is shown how the mobile radio channels are altering the
pilot signals.
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Here the eNB is transmitting pilot subcarriers. These pilots are analyzed by the UE.
The key issue here is that one antennas is transmitting its pilot subcarriers where the
other antenna is silent. Then the UE can determine each antennas mobile radio
channel exactly. Then the UE determines how the data signal should be rotated in
the transmitter such that they are superimposing constructively at the antenna of the
receiver. This knowledge is signaled in FDD systems to the eNB. Then the eNB can
apply the beamforming weights to the data subcarriers whilst leaving the pilot
subcarriers unchanged.
For TDD systems no signaling is necessary the eNB can just analyze the uplink
signal and apply the reciprocity of the mobile radio channel in order to get the right
beamforming coefficients.
3
Once the UE moved too fast (10 – 20 km/h) then the signaling is too slow to follow
the changes of the mobile radio channel. Then AAS will not work with high
performance in the DL any more. UL AAS will still be possible.
Since the transmit antennas are only half a wavelength apart from each other they
are not independent form each other. Consequently only beamforming gain but no
diversity gain can be exploited.
[3GTS 36.211 (6.3.4)]
Room for your Notes
•
Abbreviations of this Section:
AAS
Adaptive Antenna Systems
UE
User Equipment
FDD
Frequency Division Duplex
eNB
Enhanced Node B
TDD
Time Division Duplex
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3.5.4.2.1 Practical Exercise: Draw the Antenna Diagram of AAS
3
The objective of this section is to enable the students to understand how the
directional antenna diagram of AAS works.
Image Description
- 192 -
•
This picture shows the situation that 2 antennas are spaced with a distance d
being half a wavelength.
•
The top part of the picture shows the geometry of the antenna system. It shows
how to calculate for a direction α the difference in path length of the two antennas
(Δp). Once the path length is differing by a wavelength then the phase difference
β in-between two paths is 360 degree. The table next to the top drawing leads to
the phase differences β fitting to some directions α.
•
The middle section of the picture is adding up the 2 antennas’ phasors such that
amplitude and power of the sum-phasor can be determined and filled into the
table next to the middle picture.
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The lower part of the picture gives the antenna diagram of the two antennas
together. On the lobes we can see later on from the distance to the origin of the
coordinate system how much power is radiated in what direction α. This picture is
using polar coordinates.
Your tasks:
•
1. At first the vector addition of the two antenna phasors is performed inside
the middle drawing. In order to do this it is assumed that the antenna
weights are 1 for both antennas. The path of the antenna two can be longer
than the path of antenna 1. This leads to the fact that both antenna phasors
do not add up with the same phase. The first phasor (belonging to the first
antenna) is always the same. Whilst the second phasor has to be added up
with the angle β calculated before. For each angle b draw a second phasor
and connect beginning of the first phase with the end of the second phasor.
This is already done for β equals 0 degree.
3
2. Measure the lengths of the sum vectors with a ruler and enter the measured
amplitude in cm in the table next to the drawing.
3. Square the amplitude value and enter the resulting power in the power
column of the table.
4. For the lower drawing there are already rays with the angle α given in 15
degree grid. For each of the rays with angle α draw a vector on the ray
having the length of the power (in cm) calculated before. If you like
calculate the value for 15 degree. Finally connect the tips of the vectors to a
lobe.
5. Think about how the antenna diagram will look like for a complete 360
degree circle of α.
6. How many lobes the antenna diagram would have for a distance of d = 10 λ.
Answer: __ lobes.
Room for your Notes
•
Abbreviations of this Section:
AAS
Adaptive Antenna Systems
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3.5.4.3 CDD
3
The objective of this section is to how the transmission diversity problem is
solved by CDD.
Key points of this section are that the two antennas signals can be resolved
once they are transmitted with a delay against each other and that this is
enabling MIMO to work in an open loop fashion.
Image description
•
The picture is showing the CDD case: two transmission antennas are received by
one receive antenna. It is shown how the UE can resolve the two signals.
3.5.4.3.1 Delay diversity
For UMTS the Node B is transmitting the two antennas signals with a delay which
could last for several samples. For the UE this seems like it received two
independent paths which can be resolved by the rake receiver. In a way the space
diversity at the individual antennas is transformed into multiple path diversity in the
receiver.
3.5.4.3.2 Cyclic delay diversity
In OFDM systems CDD is used. Before the CP is applied the useful part of the
symbol is cyclically shifted. This means the parts of the delayed signal which would
be outside the useful symbol will be reintroduced at the beginning. Finally the CP is
applied.
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With CDD a very big shift can be implemented such that the performance can almost
reach the performance of 2 way diversity with receive diversity. In a way the space
diversity at the individual antennas is transformed into frequency diversity in the
receiver. However, since multiple path propagation on its own is leading to inter
symbol interference and frequency selective fading there are performance penalties.
3.5.4.3.3 Cyclic delay diversity and MIMO
The key application area of CDD is that it can be used once close loop MIMO is not
working any more. Then MIMO work with less performance in an open loop fashion.
This will enable to provide a big throughput gain wherever there is a strong channel
with a bad condition of the channel matrix.
3
[3GTS 36.211 (6.3.4.2.1, 6.3.4.2.2)]
Room for your Notes
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
RF
Radio Frequency
CDD
Cyclic Delay Diversity
UE
User Equipment
CP
Cyclic Prefix
UMTS
Universal Mobile Telecommunication
System
OFDM
Orthogonal Frequency Division
Multiplexing
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3.5.4.4 SFBC
3
The objective of this section is to how the transmission diversity problem is
solved by SFBC.
Key point of this section is that the eNB is transmitting 2 subcarriers with
different order and according to a different code on the 2 transmit antennas.
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Image description
•
The picture is showing the SFBC case: two transmission antennas are received
by one receive antenna. It is shown how the mobile radio channels and the SFBC
are altering the constellation diagrams of BPSK modulated signals.
3.5.4.4.1 Space Frequency Block Codes
With SFBC the signals on two subcarriers from the same OFDM symbol are
transmitted with different orders and altered differently on the different transmission
antennas. The result is that the two symbols look like a higher order modulation
scheme at each of the receive antennas.
The SFBC decoder is able to reconstruct the two subcarrier signals completely
regardless how they superimposed on the mobile radio channel.
[3GTS 36.211 (6.3.3.3, 6.3.4.3)]
3
3.5.4.4.2 Space Time Block Codes
STBC are applying the same codes by to symbols at different times instead of
subcarriers on different frequencies. STBC’s are not used in LTE. However STBC is
used in UMTS for BCCH transmission.
STBC and SFBC for two antennas can apply 2-way transmit diversity. They are
existing only since 1998. There is no SFBC (STBC) for N>2 antennas which is
able to provide N-way diversity.
SFBC and STBC on their own are not suitable to double the peak throughput.
They only improve the receiver performance.
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
SFBC
Space Frequency Block Codes
BPSK
Binary or Bipolar Phase Shift Keying
STBC
Space Time Block Coding
LTE
Long Term Evolution (of UMTS)
eNB
Enhanced Node B
OFDM
Orthogonal Frequency Division
Multiplexing
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3.5.4.5 MIMO
3
The objective of this section is to how the MIMO signals are propagating
through the system.
Key point of this section is that the data rate can be enhanced by using
multiple antennas in the eNB and in the UE.
Image description
The picture is showing the MIMO case: two transmission antennas are received
by two receive antennas. It is shown how the mobile radio channels are altering
the signals and how the equalizer in the UE is able to separate the signals again.
For an easier understanding this picture assumes that the mobile radio channels
which go over cross are much weaker than the direct mobile radio channels.
MIMO is applying different data streams on different transmission antennas. Once
the UE is having multiple antennas to receive these signals then the UE is able to
separate the data stream again by using an equalizer. In order to increase the data
rate by N times both the eNB and the UE need to have at least N antennas.
•
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In order to prepare the equalizer the UE needs to estimate all the mobile radio
channels created by every combination of TX and RX antenna. In this example this
would be 4 channel estimations.
[3GTS 36.211 (6.3.3.2, 6.3.4)]
3.5.4.5.1 MIMO and AAS combined = multiple rank beamforming
LTE is combining MIMO with AAS then each data stream can be beamformed using
all TX antennas. Since for MIMO the TX antennas are very distant form each other in
order give good performance no distinct beans as in the original AAS will be formed.
The rank of the transmission describes how many data streams are transmitted
together. If multiple rank beamforming is applied the UE has to feedback to the eNB
what set of beamforming weights has to be applied.
3
3.5.4.5.2 When MIMO fails
The performance of MIMO is strongly dependent on the instantaneous combination
of the mobile radio channels. It could be that the individual mobile radio channels are
excellent but that MIMO fails nevertheless. In this case the equalizer is not able to
process ambiguous signals and is creating a lot of noise. The following measures are
used in order to reduce the probability of failure:
1. The TX and RX antennas are placed far enough to create a
decorrelated behavior: eNB several wave lengths and UE about half a
wavelength.
2. MIMO should be applied in the presence of multiple path propagation.
3. The UE is giving feedback to the eNB that the rank of the MIMO
transmission has to be reduced. In the extreme case the eNB is
switching back to simple AAS or SBFC.
Room for your Notes
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
RX
Receive
AAS
Adaptive Antenna Systems
TX
Transmit
LTE
Long Term Evolution (of UMTS)
UE
User Equipment
MIMO
Multiple In / Multiple Out (antenna
system)
eNB
Enhanced Node B
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3.5.4.6 The Codebook
3
The objective of this section is to how the UE and eNB are communicating
about the best set of beamforming weights for AAS and MIMO.
Key point of this section is that the UE is just providing the number of to be
transmitted streams and the number of the set of beamforming weights
according to a codebook.
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Image description
•
The picture is showing basic use of the codebook for LTE and the codebook
entries for simple AAS in detail.
3.5.4.6.1 Optimum beamforming weights
The optimum set of beamforming weights for the case that the receiver has just 1
antenna is a set of weights which is maximizing the SIR at this receive antenna.
Mathematically speaking this is the solution of a generalized Eigenvalue problem.
Once for MIMO multiple data streams are transmitted each received antenna will
have a set of optimum weights which is applicable to all the data streams. The task
here is that the best combination of weight sets has to be found which is separating
as much as possible the different data streams at the receive antennas already. This
is leading to a generalized Eigenvalue problem taking the transmission of the other
data stream as interference. The exact treatment of these problems would go far
beyond the scope of this training. The reason why the mathematical terms are
mentioned here is to illustrate two problems:
1. It will take a very big computational effort to determine the optimum sets
of beamforming weights for each data stream
2. To signal these sets will consume a very big data rate.
3
3.5.4.6.2 Signaling of sub-optimum beamforming weights
For this reasons both eNB and UE have a codebook which will contain the codes to
be used during the AAS and the MIMO operation. Then the UE only needs to signal
the code number and the number of data streams it can take. This is reducing the
signaling load.
Another advantage is that now the UE does not need to calculate (backward) the
optimum sets of beamforming weights. It will just take the entries of the codebook to
calculate (forward) the SIR’s of the codebook entries and the different numbers of
dada streams. This is requiring a lot less computational effort.
Then the UE will select the number of data streams and the number of the codebook
entry and transmit it to the eNB. Of course the result will be not optimum but it is a
good compromise in-between good performance, high data rate, and low signaling
effort.
[3GTS 36.211 (6.3.4.2.3)]
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
SIR
Signal to Interference Ratio
AAS
Adaptive Antenna Systems
UE
User Equipment
LTE
Long Term Evolution (of UMTS)
eNB
Enhanced Node B
MIMO
Multiple In / Multiple Out (antenna
system)
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3.5.5 Initial Cell Search
3.5.5.1 Primary and Secondary Synchronization Signals
3
The objective of this section this section is to provide the details and the
function of the primary sand secondary synchronization signals.
Key point of this section is primary and secondary synchronization signals
are used similar to UMTS but the details are differing a lot.
Image description
This picture is showing how the primary and secondary synchronization signals
are fitted on the DL carrier and on the DL frame together with the PBCH. As well
their structure inside their OFDM symbol is shown.
The primary and secondary synchronization signals a located together with the
PBCH (carriers the BCH) on the 72 subcarriers around the DC subcarrier of every
LTE carrier. Thus they occupy a bandwidth of 1080 kHz.
On the 72 carrier the normal 10 ms radio frame with its 20 slots is mapped. The
primary synchronization signal is the last OFDM symbol on slot 0 and on slot 10. The
secondary synchronization signal is located on the same slots as the primary
synchronization signal but is transmitted one symbol earlier.
•
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Presumably the rest of the symbols of these 72 subcarriers are occupied by the
PBCH with holds the BCH and thus partly the BCCH.
The Primary and Secondary Synchronization signal are governing the
synchronization process.
The time grid of modulation on these signals is 0.52 s which is 16 times the LTE
sampling frequency. This grid is the same as for the TA algorithm.
Sequences and codes for these signals are still discussed in the standardization
bodies. The primary synchronization sequence will have 3 sequences and it is likely
that the secondary synchronization signal will have 336 different sequences.
There are 504 = 3 * 168 L1 cell ID’s in the LTE system they are grouped in 168
groups of 3 ID’s each. The members of the group are distinguished by the P-SCH
and the groups are distinguished by the Secondary Synchronization Signal. The
Secondary Synchronization Signal is transmitted twice per radio frame 336 = 2 * 168
sequences are needed in order to distinguish finally the radio frame and the L1 cell
ID’s.
3
[3GTR 25.814 (7.1.2.4), 3GTS 36.211 (6.11), 3GTS 36.213 (4)]
Room for your Notes
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
LTE
Long Term Evolution (of UMTS)
3GTS
3rd Generation Technical
Specification
OFDM
Orthogonal Frequency Division
Multiplexing
BCCH
Broadcast Control Channel
PBCH
Physical Broadcast Channel
BCH
Broadcast Channel
PCFICH
Physical Control Format Indicator
Channel
CP
Cyclic Prefix
PDCCH
Physical Downlink Control Channel
DC
Direct Current
PDSCH
Physical Downlink Shared Channel
DL
Downlink
TA
Timing Advance
ID
Identity
UMTS
Universal Mobile Telecommunication
System
L1
Layer 1 (physical layer)
kHz
Kilo Hertz (103 Hertz)
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3.5.5.2 Procedure
3
The objective of this section is to show how primary and secondary
synchronization signal are used together with the BCH in order to achieve
perform initial cell search.
Key point of this section is that the sequence of events for the initial cell
search is exactly the same as for UMTS.
Image description
•
On the boxes of this picture the flow of events is shown.
The right of the boxes there is a description of what information the UE knows
once it has completed the individual steps successfully.
The initial cell search begins with the UE being switched on. Soon after that the USIM
card will issue a cell search request.
At this time the UE does not know anything about the cells around it and it begins to
look for strong cells in the DL band. Once it has found a good candidate with strong
72 carriers looking like they might carry the synchronization sequences and the BCH
it has performed rough frequency synchronization already.
The UE will look for the Primary Synchronization Signal. Once it has found it, it knows
the exact carrier frequency and the timing of the slot 0 or 10. At this point the UE
might already have a few hints regarding the CP configuration. It will also have
performed the first step to find the L1 cell ID of that cell. Each of the 3 Primary
Synchronization Signal sequences is linked to one group member of the 168 different
L1 cell ID groups.
•
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The next step would be to detect the Secondary Synchronization Signal. The
Secondary Synchronization Signal is transmitted 1 OFDM symbol before the Primary
Synchronization Signal. Once the Secondary Synchronization Signal is detected the
radio frame and the L1 cell ID are perfectly known. As well the UE now knows the CP
configuration exactly.
Then the UE is ready to read the BCH to get the master information block. This will
inform the UE about the SFN, the antenna configuration and the DL bandwidth of that
cell. Then the UE will read the SIB 1 and will know the PLMN ID and other valuable
system information on the BCCH.
Once the PLMN ID is suiting the USIM cards needs the UE will register in the cell.
[3GTR 25.814 (7.1.2.4), 3GTS 36.211 (6.11), 3GTS 36.213 (4)]
3
Room for your Notes
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
L1
Layer 1 (physical layer)
3GTS
3rd Generation Technical
Specification
OFDM
Orthogonal Frequency Division
Multiplexing
BCCH
Broadcast Control Channel
PLMN
Public Land Mobile Network
BCH
Broadcast Channel
SFN
System Frame Number
CP
Cyclic Prefix
SIB
System Information Block
DL
Downlink
UE
User Equipment
DL-SCH
Downlink Shared Channel
UMTS
Universal Mobile Telecommunication
System
ID
Identity
USIM
Universal Subscriber Identity Module
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3.5.6 Random Access
3.5.6.1 PRACH Structure Format 0
3
The objective of this section is to introduce the structure of the PRACH.
Key point of this section is the PRACH can be configured freely on frequency
and subframe in the UL carrier and in the UL frame structure.
Image description
This picture is showing how the PRACH is fitted on the UL carrier and on the UL
frame. As well the PRACH structure inside the subframe is shown.
72 consecutive subcarriers (1080 kHz) are used for the PRACH. This means that the
PRACH is fitting on the smallest discussed bandwidth for LTE.
The PRACH can be configured any of the 10 subframes on the given 72 subcarriers.
•
Inside the PRACH there is a long Zadoff-Chu sequence which is occupying 800 s of
the PRACH subframe. This RACH preamble is created in the frequency domain.
In the time domain then a cyclic shift may be applied and a CP is added.
The detection grid of the PRACH is 16 T(sample) being the same grid applied for the
TA control algorithm.
The UE is transmitting the PRACH with 0 TA.
The guard time at the end of the PRACH is allowing for an interference free reception
of the PRACH at the eNB up to a cell radius of 14.6 km. Once the distance inbetween the UE and the eNB is exceeding that distance interference in the following
subframe has to be expected. However since the PRACH preamble is very long and
the interference is the lower the bigger the cells become the inference is tolerable.
[3GTS 36.211 (5.7), 3GTS 36.213 (6), 3GTS 36.300 (10.1.5)]
There are other PRACH structure formats defined for bigger cells and for TDSCDMA harmonized LTE. Those are not discussed in the LTE from A-Z scope.
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Room for your Notes
3
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
TA
Terminal Adapter (ISDN)
CP
Cyclic Prefix
TDSCDMA
Time Division Synchronous Code
Division Multiple Access
LTE
Long Term Evolution (of UMTS)
UE
User Equipment
PRACH
Physical Random Access Channel
UL
Uplink
RACH
Random Access Channel
eNB
Enhanced Node B
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3.5.6.2 Random Access Procedure
3
The objective of this section is to how the PRACH is used in the random
access procedure.
Key point of this section is that the random access response and the random
access message are transmitted on ordinary physical channels.
Image description
• This picture is visualizing the random access procedure.
At the beginning of the random access procedure the UE has to be informed about
the parameters and the location of the PRACH. Then – like in UMTS – it will choose
randomly in-between the root sequences and their cyclically shifted versions and will
transmit each time according to a power ramping procedure until it gets a response
from the eNB. Unlike in UMTS the eNB does not have an AICH. It will respond on the
DL-SCH (on PDSCH) using a RA-RNTI and will provide sequence number, TA and
the allocated resources on the PUSCH and the UE will respond on the ordinary
PUSCH with the random access message.
Consequently the RACH messages are scheduled almost like the normal UL packets
and no special physical channels are used for the RACH messaging.
[3GTS 36.213 (6)]
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Room for your Notes
3
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
PRACH
Physical Random Access Channel
AICH
Acquisition Indicator Channel (UMTS
Physical Channel)
PUSCH
Physical Uplink Shared Channel
C-RNTI
Cell Radio Network Temporary
Identifier
RA
Routing Area
CCCH
Common Control Channel
RA-RNTI
Random Access - Radio Network
Temporary Identifier
DL
Downlink
RACH
Random Access Channel
DL-SCH
Downlink Shared Channel
RNTI
Radio Network Temporary Identifier
eNB
Enhanced Node B
TA
Timing Advance
L1
Layer 1 (physical layer)
UE
User Equipment
L2
Layer 2 (data link layer)
UL
Uplink
L3
Layer 3 (network layer)
UMTS
Universal Mobile Telecommunication
System
PDSCH
Physical Downlink Shared Channel
ZC
Zadoff-Chu
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3.5.7 Inter Cell Interference Mitigation
3.5.7.1 Traditional frequency reuse in LTE
3
The objective of this section is to show what are the potential problems with
traditional frequency reuse schemes in LTE.
Key point of this section is that with traditional frequency reuse schemes the
network performance is either lower because a high frequency reuse has to
be applied or lower than it could be once a frequency reuse of 1 is applied.
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Image description
•
This picture is visualizing the concept and performance for various frequency
reuse situations.
•
The pictures show TX power levels, load, IoT and TX power for the different cells
the UE’s are shown in form of dots with colors depending on their frequencies.
•
Only two cells and two frequencies are shown only in order to ease the
understanding.
3
3.5.7.1.1 Frequency reuse bigger than 1
This case is the most traditional frequency reuse scheme. In this case there are
some carriers which are not used within a given cell. By means of not using these
carriers in some cells and using them in some other cells interference in-between the
different cells is avoided. However the utilization of the carriers is restricted and the
spectrum efficiency is low. In OFDM systems there is the possibility to apply this
reuse not only on the OFDM carriers but also on the OFDM subcarriers.
3.5.7.1.2 Frequency reuse 1 with low initial load
With a frequency reuse of 1 it is possible to reuse all the OFDM carriers (subcarriers)
within all cells. Once the load of the cells is low there is no interference problem.
3.5.7.1.3 Frequency reuse 1 strongly increased load
Once suddenly the load of the network is increased the interference (IoT) rises
beyond the critical level. As a consequence there is a very high TX power in the cells
in order to compensate for this high IoT. This behavior is called party.
3.5.7.1.4 Frequency reuse 1 after “the party”
Only a few UE’s can transmit strong enough to combat the interference. The others
will lose their radio link. Finally the IoT level normalizes but there are only very few
UE’s left. This behavior is very unfavorable and needs to be combated with a strict
limitation of the cells load towards a comparatively low level.
In the OFDM case no CDMA technology available on the subcarriers. The
subcarriers will interfere amongst each other in the same way as narrowband
systems will do. Consequently a high reuse factor should be applied. To solve this
dilemma interference coordination is the method of choice for LTE.
•
Abbreviations of this Section:
CDMA
Code Division Multiple Access
OFDM
Orthogonal Frequency Division
Multiplexing
IoT
Interference over Thermal noise
TX
Transmit
LTE
Long Term Evolution (of UMTS)
UE
User Equipment
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3.5.7.2 Fractional Frequency Reuse with Intercell Interference
Coordination.
3
The objective of this section is to show how a tight frequency reuse can be
achieved with intercell interference coordination.
Key point of this section is that intercell interference coordination the LTE
system is exchanging load and interference levels and is coordinating the TX
power in the network and can thus avoid from bad interference scenarios to
happen.
Image description
•
This picture is visualizing the concept and performance of intercell interference
coordination.
•
The pictures show TX power levels, load, IoT and TX power for the different cells
the UE’s are shown in form of dots with colors depending on their frequencies.
• Two cells and two frequencies are shown only in order to ease the understanding.
Compared to the situation in the last section the two cells are using the X2 interface
in order to exchange the load and the IoT values for the two sections of their OFDM
carrier they are using. The orange and green subcarriers of their OFDM carrier are
used in a fractional frequency reuse. This fractional frequency reuse is using sections
with a lower TX power than other sections. This has the consequences that this lower
TX power section can only be used for UE’s which are close to the eNB. Since there
should always be UE’s being closer and more far from the eNB this is not a big
restriction.
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Thus, the coordination of the TX power in-between the eNB’s such that adjacent cells
are not using the same subcarriers with high TX power is allowing both cells to use
the complete OFDM carrier and enjoy a high spectral efficiency at the same time.
This system is especially advantageous for the UE’s at the cell boundaries. The
fractional frequency reuse is allowing them to have both a more secure radio link and
a higher throughput at the same time.
[3GTR 25.814 (7.1.2.6.3, 9.1.2.7.1), 3GTS 36.300 (16.1.5)]
Room for your Notes
•
3
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
OFDM
Orthogonal Frequency Division
Multiplexing
3GTS
3rd Generation Technical
Specification
TX
Transmit
IoT
Interference over Thermal noise
UE
User Equipment
LTE
Long Term Evolution (of UMTS)
eNB
Enhanced Node B
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3.6 UE Classes
3.6.1 Overview
3
The objective of this section is to give an overview of the UE classes used in
LTE.
Key point of this section is that LTE is using significantly less UE classes
than HSPA.
Table description
•
This tables relates the UE classed to the number of MIMO stream, the number of
RB’s and the peak data rates in UL and DL.
3.6.1.1 Classes 1-4
UE class 1 is the basic UE class. Here the data rates are comparable with typical
HSPA UE’s. On contrast to the UE classes 2-4 the codes rate never reaches 1 for UE
class 1. UE class 5 is limited to 5 MHz and this class is not capable to perform MIMO.
UE classes 2-4 are able process 2 MIMO streams this is the expected limit for the
first implementations.
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Please keep in mind that even though some UE categories do not support a 20
MHz allocation all the UE categories have to have a RF frontend of 20 MHz in
order to receive their allocation anywhere the eNB would like to schedule it.
3.6.1.2 UE class 5
For later implementations there is a UE class defined to have up to 4 MIMO streams
and which is also using 64-QAM in the UL.
3
Room for your Notes
•
Abbreviations of this Section:
64-QAM
64 symbols Quadrature Amplitude
Modulation
MIMO
Multiple In / Multiple Out (antenna
system)
DL
Downlink
QAM
Quadrature Amplitude Modulation
eNB
Enhanced Node B
RB
Resource Block
HSPA
High Speed Packet Access (operation RF
of HSDPA and HSUPA)
Radio Frequency
LTE
Long Term Evolution (of UMTS)
UE
User Equipment
MHz
Mega Hertz (106 Hertz)
UL
Uplink
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3.6.2 Calculation of the DL Peak Throughput for LTE UE Class 5
3
The objective of this section is to give the detailed calculation of the UE class
5’s DL max. throughput.
Key point of this section is that all UE categories have to assume 4 TX
antennas to be used..
Detailed Version:
According the previous section the max throughput for UE classes 4 is 299.6 Mbit/s
in the DL. This is assuming 4 data streams used with 4x4 antennas on 100 resource
blocks.
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Since for all UE categories 4 TX antennas have to be assumed pilot sub carriers for 4
antennas have to be assumed. The normal CP configuration is assumed such that
there are 14 OFDM symbols in a subframe. A resource block (RB) has 12 subcarriers
as shown.
Now the number of data symbols on a RB for a complete subframe has to be
calculated.
There are 6 OFDM symbols with 8 data subcarriers (these carry pilot subcarriers on 4
subcarriers) and 8 OFDM symbols with 12 data subcarriers (these carry no pilot
subcarriers).
3
So the number of data symbols is 8x12 + 6x8 = 144. If it is assumed that in each
subframe the first OFDM symbol (8 data subcarriers) is used for signaling, 136 data
symbols are left.
With 64-QAM there are 6 bit per symbol: This provides 6x136 bit = 816 bit per
subframe.
For 100 RB’s each TB can have 100x816 = 81600 bit on L1. For these bits turbo
coding with a max code rate of 92 % is assumed. This gives 74888 bit.
Please note that no UE is obliged to be able to decode a TB once the code rate is
bigger than 92%. in tis case the outcome is undefined!
Once 2 data streams per TB are assumed 149776 bit per transport block are
available.
There are 1000 subframes per second with 2 TB's in parallel such that the throughput
can be calculated as:
149776 bit x2x 1000/s = 299.6 Mbit/s
Please note that up to 110 RB's can be assigned to ease the the channel decoding
at a lower code rate. These 10 access RB's cannot be used to increase the
throughput beyond 299.6 Mbit/s.
•
Abbreviations of this Section:
64-QAM
64 symbols Quadrature Amplitude
Modulation
LTE
Long Term Evolution (of UMTS)
BCCH
Broadcast Control Channel
OFDM
Orthogonal Frequency Division
Multiplexing
CP
Cyclic Prefix
RB
Resource Block
DL
Downlink
TB
Transport Block
L1
Layer 1 (physical layer)
UE
User Equipment
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Lessons Learned / Conclusions:
3
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The Higher Layers of E-UTRAN
Chapter 4:
The Higher Layers of E-UTRAN
Objectives
Some of your questions that will be answered during this session…
•
What are the tasks of the higher layer protocol entities and functions of the
enhanced node B: MAC, RLC, PDCP, and RRC?
•
What is the structure of the protocol entities PDU’s?
•
What are the used concepts for mobility in LTE?
•
What is changing for QoS and security in LTE?
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4.1 Overview
4.1.1 E-UTRAN Architecture Control Plane
4
The objectives of this section are to show the evolution of the UTRAN
architecture to the E-UTRAN architecture and to highlight the degree of
protocol modifications for the control plane.
Key point of this section is that quite significant parts of the protocols and
concepts in the higher layer domain are retained for LTE.
Image description
This picture is visualizing the degree of change in-between UMTS and LTE on the
control plane. The stronger red the items are the stronger the change.
The NAS signaling new because of the new core in LTE.
•
For the RRC both the new air interface and the new network architecture have to be
supported. This is why most of it is new even though vital concepts are taken over
from UMTS.
The PDCP is new for the control plane. This change is due to the introduction of
ciphering in the PDCP.
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RLC is staying mostly intact even though some functionality like ciphering is
elsewhere now. The most significant change the of the RLC is the RLC PDU size is
variable.
The MAC has changed a lot because with the new air interface the chance has taken
to tailor the MAC from the start to the needs of a PS-only environment.
L1 and transport channels used are totally new.
On the transport plane the S1-AP is new. The other parts of the transport plane are
also run like this in UMTS.
[3GTR 25.813, 3GTS 36.300]
Room for your Notes
•
4
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
PS
Packet Switched
3GTS
3rd Generation Technical Specification RLC
Radio Link Control
HSDPA
High Speed Downlink Packet Access
(3GTS 25.301, 25.308, 25.401, 3GTR
25.848)
RRC
Radio Resource Control
IP
Internet Protocol (RFC 791)
RRM
Radio Resource Management
L1
Layer 1 (physical layer)
S1-AP
S1 Application Part
LTE
Long Term Evolution (of UMTS)
SCTP
Stream Control Transmission
Protocol (RFC 2960)
MAC
Medium Access Control
SDH
Synchronous Digital Hierarchy
MME
Mobility Management Entity (3GTS
23.401) (Rel. 8 onwards)
TrCH
Transport Channel (UMTS)
NAS
Non-Access-Stratum
UMTS
Universal Mobile Telecommunication
System
PDCP
Packet Data Convergence Protocol
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
PDH
Plesiochronous Digital Hierarchy
eNB
Enhanced Node B
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4.1.2 E-UTRAN Architecture User Plane
4
The objectives of this section are to show the evolution of the UTRAN
architecture to the E-UTRAN architecture and to highlight the degree of
protocol modifications for the user plane.
Key point of this section is that quite significant part of the protocols and
concepts in the higher layer domain are retained for LTE.
Image description
This picture is visualizing the degree of change in-between UMTS and LTE on the
user plane. The stronger red the items are the stronger the change.
For the user plane there is the same picture as in the control plane with the following
exemptions:
•
The PDCP has been included in the user plane already in UMTS - even though the
ciphering is changing from the RLC/MAC to the PDCP.
It is new that the GTP-U is terminated in the eNB.
[3GTR 25.813, 3GTS 36.300]
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Room for your Notes
4
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
PDP
Packet Data Protocol
3GTS
3rd Generation Technical
Specification
PDSCH
Physical Downlink Shared Channel
DL
Downlink
PUSCH
Physical Uplink Shared Channel
DL-SCH
Downlink Shared Channel
RLC
Radio Link Control
GTP
GPRS Tunneling Protocol (3GTS
29.060)
SAE
System Architecture Evolution
GTP-U
GTP User Plane
SDH
Synchronous Digital Hierarchy
GW
Gateway
UDP
User Datagram Protocol (RFC 768)
HSDPA
High Speed Downlink Packet Access
(3GTS 25.301, 25.308, 25.401,
3GTR 25.848)
UL
Uplink
IP
Internet Protocol (RFC 791)
UL-SCH
Uplink Shared Channel
LTE
Long Term Evolution (of UMTS)
UMTS
Universal Mobile Telecommunication
System
MAC
Medium Access Control
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
PDCP
Packet Data Convergence Protocol
eNB
Enhanced Node B
PDH
Plesiochronous Digital Hierarchy
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4.2 Features of MAC
4.2.1 Overview
4
The objective of this section is to introduce the key features of the medium
access control layer.
Key point of this section is that for the MAC the chance has been taken to
tune many concepts such that they fit to PS services from the start.
4.2.1.1 Data transfer logical channels ←→ transport channels
This function is similar to HSPA. The big difference it that two TB’s per UE can be
transferred at the same time. It is FFS whether this is also the case for more than two
TB’s.
4.2.1.2 Radio resource allocation
For the radio resource allocation there is a very significant change for the RACH.
Here there is not the possibility to map user plane data on the RACH.
For HARQ the basic concepts of HSPA are retained – however the HARQ is a lot
faster then in HSPA. Also the parameters and implementation details will differ.
For the priority concept a quite similar approach than in HSPA will be taken. However
detains are not specified yet.
[3GTR 25.813 (5.3.1), 3GTS 36.300 (6.1), 3GTS 36.321 (4.4)]
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Room for your Notes
4
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
MAC
Medium Access Control
3GTS
3rd Generation Technical
Specification
PS
Packet Switched
FFS
For Further Study
QoS
Quality of Service
HARQ
Hybrid ARQ
RACH
Random Access Channel
HSPA
High Speed Packet Access (operation TB
of HSDPA and HSUPA)
Transport Block
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4.2.2 MAC Random Access Procedure
4
The objective of this section is to show the random access procedure from
the MAC perspective.
Key point of this section is that for the random access procedure there are
two versions: the contention based (collisions are possible and have to be
resolved) and non-contention based (collisions are not possible.)
Image description
•
This picture is visualizing the contention based random access procedure the
non-contention based random access procedure with two different colors.
Common elements are shown in black color.
4.2.2.1 Contention based random access procedure
Here collisions are possible because the UE decides when exactly a random access
is initiated. Then it is possible that two UE’s transmit the same preamble at the same
time. The chosen preamble is 1 out of 64 preambles and is thus encoding 6 bits. 5
bits are for the ID and one other bit (group of random access preambles) signals the
length of the following scheduled transmission in the UL.
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The UE has to wait with the transmission of the random access message until it has
received the random access response on the DL-SCH. The response is using the
RA-RNTI. This response identifies the random access preamble, gives a TA value
and the UL grant for the UL scheduled transmission which is following then. Once the
eNB discovers a collision on the random access preambles it will not respond to
either of the preambles. However once the two same preambles arrive so close to
each other that hat a collision is not detected the eNB will grant the preambles and
two UE’s will transmit on the same UL resources at the same time.
With the UL scheduled transmission the UE will provide its NAS UE ID (IMSI or STMSI), an AS message, and possibly a NAS message (e.g. TA update etc.)
At last the eNB is answering with the contention resolution message giving the ID of
the UE it would like to address. Here any collision will be finally resolved. The UE not
getting this response with its ID will start the random access procedure again.
4.2.2.2 Non-contention based random access procedure
The difference to the non-contention based random access procedure is that the UE
gets assigned a specific random access preamble for a random access window (e.g.
during handover, etc.). Then the UE will use the preamble assigned and will get an
UL grant related to its service directly together with its TA. Here, of course, a
contention resolution is not necessary. The UE will have a C-RNTI already.
4
[3GTS 36.300 (10.1.5), 3GTS 36.321 (5.1)]
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
RA-RNTI
Random Access - Radio Network
Temporary Identifier
AS
Access Stratum (UMTS)
RNTI
Radio Network Temporary Identifier
C-RNTI
Cell Radio Network Temporary
Identifier
S-TMSI
SAE Temporary Mobile Subscriber
Identity
DL
Downlink
TA
Timing Advance
DL-SCH
Downlink Shared Channel
TA
Tracking Area
eNB
Enhanced Node B
TMSI
Temporary Mobile Subscriber
Identity
ID
Identity
TX
Transmit
IMSI
International Mobile Subscriber
Identity
UE
User Equipment
MAC
Medium Access Control
UL
Uplink
NAS
Non-Access-Stratum
UL-SCH
Uplink Shared Channel
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4.2.3 Structure of MAC-PDU
4
The objective of this section is to provide the structure of the MAC PDU.
Key point of this section is that the LTE MAC PDU does usually only contain
1 SDU per logical channel.
Image description
This picture is visualizing the structure of the header and the sequence of SDU’s
in the MAC PDU.
The MAC PDU is transmitting with its SDU’s one or several RLC-PDU’s at a time.
Unlike in UMTS standards (prior to R7) the size of the RLC PDU is flexible such that
it can fit the size of the MAC PDU it is mapped to.
Since both MAC and RLC are located in the eNB, the MAC knows the size of the TB
it can transmit (transmission opportunity). In case there are more than one logical
channel active for the corresponding user, the MAC has to multiplex the different
logical channels on the TB. Most likely it could e.g. map the highest priority logical
channel’s SDU on the TB. For this it will ask for an SDU with fitting size such that no
or only minimum padding is necessary. In case the RLC cannot fill the TB fully the
MAC will add the next lower priority logical channel on the TB and so forth until the
TB is full.
•
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The structure of the MAC PDU and its header are accomplishing this function. First
the MAC header is structured in sub headers in order to indicate several MAC SDU’s.
Since MAC in LTE is also fulfilling control functions there are two sub-header formats
and SDU structures:
4.2.3.1 MAC control element
Some LCID’s are reserved for control elements and 1 LCID is indicating padding. The
MAC control elements are explained in the next section. None and more then 1 MAC
Control field are also possible.
4.2.3.2 Normal MAC SDU
In order to do transport normal MAC PDU’s the MAC sub header has triplets of
information elements:
1. The LCID (Logical Channel ID) which is indicating the logical channel
used in a similar fashion than the C/T field in UMTS (4 bits).
2. There are two reserved bits.
3. The F field is indicating the length of the following length field (7 or 15
bit)
4. The L (Length) field indicating the length of the corresponding SDU. F
and L field are very close to RLC PDU in UMTS.
5. The E (End) field which is indicating the end of the MAC header (1) or
more triplets following (0).
Padding will only be used if no further SDU can be filled in or if no more RLC data is
ready to be transmitted and there is still space in the TB. In order to avoid
unnecessary extensive padding MAC may reduce the TB size in order to reduce
interference in the network.
4
[3GTS 36.321 (6)]
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
RLC
Radio Link Control
LCID
Logical Channel ID
SDU
Service Data Unit (the payload of a
PDU)
LTE
Long Term Evolution (of UMTS)
TB
Transport Block
MAC
Medium Access Control
UMTS
Universal Mobile Telecommunication
System
PDU
Protocol Data Unit or Packet Data
Unit
eNB
Enhanced Node B
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4.2.4 MAC Control Elements
4
The objective of this section is to provide different kinds of MAC control
elements.
Key point of this section is functions like RACH response, buffer status
report and timing advance are dealt with in MAC control elements.
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Image description
• These two tables are showing the MAC control elements in UL and DL.
Part of the LCID’s are reserved for MAC control elements which are serving physical
layer or MAC functions. The length of some MAC control elements is still under
discussion but the purpose is quite clear. Please keep in mid that some LCID’s are to
be reserved for yet unknown MAC control elements.
4.2.4.1 Contention resolution ID
This is the response of the Random Access Burst sent by the UE. It contains the
NAS ID of the UE.
4.2.4.2 Timing Advance
This MAC control element is used for timing advance updates.
4.2.4.3 DRX
With this MAC control element the DRX is configured similar like in the HS-DSCH
orders in UMTS R7. Since only DRX is to be commanded here this MAC control
element contains no data. Just a header field is used here.
4
4.2.4.4 Padding
Padding is no MAC control element but is also indicated with a special LCID value.
4.2.4.5 Short, long and truncated buffer status reports
Here the UE can report the occupancy of its UL buffer. There are two formats long
and short buffer reports. With the long buffer report multiple logical channel group’s
buffer status is reported.
[3GTS 36.321 (6)]
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
MAC
Medium Access Control
DL
Downlink
RACH
Random Access Channel
DRX
Discontinuous Reception
UE
User Equipment
HS-DSCH High Speed Downlink Shared
Transport Channel (3GTS 25.211,
25.212, 25.308)
UL
Uplink
ID
Identity
UL-SCH
Uplink Shared Channel
LCID
Logical Channel ID
UMTS
Universal Mobile Telecommunication
System
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4.3 Features of RLC
4.3.1 Overview
4
The objective of this section is to introduce the key features of the radio link
control layer.
Key point of this section is the RLC stays intact to the most part once it is
compared to HSPA operation.
4.3.1.1 Data transfer
At the first glance the RLC is only not altered very significantly. However that the
second glace it could be noticed that for RLC the ciphering is missing and that
compared the HSPA LTE can provide TM data transmission again. Another special
point is the duplicate deletion in case of a handover. During the handover the
received buffer is exchanged in-between source and target eNB (AM only). In HSPA
duplicates for the UL are deleted in MAC-es whereas the duplicates are deleted as
well in the RLC for the legacy UMTS traffic. The variable RLC PDU size has to be
mentioned here again.
4.3.1.2 Error detection and recovery
There is nothing to be added to what is stated in the picture.
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4.3.1.3 Reset
There is nothing to be added to what is stated in the picture.
[3GTR 25.813 (5.3.2), 3GTS 36.300 (6.2), 3GTS 36.322 (4.4)]
Room for your Notes
4
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
PDCP
Packet Data Convergence Protocol
3GTS
3rd Generation Technical
Specification
RLC
Radio Link Control
AM
Acknowledged Mode operation
TM
Transparent Mode operation
ARQ
Automatic Repeat Request
UL
Uplink
HSPA
High Speed Packet Access (operation UM
of HSDPA and HSUPA)
Unacknowledged Mode operation
LTE
Long Term Evolution (of UMTS)
UMTS
Universal Mobile Telecommunication
System
MAC
Medium Access Control
eNB
Enhanced Node B
MAC-es
MAC-E-DCH SRNC (3GTS 25.321)
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4.3.2 Structure of RLC PDU
4
The objective of this section is to provide the structure of the RLC PDU.
Key points of this section are that the LTE RLC PDU can contain segmented
PDCP PDU’s and that the RLC PDU size fits to the individual TB size to be
transmitted.
Image description
This picture is visualizing the structure of the header and the sequence of SDU’s
in the RLC PDU.
Like in UMTS there are 3 transmission modes for the RLC: TM, UM, and AM. For the
TM the structure of the RLC PDU is simple: It is transparent for the PDCP data.
For the UM and AM mode there is a header and one or more PDCP PDU’s being the
RLC SDU’s. Note here that the PDCP PDU’s can be segmented in the RLC.
Optionally, like in UMTS for AM only, a Status PDU can be at the end of the RLC
PDU.
•
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The header comprises the following information elements:
1. The D/C field is a reserved bit in UM. In AM it is indicating the presence of a
RLC control PDU (status report). A status report might also be piggy backed
at the end of the RLC PDU. Then the D/C field will indicate data. The
presence of the piggy packed status PDU is indirectly indicated by header
and SDU not completely filling out the length of the RLC PDU.
2. The RF field is a reserved bit in UM. In AM it is indicating the presence of resegmentation. This occurs once an already segmented PDCP PDU is in
need to be retransmitted and further segmented.
3. The polling flag is a reserved bit in UM. In AM it is encouraging the RLC of
the receiver side to sent status PDU’s.
4. In case of a 5 bit SN version UM PDU the first 3 fields are missing.
5. The FI filed exists in both AM and UM. It is indicating the presence of PDCP
PDU segment in the RLC PDU. In case of the presence of segments and
AM the header is extended by two bytes as described in the next section.
6. The SN (Sequence Number) which is indicating the RLC sequence number
of the RLC PDU. The length of this field can be the same in AM and UM.
However there is also an UM mode with 1 byte header and 5 bit SN filed
and no reserved bits.
7. An E field (Extension) which is indicating with (0) that data is following and
with (1) that an extension of LI (Length Indicator) and another E filed is
following.
8. The LI field (Length Indicator) of yet unknown length is indicating the length
of the PDCP PDU. Please note since there is also a length indication in the
MAC PDU one LI field in the RLC PDU is redundant.
9. Padding in the header is necessary since the E and LI field to not fill two
bytes. In case of an even number of RLC SDU’s 4 bit padding is needed to
fill up the RLC header to the byte boundary.
[3GTS 36.322 (6)]
•
4
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
RF
Radio Frequency
AM
Acknowledged Mode operation
RLC
Radio Link Control
FI
Framing Info
SDU
Service Data Unit (the payload of a
PDU)
LI
Length Indicator
SN
Sequence Number
LTE
Long Term Evolution (of UMTS)
TB
Transport Block
MAC
Medium Access Control
TM
Transparent Mode operation
PDCP
Packet Data Convergence Protocol
UM
Unacknowledged Mode operation
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4.3.3 Structure of RLC AM with PDCP PDU Segments
4
The objective of this section is to provide the structure of the RLC AM PDU
segment.
Key point of this section is that only for PDU segments the header is
extended for carrying the additional information about RLC PDU segments.
Image description
This picture is visualizing the structure of the header and SDU in the RLC AM
PDU segment PDU.
Since the sequence numbers of RLC and PDCP are different the RLC AM needs
means to identify details about the PDCP PDU segments for correct ARQ.
In this case the RLC AM PDU is containing two additional header information
elements:
1. The LSF (Last Segment Flag) is set once the PDCP PDU segment is the
last segment of the PDCP PDU.
2. The SO (Segment Offset) is determining the offset in the PDCP PDU
segment inside the PDCP PDU.
[3GTS 36.322 (6)]
•
Room for your Notes
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Room for your Notes
4
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
PDU
Protocol Data Unit or Packet Data
Unit
AM
Acknowledged Mode operation
RLC
Radio Link Control
ARQ
Automatic Repeat Request
SN
Sequence Number
LSF
Last Segment Flag
SDU
Service Data Unit (the payload of a
PDU)
LTE
Long Term Evolution (of UMTS)
SO
Segment Offset
PDCP
Packet Data Convergence Protocol
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4.4 Features of PDCP
4.4.1 Overview
4
The objective of this section is to introduce the key features of the packet
data convergence protocol.
Key point of this section is that encryption and PDCP for the control plane
are the functions which have been added to the PDCP compared to UMTS.
4.4.1.1 RoHC
It is still for further study whether to take RoHC or another scheme.
4.4.1.2 Numbering of PDCP PDU’s
The numbering of the PDCP PDU’s is very important because during the handover it
is the PDCP which will forward the data in the buffer to the target eNB.
4.4.1.3 In-sequence delivery of PDU’s
Once the data is forwarded during handover it can happen that data is coming in
already in the target eNB and there might still come some data in form the source
eNB. The data is then not in sequence and there might be some duplicates in the
buffer of the PDCP.
4.4.1.4 Duplicate deletion
See above.
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4.4.1.5 Encryption
The encryption algorithms have been located in the MAC and in the RLC for UMTS
and HSPA operation. In LTE they are transferred to the PDCP. This is due to the fact
that every eNB is equipped with its own keys and that the PDCP has to combine the
packets coming in from the other eNB’s during handover.
4.4.1.6 Integrity Protection
This is a feature only valid for the control plane in UTRA this was in the RRC layer.
This involves to calculate the MAC according the same principle but possibly with a
different algorithm.
[3GTR 25.813 (5.3.3), 3GTS 36.300 (6.3), 3GTS 36.323 (4.4)]
Room for your Notes
•
4
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
RLC
Radio Link Control
3GTS
3rd Generation Technical
Specification
RRC
Radio Resource Control
HSPA
High Speed Packet Access (operation RoHC
of HSDPA and HSUPA)
Robust Header Compression
LTE
Long Term Evolution (of UMTS)
UMTS
Universal Mobile Telecommunication
System
MAC
Message Authentication Code
UTRA
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access
PDCP
Packet Data Convergence Protocol
eNB
Enhanced Node B
PDU
Protocol Data Unit or Packet Data
Unit
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4.4.2 Structure of PDCP PDU
4
The objective of this section is to provide the structure of the PDCP PDU.
Key point of this section is that the LTE PDCP PDU can also carry control
plane information.
Image description
This picture is visualizing the structure of the header and the sequence of SDU’s
in the PDCP PDU.
In contrast to UMTS the PDCP is also existing in the control plane. Consequently
also for control plane the PDCP PDU has to be defined.
For both control plane and user plane the PDCP PDU is exhibiting a SN (Sequence
Number) and an SDU field.
For the user plane there can be optionally a RoHC (Robust Header Compression)
which is compressing the e.g. 40 byte header to a 2-3 byte compressed header.
In order to control RoHC in the user plane, user plane PDCP PDU contain a D/C field
indicating control or data.
•
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For the control plane for integrity protection purposes the MAC field might be added
at the end. The MAC field is calculated according to similar guidelines as the MAC in
UMTS.
[3GTS 36.323 (6)]
Room for your Notes
4
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
RoHC
Robust Header Compression
LTE
Long Term Evolution (of UMTS)
SDU
Service Data Unit (the payload of a
PDU)
MAC
Message Authentication Code
SN
Sequence Number
PDCP
Packet Data Convergence Protocol
UMTS
Universal Mobile Telecommunication
System
PDU
Protocol Data Unit or Packet Data
Unit
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4.5 Features of RRC
4.5.1 Overview
4
The objective of this section is to introduce the key features of the radio
resource control layer.
Key point of this section is that the tasks of the RRC stay mostly the same as
UMTS and HSPA, but since the air interface is different there are significant
changes in the implementation.
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4.5.1.1 Transmission of broadcast information
Here is it very important to know that only the MIB is transmitted on the BCH. All the
other SIB’s are grouped in SU’s according to their transmission periodicity and are
transmitted on the DL-SCH.
4.5.1.2 Establish and maintain services
Here the basic concepts are very different. The RRC connection setup procedure has
been extended to the initial context setup procedure. RRC and NAS link are
established in parallel. Moreover since there is a new air interface technology
(OFDMA and SC-FDMA) used the message contents are different. Another very
significant change is the drastic reduction of RRC states mentioned earlier.
4.5.1.3 QoS control
Nothing to add to what is stated in the picture.
4
4.5.1.4 Transfer of dedicated control information
Nothing to add to what is stated in the picture.
[3GTR 25.813 (5.4), 3GTS 36.300 (7), 3GTS 36.331 (4.4)]
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
NAS
Non-Access-Stratum
3GTS
3rd Generation Technical
Specification
OFDMA
Orthogonal Frequency Division
Multiple Access
BCH
Broadcast Channel
QoS
Quality of Service
DL
Downlink
RRC
Radio Resource Control
DL-SCH
Downlink Shared Channel
SC-FDMA Single Carrier Frequency Division
Multiple Access
EPC
Evolved Packet Core (3GTS 23.401)
(Rel. 8 onwards)
SIB
System Information Block
FDMA
Frequency Division Multiple Access
SU
Scheduling Unit
HSPA
High Speed Packet Access (operation UE
of HSDPA and HSUPA)
User Equipment
MIB
Master Information Block
Universal Mobile Telecommunication
System
UMTS
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4.5.2 State Characteristics of RRC
4
The objective of this section is to introduce the key features of the radio
resource control states.
Key point of this section is that there are only 2 (3) RRC states in LTE.
Image description
•
The picture is shows the RRC states in LTE and their main characteristics. It
focuses on the processes of the E-UTRAN.
4.5.2.1 RRC_IDLE
During RRC_IDLE the UE can be paged and will listen to the PCH and the BCH, but
it is not known by the eNB it will perform cell reselections. Keep also in mind that this
state will also assumed once the UE is switched on and will perform initial cell
search.
4.5.2.2 RRC_CONNECTED
Here the UE is fully connected to the eNB. That means it has a C-RNTI and it is
known on cell level. It will do neighbor cell measurements and handover. This state is
also assumed to be used for MBMS services.
[3GTR 25.813 (5.4.2), 3GTS 36.300 (7.2)]
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Room for your Note
4
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
RACH
Random Access Channel
3GTS
3rd Generation Technical
Specification
RNTI
Radio Network Temporary Identifier
BCCH
Broadcast Control Channel
RRC
Radio Resource Control
BCH
Broadcast Channel
RRC_CO RRC state in E-UTRA
NNECTED
C-RNTI
Cell Radio Network Temporary
Identifier
RRC_IDL
E
RRC state
LTE
Long Term Evolution (of UMTS)
RRC_MB
MS_CON
NECTED
RRC state in E-UTRA for UEs with
MBMS service only
MBMS
Multimedia Broadcast / Multicast
Service
UE
User Equipment
NAS
Non-Access-Stratum
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
PCH
Paging Channel
eNB
Enhanced Node B
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4.6 NAS Protocol States and Transitions
4
The objective of this section is to provide an overview about the functionality
supported in the different LTE-states.
Key point of this section is that there is a one to one relationship in-between
the RRC states and the NAS states.
Image description
•
The picture is shows the NAS states in LTE and their main characteristics. It
focuses on the processes in the EPC.
4.6.1 EMM-DEREGISTERED & ECM-IDLE
Here the UE has only its IMSI and it is not known by the network all. Once it selects
the PLMN it will go to EMM-REGISTERED & ECM-CONNECTED during registration.
4.6.2 EMM-REGISTERED & ECM-IDLE
Here is UE has the full set of ID’s: S-TMSI, TAI and an IP address. Its position is
known on TA level and has a context prepared in the EPC which can be activated
very fast. The UE has to perform TA updates.
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4.6.3 EMM-REGISTERED & ECM-CONNECTED
In this state the UE has a full context for data transmission and data reception. It is
known by the EPC on eNB level. In case there in an inter MME handover the EPC
will be involved in this handover.
[3GTR 25.813 (5.5.2), 3GTS 36.300 A.2)]
Abbreviations of this Section:
•
3GTR
3rd Generation Technical Report
MME
Mobility Management Entity (3GTS
23.401) (Rel. 8 onwards)
3GTS
3rd Generation Technical
Specification
NAS
Non-Access-Stratum
DL
Downlink
PLMN
Public Land Mobile Network
DRX
Discontinuous Reception
RRC
Radio Resource Control
EMMREGISTERE
D & ECMCONNECTE
D
Enhanced Mobility Management
state for active packet
transmission
RRC_CO
NNECTE
D
RRC state in E-UTRA
4
EMMEnhanced Mobility Management RRC_IDL RRC state
DEREGISTE state for UE not being registered E
RED & ECM- in the network
IDLE
EMMREGISTERE
D & ECMIDLE
Enhanced Mobility Management S-TMSI
state for non active packet
transmission
SAE Temporary Mobile Subscriber
Identity
EPC
Evolved Packet Core (3GTS
23.401) (Rel. 8 onwards)
TA
Tracking Area
ID
Identity
UE
User Equipment
IMSI
International Mobile Subscriber
Identity
UL
Uplink
IP
Internet Protocol (RFC 791)
eNB
Enhanced Node B
LTE
Long Term Evolution (of UMTS)
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4.7 Mobility
4.7.1 Mobility Management in the EMM-DEREGISTERED & ECMIDLE State
4
The objective of this section is to give the characteristics of the mobility
management procedure in the EMM-DEREGISTERED & ECM-IDLE state
with special emphasis of what changes with respect to UTRAN.
Key point of this section is that the cell selection is basically following the
same principle as in UTRA.
Image description
The picture is visualizing the steps and the decisions taken for the cell selection
process.
Like in UTRA the cell selection process is running in two steps:
•
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The first step the UE is looking for a suitable cell. A suitable cell fulfills the cell
selection criteria is not barred and belongs to the selected PLMN. The selected
PLMN is given by the SIM card which is initiating the cell selection procedure.
Once there is no suitable cell found the UE is looking for acceptable cells. These
cells belong to another PLMN and fulfill the cell selection criteria and are not barred.
Barred cells are in the list “forbidden tracking areas for roaming”. These might be
trail networks of the related operators.
[3GTR 25.813 (9.1.2), 3GTS 36.300 10.1.1.1]
Room for your Notes
4
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
PLMN
Public Land Mobile Network
3GTS
3rd Generation Technical
Specification
SIM
Subscriber Identity Module
BCH
Broadcast Channel
UE
User Equipment
EMMEnhanced Mobility Management UTRA
DEREGISTE state for UE not being registered
RED & ECM- in the network
IDLE
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access
FFS
For Further Study
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
LTE
Long Term Evolution (of UMTS)
UTRAN
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4.7.2 Mobility Management in the EMM-REGISTERED & ECM-IDLE
State
4
The objective of this section is to give the characteristics of the mobility
management procedure in the EMM-REGISTERED & ECM-IDLE state with
special emphasis of what changes with respect to UTRAN.
Key point of this section is that for the cell reselection procedure in contrast
to UTRA the neighbor cells are only given by their carrier frequency (band).
The UE will look for the neighbor cells on it own.
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Image description
The picture is visualizing the steps and the decisions taken for the cell reselection
process.
For the cell reselection process there are quite a few changes compared to UTRA:
1. The UE can omit to do neighbor cell measurements once the selected cells
can be received with very high quality. This will prolongate the battery
lifetime of the UE’s being close to the eNB.
2. The neighbor cells are only given by their frequency or frequency bands.
This is also applying for other RAT systems. This has the consequence that
the UE needs to look for the neighbor cells on its own and will not get cell
specific reselection criteria from the old cell but has to read the BCCH (MIB)
of the neighbor cells for this information. However, optionally a neighbor cell
list can be transmitted.
3. The Location Area updates, Routing Area updates and the URA updates are
now all covered by the TA updates. As in UTRA periodical updates and
updates relating to the change of the TA can be performed.
[3GTR 25.813 (9.1.3), 3GTS 36.300 10.1.1.2)]
•
4
Room for your Notes
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
RAT
Radio Access Technology (e.g.
GERAN, UTRAN, ...)
3GTS
3rd Generation Technical
Specification
TA
Tracking Area
BCCH
Broadcast Control Channel
UE
User Equipment
EMMEnhanced Mobility Management URA
REGISTER state
for non active packet
ED & ECM- transmission
IDLE
UTRAN Registration Area
FFS
For Further Study
UTRA
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access
ID
Identity
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
MIB
Master Information Block
eNB
Enhanced Node B
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4.7.3 Mobility Management in the EMM-REGISTERED & ECMCONNECTED State
4
The objective of this section is to give the characteristics of the mobility
management procedure in the EMM-REGISTERED & ECM-CONNECTED
state with special emphasis of what changes with respect to UTRAN.
Key point of this section is that the key difference to UTRA is that most
handovers are negotiated in-between the eNB’s directly.
Image description
The picture is visualizing the steps and the decisions taken for the handover
process.
For the neighbor cell measurements the same changes apply as in the idle mode.
However here the neighbor cells measurement need to be performed according to
the measurement control messages of the eNB. Since the RNC does not exist in LTE
the source eNB decides whether a handover is required.
•
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Then the source eNB will coordinate the handover with the target eNB (or the EPC).
In case of success the handover command will be sent to the UE and another new
concept of LTE will be used: DL data forwarding.
Since the core network does not now about the handover yet it will still send the user
plane data to the source eNB. Since for a handover there should not be data loss or
delay, the source eNB will forward the DL data to the target eNB whilst keeping the
UL user plane to the core. After the handover command the UE will be busy to
synchronize) with the target eNB (using a contention free random access procedure
and will get some DL data from it immediately.
Once the UE is synchronized the target eNB will redirect the user plane to itself and
will stop the data forwarding. Then the source eNB will flush its buffers to the target
eNB and will also provide the UL TB’s which cannot be transmitted to the core
because of retransmissions are blocking an in sequence delivery of these TB’s to the
core directly.
4
In case of an inter MME handover the eNB’s do not coordinate the handover
directly. Instead the coordination is done using the MME’s.
[3GTR 25.813 (9.1.5), 3GTS 36.300 10.1.2.1)]
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
QoS
Quality of Service
3GTS
3rd Generation Technical
Specification
RACH
Random Access Channel
BCH
Broadcast Channel
RNC
Radio Network Controller
DL
Downlink
TB
Transport Block
EMMEnhanced Mobility Management
REGISTERED state for active packet
& ECMtransmission
CONNECTED
TX
Transmit
EPC
Evolved Packet Core (3GTS
23.401) (Rel. 8 onwards)
UE
User Equipment
FFS
For Further Study
UL
Uplink
HO
Handover
UTRA
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access
LTE
Long Term Evolution (of UMTS)
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
MME
Mobility Management Entity
(3GTS 23.401) (Rel. 8 onwards)
eNB
Enhanced Node B
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4.7.4 Inter RAT Mobility Management
4
The objective of this section is to give the characteristics of the mobility
management procedures for inter-RAT mobility.
Key point of this section is even though the neighbor cell information is also
minimized for inter RAT mobility the basic concepts have been taken from
UTRA.
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4.7.4.1 Cell Reselection (EMM-REGISTERED & ECM-IDLE)
Here as well the neighbor cell information is kept to a minimum. Once the LTE cell is
received very good then all the neighbor cells measurements can be omitted.
4.7.4.2 Handover (EMM-REGISTERED & ECM-CONNECTED)
As in UTRA the handovers are backward handovers. That means the handovers are
negotiated with the target network before they are communicated to the UE. Like this
unnecessary call drops and delays in the user plane are avoided.
There is a similar procedure for an inter MME handover.
For the inter RAT handover like in UTRAN the handover messages sent to the UE
will encapsulate the handover messages from the target network.
[3GTR 25.813 (9.2 3GTS 36.300 10.2)]
•
4
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
LTE
Long Term Evolution (of UMTS)
3GTS
3rd Generation Technical
Specification
MME
Mobility Management Entity (3GTS
23.401) (Rel. 8 onwards)
QoS
Quality of Service
EMMEnhanced Mobility Management
REGISTERED state for active packet
& ECMtransmission
CONNECTED
EMMEnhanced Mobility Management RAT
REGISTERED state for non active packet
& ECM-IDLE transmission
Radio Access Technology (e.g.
GERAN, UTRAN, ...)
E_UTRA
Evolved UMTS Terrestrial Access
UE
User Equipment
FFS
For Further Study
UTRA
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access
HO
Handover
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
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4.8 QoS in LTE
4.8.1 Bearer Architecture
4
The objective of this section is to provide bearer structure of LTE.
Key point of this section is that the UMTS bearer architecture has been
generalized to the EPS bearer architecture.
Image description
The picture shows how the different bearer services used in LTE or better said
SAE.
The bearer architecture looks similar to the UMTS bearer architecture. Due to the
changes of the SAE architecture, i.e. new network elements the structure of the
bearer architecture is different. As well there are new SAE related bearers. Since
services are a core network issue the naming is coming from the core network (SAE)
and not from the cases network (LTE or E-UTRAN).
•
[3GTR 25.813 (8), 3GTS 36.300 (13), 3GTS 23.401 (4.6)]
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Room for your Notes
4
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
GW
Gateway
3GTS
3rd Generation Technical
Specification
LTE
Long Term Evolution (of UMTS)
E-UTRAN Evolved UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
SAE
System Architecture Evolution
EPC
Evolved Packet Core (3GTS 23.401)
(Rel. 8 onwards)
UMTS
Universal Mobile Telecommunication
System
EPS
Evolved Packet System
eNB
Enhanced Node B
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4.8.2 QoS Parameters
4
The objective of this section is to provide the procedures how QoS is
handled in LTE.
Key point of this section is that the basic QoS concept is the same as in
UTRAN however there are some optimizations done.
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4.8.2.1 ARP
This concept is like in UTRAN.
4.8.2.2 Label
To differentiate different QoS profiles with labels is new for LTE and it is easing the
setup of a service.
4.8.2.3 GBR
Same as in UTRAN.
4.8.2.4 MBR
Same as in UTRAN.
4
4.8.2.5 AMBR
Multiple services together cannot surpass the AMBR.
[3GTR 25.813 (8), 3GTS 36.300 (13), 3GTS 23.401 (4.7)]
Room for your Notes
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
LTE
Long Term Evolution (of UMTS)
3GTS
3rd Generation Technical
Specification
MBR
Maximum Bit Rate
AMBR
Aggregated Maximum Bit Rate
PDB
Packet Delay Budget
ARP
Allocation and Retention Priority
PLR
Packet Loss Rate
GBR
Guaranteed Bit Rate
QoS
Quality of Service
L2
Layer 2 (data link layer)
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
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4.8.3 QoS Classes Identifier
4
The objective of this section is to provide an overview of the QCI indicated
by the labels in LTE.
Key point of this section is that the QCI are replacing the QoS classes used
previously.
Table description
The table is relating the different QCI characteristics to L2 packet delay budget,
L2 packet loss rates and gives examples for the services.
The QCI’s can be grouped into two groups the GBR and the non-GBR QCI’s. Both
groups lave low, medium, and high L2 packet delay budgets.
•
[3GTS 23.203 (6.1.7)]
Room for your Notes
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Room for your Notes
4
•
Abbreviations of this Section:
GBR
Guaranteed Bit Rate
QoS
Quality of Service
IMS
Internet Protocol Multimedia Core
TCP
Network Subsystem (Rel. 5 onwards)
Transmission Control Protocol
L2
Layer 2 (data link layer)
UMTS
Universal Mobile Telecommunication
System
LTE
Long Term Evolution (of UMTS)
VoIMS
Voice over IMS
QCI
QoS Classes Identifier
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4.9 Security in LTE
4
The objective of this section is to describe to different security procedures
and their location in LTE.
Key point of this section is that the security algorithms are the same as for
UTRAN. However the EPC transforms the keys such that different keys are
applied for encryption and integrity protection and for the different individual
network elements.
Image description
The picture shows how the different security keys in LTE are derived from one
another.
As it can be seen in the picture there is still an USIM used in LTE. This USIM is
generating the keys in the same way as in UTRAN.
The authentication is following the same procedure as in UTRAN.
For the encryption and the integrity protection the HSS will create a new key –
KASME. This key will be used by the EPC to create 3 specific keys for the MME:
once key for encryption of NAS messages and another key for integrity protection for
the NAS messages. Each individual eNB will also get its own master key KeNB. How
the network entity specific keys are created exactly is FFS.
•
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The eNB will then create 3 different keys from its master keys:
1. An encryption key for the RRC messages
2. An integrity protection key for the RRC messages
3. An encryption key for the user plane messages (integrity protection for the
user plane is not necessary)
The UE is aware of all theses keys and will change the eNB specific keys upon
handover or cell change.
The usage of the integrity protection and ciphering keys will most likely be the same
as in UTRAN again.
[3GTR 25.813 (10), 3GTS 36.300 (14)]
Room for your Notes
•
4
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
MAC
Medium Access Control
3GTS
3rd Generation Technical
Specification
MME
Mobility Management Entity (3GTS
23.401) (Rel. 8 onwards)
AK
Anonymity Key (3GTS 33.102)
NAS
Non-Access-Stratum
AMF
Authentication management field
(3GTS 33.102)
RAND
Random Number
AuC
Authentication Center
RRC
Radio Resource Control
CK
Ciphering Key (3GTS 33.102)
SQN
Sequence number (used in UMTSsecurity architecture / 3GTS 33.102)
EPC
Evolved Packet Core (3GTS 23.401)
(Rel. 8 onwards)
UE
User Equipment
FFS
For Further Study
USIM
Universal Subscriber Identity Module
HSS
Home Subscriber Server (3GTS
23.002). HSS replaces the HLR with
3GPP Rel. 5
UTRAN
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access Network
IK
Integrity Key (3GTS 33.102)
XRES
Expected Response (3GTS 33.102)
LTE
Long Term Evolution (of UMTS)
eNB
Enhanced Node B
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Lessons Learned / Conclusions:
4
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Selected E-UTRAN Scenarios
Chapter 5:
Selected E-UTRAN Scenarios
Objectives
Some of your questions that will be answered during this session…
•
How an initial context setup is performed?
•
How the UE is performing a tracking area update?
•
How a PDP context is established?
•
How an intra MME handover works in the LTE network?
•
How an inter MME handover works in the LTE network?
•
How in detail the TCP packets travel to the UE?
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5.1 Initial Context Setup Procedure
5
The objective of this section is to show the information flow during initial
context setup procedure.
Key point of this section is that for the initial context setup procedure the
UTRA RRC connection establishment procedure and the initial NAS
messages have been merged on order to save setup time.
In LTE there is no RRC connection establishment procedure. The reason is that there
is no RNC any more and in order to save time the RRC establishment procedure has
been merged with the initial NAS messaging and the S1 resource establishment.
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As shown in the picture there id the random access procedure which can together
with the RRC connection request also sent a NAS message. What is send depends
on what the mobile station wants: TA updates, service request, attachment etc.
In the next step the eNB is initializing with the INITIAL UE MESSAGE the
establishment of the S1 connection for the UE.
The MME is answering with the INITIAL CONTEXT SETUP REQUEST which is also
carrying already the NAS response messages being the reaction to whatever the UE
requested from the core before. The eNB reacts with packing the whole NAS
information inside the RRC radio bearer setup message.
The response of the UE the RRC Radio Bearer Setup Complete is containing again
some NAS messages. The reaction of the eNB is the INITIAL CONTEXT SETUP
COMPLETE message which will forward the UE’s NAS messages to the MME and
will terminate the initial context setup procedure.
From then on the communication with the core is handled by UPLINK NAS
TRANSPORT and DOWNLINK NAS TRANSPORT messages on the S1-MME
interface.
[3GTS 36.300 (19.2.2.3)]
•
5
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
RA-RNTI
Random Access - Radio Network
Temporary Identifier
AP
Access Preamble
RACH
Random Access Channel
C-RNTI
Cell Radio Network Temporary
Identifier
RNC
Radio Network Controller
CCCH
Common Control Channel
RNTI
Radio Network Temporary Identifier
DCCH
Dedicated Control Channel
RRC
Radio Resource Control
DL
Downlink
S-TMSI
SAE Temporary Mobile Subscriber
Identity
DL-SCH
Downlink Shared Channel
S1-AP
S1 Application Part
ID
Identity
TA
Timing Advance
IMSI
International Mobile Subscriber
Identity
UE
User Equipment
LTE
Long Term Evolution (of UMTS)
UL
Uplink
MME
Mobility Management Entity (3GTS
23.401) (Rel. 8 onwards)
UL-SCH
Uplink Shared Channel
NAS
Non-Access-Stratum
UTRA
UMTS (Universal Mobile
Telecommunication System)
Terrestrial Radio Access
PDCCH
Physical Downlink Control Channel
eNB
Enhanced Node B
PUCCH
Physical Uplink Control Channel
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5.2 Tracking Area Update
5
The objective of this section is to show the information flow for a TA update
of a UE.
Key point of this section is that for a TA update quite similar procedures are
used as for the RA updates in UMTS and GPRS networks.
5.1.1 Inter MME tracking area update
The first step of the tracking area update is that a UE has selected a new cell found a
new cell with a different TAI. Then it will initiate the TA update procedure and will
send a tracking area registration message. This message will contain the old S-TMSI
and the old TAI.
For the inter MME TA update procedure the MME which is connected to the eNB will
find out that it has not administered the UE before and will contact the old MME
which has previously administered that UE. This will be done by means of a request
for transfer of the contexts which is accompanied by the old S-TMSI.
By means of the old S-TMSI the old MME will initiate the transfer of the UE’s contexts
to the new MME and the new Serving GW. Since old and new Serving GW are not
logically interconnected the relaying of Serving GW’s part of the UE context will
involve S11 messaging on both sides.
Once the new MME has received the UE’s contexts it might ask for UE authentication
and for ciphering of the remaining procedure.
Then it will register as the MME responsible for the UE with the UE’s HSS. The HSS
will initiate the de-registration of the UE’s contexts with the old MME and will then
confirm the registration with the new MME.
Then the UE is informed that the TA registration is complete.
Finally the Serving GW will perform the user plane rout update with the PDN GW.
[3GTS 23.882 (7.7.2.3)]
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5.1.2 Intra MME tracking area update
Once the TA update is necessary within the service area of the MME the TA update
procedure become quite simple. Only the two MM messages indicated in the picture
will be exchanged.
[3GTS 23.882 (7.7.2.2)]
Room for your Notes
5
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
RA
Routing Area
EMM
Evolved Mobility Management
SAE
System Architecture Evolution
GPRS
General Packet Radio Service
S-TMSI
SAE Temporary Mobile Subscriber
Identity
GW
Gateway
TA
Tracking Area
HSS
Home Subscriber Server (3GTS
23.002). HSS replaces the HLR with
3GPP Rel. 5
UE
User Equipment
ID
Identity
UMTS
Universal Mobile Telecommunication
System
MME
Mobility Management Entity (3GTS
23.401) (Rel. 8 onwards)
eNB
Enhanced Node B
PDN
Packet Data Network
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5.3 PDP Context Establishment
5
The objective of this section is to show the information flow during a PDP
context establishment of an UE.
Key points of this section are that the PDP context establishment is
embedded in the initial context setup procedure and that for LTE the Serving
GW starts already to forward data to the eNB even though the PDP context
establishment procedure has not finished.
Precondition for the PDP context establishment procedure is that the UE is in EMMREGISTERED & ECM-IDLE and default IP-connectivity has already been
established.
In this example the PDP context is establishment is initiated by the network the
difference to the UE initiated PDP context establishment procedure is that paging is
used in order to reach the UE and that the UE might be requested to perform a noncontention based random access procedure. In case of a UE initiated initial context
procedure the random access is always contention based.
The first step of the network initiated PDP context establishment procedure is that the
PDN GW has data for the UE. By means the default IP connectivity already
established it knows which Serving GW is responsible for that UE and it will send the
data to the Serving GW. The Serving GW will discover that it has no S1-U resources
for that UE and it will request the MME to get these resources established. The MME
will then issue a paging message to the eNB’s responsible for the UE’s TA.
Optionally the eNB can assign RA resources being non-contention based to the UE
and will indicate this by the RA preamble to be used.
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The next step is the RA procedure initiated by the UE. With the CCCH it will transmit
the RRC connection request containing the service request. This service request will
be forwarded with the INITIAL UE MESSAGE to the MME. The MME – knowing that
it relates to the paging it has initiated before - will trigger the Serving GW to start to
transmit data to the eNB.
[3GTR 23.882 (7.14), 3GTS 36.300 (19.2.2.3)]
Room for your Notes
5
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
PDP
Packet Data Protocol
3GTS
3rd Generation Technical
Specification
RA
Routing Area
CCCH
Common Control Channel
RACH
Random Access Channel
EMMEnhanced Mobility Management
REGISTER state for non active packet
ED & ECM- transmission
IDLE
RRC
Radio Resource Control
GW
Gateway
S1-AP
S1 Application Part
ID
Identity
SAE
System Architecture Evolution
IP
Internet Protocol (RFC 791)
TA
Timing Advance
LTE
Long Term Evolution (of UMTS)
TX
Transmit
MME
Mobility Management Entity (3GTS
23.401) (Rel. 8 onwards)
UE
User Equipment
NAS
Non-Access-Stratum
UL
Uplink
PCCH
Paging Control Channel
UL-SCH
Uplink Shared Channel
PCH
Paging Channel
eNB
Enhanced Node B
PDN
Packet Data Network
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5.3 PDP Context Establishment
5
Key point of this section is that while the PDP context establishment
procedure continues with the Serving GW is already transmitting data to the
eNB.
The steps taken on this picture are that in order to save time many NAS messages
are issued at the same time such as the SAE bearer setup, the security context
setup, the service accept and the PDP context activation message. The eNB will
process these messages and translate/forward them to the UE with the RRC radio
bearer setup message.
The UE will accept the PDP context and will signal to the eNB that it also completes
the security mode command (ciphering) and the RAB assignment. The eNB will then
inform the MME that the PDP context has been accepted and confirm the SAE
bearer setup whilst it will start already to transmit ciphered data to the UE.
[3GTR 23.882 (7.14), 3GTS 36.300 (19.2.2.3)]
Room for your Notes
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Selected E-UTRAN Scenarios
Room for your Notes
5
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
MME
Mobility Management Entity (3GTS
23.401) (Rel. 8 onwards)
3GTS
3rd Generation Technical
Specification
NAS
Non-Access-Stratum
ACK
Acknowledgement
PDP
Packet Data Protocol
AS
Access Stratum (UMTS)
RAB
Radio Access Bearer
DCCH
Dedicated Control Channel
RB
Radio Bearer
DL
Downlink
RRC
Radio Resource Control
DL-SCH
Downlink Shared Channel
S1-AP
S1 Application Part
DTCH
Dedicated Traffic Channel
SAE
System Architecture Evolution
FSS
For Further Study
UE
User Equipment
GW
Gateway
eNB
Enhanced Node B
ID
Identity
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5.4 Intra MME Handover
5
The objective of this section is to show the information flow for an intra MME
handover.
Key points of this section are that the eNB’s are “finalizing” the intra MME
handover by themselves before they inform the MME and that data
forwarding like in the core is introduced in-between the eNB’s.
The precondition of this procedure is that the source eNB is informed about the area
restrictions that means to which eNB it can handover through the intra MME
handover.
In order to prepare possible handovers the eNB is issuing measurement control
messages to the UE and the UE is providing measurement reports back.
Once the source eNB has come to the conclusion that a handover is necessary it will
issue a handover request on the X2 interface to the target eNB. This handover
request is negotiating the handover in-between the two eNB’s. The target eNB will
verify whether a handover can be supported and will give back a handover request
ACK in case it will support the inter eNB handover. With this acknowledgement the
target eNB will also give some parameters e.g. the C-RNTI, and the preamble it
would like to the UE to use.
The source eNB is then transmitting the handover command to the UE and starts to
forward the DL data it receives from the Serving GW to the target eNB.
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The eNB’s are arranging the handover in-between themselves and the MME or the
Serving GW does not know about the handover. They expect that the source eNB
still receives the DL data and that it still transmits UL data to them. Data forwarding
is necessary to keep delay sensitive services alive and to prevent data loss. UL
data forwarding is not necessary at this point. The eNB will send the UL data to the
Serving GW as normal.
According to the opinion of the author the source eNB keeps the data it has
forwarded in the buffer. In case the handover is not successful the UE will come back
to the source eNB.
From the time of the handover command onwards the UE will only communicate with
the target eNB. It will only come back to the source eNB in case the handover is not
successful. The UE will send its assigned preamble in a non-contention based
random access procedure and will get new TA and an UL grant in response. Then it
can transmit the HANDOVER NOTIFY message to the target eNB. After that it will
address the target eNB with the UL data and the target eNB will request that the data
path is switched to it. It is unclear to the author whether the HANDOVER NOTIFY
message is then still necessary.
5
Now the target eNB will inform the MME about the handover being successful
already in the RAN. This is done in order to initiate that the MME and the Serving GW
send their messages and the data to the target eNB from then on. The MME will
initiate a user plane update together with the Serving GW.
[3GTS 36.300 (10.1.2.1.1)]
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
RNTI
Radio Network Temporary Identifier
ACK
Acknowledgement
RRC
Radio Resource Control
C-RNTI
Cell Radio Network Temporary
Identifier
S1-AP
S1 Application Part
DCCH
Dedicated Control Channel
SAE
System Architecture Evolution
DL
Downlink
TA
Timing Advance
DL-SCH
Downlink Shared Channel
UE
User Equipment
GW
Gateway
UL
Uplink
MME
Mobility Management Entity (3GTS
23.401) (Rel. 8 onwards)
UL-SCH
Uplink Shared Channel
PUSCH
Physical Uplink Shared Channel
X2-AP
X2 Application Part
RACH
Random Access Channel
eNB
Enhanced Node B
RAN
Radio Access Network
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5.4 Intra MME Handover
5
Key point of this section is that the UL data is only forwarded in the last step
of the handover from the source to the target eNB.
Once the target eNB will receive the HANDOVER COMPLETE ACK form the
MME then it will initiate to empty its DL buffer complete and also forward the
UL data still being in the buffer and waiting of successful transmission of
earlier TB’s to the target eNB. The other UL data it will forward to the Serving
GW.
Then the Handover will be complete and the UE will communicate with the new MME
and the new Serving GW.
[3GTS 36.300 (10.1.2.1.1)]
Room for your Notes
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Selected E-UTRAN Scenarios
Room for your Notes
5
•
Abbreviations of this Section:
3GTS
3rd Generation Technical
Specification
SAE
System Architecture Evolution
ACK
Acknowledgement
TB
Transport Block
DL
Downlink
UE
User Equipment
GW
Gateway
UL
Uplink
MME
Mobility Management Entity (3GTS
23.401) (Rel. 8 onwards)
X2-AP
X2 Application Part
S1-AP
S1 Application Part
eNB
Enhanced Node B
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5.4.1 Practical Exercise: Intra eNB Handover
5
The objective of this section is to let the students develop the flow for the
intra eNB handover.
Image Description
•
The picture shows the to be completed flow for the intra eNB handover.
Your tasks:
1. Complete the flow with the communication in-between source cell, target
cell and UE.
Room for your Notes
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Room for your Notes
5
•
Abbreviations of this Section:
DCCH
Dedicated Control Channel
S1-AP
S1 Application Part
GW
Gateway
SAE
System Architecture Evolution
MME
Mobility Management Entity (3GTS
23.401) (Rel. 8 onwards)
UE
User Equipment
MME
Mobility Management Entity (3GTS
23.401) (Rel. 8 onwards)
UL
Uplink
PUSCH
Physical Uplink Shared Channel
eNB
Enhanced Node B
RRC
Radio Resource Control
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5.5 Inter MME Handover
5
The objective of this section is to show the information flow for an inter MME
handover.
Key point of this section is that for the inter MME handover there is no data
forwarding in-between the eNB’s but inside the core.
Here the procedure is exactly the same as the intra MME handover until the source
eNB decided to ask for a handover. Since this is an inter MME handover the source
eNB will not address the target eNB directly but it will address its MME and will inform
it that it should prepare a handover together with the target MME.
The source MME will then contact the target MME with the hand over request. Then
the target MME will first clarify with the target eNB whether a handover is possible.
Once this is successful the target MME will inform the target Serving GW about the
handover.
Once all that is successful the target MME will inform the source MME that the
handover can commence now. The source MME will then trigger the data forwarding
in-between the source Serving GW and the target Serving GW. Instead of a data
forward also bicasting is possible for the core.
Since there is no interface in-between the Serving GW’s it is unclear to the author
how exactly the data forward will be done. Whether there will be an interface inbetween the Serving GW’s or whether the forwarding will take place using the S11
and S10 interfaces.
[3GTR 23.882 (7.15.2.2), 3GTS 36.300 (19.2.2)]
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Selected E-UTRAN Scenarios
Room for your Notes
5
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
PUSCH
Physical Uplink Shared Channel
3GTS
3rd Generation Technical
Specification
RRC
Radio Resource Control
ACK
Acknowledgement
S1-AP
S1 Application Part
DCCH
Dedicated Control Channel
SAE
System Architecture Evolution
GW
Gateway
SM
Session Management (3GTS 23.060,
3GTS 24.008)
ID
Identity
UE
User Equipment
MM
Mobility Management
UL
Uplink
MME
Mobility Management Entity (3GTS
23.401) (Rel. 8 onwards)
eNB
Enhanced Node B
PDN
Packet Data Network
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5.5 Inter MME Handover
5
Key point of this section is for the second part of the handover in the inter
MME handover the route update is also involving the PDN GW.
Once the source MME is informed that the rest of the network is prepared for the
inter MME handover it will issue the handover command to the source eNB which will
then issue the handover command to the UE. For then on the procedure will be the
same as for the intra MME handover until the handover complete will be issued to the
target MME. There is one exemption: the source eNB will not forward any data to the
target eNB. This is already done in the core.
The target MME will then trigger a route update with the target Serving GW and the
PDN GW. Once this is done the target MME will trigger the source MME to stop the
data forwarding to release the resources.
The discussion for the inter MME handover is not finished. Other possibilities in the
discussion are to do mobility management like in the idle mode (TA updates and
cell updates) for low delay constraint data services or having overlapping coverage
areas for the MME’s.
[3GTR 23.882 (7.15.2.2), 3GTS 36.300 (19.2.2)]
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Room for your Notes
5
•
Abbreviations of this Section:
3GTR
3rd Generation Technical Report
RACH
Random Access Channel
3GTS
3rd Generation Technical
Specification
RRC
Radio Resource Control
C-RNTI
Cell Radio Network Temporary
Identifier
S1-AP
S1 Application Part
DCCH
Dedicated Control Channel
SAE
System Architecture Evolution
DL
Downlink
TA
Timing Advance
DL-SCH
Downlink Shared Channel
UE
User Equipment
GW
Gateway
UL
Uplink
MME
Mobility Management Entity (3GTS
23.401) (Rel. 8 onwards)
UL-SCH
Uplink Shared Channel
PDN
Packet Data Network
eNB
Enhanced Node B
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5.6 How a TCP/IP MTU is reaching the UE / the Internet
5
The objective of this section is to show the stations and the transformations
of a TCP/IP MTU in the LTE network until it reaches the UE.
Key point of this section is that with respect to the very high data rate for LTE
and the protocol development from the scratch there are a few differences to
HSPA.
Image description
•
The picture is showing the CDD case: two transmission antennas are received by
one receive antenna. It is shown how the UE can resolve the two signals.
5.6.1 TCP/IP layer
A TCP/IP MTU can have up to 1500 byte including 40 byte header.
5.6.2 PDCP layer
In the PDCP first RoHC can be applied this would reduce 40 byte TCP/IP header to
typically 3 byte header. In the user plane PDCP needs 2 byte own header.
5.6.3 RLC layer
According to the transport block size the RLC can assume variable RLC PDU size.
Either the TB is so small that the PDCP PDU needs to be segmented or it is that big
that multiple PDCP PDU’s fir in. For the RLC header it can be configured to have 1 or
2 byte in UM.
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For AM and 1 RLC SDU the header size is 2 byte in case of no segmentation and 4
byte in case of segmentation. For RLC AM each additional RLC SDU will add 1.5
byte header. In case a byte header is not filled completely 4 bit header padding has
to be added. Flexible RLC PDU’s and multiple RLC SDU’s are new to LTE and are
not used in UMTS RLC until. R7
5.6.4 MAC layer
In case the MAC is transporting only 1 MAC SDU the header length will be 1 byte
only in case more MAC SDU’s are transmitted the header will increase by 2-3 byte.
Please also take into account that padding and MAC Control Elements will be
unavoidable. The use of MAC control elements is new in LTE.
5.6.5 PHY layer
The physical layer has to deal with very huge TB’s. TB’s of 150000 bit cannot be
protected with a single CRC check any more. This is why there is a own 3 byte CRC
foreseen for every of the up to 6144 bit long Code Block Segments.
Room for your Notes
•
5
Abbreviations of this Section:
AM
Acknowledged Mode operation
PHY
Physical Layer
CDD
Cyclic Delay Diversity
RLC
Radio Link Control
CRC
Cyclic Redundancy Check
RoHC
Robust Header Compression
HSPA
High Speed Packet Access (operation SDU
of HSDPA and HSUPA)
Service Data Unit (the payload of a
PDU)
LTE
Long Term Evolution (of UMTS)
TB
Transport Block
MAC
Medium Access Control
TCP/IP
Transmission Control Protocol over IP
MTU
Maximum Transmit Unit (IP)
UE
User Equipment
PDCP
Packet Data Convergence Protocol
UM
Unacknowledged Mode operation
PDU
Protocol Data Unit or Packet Data
Unit
UMTS
Universal Mobile Telecommunication
System
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Lessons Learned / Conclusions:
5
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Solutions for Practical Exercises
Solutions
Solutions for Practical Exercises
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Chapter 2 / Section 2.1.2: Physical Basics of OFDM
6
•
Your way to the resolution:
Question No 3:
We know that the throughput rate is R = 6bit/s which means that each subcarrier
transmits 2 bits per second.
This provides us the response for question No 3:
2 x T(b) = 1 s and therefore T(b) = 500 ms.
Another way to view this is to take into account the number of subcarriers. Consider
we would have used six subcarriers. In this case T(b) = 1 s.
This relationship between number of subcarriers and symbol duration is inherent to
OFDM.
Question No 4:
When you look at your own drawing, it becomes obvious that the BPSK-signal needs
to complete a full period (2 PI) during T(b) on the lowest numbered subcarrier 0
which also uses the lowest frequency.
Consequentially, f(0) = 1/T(b) = 2 Hz
Question No 5:
Since in OFDM-systems all subcarriers are harmonics (integer multiples of the base
frequency f(0)) the response is obvious: f(1) = 2 x f(0), f(2) = 3 x f(0) and therefore:
Δf = f(0) = 2 Hz.
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Solutions for Practical Exercises
This relationship between base frequency f(0), subcarrier spacing Δf and symbol
duration T(b) is crucial for OFDM.
6
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Chapter 2 / Section 2.1.3: Scaling Issues of OFDM-Systems
6
•
Remarks on the Resolution:
Question No 1:
•
Option 1: no remarks
•
Option 2: please refer to question No 2.
Question No 2:
•
- 290 -
LTE might later operate at frequencies of about 2 – 3.5 GHz. At 3.5 GHz the
wavelength is LAMBDA = 8.6 cm. Deep fading effects known as Rayleigh fading
(see image on next page) will impact the related signal at distances of app.
LAMBDA / 2 = 4.3 cm along the path of the mobile station.
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⇒ At 3.5 GHz the radio channel changes its conditions quite rapidly within very
small distances of only a few centimeters (app. 4.3 cm).
⇒ Mobile receivers shall be simple and shall assume equal radio conditions
during one symbol duration (even while moving).
⇒ Therefore, the maximum moving distance of a mobile station during one
symbol duration must be much shorter than this LAMBDA/2.
⇒ Consequentially, the symbol duration must be short enough to accommodate
these fading conditions.
6
Accordingly:
•
If the subcarrier spacing is selected with Δf = 1 kHz we get a symbol duration of 1
ms (T(b) = 1 / Δf).
•
At a speed of 120 km/h, the mobile station will move 3.3 cm within this 1 ms
which is obviously too far to maintain an equal channel condition during one
symbol duration.
•
Much better is a subcarrier spacing of Δf = 10 kHz with a symbol duration of 0.1
ms and a moving distance of only 3.3 mm at 120 km/h.
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Chapter 3 / Section 3.5.4.2.1: Draw the Antenna Diagram of AAS
6
•
Your way to the resolution:
Question No 1 - 4:
Strictly follow the instruction.
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Solutions for Practical Exercises
Question No 5:
For the angles ́α ranging from 0 to -90 degree the angles β will be negative all
amplitudes and power have the same value as for the positive α angles.
Consequently the lobe has to be mirrored on the I-axis. Angles being bigger than 90
degree the circle in the middle drawing is continued. Again mirror the lobe already got
on the Q-axis to get the two lobe picture being typical for the two antenna AAS case.
All in all the circle is gone though two times and two lobes are generated.
Question No 6:
For a distance of 10 λ (20 x 0.5 λ) in-between the two antennas the circle is gone
through for 40 times. Consequently 40 lobes are constructed. This is typical for the
antenna diagram for antenna diversity use. This is the reason why the antennas as
always spaced multiple of 0.5 λ to form a single distinct beam in the AAS approach.
6
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Chapter 5 / Section 5.4.1: Intra eNB Handover
6
•
Your way to the resolution:
Question No 1:
Basically the intra eNB handover is looking like the inter eNB handover. The
difference is that the X2 interface communication and the data forwarding is not
necessary because this is handled by the eNB internally.
- 294 -
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List of Acronyms
List of Acronyms
Term
Explanation
(V)ASSI
Visited Alias Short Subscriber Identity
16-APK
16 symbols Amplitude Phase Keying
16-QAM
16 symbols Quadrature Amplitude Modulation
16VSB
16-level vestigial sideband modulation
1xEV-DO
One Carrier (1.25 MHz) Evolution - Data Only (cdma2000)
1xEV-DV
One Carrier (1.25 MHz) Evolution - Data and Voice
2B1Q
Two Binary One Quaternary (Line Coding used on the ISDN UInterface)
3G ...
3rd Generation ...
3GPP
Third Generation Partnership Project (Collaboration between
different standardization organizations (e.g. ARIB, ETSI) to
define advanced mobile communications standards,
responsible for UMTS)
3GPP2
Third Generation Partnership Project 2 (similar to 3GPP, but
consisting of ANSI, TIA and EIA-41, responsible for cdma2000,
EvDO and EVDV)
3GTR
3rd Generation Technical Report
3GTS
3rd Generation Technical Specification
4-PAM
4 symbols Pulse Amplitude Modulation
4G
4th Generation ...
64-QAM
64 symbols Quadrature Amplitude Modulation
8-PSK
8 Symbol Phase Shift Keying
8VSB
8-level Vestigial Sideband Modulation (ATSC)
A&S
Applications & Services domain or server
A-Bit
Acknowledgement Request Bit (used in LLC-protocol Logical
Link Control)
A/V
Audio / Video
AA
Anonymous Access
AAA
Authentication, Authorization and Accounting
AAA
Authorize Authenticate Answer (DIAMETER message type)
AACH
Access Assignment CHannel
AACH-Q
Access Assignment CHannel, QAM
AAL
ATM-Adaption Layer
AAL-2
ATM Adaptation Layer 2 (for real-time services) (ITU-T
I.363.2)
AAL-5
ATM-Adaptation Layer 5 (non-real time) (ITU-T I.363.5)
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AAR
Authorize Authenticate Request (DIAMETER message type)
AAS
Adaptive Antenna Systems
ABM
Asynchronous Balanced Mode
ABNF
Augmented Backus Naur Form (RFC 2234)
AC
Alternate Current
ACC
Access Control Class (3GTS 22.011)
ACCH
Associated Control Channel (GSM / can be an SACCH or an
FACCH)
ACELP
Algebraic Codebook Excited Linear Prediction
ACK
Acknowledgement
ACM
Address Complete Message (ISUP-message type)
ACS
Active Codec Set
ADCH
Associated Dedicated Channel (3GTS 45.902)
ADM
Asynchronous Disconnected Mode
ADPCM
Adaptive Differential Pulse Code Modulation
ADSL2
Asynchronous Digital Subscriber Line 2 (ITU-T G.992.3)
AES
Advanced Encryption Standard / Cipher Key Lengths: 128 bit,
192 bit or 256 bit
AESA
ATM End System Address
AF
Assured Forwarding (DiffServ Term)
AG
Absolute Grant (3GTS 25.309)
AGA
Air - Ground - Air service
AGCH
Access Grant Channel (GSM)
AGS
Absolute Grant Scope ('All' or 'Single' HARQ process)
AGV
Absolute Grant Value (INACTIVE or Zero_Grant or EDPDCH/DPCCH power ratio)
AH
Authentication Header (RFC 4302)
AI
Acquisition Indicator
AI
Air Interface
AICH
Acquisition Indicator Channel (UMTS Physical Channel)
AIPN
All IP Network
AJAX
Asynchronous Javascript and XML
AK
Anonymity Key (3GTS 33.102)
AK
Authentication Key (IEEE 802.16)
AKA
Authentication and key agreement (3GTS 33.102)
AKD
Authentication Key Distribution
AL
Advanced Link
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AL
Ambience Listening
ALC
Asynchronous Layered Coding
ALCAP
Access Link Control Application Part (ITU-T Q.2630.1 /
Q.2630.2)
ALG
Application Layer Gateway
AM
Acknowledged Mode operation
AM
Amplitude Modulation
AMBR
Aggregated Maximum Bit Rate
AMC
Adaptive Modulation and Coding
AMD
Acknowledged Mode Data (UMTS RLC PDU-type)
AMF
Authentication management field (3GTS 33.102)
AMI
Alternate Mark Inversion (Line Coding)
AMPS
Advanced Mobile Phone System
AMR
Adaptive Multirate Encoding (3GTS 26.090)
AMR-WB
Adaptive Multi-Rate - WideBand speech codec (3GTS 26.273,
ITU-T G.722.2)
AMR-WB+
Extended Adaptive Multi-Rate - WideBand speech codec (3GTS
26.304, 26.410, ITU-T G.722.1)
AMR_HR
Adaptive Multi Rate with Half-Rate Codec
ANSI
American National Standards Institute
AP
Access Point (IEEE 802.11, 802.16)
AP
Access Preamble
AP-AICH
CPCH Access Preamble Acquisition Indicator Channel (UMTS
Physical Channel)
APCO
Association of Police Communications Officers
API
Access Preamble Acquisition Indicator
API
Application Programming Interface
APK
Amplitude Phase Keying
APN
Access Point Name (Reference to a GGSN)
APP
A Posteriori Probability (Turbo Decoding)
AR
Assured Rate PDB (DiffServ Term)
ARFCN
Absolute Radio Frequency Channel Number
ARIB
Association of Radio Industries and Businesses (Japanese)
ARP
Address Resolution Protocol (RFC 826)
ARP
Allocation and Retention Priority
ARPU
Average Revenue Per User
ARQ
Automatic Repeat Request
AS
Access Stratum (UMTS)
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AS
Application Server
AS
application specific (within SDP-bandwidth specification / bline)
AS-ILCM
Application Server - Incoming Leg Control Model
AS-OLCM
Application Server - Outgoing Leg Control Model
ASC
Access Service Class
ASCA
Adjacent Subcarrier Allocation
ASCI
Advanced Speech Call Items (GSM-R)
ASCII
American Standard Code for Information Interchange (ANSI
X3.4-1986)
ASIC
Application Specific Integrated Circuit
ASN
Access Service Network
ASN-GW
Access Service Network-Gateway
ASN.1
Abstract Syntax Notation 1 (ITU-T X.680 / X.681)
ASP
Application Server Process
ASSI
Alias Short Subscriber Identity
AT-Command
Attention-Command
ATCA
Advanced Telecommunications Computing Architecture
ATID
Address Type Identifier in Demand
ATIS
Alliance of Telecommunications Industry Solutions
ATM
Asynchronous Transfer Mode (ITU-T I.361)
ATSC
Advanced Television System Committee
ATSI
Alias TETRA Subscriber Identity
AT_MAC
Message Authentication Code
AUTN
Authentication Token (3GTS 33.102)
AV
Authentication Vector (3GTS 33.102)
AVC
Advanced Video Coding
AVL
Automatic Vehicle Location
AWGN
Additive White Gaussian Noise
AoD
Audio on Demand
AuC
Authentication Center
B2BUA
Back-to-Back User Agent (SIP term / RFC 3261, RFC 3725)
B2DA
Back-to-Back Dynamic Allocation
B8ZS
Bipolar with Eight-Zero Substitution (Line Code used at the
T1-Rate (1.544 Mbit/s))
BAS
Basic rate access ISDN-user interface for single lines (2 Bchannels plus one D-Channel with 16 kbit/s)
BAT
Bouquet Association Table (MPEG, DVB-SI)
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List of Acronyms
BB
Base Band module
BBK
Broadcast BlocK
BC
Broadcast
BCAST
Broadcast
BCC
Base Station Color Code
BCC
Broadcast Call Control (3GTS 44.069)
BCCH
Broadcast Control Channel
BCCH-Q
Broadcast Control CHannel, QAM
BCD
Binary Coded Decimal
BCH
Broadcast Channel
BCMCS
Broadcast and Multicast Services (CDMA-2000 Rev. D)
BCTP
Bearer Control Tunneling Protocol (ITU-T Q.1990)
BE
Best Effort
BEC
Backward Error Correction
BEG
BEGin Message (TCAP)
BER
Bit Error Rate
BFCP
Binary Floor Control Protocol (draft-ietf-xcon-bfcp-05)
BFI
Bad Frame Indication
BG
Border Gateway
BGCF
Breakout Gateway Control Function
BIB
Backward Indicator Bit
BIC
Blind Interference Cancellation
BICC
Bearer Independent Call Control (ITU-T Q.1902.1 - Q.1902.6)
BKN1
Broadcast blocK 1
BKN2
Broadcast blocK 2
BL
Basic Link
BLCH
Base station Linearization CHannel
BLER
Block Error Rate
BM-IWF
Broadcast Multicast Interworking Function
BM-SC
Broadcast Multicast Service Center (3GTS 23.346)
BMC
Broadcast / Multicast Control (3GTS 25.324)
BN
Bit Number
BNCH
Broadcast Network CHannel
BNCH-Q
Broadcast Network CHannel, QAM
BNF
Backus Naur Form (RFC 2234)
BPSK
Binary or Bipolar Phase Shift Keying
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BQA
Bluetooth Qualification Administer
BQB
Bluetooth Qualification Body
BQRB
Bluetooth Qualification Review Board
BQTF
Bluetooth Qualification Test Facility
BR
Bandwidth Request (WiMAX Term)
BRA
Bit Rate Adaptation
BRAN
Broadband Radio Access Network
BS
Base Station (IEEE 802.16)
BSC
Base Station Controller
BSCH
Broadcast Synchronization CHannel
BSD
Berkeley Software Distribution
BSIC
Base Station Identity Code
BSN
Block Sequence Number (RLC) / Backward Sequence Number
(SS7)
BSS
Base Station Subsystem
BSSAP
Base Station Subsystem Application Part
BSSAP-LE
Base Station System Application Part - Location Based
Services Extension
BSSGP
Base Station System GPRS Protocol
BSSMAP
Base Station Subsystem Mobile Application Part (3GTS
48.008)
BS_CV_MAX
Maximum Countdown Value to be used by the mobile station
(Countdown Procedure)
BS_EIRP
Base Station Effective Isotropic Radiated Power
BTAB
Bluetooth Technical Advisory Board
BTC
Block Turbo Coding
BTS
Base Transceiver Station
BTTI
Basic Transmission Time Interval
BU
Bad Urban
BVCI
BSSGP Virtual Connection Identifier
BW
Bandwidth
C-RNTI
Cell Radio Network Temporary Identifier
C-SAP
Control Service Access Point
C/I
Carrier-to-Interference Ratio (like SNR)
C/N
Carrier/Noise power ratio
C/R-Bit
Command / Response Bit
C/T-Field
logical Channel / Transport channel identification Field
CAI
Channel Assignment Indicator
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List of Acronyms
CAMEL
Customized Applications for Mobile network Enhanced Logic
CAN
Connectivity Access Network
CAP
CAMEL Application Part (CCS7)
CAPEX
Capital Expenditure
CAT
Conditional Access Table (MPEG2-TS PSI)
CATV
Cable TV
CAZAC
Constant Amplitude Zero Autocorrelation Code
CB
Control uplink Burst
CBC
Cell Broadcast Center
CBC
Cipher Block Chaining (DES-Operation Mode)
CBC
Committed Burst Size
CBCH
Cell Broadcast Channel (GSM)
CBMS
Convergence of Broadcast and Mobile Services
CC
Call Control
CC
Convolutional Coding
CCC
CPCH Control Command
CCCH
Common Control Channel
CCF
Charging Collection Function
CCH
Control Channel
CCH-Q
Control CHannel, QAM
CCIR601
Comit consultatif international pour la radio, a forerunner of
the ITU-R, specification 601
CCITT
Comitéonsultatif International Tégraphique et
Téphonique (International Telegraph and Telephone
Consultative Committee)
CCK
Common Cipher Key
CCM
Common Channel Management (Protocol Part on the GSM
Abis-Interface / 3GTS 48.058)
CCM-Mode
Counter with CBC-MAC (RFC 3610) Combined Authentication
and Encryption with AES-Algorithm
CCN
Cell Change Notification (related to Network Assisted Cell
Change / 3GTS 44.060)
CCPCH
Common Control Physical Channel (see also P-CCPCH and SCCPCH)
CCS7
Common Channel Signaling System No. 7 (ITU-T Q-series of
specifications, in particular Q.700 - Q.703)
CCTrCH
Coded Composite Transport Channel (UMTS)
CCU
Channel Codec Unit
CD
Compact Disc
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CD/CA-ICH
Collision Detection / Channel Assignment Indicator Channel
(UMTS Physical Channel)
CDCH
Control-plane Dedicated Channel (3GTS 45.902)
CDD
Cyclic Delay Diversity
CDI
Collision Detection Indicator
CDMA
Code Division Multiple Access
CDMA2000
The 3G Standard 3GPP2
CDR
Call Detail Record
CELL_DCH
RRC Dedicated State
CELL_FACH
RRC FACH State in UTRA
CELL_PCH
RRC PCH State in UTRA
CEO
Chief Executive Officer
CEPT
Conférence Européne des Postes et
Técommunications
CESoP
Circuit Emulation Services over Packet
CFI
Control Format Indicator
CFN
Connection Frame Number
CG
Charging Gateway
CGF
Charging Gateway Function
CGI
Cell Global Identification
CHAP
Challenge Handshake Authentication Protocol (RFC 1334)
CI
Cell Identity
CIC
Call Instance Code (BICC)
CIC
Circuit Identity Code (ISUP)
CID
Channel Identity (ATM)
CID
Connection Identifier (WiMAX)
CIDR
Classless Inter-Domain Routing (RFC 1519)
CIF
Common Intermediate Format (352 x 240 pixels / ITU-T
H261 / H263)
CINR
Carrier to Interference and Noise Ratio
CIO
Cell Individual Offset (3GTS 25.331)
CIR
Carrier-to-Interference Ratio
CIR
Channel Impulse Response
CIR
Committed Information Rate
CK
Ciphering Key (3GTS 33.102)
CKSN
Ciphering Key Sequence Number
CLCH
Common Linearization CHannel
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List of Acronyms
CLCH-Q
Common Linearization CHannel, QAM
CMC
Codec Mode Command
CMC
Connection Mobility Control
CMCE
Circuit Mode Control Entity
CMD
Circuit Mode Data
CMI
Codec Mode Indication
CMIP
Client Mobile IP
CMIS/P
Common Management Information System/Protocol
CMR
Codec Mode Request
CMTS
Cable Modem Termination System
CN
Core Network
CNM
Central Network Management
CNMI
Central Network Management Interface
CNR
Carrier to Noise Ratio
COA
Change Over Acknowledge message (CCS7)
CODEC
Coder-decoder
COFDM
Coded Orthogonal Frequency Division Multiplexing
COMSEC
Communications Security
CON
CONtinue Message (TCAP)
CONS
Connection Orientated Network Service
COO
Change Over Order message (CCS7)
COPS
Common Open Policy Service Protocol (RFC 2748)
CORBA
Common Object Request Broker
CP
Control Physical channel
CP
Cyclic Prefix
CPC
Continuous Packet Connectivity
CPCH
Common Packet Channel (UMTS Transport Channel) FDD only
CPCS
Common Part Convergence Sublayer
CPE
Customer Premises Equipment
CPICH
Common Pilot Channel (UMTS Physical Channel / see also PCPICH and S-CPICH)
CPICH_Ec/No
Common Pilot Channel Energy per Chip to Noise Radio
CPIM
Common Presence and Instant Messaging (RFC 3862)
CPS
Coding and Puncturing Scheme
CPS
Common Part Sublayer
CPTI
Calling Party Type Identifier
CPU
Central Processing Unit
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CQI
Channel Quality Indicator
CQICH
Channel Quality Indicator Channel
CRC
Cyclic Redundancy Check
CRC_HS
CRC of High Speed Channel (HS-DSCH)
CRNC
Controlling RNC
CRSC
Contributing Source
CS
Circuit Switched
CS
Class Selector (DiffServ Term / RFC 2474)
CS
Coding Scheme
CS
Convergence Sublayer
CS-X
Coding Scheme (1 - 4)
CSCF
Call Session Control Function (SIP)
CSD
Circuit Switched Data
CSI
Channel State Information
CSICH
CPCH Status Indicator Channel (UMTS Physical Channel)
CSMA-CA
Carrier-Sense Multiple Access - Collision Avoidance
CSN
Connectivity Service Network
CSN.1
Code Syntax Notation 1 (3GTS 24.007)
CSPDN
Circuit Switched Public Data Network
CSRC
Synchronisation Source (RTP)
CSS
Carrier Specific Signalling
CT
Core Network and Terminal (Technical Specification Group
within 3GPP)
CTC
Convolutional Turbo Coding
CTCH
Common Traffic Channel (Logical) PTM
CTFC
Calculated Transport Format Combination (3GTS 25.331)
CUB
Control Uplink Burst
CV
Constellation Version
CV
Countdown Value
CVO
Clear Voice Override
CW
Code Word
CmCH-PI
Common Channel Priority Indicator
CoA
Care of Address (MIP)
CoU
Class of Usage
D-CT
Downlink-Continuous Transmission
D-CTT
Downlink-Carrier Timesharing Transmission
D-MCCTT
Downlink - Main Control Channel Timesharing Transmission
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List of Acronyms
D-TxAA
Double Transmit Antenna Array
DAB
Digital Audio Broadcasting
DARP
Downlink Advanced Receiver Performance (3GTS 45.015,
3GTS 24.008)
DAS-X
egprs2 Downlink level A modulation and coding Scheme (x =
5..12)
DASS
Digital Access Signaling System
DBC
Dynamic Bearer Control
DBP
Diameter Base Protocol (RFC 3588)
DBPSCH
Dedicated Basic Physical SubCHannel
DBS-X
egprs2 Downlink level B modulation and coding Scheme (x =
5..12)
DC
Direct Current
DCCH
Dedicated Control Channel
DCD
Downlink Channel Descriptor (WiMAX Message)
DCF
DRM Content Format
DCH
Dedicated Channel (Transport)
DCI
Downlink Control Indicator
DCK
Derived Cipher Key
DCM
Dedicated Channel Management (Protocol Part on the GSM
Abis-Interface / 3GTS 48.058)
DCOMP
Data COMpression Protocol
DCS
Digital Communication System
DDDS
Dynamic Delegation Discovery System (RFC 3401 - RFC 3404)
DDI
Data Description Indicator (3GTS 25.309, 25.331, 25.321)
DEC
Decision (COPS message type)
DEMUX
De-Multiplexer
DES
Data Encryption Standard
DF
Default Forwarding (DiffServ Term / RFC 2474)
DF
Do not Fragment (bit in IPv4 header)
DFT
Discrete Fourier Transformation
DGNA
Dynamic Group Number Assignment
DHCP
Dynamic Host Configuration Protocol (RFC 2131)
DHCPv4
Dynamic Host Configuration Protocol Version 4 (RFC 2131)
DHCPv6
Dynamic Host Configuration Protocol Version 6 (RFC 3315)
DIA
Diameter Protocol (RFC 3588, RFC 3589)
DIUC
Downlink Interval Usage Code (WiMAX Term)
DL
Downlink
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DL-MAP
Downlink-Medium Access Protocol (MAC-Message in WiMAX /
IEEE 802.16)
DL-SCH
Downlink Shared Channel
DLCI
Data Link Connection Identifier
DLFP
Downlink Frame Prefix
DLL
Data Link Layer
DLR
Destination Local Reference (SCCP term)
DLS
Downloadable Sounds
DMA
Division Multiple Access
DMB
Digital Multimedia Broadcasting
DMO
Direct Mode Operation
DMR
Digital Mobile Radio
DNS
Domain Name System
DOCSIS
Data Over Cable Service Interface Specification (defined by
CableLabs)
DPC
Destination Point Code
DPCCH
Dedicated Physical Control Channel (UMTS Physical Channel)
DPCH
Dedicated Physical Channel (UMTS / Term to combine DPDCH
and DPCCH)
DPDCH
Dedicated Physical Data Channel (UMTS Physical Channel)
DPDCH_P
DPDCH_Power or DPDCH_Pwr: Transmit power of DPDCH
DPNSS
Digital Private Network Signaling System
DPSK
Differential Phase Shift Keying
DQPSK
Differential Quadrature Phase Shift Keying
DRA
Dynamic Resource Allocation
DRM
Digital Rights Management
DRNC
Drift Radio Network Controller
DRX
Discontinuous Reception
DS-CDMA
Direct Sequence Code Division Multiple Access
DSCA
Diversity / Distributed Subcarrier Allocation
DSCH
Downlink Shared Channel (UMTS Transport Channel)
DSCP
Differentiated Services Code Pointer
DSL
Digital Subscriber Line
DSLAM
Digital Subscriber Line Access Multiplexer
DSM-CC
Digital Storage Media Call Control
DSN
Digital Switching Network
DSP
Digital Signal Processor
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DSR
Dual Symbol Rate
DSS
Downlink sync Sequence Set
DSS1
Digital Subscriber Signaling System No.1 (also referred to as
LAPD-signaling / ITU-T Q.931)
DSSS
Direct Sequence Spread Spectrum
DT1
Data Form 1 (SCCP message type)
DTAP
Direct Transfer Application Part
DTCH
Dedicated Traffic Channel
DTM
Dual Transfer Mode [3GTS 43.055]
DTMB
Digital Terrestrial Multimedia Broadcast
DTMF
Dual Tone Multiple Frequency
DTS
Decode Time Stamp
DTX
Discontinuous Transmission
DUA
DPNSS 1 / DASS 2 User Adaptation Layer (RFC 4129)
DVB
Digital Video Broadcasting
DVB-C
Digital Video Broadcasting - Cable TV
DVB-H
Digital Video Broadcasting - Handheld
DVB-S
Digital Video Broadcasting - Satellite
DVB-T
Digital Video Broadcasting - Terrestrial
Digit
4 bit
DoS
Denial of Service attack
E-AGCH
E-DCH Absolute Grant Channel
E-DCH
Enhanced Uplink Dedicated Transport Channel (3GTS 25.211,
25.309)
E-DCH-FP
E-DCH Frame Protocol (Enhanced Dedicated Channel)
E-DPCCH
Enhanced Uplink Dedicated Physical Control Channel (3GTS
25.211)
E-DPDCH
Enhanced Uplink Dedicated Physical Data Channel (3GTS
25.211)
E-GSM
Extended GSM (GSM 900 in the Extended Band)
E-HICH
E-DCH HARQ Acknowledgement Indicator Channel (3GTS
25.211)
E-OTD
Enhanced Observed Time Difference
E-RGCH
E-DCH Relative Grant Channel (3GTS 25.211)
E-RNTI
E-DCH Radio Network Temporary Identifier (3GTS 25.401)
E-TFC
E-DCH Transport Format Combination (3GTS 25.309)
E-TFCI
E-DCH Transport Format Combination Identifier (Enhanced
Dedicated Channel)
E-UTRA
Evolved UMTS Terrestrial Radio Access
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E-UTRAN
Evolved UMTS (Universal Mobile Telecommunication System)
Terrestrial Radio Access Network
EAP
Extensible Authentication Protocol (RFC 3748)
EAP-AKA
Extensible Authentication Protocol method for 3rd generation
Authentication and Key Agreement (RFC 4187)
EAP-SIM
Extensible Authentication Protocol method for gsm Subscriber
Identity Module (RFC 4186)
EAP-TLS
Extensible Authentication Protocol - Transport Layer Security
(RFC 2716)
EAP-TTLS
Extensible Authentication Protocol - Transport Layer Security
(draft-funk-eap-ttls-v0-01.txt)
EAPOL
EAP encapsulation Over Lan or wlan (IEEE 802.1X)
ECC
Electronic Communications Committee
ECCH
Extended Control CHannel
ECN
Explicit Congestion Notification
ECSD
Enhanced Circuit Switched Data (HSCSD + EDGE)
EDGE
Enhanced Data Rates for Global Evolution
EDR
Enhanced Data Rate (more speed with Bluetooth 2.0 (2.0 - 3.0
Mbit/s)
EF
Expedite Forwarding (DiffServ Term)
EFR
Enhanced Full Rate speech codec
EGAN
Evolved Generic Access Network
EGPRS
Enhanced General Packet Radio Service
EGPRS2
Enhanced GPRS phase 2 [3GTS 43.064]
EGPRS2-A
Enhanced GPRS Phase 2 Level A [3GTS 43.064, 3GTS 44.060]
EGPRS2-B
Enhanced GPRS Phase 2 Level B [3GTS 43.064, 3GTS 44.060]
EIA
Electronic Industries Alliance (US-organization to support US
industry)
EIR
Equipment Identity Register
EIRENE
European Integrated Railway Radio Enhanced Network (GSMR)
EIRP
Equivalent Isotropic Radiated Power
EIT
Event Information Table (MPEG, DVB-SI)
EMSK
Extended Master Session Key
EN
European Norm
END
END Message (TCAP)
ENUM
E.164-telephone number to URI (Uniform Resource Identifier)
translation (RFC 3761)
EPC
Evolved Packet Core (3GTS 23.401) (Rel. 8 onwards)
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List of Acronyms
EPS
Evolved Packet Switched
EPT
ETSI Project TETRA
EQ200
Equalizer Test 200 km/h
ERO
European Radiocommunications Office
ES
Elementary Stream
ES-Id
Encoding Symbol-Id
ESCR
Elementary Stream Clock Reference
ESG
Electronic Service Guide
ESN
Electronic Serial Number (North American Market)
ESP
Encapsulating Security Payload (RFC 4303)
ETS
European Telecommunication Standard
ETSI
European Telecommunications Standard Institute
EUL
Enhanced Uplink
EV-DO
Evolution Data Only or Evolution Data Optimized (cdma2000)
EV-DV
Evolution Data/Voice (cdma2000)
EVM
Error Vector Magnitude
E_UTRA
Evolved UMTS Terrestrial Access
Ec/No
Received energy per chip / power density in the band
Es/No
Energy per symbol / Noise power spectral density
Ethernet
Layer 2 Protocol for IP (IEEE 802.3)
F-DPCH
Fractional Dedicated Physical Channel (3GTS 25.211)
FA
Foreign Agent (Mobile IP / RFC 3344)
FACCH
Fast Associated Control Channel (GSM)
FACH
Forward Access Channel (UMTS Transport Channel)
FANR
Fast Ack/Nack Reporting
FBI
Feedback Information (UMTS)
FBI
Final Block Indicator
FBSS
Fast Base Station Switching
FCB
Frequency Correction downlink burst
FCC
Federal Communications Commission
FCCH
Frequency Correction Channel (GSM)
FCH
Frame Control Header
FCS
Frame Check Sequence (CRC-Check)
FDD
Frequency Division Duplex
FDDI
Fiber Distributed Data Interconnect (optical Layer 2)
FDM
Frequency Division Multiplexing
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FDMA
Frequency Division Multiple Access
FDPS
Full-slot Downlink Pilots Set
FDT
File Delivery Table
FEC
Forward Error Correction
FER
Frame Error Rate
FFH
Fast Frequency Hopping
FFRS
Fractional Frequency Reuse Scheme
FFS
For Further Study
FFT
Fast Fourier Transformation
FH-CDMA
Frequency Hopping Code Division Multiple Access
FIB
Forward Indicator Bit
FIPS
Federal Information Processing Standard
FISU
Fill In Signal Unit
FLO
Flexible Layer 1 (3GTS 45.902)
FLUTE
File Delivery over Unidirectional Transport (RFC 3926)
FM
Frequency Modulation
FMC
Fixed Mobile Convergence
FN
Frame Number
FP
Frame Protocol
FPB
First Partial Bitmap
FQDN
Fully Qualified Domain Name. Fully qualified domain names
consist of a host and a domain name whereas the domain
name needs to include a top-level domain (e.g. 'de' or 'org').
Examples: 'www.inacon.de' and 'PC10.inacon.com' are fully
qualified domain names. 'www' and 'PC10' represent the host,
'inacon' is the second-level domain, 'de' and 'com' are the top
level domain.
FR
Fullrate or Frame Relay
FRMR
Frame Reject
FRS
Frequency Reuse Scheme
FSN
Forward Sequence Number
FTP
File Transfer Protocol (RFC 959)
FUPS
Full-slot Uplink Pilots Set
FUSC
Full Usage of Subchannels
FWA
Fixed Wireless Access
FiSA
Filler Set A
FiSB
Filler Set B
FrCS
Frequency Correction Set
G-MSC
Gateway MSC
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List of Acronyms
G-PDU
T-PDU + GTP-Header
G-RNTI
GERAN Radio Network Temporary Identifier
GA
Generic Access (3GTS 43.318)
GA-CSR
Generic Access - Circuit-Switched Resources (3GTS 43.318)
GA-PSR
Generic Access - Packet-Switched Resources (3GTS 43.318)
GA-RC
Generic Access - Resource Control (3GTS 43.318)
GAA
Generic Authentication Architecture (3GTS 33.220)
GAN
Generic Access Network
GANC
Generic Access Network Controller (3GTS 43.318)
GBA
Generic Bootstraping Architecture (3GTS 33.220)
GBR
Guaranteed Bit Rate
GCC
Generic Call Control
GCF
General Certification Forum
GCK
Group Cipher Key
GEA
GPRS Encryption Algorithm
GERAN
GSM EDGE Radio Access Network
GGSN
Gateway GPRS Support Node
GHz
Giga Hertz (109 Hertz)
GIAT
Group Identity Address Type
GIF
Graphics Interchange Format
GITI
Group Identify Type Identifier
GK
Gatekeeper
GMLC
Gateway Mobile Location Center
GMM
GPRS Mobility Management
GMSC
Gateway MSC
GMSC-S
Gateway MSC Server
GMSK
Gaussian Minimum Shift Keying
GNU
recursive acronym for GNU is Not Unix. Today a synonym for
free Sourcecode Software.
GOP
Group of Pictures
GPCS
Generic Packet Convergence Sublayer (IEEE 802.16)
GPRS
General Packet Radio Service
GPRS-CSI
GPRS CAMEL Subscription Information
GPRS-SSF
GPRS Service Switching Function (CAMEL)
GPS
Global Positioning System
GRA
GERAN Registration Area
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GRE
Generic Routing Encapsulation (RFC 2784)
GRX
GPRS Roaming Exchange (GSM-Association IR.34)
GSM
Global System for Mobile Communication
GSM-R
GSM for Railways
GSMS
GPRS Short Message Service
GSN
GPRS Support Node
GSSI
Group Short Subscriber Identity
GTP
GPRS Tunneling Protocol (3GTS 29.060)
GTP-C
GTP Control Plane
GTP-U
GTP User Plane
GTSI
Group TETRA Subscriber Identity
GTT
Global Title Translation (ITU-T Q.714 (2.4))
GTTP
GPRS Transparent Transport Protocol (3GTS 44.018)
GUMMEI
Global Unique MME Identity
GUP
Generic User Profile
GUTI
Global Unique Terminal Identity
GW
Gateway
GZIP
GNU ZIP (compression format)
GoS
Grade of Service
H-PLMN
Home PLMN
H-RNTI
HS-DSCH Radio Network Transaction Identifier (3GTS 25.331,
25.433)
HA
Home Agent (Mobile IP / RFC 3344)
HARQ
Hybrid ARQ
HB
Heartbeat
HBDC
Happy Bit Delay Condition (3GTS 25.309)
HC-SDMA
High Capacity - Spatial Division Multiple Access
HCS
Hierarchical Cell Structure
HDB3
High Density Bipolar Three (Line Coding used for E1 (PCM 30)
HDLC
High level Data Link Control
HDTV
High Definition Television
HE
Header Extension Field
HFC
Hxbrid Fiber Cable (relates to the layer 1 of CableTVoperators)
HFC-Network
Hybrid Fiber- / Coaxial-cable
HI
HARQ Indicator
HIPERLAN/2
High Performance Radio Local Area Network type 2
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List of Acronyms
HLR
Home Location Register
HMAC
Keyed Hashing for Message Authentication (RFC 2104)
HO
Handover
HOM
Higher Order Modulation
HOMTC
Higher Order Modulation and Turbo Coding
HOT
Higher Order modulation and Turbo coding for downlink
HP
High Priority Path (MPEG, DVB)
HPLMN
Home Public Land Mobile radio Network
HR
Halfrate
HS
High Speed
HS-DPCCH
High Speed Dedicated Physical Control Channel (3GTS 25.211)
HS-DSCH
High Speed Downlink Shared Transport Channel (3GTS
25.211, 25.212, 25.308)
HS-HARQ
High Speed Hybrid Automatic Repeat Request
HS-PDSCH
High Speed Physical Downlink Shared Channel (3GTS 25.211)
HS-SCCH
High Speed Shared Control Channel (3GTS 25.211, 25.214)
HSCSD
High Speed Circuit Switched Data
HSDPA
High Speed Downlink Packet Access (3GTS 25.301, 25.308,
25.401, 3GTR 25.848)
HSPA
High Speed Packet Access (operation of HSDPA and HSUPA)
HSPA+
Enhanced High Speed Packet Access (operation of enhanced
HSDPA and enhanced HSUPA)
HSR
Higher Symbol Rate
HSS
Home Subscriber Server [3GTS 23.002]. HSS replaces the HLR
with 3GPP Rel. 5
HSUPA
High Speed Uplink Packet Access (3GTS 25.301, 25.309,
25.401, 3GTR 25.896)
HT200
Hilly Terrain 200 km/h
HTML
Hypertext Markup Language
HTTP
HyperText Transfer Protocol (RFC 2616)
HTTPS
Hypertext Transfer Protocol Secure
HUGE
Higher Uplink performance for Geran Evolution
HUMAN
High-speed Unlicensed Metropolitan Area Network
HUPS
Half-slot Uplink Pilots Set
HW
Hardware
HiperMAN
High Performance Radio Metropolitan Area Network
HoA
Home Address
I+S
Information + Supervisory
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I-CSCF
Interrogating Call Session Control Function (SIP)
I-WLAN
Interworking WLAN (Wireless Local Area Network) (3GTS
23.234)
IAM
Initial Address Message (ISUP ISDN User Part)
IANA
Internet Assigned Numbers Authority
IBS
Integrated Base Station
IC
Interference Cancellation
ICANN
Internet Corporation for Assigned Names and Numbers
ICH
Indicator Channel (UMTS Physical Channel / see also PICH,
AICH, CD/CA-ICH)
ICIC
Inter-Cell Interference Coordination
ICM
Initial Codec Mode
ICMP
Internet Control Message Protocol (RFC 792)
ICS
Implementation Conformance Statement
ID
Identity
IDEA
International Data Encryption Algorithm
IDFT
Inverse Discrete Fourier Transformation
IDNNS
Intra-Domain NAS Node Selector
IE
Information Element
IEC
International Electrotechnical Commission
IEEE
Institute of Electrical and Electronics Engineers
IETF
Internet Engineering Task Force (www.ietf.org)
IFFT
Inverse Fast Fourier Transformation
IGMP
Internet Group Multicast Protocol (RFC 1112, RFC 2236)
IHOSS
Internet Hosted Octet Stream Service
IIR-Filter
Infinite Impulse Response Filter
IK
Integrity Key (3GTS 33.102)
IKE
Internet Key Exchange (RFC 2409)
IKEv2
Internet Key Exchange protocol / version 2 (RFC 4306)
IKMP
Internet Key Management Protocol
ILCM
Incoming Leg Control Model
IM
Instant Messaging
IMEI
International Mobile Equipment Identity
IMEISV
International Mobile Equipment Identity - amended by
Software Version number
IMM
IMMediate access parameter
IMPI
IP Multimedia Private Identity; the private user identity of an
IMS-subscriber, formatted as an NAI (3GTS 33.203)
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List of Acronyms
IMPU
IP Multimedia Public Identity; the public user identity of an
IMS-subscriber, formatted as SIP-URI or TEL-URI (3GTS
33.203)
IMS
Internet Protocol Multimedia Core Network Subsystem (Rel. 5
onwards)
IMS-AG
IMS-Access Gateway
IMS-SSF
IP Multimedia Subsystem - Service Switching Function
IMSI
International Mobile Subscriber Identity
IMT
International Mobile Telecommunications
IMT-2000
International Mobile Telecommunications for the year 2000
IN
Intelligent Networking
INAP
Intelligent Network Application Part (CCS7)
INT
IP-MAC Notification Table (DVB-H SI)
IOP
Interoperability (of TETRA equipment)
IOV
Input / Offset Variable [3GTS 44.064]
IOV-I / IOV-UI
Input Offset Variable for I+S and UI-Frames (for ciphering in
GPRS)
IP
Internet Protocol (RFC 791)
IP-CAN
Internet Protocol - Connectivity Access Network (e.g. DSL, TVCable, WiMAX, UMTS)
IP-CS
IP-Convergence Sublayer
IPBCP
IP Bearer Control Protocol (ITU-T Q.1970)
IPCP
Internet Protocol Control Protocol (RFC 1332)
IPDC
IP Datacast
IPDV
IP-packet delay variation (ITU-T Y.1540)
IPER
IP-packet error ratio (ITU-T Y.1540)
IPLR
IP-packet loss ratio (ITU-T Y.1540)
IPR
Intellectual Property Rights
IPTD
IP-packet transfer delay (ITU-T Y.1540)
IPTV
Internet Protocol Television
IPsec
Internet Protocol / secure (RFC 4301)
IPv4
Internet Protocol (version 4)
IPv6
Internet Protocol (version 6)
IQ
Inphase and Quadrature
IR
Incremental Redundancy (ARQ II)
IS
Interim Standard (ANSI Standard)
IS-95
Interim Standard - 95 (Qualcomm CDMA)
ISAKMP
Internet Security Association and Key Management Protocol
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LTE from A-Z
(RFC 2408)
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ISBN
International Standard Book Number
ISC
IP multimedia subsystem Service Control-Interface
ISCP
Interference Signal Code Power (3GTS 25.215 / 3GTS 25.102)
ISCTI
Istituto Superiore delle Comunicazioni e delle Tecnologie
dell'Informazione
ISDB
Integrated Services Digital Broadcasting
ISDN
Integrated Services Digital Network
ISI
Inter-Symbol Interference
ISI
Inter-System Interface
ISIM
IMS capable Subscriber Identity Module
ISM
Industrial, Scientific and Medical (term for license-free
frequencies)
ISO
International Standardization Organization
ISP
Internet Service Provider
ISPC
International Signaling Point Code (ITU-T Q.708)
ISSI
Individual Short Subscriber Identity
ISUA
ISDN User Adaptation Layer
ISUP
ISDN User Part (ITU-T Q.761 - Q.765)
IT
Information Technology
ITSI
Individual TETRA Subscriber Identity
ITU
International Telecommunication Union
ITU-R
International Telecommunication Union Radiocommunications
ITU-T
International Telecommunication Union - Telecommunication
Sector
IUA
ISDN Q.921 User Adaptation Layer (RFC 4233)
IUT
Implementation under Test
IoT
Interference over Thermal noise
Iu-FP
Iu-Frame Protocol (3GTS 25.415)
Iub-FP
Iub-Frame Protocol (3GTS 25.427 / 25.435)
Iub_HS
Iub Interface with High Speed connection
Iur-FP
Iur-Frame Protocol (3GTS 25.424, 3GTS 25.425, 25.426,
25.435)
JD
Joint Detection
JPEG
Joint Picture Expert Group
KEK
Key Encryption Key (IEEE 802.16)
KMC
Key Management Centres
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List of Acronyms
KSG
Key Stream Generator
L1
Layer 1 (physical layer)
L2
Layer 2 (data link layer)
L2TP
Layer 2 Tunneling Protocol (RFC 2661)
L3
Layer 3 (network layer)
LA
Link Adaptation
LA
Location Area
LAC
Location Area Code
LACC
Location Area Country Code
LAI
Location Area Identification (LAI = MCC + MNC + LAC) [3GTS
23.003]
LAN
Local Area Network
LANC
Location Area Network Code
LAPB
Link Access Procedure Balanced
LAPD
Link Access Protocol for the ISDN D-Channel
LAPDm
Link Access Protocol for the D-Channel / modified for the GSM
air interface (3GTS 44.006)
LAPV5
Link Access Protocol for V5-interface
LATRED
Latency Reduction (Work item within GERAN-Evolution)
LB
Linearization Burst
LB
Load Balancing
LBS
Location Based Service
LCH
Logical Channel (3GTS 25.321 MAC-ehs)
LCH-Q
Linearization CHannel, QAM
LCID
Logical Channel ID
LCMC-SAP
Link entity Circuit Mode Control entity - Service Access Point
LCP
Link Control Protocol (PPP)
LCR
Low Chip Rate TDD
LCS
LoCation Service
LCT
Layered Coding Transport
LDAP
Lightweight Directory Access Protocol (RFC 3928)
LDB
Linearization Downlink Burst
LDPC
Low Density Parity Check
LE
Lower Effort PDB (DiffServ Term)
LER
Label Edge Router (MPLS)
LEX
Local Exchange Carrier
LI
Length Indicator
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LIP
Location Information Protocol
LIP-SAP
Location Information Protocol - Service Access Point
LLC
Logical Link Control-Protocol
LLME
Lower Layer Management Entity
LMDS
Local Multipoint Distribution Services
LMM-SAP
Link entity Mobility Management - Service Access Point
LMMSE
Linear Minimum Mean Square Error receiver
LMU
Location Measurement Unit
LNET
ORF ATM Network
LNM
Local Network Management
LOG10
Logarithm of basis 10
LOS
Line Of Sight
LP
Low Priority Path (MPEG, DVB)
LPC
Linear Predictive Coding
LPD
Link Protocol Discriminator
LR
Location Register
LS
Line Station
LSB
Least Significant Bit
LSF
Last Segment Flag
LSI
Line Station Interface
LSP
Label Switched Path (MPLS)
LSR
Label Switch Router (MPLS)
LSSU
Link Status Signal Unit
LTE
Long Term Evolution (of UMTS)
LTE_ACTIVE
LTE State for active packet transmission
LTE_DETACHED
LTE State for UE not being registered in the network
LTE_IDLE
LTE State for non active packet transmission
LTPD-SAP
Link entity TETRA Packet Data - Service Access Point
LUPR
Last User Power Ratio
LZS
Linearisation downlink Zeroed Set
M-TMSI
MME - Temporary Mobile Subscriber Identity
M-bit
More bit
M2PA
MTP-2 user Peer-to-Peer Adaptation Layer (RFC 4165)
M2UA
MTP-2 User Adaptation Layer (RFC 3331)
M3UA
MTP-3 User Adaptation Layer (RFC 4666)
MAC
Medium Access Control
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List of Acronyms
MAC
Message Authentication Code
MAC-d
Medium Access Control for the Dedicated Transport Channel
(3GTS 25.321)
MAC-e
MAC-E-DCH (3GTS 25.321)
MAC-ehs
MAC-Evolved High Speed
MAC-es
MAC-E-DCH SRNC (3GTS 25.321)
MAC-hs
MAC-High Speed (3GTS 25.321)
MAN
Metropolitan Area Network
MAP
Mobile Application Part (3GTS 29.002)
MAP-B
Mobile Application Part - B-interface protocol between MSC
and VLR
MAP-X
Mobile Application Part - various interface protocols like B-, C-,
D-, E-, F- or G-interface
MAR
Minimum to Average power Ratio
MASF
Minimum Available Spreading Factor
MBMS
Multimedia Broadcast / Multicast Service (3GTS 23.246, 3GTS
43.846)
MBMS_RRC_CONN RRC state for E-MBMS in LTE
ECTED
MBR
Maximum Bit Rate
MBS
Multicast Broadcast Services
MBSAT
Mobile Broadcast Satellite
MBSFN
MBMS Single Frequency Network
MBWA
Mobile Broadband Wireless Access [IEEE 802.20]
MBZ
Must Be Zero
MBit
Mega Bit
MCC
Mobile Country Code [ITU-T E.212]
MCCH
MBMS point-to-multipoint Control Channel
MCCH
Main Control CHannel
MCH
Multicast Channel
MCM
Minimum Control Mode
MCS
Modulation and Coding Scheme
MCS-X
Modulation and Coding Scheme (1 - 9) and for HSDPA /
HSUPA
MCU
Multipoint Control Unit (H.323 equipment)
MD
Message Digest algorithm (e.g. MD-5)
MD-X
Message Digest Algorithm (MD-2, 4, 5 are defined) (MD-5 RFC
1321)
MDHO
Macro-Diversity Handover
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MDSR
Modified Dual Symbol Rate
ME
Mobile Equipment (ME + SIM = MS)
MEGACO
Media Gateway Control Protocol (ITU-T H.248 incl. Annex F - H
and IETF RFC 3015)
MELPe
Mixed Excitation Linear Predictive
MER
Message Erasure Rate
MEX
Multimedia Exchange Layer
MExE
Mobile Station Application Execution Environment
MGC
Media Gateway Controller
MGCF
Media Gateway Control Function
MGCK
Modified Group Cipher key
MGCP
Media Gateway Control Protocol (RFC 2705)
MGT
MPEG PSI tables for ARIB
MGW
Media Gateway
MHP
Multimedia Home Platform
MHz
Mega Hertz (106 Hertz)
MIB
Management Information Base
MIB
Master Information Block
MICH
MBMS Notification Indicator Channel
MIDI
Musical Instrument Digital Interface
MIH
Media Independent Handover (IEEE 802.21)
MII
Ministry of Information Industry
MIKEY
Multimedia Internet KEYing (RFC 3830)
MIME
Multipurpose Internet Mail Extensions
MIMO
Multiple In / Multiple Out (antenna system)
MIN
Mobile Identity Number (North American Market)
MINA
Mobile Internet Network Architecture
MIP
Mobile IP (RFC 2002, 3344, 3775)
MIPv4
Mobile IP Version 4
MISO
Multiple In / Single Out (antenna system)
MLD
Multicast Listener Discovery (RFC 2710)
MLE
Mobile Link Entity
MLP
MAC Logical Channel Priority
MLPP
Multi-Level Precedence and Pre-emption (ITU-T Q.85 / Clause
3)
MM
Mobility Management
MMCC
Multimedia Call Control
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MMD
IP Multimedia Domain (name of the IMS in 3GPP2)
MMDS
Multipoint Microwave Distribution System or Multi-channel
Multi-point Distribution System
MME
Mobility Management Entity (3GTS 23.401) (Rel. 8 onwards)
MMEC
MME Code
MMEGI
MME Group Identity
MMEI
MME Identity
MMI
Man-Machine-Interface
MMS
Multimedia Messaging Service (3GTS 22.140, 3GTS 23.140)
MN
Multiframe Number
MNC
Mobile Network Code
MNI
Mobile Network Identity
MNRG
Mobile Not Reachable for GPRS flag
MO
Mobile station Originating
MOBIKE
IKEv2 Mobility and Multihoming Protocol (RFC 4555)
MOC
Mobile Originating Call
MOPS
Million Operations Per second
MORE
Modulation Order and symbol Rate Enhancement
MOS
Mean Opinion Score
MP3
MPEG-1 Audio Layer 3
MPCC
Multiparty Call Control
MPE
Multi Protocol Encapsulation (DVB-H)
MPEG
Motion Picture Expert Group
MPEG2-TS
MPEG-2 Transport Stream (DVB)
MPLS
Multi Protocol Label Switching
MPN
Monitoring Pattern Number
MPRACH
MBMS Packet Random Access Channel ((E)GPRS)
MRC
Maximum Ratio Combining
MRF
Multimedia Resource Function
MRFC
Multimedia Resource Function Controller
MRFP
Multimedia Resource Function Processor
MRU
Maximum Receive Unit (PPP)
MRW
Move Receiving Window
MS
Mobile Station
MS
Mobile Subscriber Station [IEEE 802.16]
MS-ISDN
Mobile Subscriber - International Service Directory Number
MS-PD
Multislot Packet Data
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MSB
Most Significant Bit
MSC
Mobile Services Switching Center
MSC-S
MSC-Server
MSCH
MBMS point-to-multipoint Scheduling Channel
MSK
Master Session Key
MSRD
Mobile Station Receive Diversity
MSRN
Mobile Station Roaming Number
MSRP
Message Session Relay Protocol (draft-ietf-simple-messagesessions-XX)
MSS
Maximum Segment Size (TCP)
MST
Multiple Slot Transmission
MSU
Message Signal Unit
MT
Mobile Terminal or Mobile Terminating
MT0
Mobile station Termination type 0
MT2
Mobile station Termination type 2
MTBF
Mean Time Between Failure
MTC
Mobile Terminating Call
MTCH
MBMS point-to-multipoint Traffic Channel
MTK
MBMS Traffic Key
MTP
Message Transfer Part (ITU-T Q.701 - Q.709)
MTP-3b
Message Transfer Part level 3 / broadband (ITU-T Q.2210)
MTTR
Mean Time To Repair
MTU
Maximum Transmit Unit (IP)
MUD
Multi-User-Detection unit
MUX
Multiplex
MVNO
Mobile Virtual Network Operator
Max [X, Y]
The value shall be the maximum of X or Y, which ever is
bigger
Mcps
Mega Chip Per Second
Min [X, Y]
The value shall be the minimum of X or Y, which ever is
smaller
MitM
Man in the Middle (attack)
N(R)
Received SDU (TL-SDU) Number
N(S)
Sent SDU (TL-SDU) Number
N-PDU
Network-Protocol Data Unit (IP-Packet, X.25-Frame)
N-SAW
N-Channel Stop and Wait (3GTS 25.309, 3GTR 25.848)
NACC
Network Assisted Cell Change (3GTS 44.060)
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NACK
Negative Acknowledgement
NAF
Network Application Function (part of the Generic
Authentication Architecture (GAA))
NAI
Network Access Identifier (RFC 2486)
NAP
Network Access Provider
NAPT
Network Address Port Translation (RFC 3022)
NAPTR
Naming Authority Pointer (RFC 2915)
NAS
Non-Access-Stratum
NASS
Network Attachment SubSystem (part of the TISPAN NGNarchitecture)
NAT
Network Address Translation (RFC 1631)
NATO
North Atlantic Treaty Organisation
NBAP
NodeB Application Part (3GTS 25.433)
NBNS
NetBios Name Service
NC
Neighbor Cell
NC
Network Connection
NCC
Network Color Code
NCM
Normal Control Mode
NCP
Network Control Protocol (PPP)
NDB
Normal Downlink Burst
NDI
New Data Indicator
NGMN
Next Generation Mobile Networks
NGN
Next Generation Networks
NI
Network Indicator
NIC
Network Interface Card
NIT
Network Information Table (MPEG2-TS PSI, DVB-SI)
NLOS
Non Line Of Sight
NMS
Network Management Subsystem
NMT
Nordic Mobile Telephone (analog cellular standard, mainly
used in Scandinavia)
NNI
Network-to-Network Interface
NOM
Network Operation Mode [3GTS 23.060]
NPB
Next Partial Bitmap
NPM
Non-Persistent Mode
NRA
National Regulatory Administration
NRI
Network Resource Identifier
NS
Network Service
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NS-VC
Network Service - Virtual Connection
NS-VCG
Network Service - Virtual Connection Group
NS-VL
Network Service - Virtual Link
NSAP
Network Service Access Point
NSAPI
Network Service Access Point Identifier
NSE
Network Service Entity
NSF
NAS Node Selection function
NSIS
Next Steps in Signaling (RFC 4080)
NSLP
NSIS Signaling Layer Protocol (e.g. for resource reservation)
NSP
Network Service Provider
NSPC
National Signaling Point Code
NSR
Normal Symbol Rate
NSS
Network Switching Subsystem
NT
Network Termination
NTSC
National Television System Committee (video standard for
North America)
NUB
Normal Uplink Burst
NWG
Network Working Group (WiMAX Forum)
O&M
Operation and Maintenance
O-bit
Optional bit
OCNS
Orthogonal Channel Noise Simulator
OFDM
Orthogonal Frequency Division Multiplexing
OFDMA
Orthogonal Frequency Division Multiple Access
OFUSC
Optional FUSC (Full Usage of Subchannels)
OLCM
Outgoing Leg Control Model
OMA
Open Mobile Alliance (http://www.openmobilealliance.org/)
OMAC
One-Key CBC-MAC (NIST standard: SP 800-38B and
http://csrc.nist.gov/CryptoToolkit/modes/proposedmodes/)
OMAP
Operation & Maintenance Application Part
OMC
Operation and Maintenance Center
OOK
On OFF Keying
OP
Optional
OPC
Originating Point Code
OPEX
Operational Expenditure
OPUSC
Optional PUSC (Partial Usage of Subchannels)
OPWA
One Pass With Advertising (Term in RSVP)
ORF
Oesterreichischer Rundfunk
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and will be prosecuted to the full extent of German and international laws. Version Number 2.030
List of Acronyms
OSA
Open Service Access
OSA-SCS
Open Service Access - Service Capability Server
OSCP
Online Certificate Status Protocol (RFC 2560)
OSI
Open System Interconnection
OSP
Octet Stream Protocol
OTAR
Over The Air Re-keying
OTDOA
Observed Time Difference Of Arrival
OVSF
Orthogonal Variable Spreading Factor
Octet
8 bit
OoBTC
Out of Band Transcoder Control (3GTS 23.153)
P-CCPCH
Primary Common Control Physical Channel (UMTS / used as
bearer for the BCH TrCH)
P-CPICH
Primary Common Pilot Channel (UMTS Physical Channel)
P-CSCF
Proxy Call Session Control Function (SIP)
P-SCH
Primary Synchronization Channel
P-TMSI
Packet TMSI
P/F-Bit
Polling/Final - Bit
P/S
Parallel to Serial
PA
Pedestrian A mobile radio channel
PA
Power Amplifier
PA
Presence Agent (RFC 3856)
PABX
Private Automatic Branch Exchange
PACCH
Packet Associated Control Channel ((E)GPRS)
PACQ
Probability of synchronization burst ACQuisition
PACS
Personal Access Communication System
PAD
Packet Assembly Disassembly
PAGCH
Packet Access Grant Channel ((E)GPRS)
PAL
Phase Alternating Line (TV Norm)
PAMR
Public Access Mobile Radio
PAN
Piggybacked Ack/Nack
PAP
Password Authentication Protocol (RFC 1334)
PAPR
Peak-to-Average Power Ratio
PAR
Peak to Average power Ratio
PAT
Program Assocation Table (MPEG2-TS)
PB
Pedestrian B mobile radio channel
PBCCH
Packet Broadcast Control Channel ((E)GPRS)
PBCH
Physical Broadcast Channel
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PBS
Peak Burst Size
PC
Paging Controller
PC
Power Control
PC
Protocol Class (SCCP)
PC
Protocol Control
PCCC
Parallel Concatenated Convolutional Code (possible Turbo
Coding Scheme)
PCCCH
Packet Common Control Channel ((E)GPRS)
PCCH
Paging Control Channel
PCFICH
Physical Control Format Indicator Channel
PCH
Paging Channel
PCI
Peripheral Component Interconnect (computer bus standard to
interconnect peripherals to the CPU)
PCI
Precoding Control Indication
PCM
Pulse Code Modulation
PCN
Personal Communication Network
PCOMP
Protocol COMpression Protocol
PCPCH
Physical Common Packet Channel (UMTS Physical Channel)
PCR
Program Clock Reference (MPEG)
PCRF
Policy Control and Charging Rules Function (3GTS 23.203)
(Rel. 7 onwards)
PCS
Personal Communication System
PCU
Packet Control Unit
PD
Packet Data
PD
Protocol Discriminator
PDA
Personal Digital Assistant
PDB
Packet Delay Budget
PDB
Per Domain Behavior (DiffServ Term)
PDBF
Profile DataBase Function (TISPAN term / ETSI ES 282 004)
PDC
Personal Digital Communication (ARIB-Standard)
PDCCH
Physical Downlink Control Channel
PDCH
Packet Data Channel
PDCP
Packet Data Convergence Protocol
PDF
Policy Decision Function (Part of the IP Multimedia Subsystem)
PDF
Probability Density Function
PDG
Packet Data Gateway
PDH
Plesiochronous Digital Hierarchy
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List of Acronyms
PDN
Packet Data Network
PDO
Packet Data Optimised
PDP
Packet Data Protocol
PDS
Packet Data Subsystem (3GPP2)
PDS
Power Density Spectrum
PDSCH
Physical Downlink Shared Channel
PDSN
Packet Data Support Node (the SGSN in 3GPP2)
PDTCH
Packet Data Traffic Channel ((E)GPRS)
PDU
Protocol Data Unit or Packet Data Unit
PEAP
Protected Extensible Authentication Protocol
PEI
Peripheral Equipment Interface
PEP
Policy Enforcement Point (3GTS 23.209)
PER
Packed Encoding Rules (ITU-T X.691)
PES
PSTN/ISDN Emulation Subsystem (part of the TISPAN NGNarchitecture)
PES
Packetised Elementary Stream (DVB)
PFC
Packet Flow Context
PFI
Packet Flow Identifier
PG
Processing Gain: 10 * LOG10 (3.84 Mcps / user_data_rate)
PHB
Per Hop Behavior (DiffServ Term)
PHICH
Physical HARQ Acknowledgement Indicator Channel
PHS
Payload Header Suppression (IEEE 802.16)
PHS
Personal Handy phone System
PHY
Physical Layer
PHz
Peta Hertz (1015 Hertz)
PI
Paging Indicator
PI
Priority Indicator
PICH
Page Indicator Channel (UMTS Physical Channel)
PICMG
PCI (Peripheral Component Interconnect) Industrial Computer
Manufacturers Group (http://www.picmg.org/)
PICS
Protocol Implementation Conformance Statement
PID
Packet Identifier (MPEG2-TS)
PIDF
Presence Information Data Format (RFC 3863)
PIR
Peak Information Rate
PIXIT
Protocol Implementation Extra Information for Testing
PKCS
Public Key Cryptography Standard
PKMv2
Privacy Key Management Version 2
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PL
Physical Layer
PL
Puncturing Limit (3GTS 25.212)
PL-SAP
Packet link Layer Service Access Point
PLC
Power Line Communications
PLMN
Public Land Mobile Network
PLR
Packet Loss Rate
PLmax
E-DCH maximum Puncturing Limit (3GTS 25.212)
PLnon-max
Puncturing Limit not requiring maximum physical channels
(3GTS 25.212)
PMCH
Physical Multicast Channel
PMI
Precoding Matrix Indicator
PMIP
Proxy Mobile IP
PMM
Packet Mobility Management
PMR
Private Mobile Radio
PMT
Program Map Table (MPEG2-TS)
PMTU
Path MTU
PN
Pseudo Noise
PNCH
Packet Notification Channel ((E)GPRS)
PNG
Portable Network Graphics
PO
Power Offset
POP
Post Office Protocol (RFC 1939)
POP3
Post Office Protocol version 3
POTS
Plain Old Telephone Service
PPCH
Packet Paging Channel ((E)GPRS)
PPP
Point-to-Point Protocol (RFC 1661)
PRA
PCPCH Resource Availability
PRACH
Packet Random Access Channel
PRACH
Physical Random Access Channel
PRACK
Provisional Response Acknowledgement (SIP-method type)
PRD
Bluetooth Qualification Program Reference Document
PRF
Pseudo Random Function
PRI
Primary rate access ISDN-user interface for PABX's (23 or 30
B-channels plus one D-Channel)
PS
Packet Switched
PS
Physical Slot (IEEE 802.16)
PS
Program Stream
PS
Puncturing Scheme
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List of Acronyms
PSC
Primary Synchronization Code or Primary Scrambling Code
(both used in UMTS)
PSD
Power Spectral Density (3GTS 25.215 / 3GTS 25.102)
PSI
Program Specific Information (MPEG2-TS)
PSIP
MPEG PSI tables for ARIB, similar to DVB-PSI
PSK
Phase Shift Keying
PSPDN
Packet Switched Public Data Network
PSS 1
Private integrated Signalling System No. 1
PSTN
Public Switched Telephone Network
PT
Protocol Type (GTP or GTP')
PTCCH
Packet Timing Advance Control Channel ((E)GPRS)
PTCCH/D
Packet Timing Advance Control Channel / Downlink Direction
((E)GPRS)
PTCCH/U
Packet Timing Advance Control Channel / Uplink Direction
((E)GPRS)
PTM
Point to Multipoint
PTP
Point to Point
PTS
Presentation Time Stamp
PTT
Post, Telephone & Telegraph (abbreviation for the former
government owned organizations that were responsible for all
three services)
PUA
Presence User Agent (RFC 3856)
PUCCH
Physical Uplink Control Channel
PUEM
Probability of Undetected Erroneous Message
PUSC
Partial Usage of Subchannels
PUSCH
Physical Uplink Shared Channel
PVC
Permanent Virtual Circuit
PhCH
Physical Channel
PoC
Push to talk over Cellular (3GTR 29.979 and various OMAspecifications)
PoE
Power over Ethernet
QAM
n symbols Quadrature Amplitude Modulation (n = 16, 32,
64, ...)
QCI
QoS Classes Identifier
QCIF
Quarter Common Intermediate Format (176 x 144 pixels ITU-T
H261 / H263)
QE
Quality Estimate
QPSK
Quadrature Phase Shift Keying
QSIG
Q-interface signaling protocol
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QoS
Quality of Service
R-GSM
Railways-GSM
RA
Registered Area
RA
Routing Area
RA-RNTI
Random Access - Radio Network Temporary Identifier
RAA
RE-Auth-Answer command (Diameter BASE, RFC 3588)
RAB
Radio Access Bearer
RAB
Random Access uplink Burst
RAC
Radio Admission Control
RAC
Routing Area Code
RACC
Routing Area Color Code [3GTS 44.018 (10.5.2.34)]
RACH
Random Access Channel
RACS
Resource and Admission Control Subsystem (part of the
TISPAN NGN-architecture)
RADIUS
Remote Authentication Dial In User Service (RFC 2865)
RAI
Routing Area Identification
RAM
Random Access Memory
RAN
Radio Access Network
RANAP
Radio Access Network Application Part (3GTS 25.413)
RAND
Random Number
RAR
RE-Auth-Request command (Diameter BASE, RFC 3588)
RAT
Radio Access Technology (e.g. GERAN, UTRAN, ...)
RATSCCH
Robust AMR Traffic Synchronized Control CHannel
RB
Radio Bearer
RB
Receive Block Bitmap (EGPRS)
RB
Resource Block
RBB
Receive Block Bitmap (GPRS)
RBC
Radio Bearer Control
RBPSCH
Shared Basic Physical SubCHannel
RCPC
Rate Compatible Punctured Convolutional
RDC
Radio Downlink Counter
RDC-NC
Radio Downlink Counter - Non Conforming channel
RDC-Q
Radio Downlink Counter, QAM
RED
REduced symbol Duration
RED
Random Early Detection
REJ
Reject
REQ
Request (COPS message type)
© INACON GmbH 1999 - 2009. All rights reserved. Reproduction and/or unauthorized use of this material is prohibited
and will be prosecuted to the full extent of German and international laws. Version Number 2.030
List of Acronyms
RES
Response
RF
Radio Frequency
RFC
Request for Comments (Internet Standards)
RFID
Radio Frequency Identification
RG
Relative Grant (3GTS 25.309)
RL
Radio Link (3GTS 25.433)
RL-TBF
Reduced Latency Temporary Block Flow [3GTS 43.064]
RLC
Radio Link Control
RLM
Radio Link Management (Protocol Part on the GSM AbisInterface / 3GTS 48.058)
RLP
Radio Link Protocol (3GTS 24.022)
RLS
Radio Link Set (3GTS 25.309, 25.433)
RM
Rate Matching
RM
Reed-Muller
RMS
Root Mean Square
RNC
Radio Network Controller
RNL
Radio Network Layer
RNR
Receive Not Ready
RNS
Radio Network Subsystem
RNSAP
Radio Network Subsystem Application Part (3GTS 25.423)
RNSN
Radio Network Serving Node
RNTI
Radio Network Temporary Identifier
ROHC
Robust Header Compression
ROI
Return On Invest
RPE/LTP
Regular Pulse Excitation / Long Term Prediction (Speech
Codec)
RPID
Rich Presence Information Data
RPLMN
Registered PLMN
RPR
Resilient Packet Ring (IEEE 802.17)
RR
Radio Resource Management
RR
Receive Ready (LAPD/LLC/RLP-Frame Type)
RRA
Radio Resource Agent
RRBP
Relative Reserved Block Period
RRC
Radio Resource Control
RRC-Filter
Root Raised Cosine Filter
RRC_CONNECTED RRC state in E-UTRA
RRC_IDLE
RRC state
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RRC_MBMS_CONN RRC state in E-UTRA for UEs with MBMS service only
ECTED
- 332 -
RRLP
Radio Resource LCS Protocol
RRM
Radio Resource Management
RS
Reference Signal
RSA
Ron Rivest, Adi Shamir and Leonard Adleman-algorithm
(Public Key Encryption / PKCS #1)
RSADP
RSA-Decryption Primitive (RFC 3447 (5.1.2) or PKCS #1
(5.1.2); PKCS = Public Key Cryptography Standard)
RSAEP
RSA-Encryption Primitive (RFC 3447 (5.1.1) or PKCS #1
(5.1.1); PKCS = Public Key Cryptography Standard)
RSAES-OAEP
RSA Encryption Scheme - Optimal Asymmetric Encryption
Padding (PKCS #1 / RFC 3447)
RSC
Recursive Systematic Convolutional Coder (Turbo Coding,
25.212)
RSCP
Received Signal Code Power (3GTS 25.215)
RSN
Retransmission Sequence Number (3GTS 25.309, 25.212)
RSRP
Reference Signal Received Power
RSRQ
Reference Signal Received Quality
RSSI
Received Signal Strength Indicator
RST
Running Status Table (DVB-SI)
RSTD
Reference Signal Time Difference
RSVP
Resource Reservation Protocol (RFC 2205)
RT
Real Time
RTCM
Radio Technical Commission for Maritime Services
RTCP
Real-time Transport Control Protocol
RTG
Receive transmit Transition Gap (IEEE 802.16 (3.45)) the time
between an uplink subframe and the subsequent downlink
subframe in a TDD-system
RTO
Retransmission Time Out
RTP
Real-time Transport Protocol (RFC 3550, RFC 3551)
RTP/AVP
Real-time Transport Protocol / Audio Video Profile (RFC 3551)
(used in SDP-descriptions)
RTP/AVPF
Real-time Transport Protocol / extended Audio Video Profile for
rtcp Feedback (used in SDP-descriptions)(draft-ietf-avt-rtcpfeedback-11.txt)
RTP/SAVP
Real-time Transport Protocol / Secure Audio Video Profile (RFC
3711) (used in SDP-descriptions)
RTSP
Real Time Streaming Protocol (RFC 2326)
RTT
Round Trip Time
RTTI
Reduced Transmission Time Interval
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List of Acronyms
RTTVAR
Round Trip Time Variation
RTWP
Received Total Wideband Power
RUIM
Removable User Identity Module
RV
Redundancy and Constellation Version (3GTS 25.212)
RX
Receive
RoHC
Robust Header Compression
RoT
Rise over Thermal (interference rise relative to zero load)
Roope53vISO
International Organization for Standardization
Rx
Receive(r)
S(R)
Received segment Sequence number
S(S)
Sent segment Sequence number
S-CCPCH
Secondary Common Control Physical Channel (used as bearer
for the FACH and PCH TrCH's / UMTS Physical Channel)
S-CPICH
Secondary Common Pilot Channel (UMTS Physical Channel)
S-CSCF
Serving Call Session Control Function (SIP)
S-SCH
Secondary Synchronization Channel (physical)
S-TMSI
SAE Temporary Mobile Subscriber Identity
S/P
Serial to Parallel
S1-AP
S1 Application Part
SA
Security Association
SA
Service Area
SA
System Architecture
SAAL-NNI
Signaling ATM Adaptation Layer - Network Node Interface
SAB
Service Area Broadcast
SABM(E)
Set Asynchronous Balanced Mode (Extended for Modulo 128
operation) (LAPD/LLC/RLP-Frame Type)
SABP
Service Area Broadcast Protocol (3GTS 25.419)
SACCH
Slow Associated Control Channel (GSM)
SACCH/MD
SACCH Multislot Downlink (related control channel of TCH/FD/
GSM)
SACK
Selective Acknowledgement
SAE
System Architecture Evolution
SAI
Service Area Identifier
SAIC
Single Antenna Interference Cancellation
SANC
Signaling Area Network Code (ITU-T Q.708)
SAP
Service Access Point
SAPI
Service Access Point Identifier
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SAR
Segmentation And Reassembly (ATM-sublayer)
SAR
Specific Absorption Rate
SAT
Satellite
SAW
Stop and Wait Machine
SB
Scheduling Block
SB
Synchronization downlink Burst
SBC
Session Border Controller (SIP term, usually a B2BUA with
NAT-function and media gateway)
SBN
Source Block Number
SBPSCH
Shared Basic Physical SubCHannel
SC
Serving Cell
SC
Subcarrier
SC-FDMA
Single Carrier Frequency Division Multiple Access
SCCH
Secondary Control CHannel
SCCP
Signaling Connection Control Part (ITU-T Q.711 - Q.714)
SCF
Service Control Function (CAMEL)
SCH
Signalling CHannel
SCH
Synchronization Channel
SCH-P8/F
Signalling CHannel, p/8-D8PSK, Full size
SCH-P8/HD
Signalling CHannel, p/8-D8PSK, Half size Downlink
SCH-P8/HU
Signalling CHannel, p/8-D8PSK, Half size Uplink
SCH-Q
Signalling CHannel, QAM
SCH-Q/D
Signalling CHannel, QAM Full size Downlink
SCH-Q/HU
Signalling CHannel, QAM Half size Uplink
SCH-Q/RA
Signalling CHannel, QAM Random Access Uplink
SCH-Q/U
Signalling CHannel, QAM Full size Uplink
SCH/F
Signalling CHannel, Full size
SCH/HD
Signalling CHannel, Half size Downlink
SCH/HU
Signalling CHannel, Half size Uplink
SCK
Static Cipher Key
SCLNS
Specific ConnectionLess Network Service
SCN
Switching Control Node
SCP
Service Control Point (IN)
SCR
Source Controlled Rate
SCTP
Stream Control Transmission Protocol (RFC 2960)
SD
Sample Duration
SDCCH
Stand Alone Dedicated Control Channel
© INACON GmbH 1999 - 2009. All rights reserved. Reproduction and/or unauthorized use of this material is prohibited
and will be prosecuted to the full extent of German and international laws. Version Number 2.030
List of Acronyms
SDH
Synchronous Digital Hierarchy
SDK
Software Development Kit
SDMA
Space Division Multiple Access
SDP
Session Description Protocol (RFC 2327, RFC 3266, RFC 3264)
SDS
Short Data Service
SDT
Service Description Table (DVB-SI)
SDTI
Short Date Type Identifier
SDTV
Standard Definition TV
SDU
Service Data Unit (the payload of a PDU)
SEG
Security Gateway
SEP
Signaling End Point (CCS7)
SF
Slot Flag
SF
Spreading Factor
SFBC
Space Frequency Block Codes
SFH
Slow Frequency Hopping
SFID
Service Flow Identity
SFN
Single Frequency Network
SFN
System Frame Number
SFPG
Security and Fraud Prevention Group
SG
Security Gateway (IPsec / RFC 2401)
SG
Serving Grant respectively Power Grant (3GTS 25.213,
25.309, 25.321)
SGLUPR
Last Used Power Ratio according to SG table index (3GTS
25.321)
SGSN
Serving GPRS Support Node
SGW
Signaling Gateway
SGi
Reference Point in LTE
SHA
Secure Hash Algorithm
SHCCH
Shared Channel Control Channel (UMTS Logical Channel / TDD
only)
SHO
Soft Handover (UE is having more than one radio link at the
same time and combines them)
SI
Scheduling Info
SI
Segment Indicator
SI
Service Indicator
SI
Service Information
SIB
LSSU with status indication busy
SIB
System Information Block
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SIC
Serial Interference Cancellation
SICH-Q
Slot Information CHannel, QAM
SICH-Q/D
Slot Information CHannel, QAM Downlink
SICH-Q/U
Slot Information CHannel, QAM Uplink
SID
Silence Insertion Descriptor
SID
Size InDex (3GPP 25.321)
SIE
LSSU with status indication emergency alignment
SIF
Signaling Information Field
SIG
Special Interest Group (e.g. Bluetooth)
SIGTRAN
Signaling Transport (RFC 2719)
SIM
Subscriber Identity Module
SIMO
Single In / Multiple Out (antenna system)
SIN
LSSU with status indication normal alignment
SIO
LSSU with status indication out of alignment
SIO
Service Information Octet
SIOS
LSSU with status indication out of service
SIP
Session Initiation Protocol (RFC 3261)
SIP-AS
SIP-Application Server
SIP-B
SIP for Businesses (abbreviation for a set of PABX-specific SIPextensions)
SIP-I
SIP with encapsulated ISUP (ITU-T Q.1912.5)
SIP-T
SIP for Telephones (RFC 3372, RFC 3398)
SIPO
LSSU with status indication processor outage
SIQ
Service Information Query
SIR
Signal to Interference Ratio
SISO
Single In / Single Out (antenna system)
SLA
Service Level Agreement
SLC
Signaling Link Code
SLF
Subscriber Locator Function
SLR
Source Local Reference
SLS
Signaling Link Selection
SLTA
Signaling Link Test Acknowledge
SLTM
Signaling Link Test Message
SM
Session Management (3GTS 23.060, 3GTS 24.008)
SM-SC
Short Message Service Center
SME
Small and Medium size Enterprises (Type of Business)
SMG
Special Mobile Group
© INACON GmbH 1999 - 2009. All rights reserved. Reproduction and/or unauthorized use of this material is prohibited
and will be prosecuted to the full extent of German and international laws. Version Number 2.030
List of Acronyms
SMI
Short Management Identity
SMIL
Synchronized Multimedia Integration Language
SMLC
Gateway Mobile Location Center
SMS
Short Message Service (3GTS 24.011, 3GTS 23.040)
SMS-G-MSC
SMS Gateway MSC (for Short Messages destined to Mobile
Station)
SMS-IW-MSC
SMS Interworking MSC (for Short Messages coming from
Mobile Station)
SMSCB
Short Message Services Cell Broadcast
SMTP
Simple Mail Transfer Protocol (RFC 2821)
SN
Sequence Number
SN
Symbol Number or SNDCP
SN-PDU
Segmented N-PDU (SN-PDU is the payload of SNDCP)
SN-Q
Symbol Number in QAM
SN-SAP
SNDCP-Service Access Point
SNA
Short Number Address
SND
Sequence Number Downlink (GTP)
SNDCP
Subnetwork Dependent Convergence Protocol
SNEI
SNDCP Network Endpoint Identifier
SNIR
Signal to Noise and Interference Ratio
SNM
Signaling Network Management Protocol (ITU-T Q.704 (3))
SNN
SNDCP N-PDU Number Flag
SNR
Signal to Noise Ratio
SNTM
Signaling Network Test & Maintenance (ITU-T Q.707)
SNTP
Simple Network Time Protocol (RFC 2030)
SNU
Sequence Number Uplink (GTP)
SO
Segment Offset
SOAP
Simple Object Access Protocol
(http://www.w3.org/TR/2000/NOTE-SOAP-20000508)
SOHO
Small Office Home Office (Type of Business)
SP
Signaling Point
SPC
Signaling Point Code
SPI
Security Parameter Index (RFC 2401)
SQCIF
Semi Quarter Common Intermediate Format (128 x 96 pixels
ITU-T H261 / H263)
SQN
Sequence number (used in UMTS-security architecture / 3GTS
33.102)
SRB
Signaling Radio Bearer
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SRES
Signed Response
SRF
Service Resource Function (CAMEL)
SRNC
Serving Radio Network Controller
SRNS
Serving Radio Network Subsystem
SRS
Sounding Reference Symbol
SRTP
Secure RTP (RFC 3711)
SRTT
Smoothed RoundTrip Time
SRV
Service Location (DNS-related / RFC 2782)
SS
Subscriber Station (IEEE 802.16)
SS
Supplementary Service
SS7
Signaling System No 7
SSC
Secondary Synchronization Code
SSCF
Service Specific Co-ordination Function
SSCF/NNI
Service Specific Coordination Function - Network Node
Interface Protocol (ITU-T Q.2140)
SSCF/UNI
Service Specific Coordination Function - User Network
Interface Protocol (ITU-T Q.2130)
SSCOP
Service Specific Connection Oriented Protocol (ITU-T Q.2110)
SSCOPMCE
Service Specific Connection Oriented Protocol in a Multi-link or
Connectionless Environment (ITU-T Q.2111)
SSCS
Service Specific Convergence Sublayer
SSDT
Site Selection Diversity Transmission
SSF
Service Switching Function (CAMEL)
SSI
Short Subscriber Identity
SSID
Service Set Identifier (IEEE 802.11)
SSN
Send Sequence Number (GSM MM and CC-Protocols)
SSN
Start Sequence Number (related to ARQ-Bitmap in GPRS /
EGPRS) or Send Sequence Number (GSM MM and CCProtocols) or Sub-System Number (SCCP)
SSN
SubSlot Number
SSP
Service Switching Point (IN)
SSRC
Contributing Source (RTP)
SSRTG
Subscriber Station Receive to transmit Turnaround Gap (IEEE
802.16 (3.53)) Time that the SS needs to switch from receive
to transmit.
SSS
Secondary sync Sequence Set
SSSAR
Service Specific Segmentation And Reassembly (ITU-T
I.366.1)
SSTTG
Subscriber Station Transmit to receive Turnaround Gap (IEEE
802.16 (3.54)) Time that the SS needs to switch from transmit
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to receive.
SSVE
Sum Square Vector Error
ST
Stuffing Table (DVB-SI)
STANAG
Standardisation Agreement (NATO)
STBC
Space Time Block Coding
STC
Signaling Transport Converter on MTP-3 and MTP-3b (ITU-T
Q.2150.1) / Signaling Transport Converter on SSCOP and
SSCOPMCE (ITU-T Q.2150.2)
STC
Space Time Coding
STCH
STealing CHannel
STP
Signaling Transfer Point
STTD
Space Time block coding based Transmission Diversity
STUN
Simple Traversal of UDP through Network Address Translators
(RFC 3489)
SU
Scheduling Unit
SUA
SCCP User Adaptation Layer (RFC 3868)
SUERM
Signal Unit Error Rate Monitor (ITU-T Q.703 (10))
SUFI
Super Field (RLC-Protocol)
SUN
Originally stood for Stanford University Network
SVC
Switched Virtual Circuit
SVG
Scalable Vector Graphics
SWAP
Shared Wireless Access Protocol (Home RF)
SYNC
Synchronization protocol in LTE for E-MBMS
SwMI
Switching and Management Infrastructure
T-PDU
Payload of a G-PDU which can be user data, i.e. possibly
segmented IP-frames, or GTP signaling information (GTP)
T.38
Fax Specification
TA
Terminal Adapter (ISDN)
TA
Timing Advance
TA
Tracking Area
TAC
Tracking Area Code
TACS
Total Access Communication System
TAF
Terminal Adopter Function (3GTS 27.001)
TAI
Timing Advance Index
TB
Transport Block
TBCP
Talk Burst Control Protocol
TBF
Temporary Block Flow
TBS
Transport Block Set
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TC
Technical Committee
TC
Turbo Coding (3GTS 25.212)
TCAP
Transaction Capabilities Application Part (Q.771 - Q.773)
TCB
Transmission Control Block
TCH
Traffic Channel
TCH-AFS
Traffic CHannel Adaptive Full rate Speech
TCH-AHS
Traffic Channel Adaptive Half rate Speech
TCH-P8/10,8
Traffic CHannel, p/8-D8PSK, net rate = 10,8 kbit/s
TCH/2,4
Traffic CHannel, net rate = 2,4 kbit/s
TCH/4,8
Traffic CHannel, net rate = 4,8 kbit/s
TCH/7,2
Traffic CHannel, net rate = 7,2 kbit/s
TCH/FD
Traffic Channel / Fullrate Downlink
TCH/S
Speech Traffic CHannel
TCP
Transmission Control Protocol
TCP/BFCP
Transmission Control Protocol / Binary Floor Control Protocol
(draft-ietf-xcon-bfcp-05.txt)
TCP/IP
Transmission Control Protocol over IP
TCP/RTP/AVP
Real-time Transport Protocol / Audio Video Profile over TCP
(used in SDP-descriptions)(draft-ietf-avt-rtp-framing-contrans06.txt)
TCP/TLS/BFCP
Transmission Control Protocol / Transport Layer Security /
Binary Floor Control Protocol (draft-ietf-xcon-bfcp-05.txt)
TCTF
Target Channel Type Field
TCTV
Transport Channel Traffic Volume
TDD
Time Division Duplex
TDM
Time Division Multiplexing
TDMA
Time Division Multiple Access
TDOA
Time Difference of Arrival
TDT
Time and Date Table (DVB-SI)
TE
Terminal Equipment
TE2
TE presenting a TETRA interface
TEA1/2/3/4
TETRA Encryption Algorithm(s) 1,2,3 and 4
TEBS
Total E-DCH Buffer Status
TEDS
TETRA Enhanced Data Service
TEI
Terminal Equipment Identity
TEID
Tunnel Endpoint Identifier (GTP / 3GTS 29.060)
TEK
Traffic Encryption Key (IEEE 802.16)
TETRA
Terrestrial Trunked Radio
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TETRA V+D
TETRA Voice + Data
TF
Transport Format
TFC
Transport Format Combination
TFCI
Transport Format Combination Identifier
TFCS
Transport Format Combination Set
TFI
Temporary Flow Identity ((E)GPRS)
TFI
Transport Format Indication (UMTS)
TFO
Tandem Free Operation (3GTS 22.053)
TFRC
Transport Format and Resource Combination (3GTS 25.308)
TFRI
Transport Format and Resource Indicator (3GTS 25.308,
25.321)
TFS
Transport Format Set
TFT
Traffic Flow Template
TFTP
Trivial File Transfer Protocol (RFC 1350)
TGD
Transmission Gap start Distance (3GTS 25.215)
TGL
Transmission Gap Length (3GTS 25.215)
TGPRC
Transmission Gap Pattern Repetition Count (3GTS 25.215)
TGSN
Transmission Gap Starting Slot Number (3GTS 25.215)
TH-CDMA
Time Hopping Code Division Multiple Access
THIG
Topology Hiding Inter Network Gateway
THP
Traffic Handling Priority (DiffServ Term)
THz
Tera Hertz (1012 Hertz)
TI
Transaction Identifier
TIA
Telecommunications Industry Association
TID
Tunnel Identifier
TIP
TETRA Interoperability Profile
TIPHON
Telecommunications and Internet Protocol Harmonization Over
Networks (ETSI Project)
TISPAN
Telecoms & Internet converged Services & Protocols for
Advanced Networks (ETSI Working Group to define IMS for
fixed broadband access networks)
TL
TETRA LLC
TLA-SAP
TETRA LLC Service Access Point A
TLB-SAP
TETRA LLC Service Access Point B
TLC-SAP
TETRA LLC Service Access Point C
TLE-SAP
TETRA LLC Service Access Point E
TLLI
Temporary Logical Link Identifier
TLS
Transport Layer Security (RFC 2246 / RFC 3546 / formerly
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known as SSL or Secure Socket Layer)
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TLV
Tag / Length / Value Notation
TM
TETRA MAC
TM
Transmission Modules
TM
Transparent Mode operation
TM
Trunked Mode
TMA-SAP
TETRA MAC Service Access Point A
TMB-SAP
TETRA MAC Service Access Point B
TMC-SAP
TETRA MAC Service Aaccess Point C
TMD
Transparent Mode Data (UMTS RLC PDU-type)
TMD-SAP
TETRA MAC Service Aaccess Point D
TMGI
Temporary Mobile Group Identity (3GTS 23.003 (15.2))
TMN
Telecommunication Management Network
TMSI
Temporary Mobile Subscriber Identity
TMV-SAP
TETRA MAC Virtual SAP
TN
Timeslot Number
TNCC-SAP
TETRA Network layer Call Control - Service Access Point
TNL
Transport Network Layer (3GTS 25.401)
TNMM
TETRA Network Mobility Management
TNP
TETRA Network Protocol
TNSDS-SAP
TETRA Network layer Short Data Service - Service Access
Point
TNSS-SAP
TETRA Network layer Supplementary Services - Service Access
Point
TOI
Transport Object Identifier
TOM
Tunneling Of Messages [3GTS 44.064]
TOM2
Tunneling Of Messages over LLC-SAPI 2 (for high priority
signaling messages)[3GTS 44.064]
TOM8
Tunneling Of Messages over LLC-SAPI 8 (for low priority
signaling messages)[3GTS 44.064]
TOS
Type of Service
TOT
Time Offset Table
TP
Traffic Physical channel
TP-UD
Transfer Protocol - User Data (in GSM)
TPC
Transmit Power Command
TPS
Transmission Parameter Signaling (DVB-H)
TPTI
Transmitting Party Type Identifier
TQI
Temporary Queuing Identifier
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TRAU
Transcoder and Rate Adaption Unit
TRX
Transmitter / Receiver
TS
Time Sharing
TS
Timeslot
TS
Transport Stream
TSC
Training Sequence Code
TSI
TETRA Subscriber Identity
TSN
Transmission Sequence Number
TSTD
Time Switched Transmit Diversity
TTA
Telecommunications Technology Association (South Korean
standards organization)
TTG
Transmit receive Transition Gap (IEEE 802.16 (3.63)) the time
between a downlink subframe and the subsequent uplink
subframe in a TDD-system
TTG
Tunnel Termination Gateway
TTI
Transmission Time Interval
TTL
Time To Live (IP-Header / RFC 791)
TTR
TETRA Association Technical Report
TU50
Typical Urban 50 km/h
TUA
TCAP User Adaptation Layer
TUP
Telephone User Part
TUSC
Tile Use of Subchannels
TV
Television
TX
Transmit
Term
Explanation
ToIP
Text over IP
TrCH
Transport Channel (UMTS)
TrFO
Transcoder Free Operation
TrGw
Transition Gateway (IPv4 IPv6) (3GTS 23.228 (5.18))
Tx
Transmit(ter)
TxAA
Transmit Adaptive Arrays
U-MST
Uplink Multiple Slot Transmission
U-SAP
User Service Access Point
UA
Unnumbered Acknowledgement (LAPD/LLC/RLP-Frame Type)
UA
User Agent (SIP-Term / RFC 3261)
UAC
User Agent Client (SIP-Term / RFC 3261)
UARFCN
UMTS Absolute Radio Frequency Channel Number
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UART
Universal Asynchronous Receiver and Transmitter
UAS
User Agent Server (SIP-Term / RFC 3261)
UAS-X
egprs2 Uplink level A modulation and coding Scheme (x =
7..11)
UBS-X
egprs2 Uplink level B modulation and coding Scheme (x =
5..12)
UCD
Uplink Channel Descriptor (WiMAX Message)
UCI
Uplink Control Indicator
UCS
Universal Character Set
UCS-2
Universal Character Set coded in 2 octets
UDCH
User-plane Dedicated Channel (3GTS 45.902)
UDH
User Data Header
UDP
User Datagram Protocol (RFC 768)
UDPTL
UDP Transport Layer (used in SDP-description for T.38 faxapplications)
UE
User Equipment
UEA
UMTS Encryption Algorithm (3GTS 33.102)
UGS
Unsolicited Grant Service (IEEE 802.16 Traffic Class)
UHF
Ultra High Frequency
UI
Unnumbered Information (LAPD) / Unconfirmed Information
(LLC) / Frame Type
UIA
UMTS Integrity Algorithm (3GTS 33.102)
UICC
Universal Integrated Circuit Card (3GTS 22.101 / Bearer card
of SIM / USIM)
UIUC
Uplink Interval Usage Code (WiMAX Term)
UL
Uplink
UL-MAP
Uplink-Medium Access Protocol (MAC-Message in WiMAX /
IEEE 802.16)
UL-SCH
Uplink Shared Channel
UL_DTX
Uplink Discontinuous Transmission
UM
Unacknowledged Mode operation
UMA
Unlicensed Mobile Access (3GTS 43.318)
UMAN
Unlicensed Mobile Access Network
UMB
Ultra Mobile Broadband (3GPP2's EV-DO Rev C)
UMD
Unacknowledged Mode Data (UMTS RLC PDU-type)
UMS
User Mobility Server (HSS = HLR + UMS)
UMTS
Universal Mobile Telecommunication System
UNC
UMA Network Controller
UNC-SGW
UMA Network Controller Security Gateway
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List of Acronyms
UNI
User-to-Network Interface
UP
Unallocated Physical channel
URA
UTRAN Registration Area
URA_PCH
RRC URA State in UTRA
URB
User Radio Bearer
URI
Uniform Resource Identifier
URL
Uniform Resource Locator (RFC 1738)
US
United States
USA
United States of America
USAT
USIM Application Toolkit
USB
Universal Serial Bus
USCH
Uplink Shared Channel (UMTS Transport Channel TDD only)
USD
User Service Description
USF
Uplink State Flag
USIM
Universal Subscriber Identity Module
USS
Uplink sync Sequence Set
USSI
Unexchanged Short Subscriber Identity
UTF-16BE
Unicode Transformation Format serialized as two bytes in BigEndian format
UTF-8
Unicode Transformation Format-X (Is an X-bit) lossless
encoding of Unicode characters
UTRA
UMTS (Universal Mobile Telecommunication System)
Terrestrial Radio Access
UTRAN
UMTS (Universal Mobile Telecommunication System)
Terrestrial Radio Access Network
UUI
User to User Information
UUS
User-User-Signaling (3GTS 23.087)
UV
Ultra Violet
UWB
Ultra-Wide Band (IEEE 802.15.3)
UWC
Universal Wireless Convergence (Merge IS-136 with GSM)
V+D
Voice plus Data
V-PLMN
Visited PLMN
V5UA
V5.2-User Adaptation Layer (RFC 3807)
VA
Vehicular A mobile radio channel
VAD
Voice Activity Detector
VBS
Voice Broadcast Service (GSM-R)
VC
Virtual Circuit
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VCI
Virtual Circuit Identifier (ATM)
VCO
Voltage Controlled Oscillator
VCT
MPEG PSI tables for ARIB
VDSL
Very high data rate Digital Subscriber Line (ITU-T G.993.1)
VE
Virtual Engine
VGCS
Voice Group Call Service (GSM-R)
VHE
Virtual Home Environment (3GTS 22.121, 3GTS 23.127)
VHF
Very High Frequency
VLAN
Virtual LAN
VLR
Visitor Location Register
VPI
Virtual Path Identifier (ATM)
VPLMN
Visited Public Land Mobile radio Network
VPN
Virtual Private Network
VSRB
Variable Sized Radio Blocks
VW
Virtual Wire PDB (DiffServ Term)
VoD
Video on Demand
VoIMS
Voice over IMS
VoIP
Voice over IP
W-AMR
Wideband AMR-Codec (Adaptive Multirate) (3GTS 26.190)
W-AMR+
Extended Wideband AMR-Codec (Adaptive Multirate) (3GTS
26.290)
W-APN
WLAN-APN (Wireless Local Area Network - Access Point Name)
(3GTS 23.234)
WAG
WLAN (Wireless Local Area Network) Access Gateway
WAN
Wide Area Network
WAP
Wireless Application Protocol
WCDMA
Wide-band Code Division Multiple Access
WEP
Wired Equivalent Privacy
WG
Working Group
WI
Work Item
WINS
Windows Internet Name Service
WLAN
Wireless Local Area Network (IEEE 802.11)
WMAN
Wireless Metropolitan Area Network
WMAX
Alliance of IEEE-802.11-Standard Manufacturers
WPA
WiFi Protected Access
WRED
Weighted Random Early Detection
WS
Window Size
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List of Acronyms
WSN
Window Size Number
WWW
World Wide Web
WiBro
Wireless Broadband, Korean WiMAX Version
WiFi
Wireless Fidelity (www.wi-fi.org)
WiMAX
Worldwide Interoperability for Microwave Access (IEEE
802.16)
X-CSCF
Call Session Control Function (any, there is I-CSCF, P-CSCF
and X-CSCF)
X2-AP
X2 Application Part
XHTML
Extensible Hypertext Markup Language
XID
Exchange Identification (LAPD/LLC-Frame Type)
XMAC
Expected Message Authentication Code
XMF
Extensible Music Format
XOR
Exclusive-Or Logical Combination
XRES
Expected Response (3GTS 33.102)
XUA
Any User Adaptation Layer (M2UA, M3UA, SUA)
XXX_PCH
RRC States: CELL_PCH or URA_PCH
ZF
Zero Forcing
cwnd
Congestion window
dBm
The unit dBm measures a power. The conversion of a power
value from Watt [W] to dBm is done in the following way:X
[dBm] = 10 x log10(X [W] / 0.001 [W])
e2e
End-to-End
eBM-SC
Enhanced Broadcast and Multicast Service Center
eHSPA
Evolved HSPA
eMLPP
enhanced Multi-Level Precedence and Pre-emption (3GTS
23.067)
eNB
Enhanced Node B
ert-PS
Extended Real-Time Polling Service (WiMAX Traffic Class)
ertPS
Extended Real-Time Polling Service (IEEE 802.16 Traffic Class)
iBurst
Data Communication Standards
iLBC
Internet Low Bitrate Codec (RFC 3951 / RFC 3952)
kHz
Kilo Hertz (103 Hertz)
kbps
kilo-bits per second
mod
modulo (base for counting)
p/4-DQPSK
p/4-shifted Differential Quaternary Phase Shift Keying
p/8-D8PSK
p/8-shifted Differential 8 Phase Shift Keying
ssthresh
Slow start threshold (RFC 2001, RFC 2960)
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and will be prosecuted to the full extent of German and international laws. Version Number 2.030
Index
Index
16-QAM....................................................................................................................170
3G.................................................................................................................................2
4G.................................................................................................................................2
64-QAM....................................................................................................................170
ACK..........................................................................................................................158
Adaptive antenna systems.................................................................................22, 190
AIPN.................................................................................................................8, 32, 80
AM............................................................................................................................232
AMC............................................................................................................................14
bandwidth...................................................................................................................13
Bandwidth...................................................................................................................28
BCCH.................................................................................................................66, 205
BCH....................................................................................................................68, 205
Broadcast information...............................................................................................243
CAZAC sequences...................................................................................................162
CCCH.........................................................................................................................66
CDMA.......................................................................................................................116
Cell ID.........................................................................................................................50
Cell reselection.................................................................................................251, 255
Channel estimation...................................................................................................180
Channel mapping.......................................................................................................74
Codebook.................................................................................................................200
CQI...........................................................................................................................164
Cyclic prefix..............................................................................................110, 152, 167
DC-subcarrier...........................................................................................................113
DCCH.........................................................................................................................67
Delay diversity..........................................................................................................194
Delay spread............................................................................................................108
DFT...........................................................................................................................166
Different....................................................................................................................262
Direct Tunnel..............................................................................................................36
DL-SCH......................................................................................................................69
Downlink processing chain.......................................................................................150
Downlink reference signal..................................................................................72, 142
DTCH..........................................................................................................................67
E-UTRAN....................................................................................................................54
ECM-CONNECTED..................................................................................................246
EMM.........................................................................................................................246
EMM-DEREGISTERED............................................................................................246
EMM-IDLE................................................................................................................246
EMM-REGISTERED.................................................................................................246
eNB.............................................................................................................................38
eNB ID........................................................................................................................50
eNB S1-AP UE ID.......................................................................................................52
EPC............................................................................................................................34
EPS bearer ID............................................................................................................50
Extended configuration.............................................................................................128
fast scheduling............................................................................................................14
FDD..........................................................................................................134, 136, 138
FDMA.......................................................................................................................116
FFT ..........................................................................................................................102
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LTE from A-Z
FMC..............................................................................................................................4
Fractional frequency reuse.......................................................................................212
Frame structure................................................................................................126, 140
Frequency reuse.......................................................................................................210
GTP-U......................................................................................................................222
GUMMEI.....................................................................................................................50
GUTI...........................................................................................................................52
Handover..........................................................................................252, 255, 274, 280
HARQ.......................................................................................................................224
I / Q plane.................................................................................................................100
IFFT..........................................................................................................102, 152, 167
IMEI............................................................................................................................52
IMSI............................................................................................................................52
Initial cell search.......................................................................................................204
Initial context setup procedure..................................................................................266
Intercell interference coordination............................................................................212
interference coordination............................................................................................14
ISI.............................................................................................................................108
Latency.................................................................................................................82, 84
Layer mapper...........................................................................................................152
LMMSE.....................................................................................................................123
Logical channel...........................................................................................................66
LTE...............................................................................................................................8
MAC..........................................................................................................................224
MAC control element................................................................................................230
MAC PDU.................................................................................................................228
MBMS.........................................................................................................................24
MCCH.........................................................................................................................66
MCH...........................................................................................................................69
MIMO................................................................................19f., 114, 122, 143, 198, 201
MISO..........................................................................................................................19
MME...........................................................................................................................42
MME S1-AP UE ID.....................................................................................................52
MMEGI.......................................................................................................................50
MMEI..........................................................................................................................50
Mobility management.......................................................................248, 250, 252, 254
Modulation........................................................................................104, 106, 152, 166
MTCH.........................................................................................................................67
Multiple rank beamforming.......................................................................................199
NACK........................................................................................................................158
Normal configuration................................................................................................128
OFDM...........................................................................................................16, 90, 112
OFDMA.......................................................................................................16, 112, 130
Orthogonality..............................................................................................................90
PBCH............................................................................................29, 70, 142, 144, 169
PCCH.........................................................................................................................66
PCFICH......................................................................................................71, 146, 170
PCH............................................................................................................................68
PDCCH...............................................................................................70, 142, 146, 170
PDCP........................................................................................................................238
PDCP PDU...............................................................................................................240
PDN GW.....................................................................................................................46
PDP context establishment......................................................................................270
PDSCH...............................................................................................72, 142, 144, 170
- 350 -
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Index
PHICH........................................................................................................72, 142, 146
Physical channel.........................................................................................................70
PLMN ID.............................................................................................................50, 205
PMCH.........................................................................................................72, 142, 170
Power control............................................................................................................186
PRACH.......................................................................................................71, 206, 208
Precoding.................................................................................................................152
Protocol stack.............................................................................................................54
PUCCH.....................................................................................................71, 155f., 170
PUCCH format........................................................................................................164f.
PUCCH format .........................................................................................................160
PUSCH...............................................................................................................72, 170
QCI...........................................................................................................................260
QoS..........................................................................................................................258
QPSK........................................................................................................................170
Quadruple play services.............................................................................................10
RA-RNTI.............................................................................................................50, 227
RACH.........................................................................................................................68
Random access preamble..........................................................................................72
Random access procedure.......................................................................................226
Random access response........................................................................................208
Receive diversity......................................................................................................188
Resource block.........................................................................................................130
Resource element....................................................................................................130
Resource element mapper.......................................................................................167
RLC..........................................................................................................................232
RLC AM PDU segment.............................................................................................236
RLC PDU..................................................................................................................234
RNC............................................................................................................................32
RNTI...........................................................................................................................50
Roaming.....................................................................................................................36
RRC....................................................................................................................32, 242
RRC_CONNECTED.................................................................................................244
RRC_IDLE ...............................................................................................................244
S-TMSI.......................................................................................................................52
S1-AP.......................................................................................................................221
S1-flex........................................................................................................................36
SAE............................................................................................................................34
SC-FDMA.........................................................................................................130, 132
Scheduling..................................................................................................................76
Scrambling........................................................................................................150, 166
SDMA.......................................................................................................................116
Serving GW................................................................................................................44
SIM card...................................................................................................................205
SIMO..........................................................................................................................18
Single frequency network...........................................................................................24
SISO...........................................................................................................................18
Smart antenna technology..........................................................................................18
Smart Antenna Technology........................................................................................14
soft handover..............................................................................................................14
Sounding reference signal........................................................................................170
Sounding reference symbol......................................................................................155
Space frequency block code....................................................................................196
Space time block code.............................................................................................197
© INACON GmbH 1999 - 2009. All rights reserved. Reproduction and/or unauthorized use of this material is prohibited
and will be prosecuted to the full extent of German and international laws. Version Number 2.030
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Use only for participants of NSN LTE from A-Z Training
LTE from A-Z
Spectral efficiency........................................................................................................6
Subchannel...............................................................................................................130
Subframe..................................................................................................................130
Synchronization signal........................................................................................72, 202
Synchronization Signal.............................................................................................142
Synchronization signals..............................................................................................29
TAI..............................................................................................................................50
TCP/IP......................................................................................................................284
TDD..........................................................................................................134, 136, 138
TDMA...............................................................................................................116, 174
Timing advance control............................................................................................174
TM............................................................................................................................232
Tracking area update................................................................................................268
Transmission diversity..............................................................................................188
Transport channel.......................................................................................................68
Turbo coding.............................................................................................................170
UE class...................................................................................................................214
UL-SCH......................................................................................................................68
UM............................................................................................................................232
Uplink reference signal...............................................................................................72
Uplink sounding signal................................................................................................72
UTRAN.......................................................................................................................36
WiMAX....................................................................................................................8, 27
X2...............................................................................................................................60
Zadoff-Chu sequence...............................................................................................162
.....................................................................................................................................8
bearer......................................................................................................................256
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© INACON GmbH 1999 - 2009. All rights reserved. Reproduction and/or unauthorized use of this material is prohibited
and will be prosecuted to the full extent of German and international laws. Version Number 2.030
Index
© INACON GmbH 1999 - 2009. All rights reserved. Reproduction and/or unauthorized use of this material is prohibited
and will be prosecuted to the full extent of German and international laws. Version Number 2.030
- 353 -