LTE Radio Parameters, Counters and KPI
[RL30]
[RL30] CT4407-30A
LTE RRM Basics and Key Parameters
1
© Nokia Siemens Networks
RA41213EN30GLA0
Contents
1.
2.
3.
4.
5.
6.
7.
8.
9.
LTE Functionalities and Features Overview
Parameter structure and SIB’s
LTE RRM Basics and Key Parameters
OSS aspects
KPI architecture and optimization principles
Capacity areas and cell resource measurements
Paging and RRC connection
RAB and NAS counters
Mobility measurements in connected mode
2
© Nokia Siemens Networks
RA41213EN30GLA0
Module Contents
• Random Access
• Radio Admission Control
• Radio Bearer Control
• Mobility Management
• UL/DL Scheduler
• MIMO Mode Control
• UL/DL Power control
3
© Nokia Siemens Networks
RA41213EN30GLA0
Multiplexing of PRACH with PUSCH and PUCCH
PRACH slot
Duration( e.g. 1ms)
Total UL Bandwidth
PUCCH
PRACH
PRACH
(1.08MHz)
PUSCH
PRACH slot period
PUCCH
4
PRACH
bandwidth
© Nokia Siemens Networks
RA41213EN30GLA0
Time
PRACH Subcarriers
5
© Nokia Siemens Networks
RA41213EN30GLA0
PRACH Types
PRACH types:
• Type 0: 1 ms duration
• Type 1: 2 ms
• Type 2: 2 ms
• Type 3: 3 ms
6
© Nokia Siemens Networks
RA41213EN30GLA0
Format type 0 & type 1 supported
in RL30
PRACH Configuration
Type, time and frequency resources are defined by:
prachConfIndex
PRACH configuration index:
LNCEL; 3..24;1; 3
PRACH frequency offset:
Range is restricted to two different
ranges: 3-8 and 19-24 (internal)
RA
RA
nPRB
nPRB
offset
RA
UL
0 nPRBoffset
N RB
6
.
prachFreqOff
First PRB available for PRACH in UL
LNCEL; 0...94;1; 3
Max. value is ulChBw(in PRB) - 6
*3GPP TS 36.211 Table 5.7.1-2
7
© Nokia Siemens Networks
RA41213EN30GLA0
RA Procedure
The contention based random access procedure follows these steps:
raRespWinSize
(1) A preamble will be selected by UE and
transmitted in the available subframe. Based
on correlation the eNB may detect the access
and furthermore can measure the timing of
the UE transmission.
(2) The eNB answers using the same preamble
and at this point a timing advance will be
fixed. Information on the scheduled resource
will be exchanged and a temporary C-RNTI
will be assigned.
(3) The UE sends its id. The type of id depends
on the state. In case of idle state NAS info
has to be provided (IMSI, TMSI) else the CRNTI is used.
(4) The contention resolution is performed, i.e.
the eNB addresses the UE using the C-RNTI.
LNCEL; 2 (0), 3 (1), 4 (2), 5 (3), 6 (4),
7 (5), 8 (6), 10 (7); 10 TTIs (7)
UE
1
eNB
Random Access Preamble
Random Access Response
3
Contention Resolution
raContResoT
TPC command indicated in message 2
related to message 3 power
Max. Time for cont. resol.
© Nokia Siemens Networks
RA41213EN30GLA0
2
Scheduled Transmission
ulpcRarespTpc
LNCEL; -6...8dB;2dB; 0dB
8
Window size for RA response (in TTI)
LNCEL; 8ms (0), 16ms (1), 24ms (2),
32ms (3), 40ms (4), 48ms (5), 56ms (6),
64ms (7); 32ms (3)
4
RA Procedure
The contention free random access procedure
• E.g. during handover a temporary valid preamble will be issued.
• It is (temporarily) dedicated to this UE.
• No contention resolution is needed as the preamble shall not be used by other UEs.
UE
0
eNB
RA Preamble assignment
Random Access Preamble
2
9
© Nokia Siemens Networks
Random Access Response
RA41213EN30GLA0
1
RA Power Ramping
PPRACH = min{ Pmax, PREAMBLE_RECEIVED_TARGET_POWER + PATHLOSS}
prachPwrRamp
Power increment step
LNCEL; 0dB (0), 2dB (1), 4dB (2),
6dB (3); 2dB (1)
BCH information
UE sets the initial transmission power of
RACH and send preamble signal
preambTxMax
Preamble (RACH)
Max. RA transmissions
LNCEL; 3 (0), 4 (1), 5 (2), 6 (3), 7 (4), 8 (5),
10 (6), 20 (7); 8 (5)
Values 50 (8), 100 (9), 200 (10) also defined
but should not be used
Preamble (RACH)
Preamble (RACH)
PDCCH
Random access message
(UL-SCH)
10
© Nokia Siemens Networks
RA41213EN30GLA0
ulpcIniPrePwr
Initial received target power
LNCEL; -120 dBm (0), -118 dBm (1), -116 dBm (2), -114 dBm (3), 112 dBm (4), -110 dBm (5), -108 dBm (6), -106 dBm (7), -104 dBm
(8), -102 dBm (9), -100 dBm (10), -98 dBm (11), -96 dBm (12), -94
dBm (13), -92 dBm (14), -90 dBm (15); -104 dBm (8)
Preamble Generation
64 preambles made of Zadoff-Chu sequences with zero correlation zone:
• given by the logical index RACH_ROOT_SEQUENCE
• Zadoff Chu sequence u is given by
xu n e
j
un( n1)
N ZC
, 0 n N ZC 1
xu,v (n) xu (( n Cv ) mod N ZC )
• ZC sequence of length 839 (prime number) is used
• 838 different root sequences available. (PRACH Root
Sequence). Also different cyclic shifts can be used
depending on cell size
• Sub-carrier spacing is 1.25 kHz
rootSeqIndex
LNCEL;0…837;1; 0
*3GPP TS 36.211 Table 5.7.2-4
11
© Nokia Siemens Networks
RA41213EN30GLA0
Preamble Generation
Root Zadoff-Chu sequence order
for preamble formats 0 – 3.:
First: take all available cyclic shifts of one root
Zadoff-Chu sequence:
If not enough: take next logical index and so on
prachCS
Preamble cyclic shift (Ncs configuration)
LNCEL;0…15;1; 0
Restricted set (high speed) NOT in RL30
prachHSFlag
Unrestricted or restricted (high speed) set selection
LNCEL; false; false
Only unrestricted set could be selected in RL30
• Cyclic shift given by
vN CS
Cv 0
RA
RA
v nshift
(v mod nshift
d
) N CS
start
*3GPP TS 36.211 Table 5.7.2-2
12
© Nokia Siemens Networks
RA41213EN30GLA0
v 0,1,..., N ZC N CS 1, N CS 0 for unrestricted sets
N CS 0
for unrestricted sets
RA RA
RA
v 0,1,..., nshift
ngroup nshift
1
for restricted sets
Preamble generation
-Exercise
Consider a cell of 37 km radius.
Provide a sensitive setting for the cell size dependent parameters
13
© Nokia Siemens Networks
RA41213EN30GLA0
Module Contents
• Random Access
• Radio Bearer Control
• Radio Admission Control
• Mobility Management
• UL/DL Scheduler
• MIMO Mode Control
• UL/DL Power control
14
© Nokia Siemens Networks
RA41213EN30GLA0
Simplifications in QoS Profile
3G
EPS
Traffic Class
QCI (QoS Class
Identifier)
Delivery Order
ARP
Max SDU Size
SDU Format
Information
Max Bit Rate
SDU Error Ratio
Guaranteed Bit
Rate
Residual Bit
Error Ratio
Delivery of
Erroneous SDUs
Aggregate Max
Bit Rate
Transfer Delay
Traffic Handling
Priority
Source Statistics
Descriptor
Signalling
Indication
For GBR bearers
For non-GBR bearers
• Number of QoS parameters has
been decreased
• AMBR as part of rate capping feature
(LTE13) is supported from RL20
ARP
Max Bitrate
Guaranteed
Bitrate
15
© Nokia Siemens Networks
RA41213EN30GLA0
AMBR: Aggregate Max Bit Rate for non-GBR EPS
bearer
ARP: Allocation & Retention Priority
RL20 Supported QCIs
•
•
NSN RL20 release supports the QCIs for non-GBR radio bearer services: QCI 5, 6, 7, 8 and 9
In addtion features such as LTE10 enable QCI=1 conversational voice.
Packet Packet
Resource
Delay
Loss
Default QCI
QCI
Type
Priority Budget Rate
Support
1
GBR
2
100 ms 1.0E-02
2
GBR
4
150 ms 1.0E-03
3
GBR
3
50 ms 1.0E-03
4
GBR
5
300 ms 1.0E-06
5 NON-GBR
1
100 ms 1.0E-06
6 NON-GBR
6
300 ms 1.0E-06
ENABLED
7 NON-GBR
7
100 ms 1.0E-03
ENABLED
8 NON-GBR
8
300 ms 1.0E-06
ENABLED
• 9 QCI
values
>
9
are
mapped
into
QCI 9.
NON-GBR
9
300 ms 1.0E-06
ENABLED
RLC PDCP Further
Default Profile Profile QoS
RLC Mode Index Index param.
...
...
...
...
...
RLC_AM
1
1
...
RLC_AM
1
1
...
RLC_AM
1
1
...
RLC_AM
1
1
...
• Parameters per QCI can be controlled on LNBTS level by qciTab.
qciTab
Structure {qci, resType, prio, Lcgid, qciSupp, rlcMode,
rlcProfIdx, pdcpProfIdx, dscp, schedulWeight, schedulPrio,
delayTarget}
LNBTS;- ;9 ; 16
© Nokia Siemens Networks
RA41213EN30GLA0
LNBTS: qcitabx
dscp
configures DSCP value associated
with the QCI; DSCP value will be
set in each IP packet sent for the
related bearer to S-GW or target
eNB. L2SWI; 0 - 63; 1; -
LNBTS: qcitabx is a structured parameter with 12 parameters
dscp
This parameter configures the DSCP (Differentiated Services Code Point)
Lcgid
Logical Channel Group Identifier for buffer status reporting
pdcpProfIdx
This parameter specifies the corresponding PDCP profile in the PDCP profile
list.
prio
This parameter gives the priority of the EPS bearer.
qci
QoS Class Identifier.
qciSupp
The given QCI is supported and enabled in this release
resType
Permanent network resources allocated for GBR
rlcMode
Configures the RLC mode of the radio bearer based on the corresponding QCI
rlcProfIdx This parameter specifies the corresponding RLC profile in the RLC profile list
schedulBSD
Configure the Bucket Size Duration (BSD) of the UL scheduler
schedulPrio
Logical Channel Priority for the UE scheduler
schedulType
Specifies how the EPS bearer with this QCI is scheduled. Only for QCI=5
schedulWeight
Specifies the scheduling weight for eNB schedulers
delayTarget
The maximum packet delay value used by the eNB MAC scheduling algorithm.
Only
for QCI=1
L2SWI: Layer 2 Switching mode weight indication
17
© Nokia Siemens Networks
RA41213EN30GLA0
BSD: Bucked Size duration: 36.321; 5.4.3.1)
LTE518 Operator Specific QCI (RL30)
•
•
•
actOperatorQCI
activates the support of the
establishment of EPS bearers
withc QCI in range 128…154
LNCEL; true(1),false(0); false(0)
In RL30 – up to 21 additional QCIs are defined
• Only for non-GBR bearers
• QCI range is 128…254
• LNBTS: qciTabOperator is a structure parameter with 13 parameters
• Mostly same parameters as the standard QCIs
• Main differentiation of QCIs by scheduling weights (and DSCPs) counterGroup
The counter group to
• For each QCI an additional counterGroup is defined
which the QCI belongs
LNCEL; 1..6;1; Examples of Counter Groups for the typical use cases:
1. Better user and service differentiation for non-GBR services for one
operator:
– Bronze users:
QCI: 130, 131, 132, 133 Counter Group 1
– Silver users:
QCI: 140, 141, 142, 143 Counter Group 2
– Gold users:
QCI: 150, 151, 152, 153 Counter Group 3
• 2. RAN sharing (operators share eNodeB) to define a set of QCIs dedicated for
each operator:
– Operator A:
– Operator B:
18
© Nokia Siemens Networks
QCI: 140, 141, 142, 143 Counter Group 1
QCI: 160, 161, 162, 163 Counter Group 2
RA41213EN30GLA0
Default Bearers
•
•
The initial Default EPS Bearer is created as part of the LTE Attach procedure.
– UE is allocated an IP address.
– QoS is based on the QCI and associated parameters.
Additional Default EPS Bearers may be created when simultaneous access to
services available via multiple Access Point Names (APN) is needed.
– Trigger of an additional Default EPS Bearer is initiated by UE.
– Default EPS Bearers are always non-GBR.
E-UTRAN
UE
EPC
eNB
S-GW
Internet
P-GW
SRB1
SRB2
Default EPS Bearer
Radio
19
© Nokia Siemens Networks
RA41213EN30GLA0
S1-U
S5 /S8
SGi
Dedicated EPS Bearers
•
Dedicated EPS Bearers (non-GBR or GBR) are created for QoS differentiation
purposes.
– The IP address allocated for the default bearer is used for the dedicated EPS
bearers within the same PDN connection.
– Utilization of default or dedicated EPS bearers is based on a TFT.
– Dedicated EPS Bearers are created by network.
– RL20 supports multiple dedicated EPS bearers (not supported in RL10)
– RL20 supports “conversational voice” on GBR dedicated EPS bearers (not
supported in RL10)
•
UE may have multiple dedicated EPS bearers linked to a default EPS bearer.
E-UTRAN
UE
EPC
eNB
S-GW
Internet
P-GW
SRB1
SRB2
Default EPS Bearer
Dedicated EPS Bearer
TFT: Traffic Flow Template;
single UE can have multiple SAE bearers system
requires kind of packet filter (UL & DL TFT) to
decide which IP datagram has to go to which SAE
bearer
Dedicated EPS Bearer
Radio
20
© Nokia Siemens Networks
S1-U
RA41213EN30GLA0
S5 /S8
SGi
LTE7 Support of Multiple EPS Bearers
Multiple sessions with different QoS
The Flexi Multiradio BTS supports up to 4 EPS bearers.
The following radio bearer combinations per UE are supported by the Flexi
Multiradio BTS:
– SRB1 + SRB2 + 1 x AM DRB (+ 1 x UM DRB with LTE10)
– SRB1 + SRB2 + 2 x AM DRB (+ 1 x UM DRB with LTE10)
– SRB1 + SRB2 + 3 x AM DRB (+ 1 x UM DRB with LTE10)
– SRB1 + SRB2 + 4 x AM DRB (+ 1 x UM DRB with LTE10)
SRB (signaling radio bearer)
GBR EPS bearer
Non-GBR EPS bearer
UE
Flexi Multiradio BTS
actMultBearers
activates the support of
multiple EPS Bearers.
LNCEL; true,false; true
S-GW
Note: LTE10 EPS bearers for conversational voice
21
© Nokia Siemens Networks
RA41213EN30GLA0
SRB1: for RRC messages
SRB2: for NAS messages
LTE9 Service Differentiation for non-GBR EPS
Bearers
QCI based service differentiation
•
The service differentiation functionality allows to assign relative scheduling
weights for each non-GBR QCI on cell level.
•
The relative weight will be considered by the UL & DL scheduler.
•
The service differentiation functionality allows further on to define 3 different
RLC/PDCP profiles per BTS which can be assigned to different QCIs.
•
The operator can enable/disable the support of individual QCIs.
•
Services are transferred to bearers which are mapped to QCIs
actnonGbrServiceDiff
activates the Service
Differentiation for non-GBR
Bearers.
LNCEL; true,false; true
22
© Nokia Siemens Networks
RA41213EN30GLA0
LTE10 EPS Bearers for Conversational Voice
• In RL20 voice service shall be transmitted using dedicated
bearers. Voice requires two bearers:
– QCI 1 for user data
– QCI 5 for IMS signaling
actConvVoice
Activates the support of the
conversational voice bearer
LNCEL; false, true; false
E-UTRAN
UE
EPC
eNB
S-GW
Internet
P-GW
SRB1
SRB2
VoIP GBR,
UM, QCI=1
Default EPS Bearer (AM)
Radio
23
© Nokia Siemens Networks
VoIP GBR,
UM, QCI=1
Dedicated EPS Bearer (UM)
RA41213EN30GLA0
S1-U
S5 /S8
SGi
* - only for QCI5
QCI Translation Table for QCI1 & 5-9
For UL and DL
24
Parameter Name
Default
s QCI1
Default
s QCI5
Default
s QCI6
Defaults
QCI7
Default
s QCI8
Default
s QCI9
QCI
1
5
6
7
8
9
Not modifiable
Resource Type
0(GBR)
1(NonGBR)
1(NonGBR)
1(NonGBR)
1(NonGBR)
1(NonGBR)
Not modifiable
Priority
2
1
6
7
8
9
Not modifiable
QCI Support
1
1
1
1
1
1
RLC Mode
RLC_UM
RLC_AM
RLC_AM
RLC_AM
RLC_AM
RLC_AM
RLC Profile Index
101
1
2
1
2
2
PDCP Profile Index
101
1
2
1
2
2
Logical Channel
Group Id
1
2
3
2
3
3
Scheduling BSD
1
1
3
1
3
3
Scheduling Priority
5
9
9
10
11
12
Scheduling Type*
n/a
1
n/a
n/a
n/a
n/a
Scheduling Weight
n/a
40
20
10
5
1
DelayTarget
80ms
n/a
n/a
n/a
n/a
n/a
DSCP
46
34
18
20
10
0
DSCP to PHB map
AF41
AF41
AF21
AF22
AF11
BE
PHB queue weight list
10000
10000
100
100
10
1
© Nokia Siemens Networks
RA41213EN30GLA0
Has to be set to
0 (signaling)
when using
LTE10
Not modifiable
If actnonGbrServiceDiff
“disabled” QCI9 must
be “enabled”
RRM configuration
related parameters
QOS/dscpMap
QOS/perHopBeha
viourWeightList
LTE131 Traffic
prioritization on IP
layer (DiffServ)
LTE 13 Rate Capping
• Feature objective:
• Limitation of the UL & DL bit rate of all non-GBR bearers per UE below UEAMBR
• The subscription parameter is stored in HSS and signaled to eNodeB during
bearer setup
• Benefits:
• Allow introducing xDSL-like pricing models
• Flat rate
• Differentiation by subscribed max. data rate
• Improves utilization of the radio interface
rcEnableDl/ Ul
Enable DL (or UL) rate capping
LNCEL; false(0), true (1); false(0)
• Note: GBR bearers are outside of scope of the UE-AMBR
25
© Nokia Siemens Networks
RA41213EN30GLA0
AMBR: Aggregate Max Bit Rate for non-GBR EPS
bearer
HSS: Home Subscriber Server
LTE 13 Rate Capping
• RRM Scheduler function:
• Introduces throughput measurements filters in the scheduler that
controls the UE throughput according to UE-AMBR values
• Measured AMBR of all non-GBR bearers is averaged over 1 second
and compared to UE-AMBR
• Scheduler restricts the physical resources (the number of PRBs) of the
UE
• AMBR is not exceeded
• Calculates the limited amount of PRBs depending on the UE-AMBR
• Remove the restriction of PRB assignment in case AMBR falls below UE
AMBR
rcAmbrMgnDl / Ul
Factor to calculate margin for
AMBR to account for overhead
of PDCP and RLC (DL & UL)
LNCEL; 1…1.5;0.01; 1.03
26
© Nokia Siemens Networks
RA41213EN30GLA0
AMBR: Aggregate Max Bit Rate for non-GBR EPS
bearer
Module Contents
• Random Access
• Radio Bearer Control
• Radio Admission Control
• Mobility Management
• UL/DL Scheduler
• MIMO Mode Control
• UL/DL Power control
27
© Nokia Siemens Networks
RA41213EN30GLA0
Radio Admission Control Introduction
• Scope of RAC is cell level
• RAC algorithms controls establishment of
– Signaling radio bearer
– Data Radio Bearer
• RAC controls number of UE in a cell
– Number of established RRC connection per cell
– Number of active UEs (users) per cell
• RAC controls number of DRB in a cell
– Number of data radio bearers (DRB)
– Number of DRB with QCI=1
• RAC controls emergency calls and emergency sessions
– Special margin considered for emergency calls
– Special margin considered for IMS emergency sessions (RL30)
28
© Nokia Siemens Networks
RA41213EN30GLA0
DRB: Data Radio Bearer
SRB: Signalling Radio Bearer
Radio Admission Control
• RL20 RAC checks against operator configurable thresholds
– on Call Establishment:
▪ max_number_of_rrc_connection
▪ max_number_of_rrc_connection_emergency_calls (LTE22
supported)
▪ max_number_of_active_users
▪ max_number_of_active_DRB (LTE7 supported)
▪ max_number_of_QCI1_DRB (LTE10 supported)
– on Intra-Frequency (incoming) Handover:
▪ additional offsets can be defined for
• time critical handover (event A5)
• handover desired for radio reasons (event A3)
▪ „all or nothing“ – SRB && DRB must be admitted in target cell
29
© Nokia Siemens Networks
RA41213EN30GLA0
LTE7: Support of multiple EPS bearers
LTE10: Conversational Voice
LTE22: Emergency Call Handling
Admission of single non-GBR radio bearer
if min(ulChBw,dlChBw) has value '10 MHz'
- maxNumActUE value range is restricted to 0...480 (default value 120)
- maxNumActUE +max(addAUeRrHo, addAUeTcHo) <= 480
if min(ulChBw,dlChBw) has value '20 MHz'
- maxNumActUE value range is restricted to 0...840 (default value 240)
- maxNumActUE +max(addAUeRrHo, addAUeTcHo) <= 840
30
addAUeRrHo
addAUeTcHo
Additional # of active UEs, which are allowed
to access a cell via handover with HO cause:
"HO desirable for radio reasons", when RRC
connection (maxNumRrc) or active UE
(maxNumActUE) limit already reached.
LNCEL; 0...840;1; 15
Additional # of active UEs, which are
allowed to access a cell via handover with
HO cause: "Time critical handover", when
RRC connection (maxNumRrc) or active
UE (maxNumActUE) limit already reached
LNCEL; 0...840;1; 20
© Nokia Siemens Networks
RA41213EN30GLA0
Admission of Multiple EPS bearers
If dlChBw is set to '5 MHz' or '10 MHz'
- maxNumActDrb + max(addNumDrbRadioReasHo,
addNumDrbTimeCriticalHo) <= 2400
If dlChBw is set to '15 MHz' or '20 MHz'
- maxNumActDrb + max(addNumDrbRadioReasHo,
addNumDrbTimeCriticalHo) <= 4200
31
addNumDrbRadioReasHo
addNumDrbTimeCriticalHo
Additional margin for the maximum
number of active DRBs in the cell
accessing the cell via HO with HO-cause:
"HO desirable for radio reasons“.
LNCEL; 0...4200;1; 35
Additional margin for the maximum
number of active DRBs in the cell
accessing the cell via HO with HO-cause:
"Time Critical HO".
LNCEL; 0...4200;1; 60
© Nokia Siemens Networks
RA41213EN30GLA0
Admission of QCI1 Conversational bearers
If dlChBw is set to '5 MHz'
- maxNumQci1Drb + max( addNumQci1DrbRadioReasHo,
addNumQci1DrbTimeCriticalHo) <= 150,
If dlChBw is set different to '5 MHz'
- maxNumQci1Drb + max( addNumQci1DrbRadioReasHo,
addNumQci1DrbTimeCriticalHo) <= 200
32
addNumQci1DrbRadioReasHo
addNumQci1DrbTimeCriticalHo
Additional margin for the maximum
number of active DRBs in the cell
accessing the cell via HO with HO-cause:
"HO desirable for radio reasons“.
LNCEL; 0...200;1; 15
Additional margin for the maximum
number of active DRBs in the cell
accessing the cell via HO with HO-cause:
"Time Critical HO".
LNCEL; 0...200;1; 20
© Nokia Siemens Networks
RA41213EN30GLA0
Radio Bearer Management
• Radio Admission Control may select UL/DL maximum bitrates for a UE:
– based on UE capability information received from UE (mbrSelector=0)
– based on O&M parameters maxBitRateUl and maxBitRateDl
(mbrSelector =1)
mbrSelector
LNCEL; 0 (ueCapability), 1 (OaM) ; 0
• The max. Bitrate for a UE in UL & DL for all radio bearers incl. SRBs are
limited to O&M parameter setting:
33
maxBitRateDl
maxBitRateUl
LNCEL; 50…300000kbps;50 ;
170000 Kbps
LNCEL; 50…75000kbps;50 ;
50000 Kbps
© Nokia Siemens Networks
RA41213EN30GLA0
Module Contents
• Random Access
• Radio Bearer Control
• Radio Admission Control
• UL/DL Power control
• Mobility Management
• UL/DL Scheduler
• MIMO Mode Control
34
© Nokia Siemens Networks
RA41213EN30GLA0
Power Control Overview
Objective
Improve cell edge behaviour, reduce inter-cell interference and power consumption.
Downlink (DL)
DL ‘Semi-static’ Power Setting
• eNodeB gives fixed power density per PRB scheduled for transport.
– Total Tx power is max. when all PRBs are scheduled
– No adaptive/dynamic power control
– (O&M parameter) Cell Power Reduction level CELL_PWR_RED [0...10] dB
attenuation in 0.1 dB steps
DL Power Control on PDCCH
dlCellPwrRed
Reduction of DL Tx power;
deducted from max. antenna TX
power.
LNCEL; 0..10; 0.1; 0 dB
Uplink (UL)
Slow Uplink Power Control
• Combination of open loop PC and closed loop PC
• Open Loop Power Control (OLPC)
– Calculated at the UE based on pathloss measurements
• Closed Loop Power Control (CLPC)
– Based on exchange of feedback data and commands between UE and
eNodeB
– SW-licensed enhancement (can be switched on and off)
35
© Nokia Siemens Networks
RA41213EN30GLA0
UL-PC: PUSCH
PPUSCH (i) min {PCMAX ,10 log10 (M PUSCH (i)) PO_PUSCH ( j ) ( j ) PL TF (i) f (i)} dBm
PH (i) PCMAX 10 log10 (M PUSCH (i)) PO_PUSCH ( j ) PL TF (i) f (i) dB
PPUSCH (i) :PUSCH Power in subframe i
PCMAX: max. allowed UE power (23 dBm for class 3)
MPUSCH: number of scheduled RBs (The UE Tx. Power increases proportionally to # of PRBs)
PO_PUSCH(j) = PO_NOMINAL_PUSCH(j) + PO_UE_PUSCH(j)
PL: pathloss [dB] = referenceSignalPower – higher layer filtered RSRP
TF (i) = 10 log 10 (2MPR Ks – 1) for Ks = 1.25 else 0, MPR = TBS/NRE, NRE : number of RE
Ks defined by deltaMCS-Enabled, UE specific
f(i): TPC (Closed Loop adjustment)
ulpcEnable
Semi-persistant: j=0 / dynamic scheduling: j=1
PO_NOMINAL_PUSCH(0,1): cell specific (SysInfo)
enable UL closed loop PC
LNCEL; true, false; false
PO_UE_PUSCH(0,1): UE specific (RRC)
(0,1) = 0.0, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0 (partial PL compensation by open loop)
Random access grant: j=2
PO_NOMINAL_PUSCH(2): PO_PRE + Preamble_Msg3
(2) = 1.0 (i.e. full PL compensation)
36
© Nokia Siemens Networks
RA41213EN30GLA0
PO_UE_PUSCH(2) = 0
*PH = Power Headroom
Open Loop PC
PPUSCH (i) min {PCMAX ,10 log10 (M PUSCH (i)) PO_PUSCH ( j ) ( j ) PL TF (i) f (i)} dBm
PO_PUSCH(j) = PO_NOMINAL_PUSCH(j) + PO_UE_PUSCH(j)
j=0 -> PUSCH transmission with semi-persistent grant (not in RL30)
j=1 -> PUSCH transmission with dynamic scheduling
j=2 -> PUSCH transmission for random access grant
PO_NOMINAL_PUSCH(j) -> cell specific component signalled from system information for
j=0, 1
This term is a common power level for all mobiles in the cell (used to control SINR)
p0NomPusch
Nominal Power for UE PUSCH Tx
Power Calculation
LNCEL; -126..24dbm; 1; -100 dBm
PO_UE_PUSCH(j)
-> UE specific component provided by higher layers (RRC) for j=0,1
This term is a UE specific offset used to correct the errors from the estimation of the
pathloss
37
© Nokia Siemens Networks
RA41213EN30GLA0
PUSCH Formula
PPUSCH (i) min {PCMAX ,10 log10 (M PUSCH (i)) PO_PUSCH ( j ) ( j ) PL TF (i) f (i)} dBm
PL: pathloss [dB] = referenceSignalPower –
higher layer filtered RSRP
This path loss compensation factor a is adjustable by O&M.
a cell - specific parameter (broadcasted on BCH).
Alpha
α is
α [0.0, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0]
α = 0 , no compensation
α = 1 , full compensation
α ≠ { 0 ,1 } , fractional compensation
ulpcAlpha
LNCEL; 0, 0.4..1.0; 0.1; 1.0
38
© Nokia Siemens Networks
RA41213EN30GLA0
Conventional & Fractional PC
• Conventional PC schemes:
– Attempt to maintain a constant SINR at the receiver
– UE increases the Tx power to fully compensate for increases in the path loss
• Fractional PC schemes:
– Allow the received SINR to decrease as the path loss increases.
– UE Tx power increases at a reduced rate as the path loss increases. Increases in
path loss are only partially compensated.
– [+]: Improve air interface efficiency & increase average cell throughputs by reducing
Inter-cell interference
• 3GPP specifies fractional power control for the PUSCH with the option to disable it &
revert to conventional based on α
UL
SINR
Conventional Power
Control: α=1
UE Tx
Power
If Path Loss increases
by 10 dB the UE Tx
power increases by 10
dB
39
© Nokia Siemens Networks
RA41213EN30GLA0
UL
SINR
UE Tx
Power
Fractional Power
Control: α ≠ { 0 ,1}
If Path Loss
increases by 10 dB
the UE Tx power
increases by < 10
dB
MCS dependent component
PPUSCH (i) min {PCMAX ,10 log10 (M PUSCH (i)) PO_PUSCH ( j ) ( j ) PL TF (i) f (i)} dBm
TF (i) 10 log10 (2MPRK s 1)
for
K S 1.25
deltaTfEnabled
0
Otherwise
Enabled TB size (MCS) impact to
UE PUSCH power calculation
LNCEL; Yes/No; -
MPR = TBS/NRE with NRE : number of RE, TBS = Transport Block Size
•
•
•
TF = Transport Format
Ks - Enabling/disabling of the transport format dependent offset on a per UE basis
If this parameter is enabled, PUSCH power calculation in UE uplink power control equation takes
the Transport Block size in account during the power calculation
Could be seen as dynamic offset of the TX power: when the BTS changes the MCS for the UE then
the UE indirectly may adapt the power
Increase the power if the Transport Format (MCS, TBS size, Number of Resource Blocks) it is so
selected to increase the number of bits per Resource Element
•
•
40
© Nokia Siemens Networks
RA41213EN30GLA0
UL-PC: PUCCH
PPUCCH (i) min{ PMAX , P0_PUCCH( j ) PL h(nCQI , nHARQ ) F_PUCCH( F ) g (i)} dBm
PPUCCH: PUCCH Power in subframe i
p0NomPucch
Pmax: max. allowed power
Nominal Power for UE PUCCH
Tx Power Calculation
LNCEL; -126..-96; 1; -100 dB
P0_PUCCH(j) = P0_NOMINAL_PUCCH(j) + P0_UE_PUCCH(j)
P0_NOMINAL_PUCCH : cell specific (SysInfo)
P0_UE_PUCCH : UE specific (RRC)
PL: pathloss [dB] = referenceSignalPower – higher layer filtered RSRP * For PUCCH higher degree of
H(nCQI, nHARQ )
• PUCCH format 1, 1a, 1b: h(n) = 0
• PUCCH format 2, 2a, 2b and :
orthogonality could be assumed
due to the usage of the
orthogonal codes so alpha=1 (full
compensation)
h(n) = 0 if nCQI < 4
h(n) = 10log10 (nCQI/4) otherwise
(here: normal CP, for extented CP also nHARQ to be considered, n:number of information bits)
F_PUCCH (F) : dFListPUCCH
(see next slide)
g(i): TPC (closed loop adjustment)
41
© Nokia Siemens Networks
RA41213EN30GLA0
Compensation Factor for
different PUCCH formats
For example if format 1a (1ACK)
is having offset 0 then format 1b
(2ACK) could have offset 3dB
UL-PC: Closed loop - PUSCH (example)
ulpcEnable
Closed loop adjustments:
enable UL closed loop PC
LNCEL; true, false; false
f(i) = f(i-1) + dPUSCH (i - KPUSCH) i.e. recursive determination
or
f(i) = dPUSCH (i - KPUSCH) i.e. absolute setting
where dPUSCH is the signalled TPC in subframe i-KPUSCH
For FDD: KPUSCH = 4
ulpcAccuEnable
PUSCH/PUCCH TPC commands
accumulation enabled
Vendor Specific
whether the recursive or absolute method is used parameter Accumulation-enabled
P (closed loop)
t
42
© Nokia Siemens Networks
RA41213EN30GLA0
UL-PC: Closed Loop - Process
High Thresh. For SINR for PUSCH
LNCEL; -47...80dB; 1dB ; 11dB
SINR
+ 1 dB or
+ 3 dB
ulpcUpqualCch
High Thresh. For SINR for PUCCH
LNCEL; -47...80dB; 1dB ; 4dB
- 1 dB
+ 1 dB or
+ 3 dB
2
3
0 dB
-1 dB
4
LOW_QUAL_**
5
6
1dB
ulpcLowqualSch
+ 1 dB or
+ 3 dB
Low Thresh. For SINR for PUSCH
LNCEL; -47...80dB; 1dB ; 8dB
+ 1 dB or
+ 3 dB
7
ulpcLowqualCch
Low Thresh. For SINR for PUCCH
LNCEL; -47...80dB; 1dB ; 1dB
© Nokia Siemens Networks
- 1 dB
1
UP_QUAL_**
43
Decision matrix
1dB
ulpcUpqualSch
LOW_LEV_**
Decision
whether to
+1dB or +3dB
+ 1 dB or
+ 3 dB
8
UP_LEV_**
9
RSSI
ulpcLowlevCch
ulpcUplevCch
Low Thresh. For RSSI for PUCCH
LNCEL; -127...0dBm;1dBm ;-103dBm
High Thresh. For RSSI for PUCCH
LNCEL; -127...0dBm;1dBm ;-98dBm
ulpcLowlevSch
ulpcUplevSch
Low Thresh. For RSSI for PUSCH
LNCEL; -127...0dBm;1dBm ;-103dBm
High Thresh. For RSSI for PUSCH
LNCEL; -127...0dBm;1dBm ;-98dBm
RA41213EN30GLA0
DL-PC
dlCellPwrRed
RL20: (static) cell power reduction
• based on single parameter CELL_PWR_RED = 0.0, 0.1 … 10.0 dB
• cell size adjustment and coverage control
pMax
• flat Power Spectral Density (PSD)
Maximum output power
LNCEL; 37.0 (0), 39.0 (1), 40.0 (2), 41.8
(3), 43.0 (4), 44.8 (5), 46.0 (6), 47.8 (7);37.0 dBm = 5 W
39.0 dBm = 8 W
40.0 dBm = 10 W
41.8 dBm = 15 W
43.0 dBm = 20 W
44.8 dBm = 30 W
46.0 dBm = 40 W
47.8 dBm = 60 W
• semi-static MIMO_COMP (if enabled)
RL30: optional power boost: PCFICH, PHICH, DL RS
PSD
PSD
PSD = (Max_TX_Pwr – CELL_PWR_RED) – 10*log10( 12*# PRBs)
Allocated DL PRBs
Frequency
DL Pilots
44
© Nokia Siemens Networks
RA41213EN30GLA0
Reduction of DL Tx power; deducted
from max. antenna TX power.
LNCEL; 0..10; 0.1; 0 dB
PSD = (Max_TX_Pwr – CELL_PWR_RED) – 10*log10( 12*# PRBs)
PDCCH
Time
PDSCH, PCH BCH, SCH
DL-PC: Power Reduction
Cell Power Reduction
PSD = (pMax - CELL_PWR_RED) - 10*log10( # PRBs_DL *12) - MIMO_COMP [dBm]
PSD: Power Spectral Density, which specifies the constant absolute Power per 15kHz Resource Element
• pMax: maximum eNodeB transmit power per Antenna in [dBm]
• CELL_PWR_RED:
O&M parameter
• # PRBs_DL: maximum Number of downlink PRBs in given LTE Carrier Bandwidth
• MIMO_COMP: Compensation Factor
• MIMO_COMP = 0 dB for SISO/SIMO
• MIMO_COMP = 0...12 dB for MIMO Diversity and for MIMO Spatial Multiplexing
- PSD given per antenna (RF amplifier output)
dlpcMimoComp
- PRBs not scheduled are blanked
Determines the power
compensation factor for
antenna-specific maximum
power in case of a downlink
transmission using at least two
TX antennas
LNCEL; 0..10; 0.01; 0 dB
Applied to UE / cell specific channels and signals:
• PSD_CELL_CTRL for BCCH i.e. PBCH+PDSCH, PCFICH and PCH
• PSD_CELL_RS for reference signals (RS) / pilots
• PSD_CELL_SYNC for synchronization channel
• PSD_UE_PDSCH for UE specific part of PDSCH
dlCellPwrRed
• PSD_UE_CTRL for PDCCH and PHICH
Reduction of DL Tx power;
deducted from max. antenna TX
power.
LNCEL; 0..10; 0.1; 0 dB
45
© Nokia Siemens Networks
RA41213EN30GLA0
DL-PC: DL power boosting for control channels
dlPcfichBoost
PCFICH power boosting
PCFICH provides information about the number of OFDM symbols for the PDCCH.
The eNB supports dedicated power control settings for the PCFICH in order to
ensure that especially cell edge UEs can properly receive the PCFICH.
A relative offset between the flat PSD (Power Spectral Density) on PDSCH and
PCFICH can be configured by O&M on cell level.
Downlink PCFICH
transmission power boost
LNCEL; 0..6; 0.1; 0 dB
dlPhichBoost
Downlink PHICH transmission
power boost
LNCEL; 0..6; 0.1; 0 dB
PHICH power boosting
The PHICH provides ACK/NACK information for the uplink transmission.
The eNB supports dedicated power control settings for the PHICH in order to ensure
that the UE can properly receive the PHICH.
PHICH power boost may not be (fully) applied if PDCCH PSD goes too low in the first OFDM symbol. In
that case, the eNB rises the PHICH Power Boost not applied warning.
A maximum relative offset between the flat PSD on PDSCH and PHICH can be configured by O&M on cell level.
Downlink reference signal boosting
dlRsBoost
The downlink reference symbols are used by the UE for
channel estimation and cell measurements (Level, Quality) for mobility.
Downlink RS transmission
The eNB supports relative RS / PDSCH power control settings.
power boost
A relative offset between the PDSCH and RS
LNCEL; 0dB (0), 1.77dB (1), 3dB
can be configured by O&M on cell level.
(2), 4.77dB (3), 6dB (4); 0 dB
The eNB ensures that total Tx power is not exceed.
The sum power for any OFDM symbol must not exceed the commited maximum power, otherwise all the configured
boosts (PHICH) may not be applied.
46
© Nokia Siemens Networks
RA41213EN30GLA0
Main target of DL-PC-CCH
• DL Power Control for PDCCH is an additional mechanism interacting with
DL AMC for PDCCH in order to make the signaling as robust as possible
• DL-PC-CCH aims at 1% target BLER but cannot modify AGG assignments
• Main actions performed by DL-PC-CCH
– Power reduction on CCEs with assigned AGG level higher than required (or equal)
– Power boosting on CCEs with assigned AGG level lower than required
– Equal power relocation among all scheduled CCEs
• Macro cell case #1
• Uniform UE distribution
enableLowAgg
4-CCE
8-CCE
47
© Nokia Siemens Networks
Very good CCEs (CQI highly
above 1% BLER target)
Bad CCEs (AGG level too high to
meet 1% BLER target)
If still some power available,
relocate equally among all CCEs
2-CCE
RA41213EN30GLA0
1-CCE
Enable lower aggregation
selection for PDCCH LA .
LNCEL; True/False; False
Principles of DL-PC-AMC
• PDCCH Power Control can be enabled/disabled by O&M switch
• Maximum transmit power of the Power Amplifier cannot be exceeded (pMax; O&M)
• Reduction and boosting range is strictly defined and is always considered as the limit for
power level modification
• DL-PC-CCH operates together with DL-AMC-CCH on TTI basis
• DCI messages with more than one CCE (AGG-…>1) have a flat PSD,
thus all CCEs belonging to one scheduled UE are transmitted with the same power
Short
Name
48
Description
Range/
Step
Default
Value
Parameter
Scope
true, false
true
Cell
Changing parameter
requires object locking.
Operator configurable.
Remark
enablePcPdcch
Enabling/disabling PC for PDCCH.
In case the parameter is disabled, a
flat downlink PSD is used.
pdcchPcBoost
Maximum power boost per CCE.
0...10 dB,
step 0.1 dB
4 dB
BTS
Not modifiable.
Vendor configurable.
pdcchPcRed
Maximum power reduction per CCE.
0...10 dB,
step 0.1 dB
6 dB
BTS
Not modifiable.
Vendor configurable.
pdcchPcReloc
Maximum limit on the equal power
relocation per CCE.
0...10 dB,
step 0.1 dB
3 dB
BTS
Not modifiable.
Vendor configurable.
© Nokia Siemens Networks
RA41213EN30GLA0
Module Contents
• Random Access
• Radio Bearer Control
• Radio Admission Control
• UL/DL Power control
• MIMO Mode Control
• Mobility Management
• UL/DL Scheduler
49
© Nokia Siemens Networks
RA41213EN30GLA0
MIMO Overview
• Main contribution to high spectral efficiency
• MIMO is the deployment of multiple antennas at Tx and Rx
• 3GPP defines 7 DL transmission modes
• RL30 allows for DL:
- Transmission on single antenna port (SISO/SIMO)
- TX diversity (2x2)
- Static open loop spatial multiplexing (2x2)
- Dynamic open loop: TX diversity (2x2) open loop spatial
multiplexing
- Adaptive closed loop (Single stream CL SM Dual stream
CL SM)
50
© Nokia Siemens Networks
RA41213EN30GLA0
Overview
MIMO
Data Transmission
Number of Antennas
Number of Users
SISO
SU-MIMO
(Single Input Single Output)
(Single User MIMO)
pre-coding
Pre-Coding
(beamforming)
single data stream sent over
multiple input antennas
X
…
MISO
(Multiple Input Single Output)
…
…
Spatial Multiplexing
X1
…
Xn
pre-coding
multiple data stream sent over
multiple input antennas
SIMO
(Single Input Multiple Output)
…
…
…
MIMO
(Multiple Input Multiple Output)
Diversity Coding
single data stream sent over
multiple input antennas
with different coding
e.g. CDMA soft handover
51
© Nokia Siemens Networks
MU-MIMO
RA41213EN30GLA0
…
…
RL30 supported transmission modes (DL)
• Single-antenna port; port 0
• Transmit diversity
• Open-loop spatial multiplexing
• Dynamic Open loop MIMO
• Closed-loop spatial multiplexing
52
RL10 (MIMO: max 2x2)
RL20 enhancements; max (2x2)
numOfTxPorts
dlMimoMode
Number of antenna ports
LNCEL; 1 (0), 2 (1); 2 (1)
Number of antenna ports
LNCEL; SingleTX (0), TXDiv (1),
Static Open Loop MIMO (2),
Dynamic Open Loop MIMO (3),
Closed Loop Mimo (4); TxDiv (1)
© Nokia Siemens Networks
RA41213EN30GLA0
Transmit Diversity
• 2x2 based on Space Frequency Block Coding (SFBC); future: also 4x4
• Supported: DL
• Increases robustness, enhances cell edge performance
• Link budget gain: min 3 dB wrt 1x2 case (Tx power per Tx branch as in single ant. case)
capacity and coverage enhancements
• Rank 1 transmission, i.e. no multiplication of data rates
• aka Alamouti scheme
• Coverage improvement example:
- 592 m 808 m (dense urban)
- 694 m 948 m (urban)
- 2024 m 2970 m (suburban)
- 7665 m 11248 m (rural)
Single antenna Tx
Tx Div
53
© Nokia Siemens Networks
RA41213EN30GLA0
Dynamic Open loop MIMO
Depending on Radio Conditions:
switch between Transmit Diversity and Spatial Multiplexing
- Open loop MIMO Switch Algorithm
- Open loop adaptive MIMO Algorithm
- Support of UE Capabilities
- UE basis
- CQI and Rank Information: used as switching criteria
Spatial
Multiplex
Diversity
x
54
© Nokia Siemens Networks
RA41213EN30GLA0
Dynamic MIMO mode
Simulation Results (Source 4GMAX)
55
© Nokia Siemens Networks
RA41213EN30GLA0
Dynamic (Adaptive) OL Switching
Various parameters are to support adaptive switching between 1-stream
Transmit Diversity and 2-stream Spatial Multiplexing:
• mimoOlCqiThD - This defines the CQI Threshold
Downgrade Switch::
for fallback to Open Loop MIMO diversity (in CQI). If
mimoCQI <= mimoDivCqiThDownOL
• mimoOlCqiThU - This defines the CQI Threshold
or
mimoRANK <= mimoDivRiThDownOL
for activation of Open Loop MIMO Spatial
Multiplexing (in CQI).
• mimoOlRiThD - This defines the Rank Threshold
Upgrade Switch :
If
for fallback to Open Loop MIMO diversity.
mimoCQI > mimoSmCqiThUpOL
and
• mimoOlRiThU - This defines the Rank Threshold
for activation of Open Loop MIMO Spatial Multiplexing. mimoRANK > mimoSmRiThUpOL
mimoOlCqiThD
CQI Threshold For
Fallback To Open Loop
MIMO diversity
LNCEL; 0...16; 0.1 ; 9
56
© Nokia Siemens Networks
mimoOlCqiThU
CQI Threshold For
Activation Of Open Loop
MIMO Spatial
Multiplexing
LNCEL; 0...16; 0.1 ; 11
RA41213EN30GLA0
mimoOlRiThD
Rank Threshold For
Fallback To Open Loop
MIMO diversity
LNCEL; 1...2; 0.05 ; 1.4
mimoOlRiThU
Rank Threshold For
Activation Of Open Loop
MIMO Spatial
Multiplexing
LNCEL; 1...2; 0.05 ; 1.6
Dynamic Open Loop MIMO mode
SM
CQI
SM
mimoOlCqiThU
mimoOlCqiThD
Time
Filtered:
Filtered
cqi, ri
RI
mimoOlRiThU
Inactivity:
Inactivity:
Aging
aging
applied
mimoOlRiThD
Time
57
© Nokia Siemens Networks
RA41213EN30GLA0
MIMO Adaptive Closed Loop
• Feature LTE703 defines the use of Adaptive Closed Loop (CL) MIMO.
• The eNB scheduler selects Spatial Multiplexing dynamically while
applying closed loop MIMO for two antennas.
• The adaptive algorithm provides the gain of high peak rates (dual stream)
when close to the cell and good cell edge performance (single stream).
• Spatial multiplexing is applied only for the PDSCH.
Dual
Stream
x
x Adaptive Switching
58
© Nokia Siemens Networks
RA41213EN30GLA0
Single
Stream
Dynamic (Adaptive) CL Switching
Various parameters are added to RL15TD to support adaptive switching
between CL MIMO 1 CW Mode and CL MIMO 2 CW Mode:
• mimoClCqiThD - This defines the CQI Threshold
for fallback to closed loop MIMO single codeword
transmission (in CQI).
• mimoClCqiThU - This defines the CQI Threshold
for activation of closed loop MIMO dual codeword
transmission (in CQI).
• mimoClRiThD - This defines the Rank Threshold
for fallback to closed loop MIMO single codeword
transmission.
• mimoClRiThU - This defines the Rank Threshold
for activation of closed loop MIMO dual codeword
transmission.
59
mimoClCqiThD
mimoClCqiThU
mimoClRiThD
CQI Threshold For
Fallback To CL MIMO
1 CW Mode
LNCEL; 0...16; 0.1 ; 9
CQI Threshold For
Activation Of CL MIMO 2
CW Mode
LNCEL; 0...16; 0.1 ; 11
Rank Threshold For
Fallback To CL
MIMO 1 CW Mode
LNCEL; 1...2; 0.05 ;
1.4
© Nokia Siemens Networks
RA41213EN30GLA0
mimoClRiThU
Rank Threshold For
Activation Of CL MIMO 2
CW Mode
LNCEL; 1...2; 0.05 ; 1.6
Dynamic Close Loop MIMO mode
2CW
CQI
2CW
mimoClCqiThU
mimoClCqiThD
Time
Filtered:
Filtered
cqi, ri
RI
mimoClRiThU
Inactivity:
Inactivity:
Aging
aging
applied
mimoClRiThD
Time
60
© Nokia Siemens Networks
RA41213EN30GLA0
Module Contents
• Random Access
• Radio Bearer Control
• Radio Admission Control
• UL/DL Power control
• MIMO Mode Control
• Mobility Management
• UL/DL Scheduler
61
© Nokia Siemens Networks
RA41213EN30GLA0
S – Criterion Cell Selection
UE selects a eUTRA cell if the S (selection) criteria is fulfilled:
Srxlev > 0
Srxlev = Qrxlevmeas – (Qrxlevmin* + Qrxlevminoffset**) - Pcompensation
UE measurement
(RSRP)
SIB1 Parameter
SIB1 Parameter
Pcompensation = max (PEMAX*** – PUMAX, 0) (dB)
SIB1 Parameter
qrxlevmin
* Qrxlevmin = LNCEL: qrxlevmin
** Qrxlevminoffset = LNCEL: qRxLevMinOffset (used
only when camped in VPLMN)
*** PEMAX = LNCEL: pMaxOwnCell
PUMAX is UE class specific max. UL Tx power
Minimum required RSRP level
LNCEL; -140…-44dBm; 2dBm; -
qRxLevMinOffset
Affects minimum required RSRP level
LNCEL; 2..16 dB; 2dB; -
pMaxOwnCell
Used to calculate Pcompensation
LNCEL; -30..34dBm; 1dBm; -
62
© Nokia Siemens Networks
RA41213EN30GLA0
*PUMAX: UE class specific max. UL Tx power; 23
dBm
Reselection Options
• Intra-LTE (or Intra-RAT) reselection with 2 options:
• Intra frequency reselection → within the same frequency band
(supported from RL10)
• Inter-frequency reselection
– reselection from LTE f1 to LTE f2
– Could be imagined as additional LTE layer for capacity reason
– Supported from RL20
• Inter-RAT reselection
• Reselection to other Radio Access Techcnologies:
•
•
•
•
63
LTE to UTRAN (from RL20)
LTE to GERAN (from RL20)
LTE to CDMA 2000 HRPD (from RL20)
LTE to CDMA 2000 1xRTT(from RL30)
© Nokia Siemens Networks
RA41213EN30GLA0
Priority Layer Concept in LTE
•
•
•
•
•
•
•
64
Cell reselection between different LTE frequencies and different RATs is based
on priorities
Priorities could be configured for each LTE frequency (including serving cell) and
for each frequency of each RAT
Priorities are provided to UE via system information
Equal priorities are not applicable for inter-RAT cell reselection
UE performs only cell reselection evaluation for inter-LTE frequency and interRAT carriers for which the UE has a priority
UE is camped on a cell which defines the priorities for the other network layers
The range of absolute priorities is 0..7 (0 is the lowest priority)
LNCEL: cellReSelPrio
Absolute priority of the serving cell
IRFIM: eutCelResPrio
Absolute priority of EUTRA carrier frequency
UFFIM: uCelResPrio
Absolute priority of the UTRA carrier frequency
GNFL: gCelResPrio
Absolute priority of the GERAN carrier frequency
CDFIM: hrpdCResPrio
frequency
Absolute priority of the CDMA2000 HRPD carrier
CDFIM: rttCResPrio
frequency
Absolute priority of the CDMA2000 1xRTT carrier
© Nokia Siemens Networks
RA41213EN30GLA0
Measurements Trigger - Intra Frequency
• When to trigger the measurements of neighbor cells?
• UE is not continuously measuring neighbor cells in search of a better cell
to camp on
• UE only performs intra frequency measurements when:
Intra - Frequency:
sIntrasearch
Srxlev <= Sintrasearch
→ Qrxlevmeas ≤ Qrxlevmin + Sintrasearch
(assuming that qRxLevMinOffset is not used)
65
© Nokia Siemens Networks
RA41213EN30GLA0
LNCEL; 0..62dB; 2dB; -
qrxlevmin
Minimum required RSRP level
LNCEL; -140…-44dBm; 2dBm; -
Measurements Trigger – Inter-frequency and InterRAT (1/2)
sNonIntrsearch
LNCEL; 0..62dB; 2dB; 66
© Nokia Siemens Networks
RA41213EN30GLA0
R Criterion – Cell Reselection
Intra-frequency Case (1/2)
•
Once the measurements for neighbor cells have been triggered the UE
will rank the measured cells which fulfill the S- Criterion according to the
R- Criterion
qHyst
LNCEL; 0dB (0),…,24dB (15); • Cell ranking criterion:
Rs = Qmeas,s + Qhyst,s
qOffsetCell
IAFIM; -24 dB (0),…,24 dB (30); - ;
Rn = Qmeas,n – Qoffset,n
0 dB(15)
Rn > Rs “cell reselection“
tReselEutr
LNCEL; 0…7s; 1s; -
Where: Qmeas,s & Qmeas,n = RSRP
• The UE shall reselect the new cell, if the following conditions are met:
• 1. The new cell is better ranked than the serving cell during a time interval tReselection
• 2. More than 1 second has elapsed since the UE has camped on the current serving
cell
67
© Nokia Siemens Networks
RA41213EN30GLA0
Note:
s – indicates the serving cell
n – indicates the candidate neighbour
R Criterion – Cell Reselection
Intra-frequency Case (2/2)
Qmeas
Rs = Qmeas,s + Qhysts
Rn = Qmeas,n - Qoffsets,n
Rn > Rs =>
„cell reselection“
qHyst
Qmeas,n
LNCEL; 0dB (0)… 24dB (15);
-
Rn
Qmeas,s
Qhysts
qOffsetCell
IAFIM; -24 dB (0)… 24 dB (30); - ; 0 dB(15)
Rs
Qoffsets,n
Treselection
tReselEutr
LNCEL; 0…7s; 1s; 68
© Nokia Siemens Networks
RA41213EN30GLA0
Time
R Criterion – Cell Reselection
Inter-frequency Equal Priority Case
• Similar to intra-frequency case
• An additional frequency offset to control the reselection is introduced:
Rs = Qmeas,s + Qhyst
Rn = Qmeas,n – Qoffset
Rn > Rs “cell reselection“
LTE f2
offset = 0 dB
LTE f2
offset = -2 dB
LTE f1
• Where:
Qmeas,s & Qmeas,n = RSRP
Qoffset = qOffCell,n + Qoffsetfrequency
qOffFrq
qOffCell
Cell specific offset
IRFIM; -24..24; 1; - dB
69
© Nokia Siemens Networks
RA41213EN30GLA0
Frequency specific offset for
equal priority EUTRAN
frequencies
IRFIM; -24..24; 2; 0 dB
LTE f1
R Criterion – Cell Reselection
Reselection to a Higher Priority LTE frequency
• The reselection to a higher absolute priority LTE layer is performed if:
SnonServingCell > Threshx,high
interFrqThrH
Threshx,high
• Where:
IRFIM; 0..62dB; 2dB; -
SnonServingCell = Qrxlevmeas – Qrxlevmin - Pcompensation
qRxLevMinInterF
Min. coverage criteria
• Qrxlevmeas = RSRP of the LTE frequency layer
IRFIM;-140..-44dBm; 2dB; • Qrxlevmin specified by the parameter qRxLevMinInterF
→ Qrxlevmeas(nonServingCell) > qRxLevMinInterF + interFrqThrH
(Assuming Pcompensation = 0)
• The criteria above must be satisfied for a time period equal to
Treselection
interTResEut
Reselection timer
IRFIM; 0..7s; 1s; -
70
© Nokia Siemens Networks
RA41213EN30GLA0
R Criterion – Cell Reselection
Reselection to a Lower Priority LTE frequency
• Reselection to a lower priority LTE Layer is performed if:
interFrqThrL
SservingCell < Thresoldserving,low AND
SNonServingCell > Threshx,low
Threshx,low
IRFIM; 0..62dB; 2dB; -
threshSrvLow
• Which means:
Thresholdserving,low
LNCEL; 0..62dB; 2dB; -
→ Qrxlevmeas(ServingCell) < qRxLevMin + thresholdSrvLow
AND
Qrxlevmeas(NonServingCell) > qRxLevMinInterF + interFreqThrL
(assuming that qRxLevMinOffset is not used and Pcompensation = 0)
qrxlevmin
qRxLevMinInterF
Minimum required RSRP level
Min. coverage criteria
LNCEL; -140…-44dBm; 2dBm; -
IRFIM;-140..-44dBm; 2dB; -
Threshx,high > Threshx,low > Thresserving,low
71
© Nokia Siemens Networks
RA41213EN30GLA0
R Criterion – Cell Reselection
Inter-RAT Reselection (1/2)
•
•
Same principle as in inter-frequency reselection
Different thresholds for different RATs: UTRAN, GERAN, CDMA2000 HRPD,
CDMA 2000 1xRTT
utraFrqThrH
Reselection to a higher priority RAT:
gerFrqThrH
SnonServingCell,x > Threshx,high
rttFrqThrH
•
hrpdFrqThrH
•
Reselection to a lower priority RAT:
SServingCell < Threshserving,low
and
SnonServingCell,x > Threshx,low
• The above conditions should be
satisfied for the duration of TreselectionRAT
Threshx,high > Threshx,low > Thresserving,low
threshSrvLow
xxxFrqThrL
xxx = utra,ger,rtt, hrpd
tResUtra
tResGer
tResRtt
tResHrpd
72
© Nokia Siemens Networks
RA41213EN30GLA0
R Criterion – Cell Reselection
Inter-RAT Reselection (2/2)
•
SnonServingCell
In case of GSM, UMTS, LTE SnonServingCell = Srxlev of the candidate cell
• In case of GSM:
Srxlev = Qrxlevmeas – Qrxlevmin – Pcompensation
qRxLevMinGer
Qrxlevmeas = RSSI
Minimum required RX. level
Qrxlevmin = qRxLevMinGer
GNFL; -115..-25dBm; 2dB; -
•
In case of UMTS:
qRxLevMinUtra
Minimum required Rx level in the
Srxlev = Qrxlevmeas – Qrxlevmin – Pcompensation
WCDMA cell
Qrxleavmeas = CPICH RSCP
UFFIM; -119..-25dBm; 2dB; Qrxlevmin = qRxLevMinUtra
Additionally Squal > 0 required for UMTS FDD qQualMinUtra
Squal = Qrxlevmeas – Qqualmin
Minimum required quality level in
the WCDMA cell
Qrxlevmeas = CPICH Ec/No
UFFIM; -24..0dB; 1dB; Qqualmin = qQualMinUtra
73
© Nokia Siemens Networks
RA41213EN30GLA0
Mobility States
• Possible mobility states are: high, medium & normal mobility speed UE’s.
• For faster moving UEs the procedure alters - speed dependent scaling rules are applied.
• UE state detection:
nCellChgHigh
LNCEL; 1..16; 1; -
tEvaluation
LNCEL; 30s (0), 60s (1), 120s
(2), 180s (3), 240s (4) ; -
– If the number of (different cells) cell reselections during the past time period tEvalulation
exceeds nCellChgHigh, high mobility has been detected.
– If the number exceeds nCellChgMed, and not nCellChgHigh, medium mobility has
been detected.
– Else Normal Mobility is considered
– REMARK: Mobility could be further applied separately for intra, inter frequency, interRAT scenarios
.
nCellChgMed
LNCEL; 1..16; 1; -
74
© Nokia Siemens Networks
RA41213EN30GLA0
Mobility States
• For High & medium mobility states, cell ranking criteria will be modified to
consider a scaling factor:
qHystSfHigh
LNCEL; -6 dB (0), -4 dB (1),
-2 dB (2), 0 dB (3); -
• High mobility:
• Multiply Qhyst by "Speed dependent ScalingFactor for Qhyst for high mobility state“ (qHystSfHigh)
• Multiply tReselection by "Speed dependent ScalingFactor for TreselectionRAT for high mobility state
for RAT cells. (RAT = EUTRAN, UTRAN, GERAN). (celResTiFHM)
celResTiFHM
qHystSfMed
LNCEL; -6 dB (0), -4 dB (1),
-2 dB (2), 0 dB (3); -
•Medium mobility:
LNCEL; 0.25 (0), 0.5 (1),
0.75 (2), 1 (3); -
• Multiply Qhyst by "Speed dependent ScalingFactor for Qhyst for medium mobility
state“ (qHystSfMed)
• Multiply tReselection by "Speed dependent ScalingFactor for TreselectionRAT for medium mobility
state for RAT cells. (RAT = EUTRAN, UTRAN, GERAN). (celResTiFMM)
celResTiFMM
LNCEL; 0.25 (0), 0.5 (1),
0.75 (2), 1 (3); 75
© Nokia Siemens Networks
RA41213EN30GLA0
Idle Mode Mobility LTE Intra-Frequency
•
Broadcast of SIB 4 is optional – no need to broadcast any intrafrequency neighbor cells
– UE is able to complete cell re-selection with SIB3 information
•
eUTRAN SIB4 informs about LTE idle mode neighbors
– Physical Cell Identifier (PCI) of neighbor cell can be broadcast
– cell (neighbor) individual re-select offset can be broadcast
•
SIB4 also informs about blacklisted cells (BC)
– A UE is not allowed to re-select a blacklisted cell
– Up to 16 groups of cells (PCIs) can be blacklisted
– UE will not measure BC cells in connected mode
•
UE will never be instructed from eNB to handover to a blacklisted cell
physCellIdNcl
PCI is a unique cell identification
in a neighboring cell list
IAFIM; 0…503; 1; 76
© Nokia Siemens Networks
RA41213EN30GLA0
qOffsetCell
IAFIM; -24 dB(0)… 24 dB (30); 0dB (15)
Idle Mode Mobility LTE to WCDMA (1/2)
SIB6
Parameter Object Structure and UFFIM Parameters
e.g.
LNBTS
tResUtra
UTRA Cell Reselection Timer
IRFIM; 0 – 7s; 1; -
LNCEL
UFFIM
uffimId Identifies the UFFIM managed objects.
tResUtra UTRA cell reselection timer
tResUtraSF (structured: 2 parameters)
utrResTiFHM The field t-ReselectionUTRA is multiplied by this factor if
x1
the
UE is in the high mobility state as defined in 36.304.
utrResTiFMM The field t-ReselectionUTRA is multiplied by this factor if the UE is in
the medium mobility state as defined in 36.304.
77
© Nokia Siemens Networks
RA41213EN30GLA0
UFFIM: UTRAN FDD Frequency Idle Mode
Idle Mode Mobility LTE to WCDMA (2/2)
SIB6
utrFddCarFrqL and utrTddCarFrqL(structured: 7 parameters)
x 16
– dlCarFrqUtra contains the DL frequency (Nd).
– pMaxUtra
UTRA maximum allowed transmit power.
– qQualMinUtra specifies minimum required quality level in the cell in dB.
– qRxLevMinUtra specifies minimum required RX level in the cell in dBm.
– uCelResPrio absolute priority of the UTRA carrier frequency.
– utraFrqThrH specifies threshold used by the UE when reselecting towards a
–
78
higher priority frequency X than the current serving frequency.
utraFrqThrL specifies threshold used in reselection towards the frequency X
priority from a higher priority frequency.
© Nokia Siemens Networks
RA41213EN30GLA0
Idle Mode Mobility LTE to GERAN (1/3)
SIB7
Parameter Object Structure and GFIM and GNFL Parameters
LNBTS
LNCEL
GFIM
GFIM Parameter Object:
GNFL
gfimId (structured: 4 parameters)
tResGer GERAN cell reselection timer
tResGerSF (structured 2 parameters)
x1
– gerResTiFHM Speed-dependent scaling factor treselection GERAN
– gerResTiFMM Speed-dependent scaling factor treselection GERAN
79
© Nokia Siemens Networks
RA41213EN30GLA0
GFIM: GERAN Frequency Idle Mode par.
GNFL: GERAN Neighbour Frequency List par.
Idle Mode Mobility LTE to GERAN (2/3)
SIB7
GNFL Parameter Object – for max 16 GERAN frequency
layers
x 16
bandInd
GERAN frequency band indicator
gCelResPrio Absolute priority of the GERAN carrier frequency
gerArfcnVal
Each ARFCN value explicitly listed
gerFrqThrH
GERAN inter-frequency threshold high
gerFrqThrL
GERAN inter-frequency threshold low
gnflId
GERAN neighbour frequency configuration identifier
nccperm
NCC permitted bitmap
pMaxGer
GERAN maximum allowed transmit power
qRxLevMinGer GERAN minimum required receive level
80
© Nokia Siemens Networks
RA41213EN30GLA0
Idle Mode Mobility LTE to CDMA2000 HRPD (1/2)
SIB8
Parameter Object Structure and CDFIM Object Parameters
LNBTS
LNCEL
CDFIM
• cdfimId
CDMA2000 frequency idle mode configuration identifier
• hrpdArfcn the carrier frequency within a CDMA2000 Band.
• hrpdCellId the CDMA "Physical cell identity".
• tResHrpd
81
© Nokia Siemens Networks
CDMA2000 HRPD cell reselection timer
RA41213EN30GLA0
x1
Idle Mode Mobility LTE to CDMA2000 HRPD (2/2)
SIB8
CDFIM Object Parameters
• tResHrpdSF (structured – 2 parameters)
– hrpResTiFHM The field t-ReselectionHrpd is multiplied by this factor if the UE is in the high
mobility state
– hrpResTiFMM The field t-ReselectionHrpd is multiplied by this factor if the UE is in the medium
mobility state
x 32
•hrpdBdClList (structured – 4 parameters)
– hrpdBdClBcl Identifies the CDMA2000 HRPD Frequency Band in which the CDMA2000 Carrier
can be found
– hrpdCResPrio Absolute priority of the Bandclass of CDMA2000 HRPD
– hrpdFrqThrH specifies the high threshold used in reselection towards CDMA2000 HRPD
– hrpdFrqThrL specifies the low threshold used in reselection towards CDMA2000 HRPD
82
© Nokia Siemens Networks
RA41213EN30GLA0
Idle Mode Mobility LTE to CDMA/1xRTT (RL30)
SIB8
CDFIM Object Parameters:
• rttNCList
x40
• rttBdClList x5
• tResrtt
• tResrttSF
(rttArfcn, rttBdClNcl, rttCellId, rttExSel)
(rttBdCl, rttBdClBcl, rttCResPrio, rttFrqThrH, rttFrqThrL)
CDMA2000 RTT Reselection Timer
(rttResTiFHM, rttResTiFMM)
1x RTT = 1Times Radio Transmission Technolgy
83
© Nokia Siemens Networks
RA41213EN30GLA0
Handovers Introduction
Handovers in LTE are:
• Hard handovers: resources are prepared in the target cell before the UE is
commanded to move to the target cell
• Lossless: Packets are forwarded from the source to the target cell.
• Network controlled: The target cell is selected by the network not by the
UE. The handover control is in the e-UTRAN not in the Core Network.
• UE-assisted: Measurements are made and reported by the UE to the
network although it is the network (eNodeB) which triggers those
measurements.
• Late path switch: Only when the inter eNodeB handover is successful, the
backhaul path is switched to new tunnel.
84
© Nokia Siemens Networks
RA41213EN30GLA0
HO Process Overview
Measurements activation/de-activation
Event based neighbor reports
Measurement Reports from UE
HO target & mode selection in eNodeB
HO execution
UE continuously monitors the
serving cell. Events A2/A1* are used
to activate/de-activate neighbors
measurements when radio conditions
are getting worse
The reports of neighbors are triggered
by A3 & A5 events for intra-RAT
neighbors and B2 event for the
inter-RAT neighbors
The “Measurement Report” message
contains a prioritized list of neighbors (bes
neighbor first)
eNodeB decides the urgency of HO and
identifies a prioritized list of HO target
cells. The eNodeB selects the target
cell for HO as well as the handover mode.
The HO/NACC mode could be:
-Intra eNB HO
-Intra LTE inter eNB via X2
-Intra LTE inter eNB via S1
-HO to WCDMA
-NACC to GSM
* LTE standard supports events A1-A5 & B1, B2
85
© Nokia Siemens Networks
RA41213EN30GLA0
NACC= network assisted cell
change
Measurement Concept (1/2)
•
•
Intra-LTE (Intra-frequency & inter-frequency) measurements
RSRP & RSRQ as event-triggering & reporting quantity
•
Resulting configurable events for reporting to E-UTRAN
–
Event A2/A1: Serving cells RSRP down/upcrossing certain RSRP threshold
–
Event A3: Neighbor cell’s RSRP is a predefined offset better than serving cell’s RSRP
–
Event A5: Serving cell’s RSRP downcrossing certain threshold, while neighbor cell’s RSRP
upcrossing an other threshold
RSRP
RSRP
RSRP
A5 trigger
A3 trigger
A2 trigger
A5 thold
2
A3 offset
A5 thold
1
A2 threshold
RSRP
serving
RSRP
serving
move
directio
n
86
© Nokia Siemens Networks
RA41213EN30GLA0
move
directio
n
RSRP
serving
move
direction
Measurement Concept (2/2)
•
•
•
•
Inter-RAT measurements (GERAN or UMTS supported in RL30)
RSRP or RSRQ as event-triggering & reporting quantity for LTE serving cell
For Inter-RAT reports trigger RSSI is used in case of GERAN and CPICH RSCP
or CPICH EC/N0 in case of UMTS
Event B2: Serving cell`s RSRP downcrossing threshold 1, while neighbor cell
RSSI or CPICH RSCP or CPICH Ec/No upcrossing threshold 2
Signal
Level
B2 trigger
Inter-RAT
Neighbor cell
signal
B2 thold
2
B2 thold
1
RSRP
serving
move
direction
87
© Nokia Siemens Networks
RA41213EN30GLA0
Intra-frequency Measurements Activation/De-activation
•
•
•
UE continuously monitors the serving cell RSRP
eNodeB configures the neighbor measurements using different thresholds
Threshold1 activates (event A2) or de-activates (event A1) the measurements
of the intra-frequency neighbors*
UE does not measure nor
report intra-frequency
neighbor list
RSRP of
serving cell
threshold1
Trigger for intra-frequency
measurements
LNCEL; 0..97dB; 1dB; -
threshold1
threshold1
UE measures intra-frequency
neighbor list and reports A3 or
A5 if respective condition(s) are
met
-140 dBm
88
time
Absolute power level: -140 dBm + threshold1
Example: if threshold 1 = 55dB -> RSRP = -140dBm + 55 dB = -85
dBm
© Nokia Siemens Networks
RA41213EN30GLA0
*Note that in the picture only event A2 is shown
as example. Event A1 when the serving cell could
become better than threshold1 is not shown
Inter-frequency Measurements Activation
•
•
Threshold2 activates the inter-frequency measurements (event A2)
Hysteresys & time to trigger could be set
threshold2InterFreq
Trigger for inter-frequency
measurements
RSRP of
serving cell
LNCEL; 0..97dB; 1dB; -
threshold2InterFreq
Hysteresis
UE measures inter-frequency
neighbors and reports A3 or A5 if
respective condition(s) are met
hysThreshold2InterFreq
-140 dBm
Hysteresis of
Threshold2InterFreq
LNCEL; 0..15dB; 0.5dB; -
89
© Nokia Siemens Networks
RA41213EN30GLA0
a2Time
To
Trigger
a2TimeToTriggerActInter
FreqMeas
Duration for which the event
A2 must be valid
LNCEL; 0ms..5120ms; -; -
Activate
Interfrequency
measuremen
t
time
Inter-frequency & Inter-RAT Measurements Activation
•
•
Similarly there are different RSRP thresholds for the activation of the interfrequency and/or inter-RAT (GERAN or UMTS) measurements
Also different hysteresis and time to trigger could be set
Threshold2:
threshold2InterFreq
threshold2Wcdma
threshold2GERAN
RSRP of
serving cell
threshold2
Hysteresis
UE measures inter-frequency
neighbors (and reports A3 or A5)
and potentially mesures interRAT neighbors (and reports B2)
-140 dBm
Activate Interfrequency or potentially
Inter-RAT measurement
a2Time
To
Trigger
Hysteresys:
Time to Trigger:
hysThreshold2InterFreq
hysThreshold2Wcdma
a2TimeToTriggerActInterFreqMea
s
hysThreshold2GERAN
a2TimeToTriggerActWCDMAMeas
a2TimeToTriggerActGERAN
90
© Nokia Siemens Networks
RA41213EN30GLA0
time
Measurements Activation Example
radio coverage by RSRP improves
Threshold2Wcdma
Intra-frequency
& Interfrequency &
GERAN & UMTS
measurements
Threshold2GERAN
Intra-frequency
& Interfrequency &
GERAN
measurements
RSRP
Threshold2InterFreq Threshold1 (reported)
Intra-frequency
& Interfrequency
measurements
Intrafrequency
measurements
only
No neighbors
measurements
except the
serving cell
Assumptions* for this example:
Threshold2Wcdma < Threshold2GERAN < Threshold2InterFreq< Threshold1
threshold2InterFreq
threshold2GERAN
threshold2Wcdma
Trigger for inter-frequency
measurements
Trigger for GERAN
measurements
Trigger for WCDMA
measurements
LNCEL; 0..97dB; 1dB; -
LNCEL; 0..97dB; 1dB; -
LNCEL; 0..97dB; 1dB; -
* Please note that this is an example only. The priority of the measurements activation could
be set-up by using the appropriate threshold settings
91
© Nokia Siemens Networks
RA41213EN30GLA0
Inter-frequency & Inter-RAT Measurements De-activation
•
Common Threshold2a for the de-activation of inter-frequency and inter-RAT
(GERAN or UMTS) measurements (event A1)
threshold2a
RSRP of
serving cell
Stop inter-frequency
measurements
LNCEL; 0..97dB; 1dB; -
Threshold2a
Hysteresis
a1Time
To
Trigger
De-activate Interfrequency measurement
time
-140 dBm
hysThreshold2a
a1TimeToTriggerDeactInterMeas
Hysteresis of Threshold2a
Duration for which event A1 must be
valid
LNCEL; 0..15dB; 0.5dB; 2dB
LNCEL; 0..5120ms; -; 92
© Nokia Siemens Networks
RA41213EN30GLA0
Better Cell Handover
• Better Cell Handover aims to keep the UE always on best cell
(measured by RSRP)
• Based on 3GPP reporting event „A3“:
▪ Event A3 defines relative offset LNCEL: a3-offset
▪ Timer to Trigger LNCEL: a3-TimeToTrigger
▪ Reporting Interval LNCEL: a3-ReportInterval
RSRP at serving cell + a3Offset < RSRP at neighbor cell
• Better Cell Handover can be enabled / disabled:
enableBetterCellHo
LNCEL; 0 (false), 1
(true); 1 (true)
93
© Nokia Siemens Networks
RA41213EN30GLA0
Handovers Event A3 used for Better Cell HO
RSRP at serving cell + a3Offset < RSRP at neighbor cell
a3Offset
LNCEL; -15..15dB; 0.5dB; -
RSRP
RSRP Neighbour Cell
A3 condition met
a3ReportInterval
LNCEL; 120ms (0), 240ms (1),
480ms (2), 640ms (3), 1024ms
(4), 2048ms (5), 5120ms (6),
10240ms (7), 1min (8), 6min
(9), 12min (10), 30min (11),
60min (12); -
a3offset
Serving Cell RSRP
time
a3TimeToTrigger
LNCEL; 0ms (0), 40ms (1),
64ms (2), 80ms (3), 100ms (4),
128ms (5), 160ms (6), 256ms
(7), 320ms (8), 480ms (9),
512ms (10), 640ms (11),
1024ms (12), 1280ms (13),
2560ms (14), 5120ms (15); -
94
© Nokia Siemens Networks
a3TimeToTrigger
a3Report Interval
Measurement
Report
reporting condition met
after Time To Trigger
RA41213EN30GLA0
Measurement
Report
eNB
Coverage Handover
•
Coverage Handover is used to HO to other eUTRA cell in case:
– serving cell RSRP gets below an abolute threshold and (&&)
– neighbour cell RSRP gets better than an absolute threshold
• Based on 3GPP reporting event „A5“:
▪
3GPP „ThresholdEUTRA“ used to define absolute RSRP level for
a) serving cell: LNCEL: threshold3 and
b) neighbour cell: LNCEL: threshold3a
▪ Timer to Trigger LNCEL: a5-TimeToTrigger
▪ Reporting Interval LNCEL: a5-ReportInterval
•
Better Cell Handover can be enabled / disabled:
enableCovHo
LNCEL; 0 (false), 1
(true); 1 (true)
3GPP event A5 is UE optional; eNB knows from feature group bits
95
© Nokia Siemens Networks
RA41213EN30GLA0
Handovers Event A5
threshold3
LNCEL; 0..97dB; 1dB; Baseline is -140dBm
Coverage
Handover
RSRP at serving cell < threshold3
AND (&&)
RSRP at target > threshold3a
RSRP
threshold3a
LNCEL; 0..97dB; 1dB; Baseline is -140dBm
threshold3a
Serving Cell RSRP
Neighbour Cell RSRP
threshold3
threshold3a
threshold3
a5TimeToTrigger
-140 dBm
96
LNCEL; 0ms (0), 40ms (1),
64ms (2), 80ms (3), 100ms (4),
128ms (5), 160ms (6), 256ms
(7), 320ms (8), 480ms (9),
512ms (10), 640ms (11),
1024ms (12), 1280ms (13),
2560ms (14), 5120ms (15); -
© Nokia Siemens Networks
RA41213EN30GLA0
time
a5TimeToTrigger
a5Report Interval
Measurement
Report
a5ReportInterval
LNCEL; 120ms, 240ms,
480ms, 640ms, 1024ms,
2048ms, 5120sm, 10240ms,
1min, 6min, 12min, 30min,
60min; -
Measurement
Report
eNB
Intra-LTE Handover via S1 (LTE54)
• S1 based handover is only applicable for inter-eNB handover
• LTE inter-eNB handover can be executed without X2 interface usage in
following scenarios:
– no X2 connectivity existing between Source and Target eNB (or blacklisted by
operator)
– MME or S-GW change required when routing via Core Network
• User data traffic and signaling messages are indirectly send via core
nodes (MME and S-GW)
• For UE there is no difference whether HO is executed via X2 or S1
interface
actLTES1Ho
Activate Intra LTE hadover over S1
LNBTS; true(1), false(0); - ; false(0)
prioTopoHO
Define priorities between the 3 topology
options for intra LTE handover
LNBTS; all equal (0), intra eNB HO prior
inter eNB HO (1), intra prior X2 prior S1
(2), low prio S1 (3); all equal (0)
97
© Nokia Siemens Networks
RA41213EN30GLA0
S1
S1
SAE-GW
MME
Inter-frequency HO (LTE 55)
Overview
actIfHo
enables the feature Inter
Frequency Handover
LNBTS; disabled (0),
enabled (1); -; enabled
(1)
• UE needs to support both bands and inter-frequency HO
• Service continuity for LTE deployment in different frequency bands as
well as for LTE deployments within one frequency band but with
different center frequencies
• The UE performs the measurements as configured by eNodeB:
eutraCarrierInfo parameter specifies the inter-frequency band
• The trigger for this procedure is:
– better neighbor cell (frequency) coverage (A3, RSRP)
– better neighbor cell (frequency) quality (A3, RSRQ)
– limited serving cell (frequency) & sufficient neighbor cell (frequency) coverage
(A5)
• Measurement gaps
– if needed then gap pattern 0 is used (6ms gap each 40ms)
eutraCarrierInfo
Mid-frequency of neighboring cell used
in Measurement Configuration
LNHOIF; 0..65535; 1; 98
© Nokia Siemens Networks
RA41213EN30GLA0
A3 event based Handover
• inter-frequency better coverage/quality based (A3) handover event
evaluation
Mn – hysA3OffsetRsr(p/q)InterFreq > Ms + a3OffsetRsr(p/q)InterFreq
hysA3OffsetRsrp/qInterFreq
Hysteresis of HO Margin
LNHOIF; 0..15; 0.5; - dB
Signal
level
(RSRP
or
RSRQ)
hysA3OffsetRsr(p/q)InterFreq
inter-frequency neighbour
cell
(Mn)
measQuantInterFreq
def. which quantity to
use for event A3
LNHOIF; RSRP, RSRQ;
both; RSRP
a3OffsetRsrp/qInterFreq
a3OffsetRsr(p/q)InterFreq
Better cell HO margin for
RSRP/Q
LNHOIF; 0..15; 0.5; - dB
serving cell (Ms)
a3TimeToTriggerRsrp/qInterFreq
LNHOIF; 0..5120ms; -; not used
time
a3TimeToTriggerRsr(p/q)InterFreq
Event A3 condition fullfilled,
UE sends measurement report
Measurement
Report
a3ReportIntervalRsr(p/q)InterFreq
a3ReportIntervalRsrp/qInterFreq
99
© Nokia Siemens Networks
RA41213EN30GLA0
Measurement
Report
LNHOIF; 120ms..60 min; -; not used
A5 event based Handover
• inter-frequency coverage based (A5) handover event evaluation
Ms + hysThreshold3InterFreq < threshold3InterFreq
and
Mn – hysThreshold3InterFreq > threshold3aInterFreq
hysThreshold3InterFreq
Signal
level
Hysteresis of HO Margin
LNHOIF; 0..15; 0.5; - dB
(RSRP)
inter-frequency neighbour
cell
(Mn)
hysThreshold3InterFreq
threshold3aInterFreq
LNHOIF; 0..97; 1; - dB
threshold3InterFreq
LNHOIF; 0..97; 1; - dB
hysThreshold3InterFreq
serving cell (Ms)
time
event A5 condition fullfilled
UE sends measurement report
a5TimeToTriggerInterFreq
a5TimeToTriggerInterFreq
LNHOIF; 0..5120ms; -; 100
© Nokia Siemens Networks
RA41213EN30GLA0
Measurement
Report
Measurement
Report
a5ReportIntervalInterFreq
LNHOIF; 120ms..60 min; -; -
HO to WCDMA (event B2)
measQuantUtraFdd
1. Ms + Hys < Thresh1 &
2. Mn + Ofn – Hys > Thresh2
Signal
level
def. which quantity to use for event B2
LNCEL; cpichRSCP, cpichEcN0;
notUsed; cpichRSCP
condition 2 fulfilled
b2threshold2UtraRscp /EcN0
Event B2 fulfilled
offsetFreqUtra
LNHOW; -5..91/ 0..49 ; 1; - dB
LNHOW; -15..15; 1; 0 dB
condition 1 fulfilled
b2threshold2UtraRscp/EcN0
offsetFreqUtra
hysB2ThresholdUtra
LNHOW; 0..15; 0.5; 2 dB
hysB2ThresholdUtra
S-cell
b2threshold1Utra
hysB2ThresholdUtra
b2threshold1Utra
reportAmount
LNHOW; 0..97; 1; - dB
hysB2ThresholdUtra
LNHOW; 0..15; 0.5; 2 dB
N-cell
time
b2TimeToTriggerUtraMeas
LNHOW; 0..5120ms; -; 101
© Nokia Siemens Networks
RA41213EN30GLA0
reportIntervalUtra
LNHOW; 120ms..60 min; -; S – serving cell LTE
N – neighbor cell WCDMA
NACC to GSM (event B2)
1. Ms + Hys < Thresh1 &
2. Mn – Hys > Thresh2
Signal
level
condition 2 fulfilled
Event B2 fulfilled
condition 1 fulfilled
hysB2ThresholdGERAN
b2threshold2RssiGERAN
LNHOG; 0..15; 0.5; 2 dB
LNHOG; 0..63; 1; - dB
hysB2ThresholdUtra
b2threshold2RssiGERAN
S-cell
b2threshold1GERAN
hysB2ThresholdGERAN
b2threshold1GERAN
reportAmount
LNHOG; 0..97; 1; - dB
hysB2ThresholdGERAN
LNHOG; 0..15; 0.5; 2dB
N-cell
time
b2TimeToTriggerGERANMeas
LNHOG; 0..5120ms; -; 102
© Nokia Siemens Networks
RA41213EN30GLA0
reportIntervalGERAN
LNHOG; 120ms..60 min; -; S – serving cell LTE
N – neighbor cell GSM
RRC connection release with redirect
• In case serving cell coverage by RSRP is on lower end of
scale, eNB can redirect the call to other frequency layer or
other RAT – this is no handover !
• 3GPP event A2 is used to define an absolute threshold
▪ LNCEL: threshold4 (3GPP: ThresholdUTRA)
▪ Risk of loosing the signaling connection with UE due to bad
coverage
• Once UE sends event triggered measurement report A2
eNB sends RRC:rrcConnectionRelease with target RAT
information to UE
103
© Nokia Siemens Networks
RA41213EN30GLA0
RRC connection release with redirect
LNCEL: threshold4 defines the absolute RSRP level of serving
cell for eNB to trigger RRC connection release with redirection.
RSRP
Serving Cell RSRP
A2 condition met
reporting condition met
after Time To Trigger
threshold4
threshold4
threshold4
LNCEL; 0..97dB; 1dB; Baseline is -140dBm
-140 dBm
a2TimeToTriggerRedirect
a2TimeToTriggerRedirect
LNCEL; 0ms (0), 40ms (1), 64ms (2),
80ms (3), 100ms (4), 128ms (5), 160ms
(6), 256ms (7), 320ms (8), 480ms (9),
512ms (10), 640ms (11), 1024ms (12),
1280ms (13), 2560ms (14), 5120ms (15);
;
104
© Nokia Siemens Networks
RA41213EN30GLA0
time
Measurement
Report
-
Module Contents
• Random Access
• Radio Bearer Control
• Radio Admission Control
• UL/DL Power control
• MIMO Mode Control
• Mobility Management
• UL/DL Scheduler
105
© Nokia Siemens Networks
RA41213EN30GLA0
DL Scheduler
• One downlink scheduler per cell,
•
•
•
•
106
separate schedulers for downlink and
uplink
Distributed transmission (with PDCCH
format 1C) used for common channels
Distributed transmission (with PDCCH
format 1A) used for Random Access
Message 4
Localised transmission (PDCCH format
1/2/2A) used for data and signalling
bearers
For DL Resource Allocation following
Allocation Types are implemented:
• Allocation Type 0 and 2
© Nokia Siemens Networks
RA41213EN30GLA0
DCI
Format
Meaning
DL Resource
Allocation
0
Scheduling of PUSCH
N/A
1
Scheduling of one PDSCH
codeword
Type 0 or 1
1A
Compact scheduling of one
PDSCH codeword or RA
procedure initiated by PDCCH
Type 2
1B
Compact scheduling of one
PDSCH codeword with precoding
information
Type 2
1C
Very compact scheduling of one
PDSCH codeword. Used for
Common Channels.
Type 2 (but
only distributed
VRBs)
1D
Compact scheduling of one
PDSCH codeword with precoding
and power offset information
Type 2
2
Scheduling PDSCH to UEs
configured in closed-loop spatial
multiplexing mode
Type 0 or 1
2A
Scheduling PDSCH to UEs
configured in open loop spatial
multiplexing mode
Type 0 or 1
3 and 3A
Transmission of TPC commands
N/A
Downlink Scheduling:
Start
Step 1: Scheduling of common channels
(SIBs, Paging and Random Access) to
PDSCH using Virtual Resource Blocks with
distributed transmission
Step 2: Evaluation of resources available for
dynamic allocation on PDSCH
1. Reserve PRB groups (RBGs) needed for
common physical channels
2. Reserve PRB groups (RBGs) needed for
PBCH and Syncronisation signals
Step 3: Evaluating which users can be
scheduled:
1. UE has data buffered in the eNodeB?
2. UE has valid CQI available?
3. Is UE in inactive DRX/DTX mode?
4. Is UE in measurement Gap?
Determine candidate set 1 CS1 of UEs
Step 4: Time domain scheduling:
Calculates the time domain Scheduling
metric and select X best users for frequency
domain scheduling. Determine candidate set
2 CS2 of UEs
The scheduling metric is given by
parameters for certain traffic types, like SRB,
data HARQ retransmission
Step 5: Frequency domain scheduling:
Allocate the selected X users to PRBs/RBGs
UEs will be scheduled to PRBs where they
experience the best channel quality
Step 6: Priority handling between logical
channels of one UE
Allocate the resources to the radio bearers
Step 7: Allocated PDCCHs to CCEs
Combined step for Downlink and Uplink after
both scheduling decisions available for the
TTI
End
107
© Nokia Siemens Networks
RA41213EN30GLA0
STEP 1
Step 1
Scheduling of common channel data:
• Evaluate the amount of physical resources for transmission of BCCH
SIBs, Paging and Random Access data
• Physical resources are scheduled from DL Packet Scheduler together with
user plane data from cell users
• Parameter LNCEL: dlsUsePartPrb parameter specifies whether dynamic
scheduling with localized transmission is used for:
– physical resource blocks to transmit synchronization signals(PSS & SSS)
– physical resource blocks to transmit synchronization signals and PBCH
dlsUsePartPrb
LNCEL; not used (0), PRBs with PSS or
SSS used (1), PRBs with PSS or SSS
and PBCH used (2); PRBs with PSS or
SSS and PBCH used (2)
108
© Nokia Siemens Networks
RA41213EN30GLA0
STEP 2
Step 2: Resource Evaluation in DL
• Main input to calculate the required resources for common channel transmission are
parameters to control coding overhead for common channel transmission
maxCrSibDL
• System Information BCCH
LNCEL: maxCrSibDl
Max. Code rate for BCCH
LNCEL; 0.05…0.5; 0.01; 0.26
• Paging
LNCEL: maxCrPgDl
maxCrPgDL
• Random Access message 2
LNCEL: maxCrRaDl
Max. Code rate for Paging
LNCEL; 0.05…0.5; 0.01; 0.12
• Random Access message 4
maxCrRaDL
maxCrRa4DL
Max. Code rate for random
access mesage 2 – RA response
Max. Code rate for random access
mesage 4 – SRB0 message
LNCEL; 0.05…0.5; 0.01; 0.12
109
LNCEL: maxCrRa4Dl
© Nokia Siemens Networks
RA41213EN30GLA0
LNCEL; 0.05…0.5; 0.01; 0.39
STEP 3
Step 3: Pre-scheduling
dlamcEnable
• UE can be candidate for downlink scheduling:
– If CQI values are available and up-to-date
Enable Adaptive Modulation
and Coding in DL
LNCEL; true, false ; true
dlamcCqiDef
Default CQI used when no
updated CQI available
LNCEL; 0..15; 1; 2
– If default CQI is used – O&M Parameter LNCEL: dlamcCqiDef
– Whenever no up-to-date CQI values are available on per-TTI basis, it shall
be possible to use the latest available CQI for a configurable period of time
as determined by parameter: dlamcThistCqi dlamcThistCqi
Time in TTIs for which historical
CQI is remembered in Adaptive
Modulation and Coding
LNBTS; 0..1000TTI; 1 TTI; 10 TTI
Vendor-specific parameter
– If available CQI is older than: dlamcThistCqi: default CQI value used
•NSN’s DL scheduler implementation is based on the UE radio channel quality
feedback (CQI)
• The availability of valid CQI values ensures reliable channel quality estimates,
and
thus optimum scheduling for the relevant UE.
110
© Nokia Siemens Networks
RA41213EN30GLA0
Downlink Scheduling:
Start
Step 1: Scheduling of common channels
(SIBs, Paging and Random Access) to
PDSCH using Virtual Resource Blocks with
distributed transmission
Step 2: Evaluation of resources available for
dynamic allocation on PDSCH
1. Reserve PRB groups (RBGs) needed for
common physical channels
2. Reserve PRB groups (RBGs) needed for
PBCH and Syncronisation signals
Step 3: Evaluating which users can be
scheduled:
1. UE has data buffered in the eNodeB?
2. UE has valid CQI available?
3. Is UE in inactive DRX/DTX mode?
4. Is UE in measurement Gap?
Determine candidate set 1 CS1 of UEs
Step 4: Time domain scheduling:
Calculates the time domain Scheduling
metric and select X best users for frequency
domain scheduling. Determine candidate set
2 CS2 of UEs
The scheduling metric is given by
parameters for certain traffic types, like SRB,
data HARQ retransmission
Step 5: Frequency domain scheduling:
Allocate the selected X users to PRBs/RBGs
UEs will be scheduled to PRBs where they
experience the best channel quality
Step 6: Priority handling between logical
channels of one UE
Allocate the resources to the radio bearers
Step 7: Allocated PDCCHs to CCEs
Combined step for Downlink and Uplink after
both scheduling decisions available for the
TTI
End
111
© Nokia Siemens Networks
RA41213EN30GLA0
Step 4: DL Time Domain Scheduling
STEP 4
• Target: determine which UEs shall be scheduled
• For all candidate UEs a TD scheduling metric is calculated
• priority per UE i:
Ci (t) C1,i (t) C2,i (t)
• Service term C1,i(t)
– Static value depending on the service scheduled for the UE
– Target: cluster UEs according to services and prioritize services against each other
buffer status report indicates DL SRB data available for transmission for UE i
prioDL (SRB)
C1_ DL ,i (t ) prioDL (HARQ) UE has pending HARQ retransmis sion forUE i
otherwise
0
• Throughput term C2,i(t)
– Dynamic value depending on the time domain scheduling metric
– Primary entity for QoS differentiation
– Depends on the activated features (See next slides)
• final result: Candidate Set 2 = a number of UEs (maxNumUe) of CS1
with highest Ci(t)
CS1= candidate set 1 from step 3
112
© Nokia Siemens Networks
RA41213EN30GLA0
Throughput term C2,i(t) (1/7)
STEP 4
Case 1: assume pure RL10 conditions
C2,i (t) C2,i,j (t)
j0
C2,i,j (t)
113
PEAK _ BIT _ RATE _ DL
for Ri , j (t ) MinBitrate Dl
Ri , j (t )
r (t )
PFi , j (t ) i
for Ri , j (t ) MinBitrate Dl
Ri , j (t )
Term
Explanation
i
Index of considered UE
j
One DRB of UEi (in RL10 only 1 DRB per UE so j = 1)
t
The considered TTI
PEAK_BIT_RATE_DL
Maximum theoretical DL cell throughput
Ri,j (t)
Mean throughput rate of DRBj of UEi (see next slide)
PFi, j (t)
Proportional fair term
ri (t)
Estimated immediate (wideband) throughput of UEi in TTI t
© Nokia Siemens Networks
RA41213EN30GLA0
DRB = data radio bearer
minBitrateDl
LNCEL; 5..300000
kbps; 5kbps; 30Kbps
STEP 4
Throughput term C2,i(t) (3/7)
Simple example*: assume 4 stationary UEs, in different radio conditions
(SINR)
2x2 DL Adaptive Open Loop MIMO is activated
The carrier frequency is 2,6GHz and the system bandwidth is 20 MHz
All 4 UEs are category 3
What will be the scheduling order?
UEs
Mean
Throughput
[Mbps]
Estimated
Immediate
Throughput
[Mbps]
Proportional
Fair Term PF
SINR [dB]
Radio
Condition
UE1
95
100
1,05
> 25
Excellent
UE2
65
80
1,23
15<x<25
Good
UE3
55
60
1,09
5<x<15
Average
UE4
25
26
1,04
0<x<5
Poor
Solution: since all the UEs have the average throughput above the minimum
bit rate then the proportional fair scheduler criterion is applied
The scheduler priority is based on the proportional fair term PF
The scheduling order is: UE2, UE3, UE1 and UE4
* Please note that the real mean throughput as well as the estimated immediate throughput may be
different
114
© Nokia Siemens Networks
RA41213EN30GLA0
STEP 4
Throughput term C2,i(t) (4/7)
Case 2: when LTE7: Support of Multiple EPS Bearers and LTE9: Service
Differentiation functionalities are activated:
PEAK _ BIT _ RATE _ DL
Ri , j (t )
PFi , j (t ) WQCI ,i , j
C2,i,j (t)
ji
for Ri , j (t ) MinBitrate Dl
for Ri , j (t ) MinBitrate Dl
The throughput termC2,i,j (t) is updated:
→ Consider up to 4 non-GBR data radio bearers per UE (j = 1..4)
WQCI, i, j associated with each
→ Consider the QCI specific relative scheduling weights
non-GBR bearer for QCI = 5,6,7,8 and 9.
→ The scheduler uses the weight values as corresponding to the QCI of a data radio
bearer (logical channel) under consideration
schedulWeight
Parameter Name
Defaults
QCI5
Defaults
QCI6
Defaults
QCI7
Defaults
QCI8
Defaults
QCI9
Should be defined for each QCI
separatelly. It is part of qciTab
parameter (see chapter 5)
QCI
5
6
7
8
9
LNBTS; 1..100; 1;
Scheduling Weight
40
20
10
5
1
Default – see the table
115
© Nokia Siemens Networks
RA41213EN30GLA0
STEP 4
Throughput term C2,i(t) 5/7)
Simple example*: assume 4 stationary UEs, in different radio conditions
(SINR)
2x2 DL Adaptive Open Loop MIMO is activated
The carrier frequency is 2,6GHz and the system bandwidth is 20 MHz
All 4 UEs are category 3 UEs
Consider also the scheduling weights (since RL20)
What will be the scheduling order?
UEs
Mean
Throughput
[Mbps]
Estimated
immediate
throughput
[Mbps]
Proportional
Fair Term PF
SINR
[dB]
Radio
Condition
QCI
Scheduling
Weight
PF Term *
Scheduling
Weight
UE1
95
100
1,05
> 25
Excellent
8
5
5,25
UE2
65
80
1,23
15<x<25
Good
7
10
12,30
UE3
55
60
1,09
5<x<15
Average
7
10
10,90
UE4
25
26
1,04
0<x<5
Poor
6
20
20,80
Solution: since all the UEs have the average throughput above the minimum bit rate
then the proportional fair scheduler criterion is applied
The scheduler priority is based on the proportional fair term PF and the scheduling
weight
The scheduling order is: UE4, UE2, UE3 and UE1
* Please note that the real mean throughput as well as the estimated immediate throughput may be different
116
© Nokia Siemens Networks
RA41213EN30GLA0
STEP 4
Throughput term C2,i(t) (6/7)
Case3: when LTE10: EPS bearers for conversational voice functionality is activated
then the delay based scheduling is supported
• Delay based scheduling: control the delay target rather then the throughput of the
data radio bearers with VoIP (QCI1)
• The minimum bit rate differentiation is no longer supported
C2,i,j (t) PFi , j (t ).Wi , j (t )
*The Head of Line HOL is the oldest
packet that has arrived in the
transmission buffer. HOL is known in
DL by the scheduler
ji
Wi , j (t ) DTj (t )
• Delay weight DTj(t) for GBR bearers is calculated using a look-up table (delay weight
versus Head of Line HOL* delay)
• UEs with QCI1 should be prioritized in scheduling such that the data is not
experiencing more delay than it is specified by the delay target
•Delay target: maximum allowed end-to-end delay that a delay sensitive service can
tolerate without causing an unacceptable service quality degradation experienced by
the subscriber
delayTarget
QCI
1
117
Resource
Type
RLC
Mode
Delay
Target
GBR
RLC_UM
80 ms
© Nokia Siemens Networks
Scheduling Scheduling
Priority
Weight
5
RA41213EN30GLA0
n/a
Maximum packet delay value
considered by the scheduling. It is
part of qciTab1 parameter (see
chapter 5). Only for QCI1
LNBTS; 50ms (0), 60ms (1), 70ms (2),
80ms (3), 90ms (4), 100ms (5);80ms(3)
STEP 4
Throughput term C2,i(t) (7/7)
Delay based scheduling does not explicitly control the probability of packets being
received correctly within a given delay target
actDlsOldtc
→ Outer Loop Delay Target (OLDTC) is defined for this
Switch to activate/deactivate
OLDTC
LNCEL;false (0), true (1); true(1)
OLDTC measures an actual scheduling delay of voice bearers in DL and compares it
with the delay target:
Measured delay > delayTarget → UE priority is increased
Measured delay < delayTarget → UE priority is decreased
Parameter dlsOldtcTarget defines the probability of a packet to exceed the
delayTarget
delayTarget
dlsOldtcTarget
Target value for OLDTC
LNCEL;0.9…0.99;0.01; 0.98
Maximum packet delay value
considered by the scheduling. It is part
of qciTab1 parameter (see chapter 5).
Only for QCI1
LNBTS; 50ms (0), 60ms (1), 70ms (2),
80ms (3), 90ms (4), 100ms (5);80ms(3)
118
© Nokia Siemens Networks
RA41213EN30GLA0
STEP 4
Step 4: DL TD scheduling
• Final result: Candidate Set 2 = a number of UEs (maxNumUeDl) of
CS1 with highest Ci(t)
• After calculation of time-domain metric for all UEs candidates for
scheduling all UEs are listed in decreasing order
• Operator configurable parameter LNCEL: maxNumUeDl can limit
maximum number of UEs for frequency domain scheduling
Time Domain Metric Calculation
maxNumUeDl
maxNumUeDl
Depending on dlChBw the
values are limited as follows:
5.0 MHz => 1...7 (default 7)
10.0 MHz => 1...10 (default 10)
15.0 MHz => 1..15 (default 12)
20.0 MHz => 1...16 (default 12)
119
© Nokia Siemens Networks
RA41213EN30GLA0
1
2
3
4
5
6
7
8
UE 7
UE 4
UE 5
UE 1
UE 6
UE 2
UE 3
UE 8
Max. Simultaneous UEs
in DL per TTI
LNCEL; 1...16; 1; 7
maxNumUeDl
(default = 7)
Downlink Scheduling:
Start
Step 1: Scheduling of common channels
(SIBs, Paging and Random Access) to
PDSCH using Virtual Resource Blocks with
distributed transmission
Step 2: Evaluation of resources available for
dynamic allocation on PDSCH
1. Reserve PRB groups (RBGs) needed for
common physical channels
2. Reserve PRB groups (RBGs) needed for
PBCH and Syncronisation signals
Step 3: Evaluating which users can be
scheduled:
1. UE has data buffered in the eNodeB?
2. UE has valid CQI available?
3. Is UE in inactive DRX/DTX mode?
4. Is UE in measurement Gap?
Determine candidate set 1 CS1 of UEs
Step 4: Time domain scheduling:
Calculates the time domain Scheduling
metric and select X best users for frequency
domain scheduling. Determine candidate set
2 CS2 of UEs
The scheduling metric is given by
parameters for certain traffic types, like SRB,
data HARQ retransmission
Step 5: Frequency domain scheduling:
Allocate the selected X users to PRBs/RBGs
UEs will be scheduled to PRBs where they
experience the best channel quality
Step 6: Priority handling between logical
channels of one UE
Allocate the resources to the radio bearers
Step 7: Allocated PDCCHs to CCEs
Combined step for Downlink and Uplink after
both scheduling decisions available for the
TTI
End
120
© Nokia Siemens Networks
RA41213EN30GLA0
Downlink Frequency Domain Scheduler (1/2)
STEP 5
• Allocates PRBs in Resource Block Groups RBGs (1-4 PRBs depending on the
bandwidth, 3 for 10MHz for example)
• Criterion for the DL allocation of the RBG: the channel quality is evaluated for
all UEs for all RBGs
• Serve each UE where it has good CQI → but serve all UEs not only the best
• How to determine the next RBG and UE? → according to the maximum value:
falloc,i, f max CTTI ,i , f (t )
i, f
Where:
dlsFdAlg
Select the frequency domain
scheduling algorithm
LNCEL; TTA(0); PFsch(1);
PFsch(1)
i is the index of the UE
f is one RBG to be allocated (total number depends on the bandwidth)
t is the current TTI
CTTI,i,f(t) depends on the allocation algorithm:
• Two algorithms in RL20: TTA (Throughput-to-Average) and
PFsch (Proportional Fair Scheduled)
(see next slides)
RBG = Resource Block
Group
121
© Nokia Siemens Networks
RA41213EN30GLA0
Downlink Frequency Domain Scheduler (2/2)
STEP 5
•TTA (Throughput-to-Average) scheduler:
CTTI,i, f (t )
Ri ( f , t )
Ri ( f , t )
Ri (t )
Ri (t )
Estimated throughput of the UE i on the RBG f at
TTI t
Estimated throughput of UE i for all free resource
block groups at TTI t
dlsFdAlg
•PFsch (Proportional Fair Scheduled) scheduler:
R ( f , t)
CTTI,i,f (t ) FDWeight i (t ). i
RschDL,i (t )
Ri ( f , t )
RschDL,i (t )
FDWeight i (t )
122
© Nokia Siemens Networks
Select the frequency domain
scheduling algorithm
LNCEL; TTA(0); PFsch(1);
PFsch(1)
Estimated throughput of the UE i on the RBG f at
TTI t
Past average throughput over the TTIs where the
UE i is selected by the time domain scheduling
Scheduling weights – similar to time domain
scheduling (to be applied only in case when the
service differentiation is activated)
RA41213EN30GLA0
Downlink Scheduling:
Start
Step 1: Scheduling of common channels
(SIBs, Paging and Random Access) to
PDSCH using Virtual Resource Blocks with
distributed transmission
Step 2: Evaluation of resources available for
dynamic allocation on PDSCH
1. Reserve PRB groups (RBGs) needed for
common physical channels
2. Reserve PRB groups (RBGs) needed for
PBCH and Syncronisation signals
Step 3: Evaluating which users can be
scheduled:
1. UE has data buffered in the eNodeB?
2. UE has valid CQI available?
3. Is UE in inactive DRX/DTX mode?
4. Is UE in measurement Gap?
Determine candidate set 1 CS1 of UEs
Step 4: Time domain scheduling:
Calculates the time domain Scheduling
metric and select X best users for frequency
domain scheduling. Determine candidate set
2 CS2 of UEs
The scheduling metric is given by
parameters for certain traffic types, like SRB,
data HARQ retransmission
Step 5: Frequency domain scheduling:
Allocate the selected X users to PRBs/RBGs
UEs will be scheduled to PRBs where they
experience the best channel quality
Step 6: Priority handling between logical
channels of one UE
Allocate the resources to the radio bearers
Step 7: Allocated PDCCHs to CCEs
Combined step for Downlink and Uplink after
both scheduling decisions available for the
TTI
End
123
© Nokia Siemens Networks
RA41213EN30GLA0
DL MAC Multiplexing of Logical Channels
Step 1:
Parameter Name
• Allocate resources to the GBR bearers based on
QCI
scheduling priority parameter
Resource Type
Scheduling Priority
• In RL30 only one GBR – QCI1 for VoIP is supported
Scheduling Type
• All the data in the buffer for the VoIP bearer is transmitted
(unless the resources for the UE are exhausted)
STEP 6
Defaults
QCI1
1
0(GBR)
5
n/a
Scheduling Weight
n/a
DelayTarget
80ms
schedulPrio
Logical channel priority for the
MAC scheduler. Here for QCI1
LNBTS; 2..16; 1; 5
Step2:
• Allocate the remaining resources to non-GBR bearers
• Allocation is based on the Weighted Round Robin algorithm
• Scheduling Weight parameter is used to prioritize between different bearers
schedulWeight
Parameter Name
Defaults
QCI6
Defaults
QCI7
Defaults
QCI8
Defaults
QCI9
QCI
6
7
8
9
Should be defined for each QCI
separatelly. It is part of qciTab
parameter
Resource Type
1(NonGBR)
1(NonGBR)
1(NonGBR)
1(NonGBR)
LNBTS; 1..100; 1;
Scheduling Weight
20
10
5
1
124
© Nokia Siemens Networks
RA41213EN30GLA0
Default – see the table
Uplink Scheduler:
Start
Step 1: Evaluate the available physical
resources for PUSCH
PRBs used for PUCCH and PRACH are not
used for PUSCH
Step 2: Reserve resources needed for
Random Access message 3
Random Access messages 3 are allocated
when PRACH preambles are reserved and
this step is needed to disable those already
allocated resources from dynamic
scheduling
Step 3: Evaluating which users can be
scheduled:
UE has data buffered / pending HARQ
retrans / has send scheduling request?
UE has UL channel synchronised?
Is UE in inactive DRX/DTX mode?
Is UE in measurement Gap?
Determine candidate set CS1 of UEs
Step 4: Time domain scheduling:
Calculates Scheduling metric and select X
best users for frequency domain scheduling
The scheduling metric is given by
parameters for certain traffic types, like SRB
data, HARQ retransmission and Scheduling
Request
Determine candidate set CS2 of UEs
Step 5: Frequency domain scheduling:
Allocate the selected X users to PRBs
UEs will be scheduled randomly on PRBs
End
125
© Nokia Siemens Networks
RA41213EN30GLA0
UL Time Domain Scheduling
• priority per UE i:
C_UL, i(t) C1_UL, i(t) C2_UL, i, j(t)
j 0
STEP 4
maxNumUeUl
5.0 MHz => 1...7 (7)
10.0 MHz => 1...10 (10)
15.0 MHz => 1…15 (12)
20.0 MHz => 1...16 (12)
• service term C1,i(t)
LNCEL; 1...16; 1; 7
– static value depending on the service scheduled for the UE
– target: cluster UEs according to services and prioritise services against each other
n x prioUL (HARQ)
prioUL (SR)
C1_UL, i(t)
prioUL (SRB)
0
if HARQ retranmission needs to be performedfor UEi
n representsthe number of retransm.occured for theHARQ proc.of UEi
if Scheduling Request is in candidate set 1
if buffer status report indicates that SRB data are available
in transmission buffer of UEi
otherwise
minBitrateUl
• throughput term C2,i(t)
– Similar to DL
– Example with service differentiation:
C2_UL,i,j (t)
PEAK _ BIT _ RATE _ UL
Ri , j (t )
PFi , j (t ) . WQCI , j (t )
ji
LNCEL; 5..75000;
5kbps; 30Kbps
for Ri , j (t ) MinBitrate Ul
for Ri , j (t ) MinBitrate Ul
• final result: Candidate Set 2 for FD scheduling = a number of UEs (maxNumUeUl) of CS1
with highest Ci(t)
126
© Nokia Siemens Networks
RA41213EN30GLA0
Uplink Frequency Domain Scheduler (1/2)
STEP 5
• Fast ATB (Adaptive Transmission Bandwidth) assigns the PRBs to the UEs
(fast ATB means every TTI, slow ATB presented later on)
•Fast ATB has following steps:
•Step 1: Evaluate the available PRBs to be allocated to the dynamic UEs:
(static UEs are UEs with HARQ retransmission or RAP for which constant #PRB
are allocated – not considered by ATB)
PRBschedule PRBmax PRBPUCCH PRBPRACH PRBHARQ PRBRAP
PRBschedule
# of PRBs available for scheduling
PRBmax
Total PRBs available in the bandwidth (e.g. 50 for 10MHz)
PRBPUCCH
# of PRBs allocated for PUCCH
PRBPRACH
# of PRBs allocated for PRACH
PRBHARQ
# of PRBs allocated for static scheduling (HARQ retransmission)
PRBRAP
# of PRBs allocated for static UEs with Random Access message 3
*PRB = Physical Resource Block
RAP = Random Access Procedure
127
© Nokia Siemens Networks
RA41213EN30GLA0
Uplink Frequency Domain Scheduler (2/2)
STEP 5
•Step 2: Allocate PRBschedule to dynamic UEs → 2 Algorithms possible in RL20:
•Round Robin Scheduler
•The scheduler assigns PRBs to the UEs selected by time domain scheduler
•Start with the entry of the highest priority
•Walk through the UE list in round robin manner – it is fair since all the UEs from time
domain will get resources
•Disadvantage: since many UEs are potentially scheduled then PDCCH shortage may
occur
ulsFdPrbAssignAlg
• Weighted Round Robin possible
Scheduler type for frequency domain UL
(based on QCI differentiation)
LNCEL;RoundRobinFD(0), ExhaustiveFD
(1); ExhaustiveFD(1)
•Exhaustive FD Scheduler
•UL resources are assigned in frequency domain according to the priority order
defined by the time domain scheduler
•The first UE in the list gets as many resources as it can use – it is unfair since
probably not all the UEs from time domain will get resources
•Less blocking on PDCCH
•Recommended with VoIP
128
© Nokia Siemens Networks
RA41213EN30GLA0
UL Scheduler: Latency Improvement (1/3)
•This feature allows for a faster allocation of UL resources for a UE who no
longer has data in the buffer to send and has no on going Scheduling
Request
•The latency improvement feature can be enabled/disabled by the parameter
ilReactionTimerUL.
•When a UE has reported no more data in the buffer and there are available
PRB’s, the UL scheduler will schedule dummy grants for these UE ‘s
•This way the UE’s are given a chance to transmit in the UL if they suddenly
have data in the buffer during a period of time ilReactionTimerUL
ilReactionTimerUl
LNCEL; 0…2000ms; 100ms;
1500 ms
Parameter is vendor specific
(not modifiable)
129
© Nokia Siemens Networks
RA41213EN30GLA0
UL Scheduler: Latency Improvement (2/3)
•The UEs which may be potentially taken into account for the improved
latency feature shall be those that:
–
–
–
–
–
–
–
–
have no pending Random Access Procedure
be synchronised in UL
not be in DRX/DTX active mode
have no HARQ retransmission
not be interrupted by a measurement gap
have no ongoing Scheduling Request
have no data in the transmission buffer (SRB and DRB)
but sent data on a dummy grant during the configurable period of time
(ilReactionTimerUL).
ilReactionTimerUl
LNCEL; 0…2000ms; 100ms;
1500 ms
Parameter is vendor specific
(not modifiable)
130
© Nokia Siemens Networks
RA41213EN30GLA0
UL Scheduler: Latency Improvement (3/3)
•The UEs have to utilize the dummy grants for the transmission of data
packets during a specifiable period of time
•When the UE doesn’t utilize the dummy grant during the specified period of
time the UE won’t be longer taken into account for the assignment
•When scheduling resources for these UE’s the channel unaware scheduler
shall take into account for each UE the predefined data volume required
specified by the parameter ilMinDatVolUL
ilMinDatVolUl
LNCEL; 0…4000bits; 80 bits;
560 bits
Parameter is vendor specific
(not modifiable)
•Deduced from the volume the number of required PRBs shall be calculated
by means of the UE-specific MCS which is provided by the LA and the
outcome of the calculation shall be sent with a so-called ‘dummy grant’ to the
UE.
131
© Nokia Siemens Networks
RA41213EN30GLA0
UL Scheduler: Interference aware UL scheduling
• Improved uplink cell edge performance in low loaded networks.
• eNodeB measures the interference plus noise power distribution over the PUSCH spectrum
• eNodeB evaluates the TX power density measurements of the UEs.
• UEs which have high TX power density are assigned to the PUSCH scheduling area which is
less affected by interference and noise.
• Arranges the PUSCH PRB allocation of the UEs in the frequency domain so that the resource
allocation or rather the interference to the adjacent cells is optimized.
ulsSchedMethod
LNCEL;
eNode B
measured
interference
PRBs
subband with high
interference
channel unaware (0),
interference aware (2)
subband with low
interference
subband with medium
interference
132
© Nokia Siemens Networks
RA41213EN30GLA0
