An Introduction of
3GPP Long Term Evolution
(LTE)
Outline





History of 3GPP LTE
Basic Concepts of LTE
Introduction of LTE Protocol
Compare with LTE and LTE-Advanced
Conclusion
2
What is LTE ?
 In Nov. 2004, 3GPP (3rd Generation Partnership
Project) began a project to define the Long-Term
Evolution (LTE) of Universal Mobile
Telecommunications System (UMTS) cellular
technology
 Higher performance
 Backwards compatible
 Wide applications
3
History of LTE
 LTE is a standard for wireless data communications
technology and an evolution of the GSM/UMTS standards.
 The goal of LTE was to increase the capacity and speed of
wireless data networks using new DSP (digital signal
processing) techniques and modulations.
 A further goal was the redesign and simplification of the
network architecture to an IP-based system with
significantly reduced transfer latency compared to the 3G
architecture.
 The LTE wireless interface is incompatible with 2G and 3G
networks, so that it must be operated on a separate wireless
spectrum.
4
History of LTE(Cont’d)
 LTE was first proposed by NTT DoCoMo of Japan
in 2004, and studies on the new standard officially
commenced in 2005.
 The LTE standard was finalized in December 2008,
and the first publicly available LTE service was
launched by TeliaSonera in Oslo and Stockholm on
December 14, 2009 as a data connection with a
USB modem.
 Samsung Galaxy Indulge being the world’s first
LTE smartphone starting on February 10, 2011.
5
History of LTE(Cont’d)
 Initially, CDMA operators planned to upgrade to
rival standards called UMB and WiMAX
 But all the major CDMA operators (such as
Verizon, Sprint and MetroPCS in the United
States, Bell and Telus in Canada, au by KDDI in
Japan, SK Telecom in South Korea and China
Telecom/China Unicom in China) have announced
that they intend to migrate to LTE after all.
 The evolution of LTE is LTE Advanced, which was
standardized in March 2011. Services are expected
to commence in 2013.
6
Evolution of Radio Access
Technologies
802.16m
802.16d/e


LTE (3.9G) :
3GPP release 8~9
LTE-Advanced :
3GPP release 10+
7
LTE Basic Concepts



LTE employs Orthogonal Frequency Division
Multiple Access (OFDMA) for downlink data
transmission and Single Carrier FDMA (SCFDMA) for uplink transmission
SC-FDMA is a new single carrier multiple access
technique which has similar structure and
performance to OFDMA
A salient advantage of SC-FDMA over OFDM is
the low Peak to Average Power (PAP) ratio :
Increasing battery life
8
LTE Uplink (SC-FDMA)
9
Multi-Antenna Techniques
10
Generic Frame Structure

Allocation of physical resource blocks (PRBs) is
handled by a scheduling function at the 3GPP base
station: Evolved Node B (eNodeB)
Frame 0 and frame 5 (always downlink)
11
Generic Frame Structure (Cont’d)



DwPTS field: This is the downlink part of the
special subframe and its length can be varied from
three up to twelve OFDM symbols.
The UpPTS field: This is the uplink part of the
special subframe and has a short duration with one
or two OFDM symbols.
The GP field: The remaining symbols in the special
subframe that have not been allocated to DwPTS
or UpPTS are allocated to the GP field, which is
used to provide the guard period for the downlinkto-uplink and the uplink-to-downlink switch.
12
Resource Blocks for OFDMA



One frame is 10 ms consisting of 10 subframes
One subframe is 1ms with 2 slots
One slot contains N Resource Blocks (6 < N < 110)


One Resource Block contains M subcarriers for
each OFDM symbol


The number of downlink resource blocks depends on the
transmission bandwidth.
The number of subcarriers in each resource block
depends on the subcarrier spacing Δf
The number of OFDM symbols in each block
depends on both the CP length and the subcarrier
spacing.
13
14
LTE Spectrum (Bandwidth and
Duplex) Flexibility
15
LTE Downlink Channels




The LTE radio interface, various "channels" are
used. These are used to segregate the different
types of data and allow them to be transported
across the radio access network in an orderly
fashion.
Physical channels: These are transmission channels
that carry user data and control messages.
Transport channels: The physical layer transport
channels offer information transfer to Medium
Access Control (MAC) and higher layers.
Logical channels: Provide services for the Medium
Access Control (MAC) layer within the LTE
protocol structure.
16
LTE Downlink Channels
Paging Control Channel
Paging Channel
Physical Downlink Shared Channel
17
LTE Downlink Logical Channels
18
LTE Downlink Logical Channels
19
LTE Downlink Transport Channel
20
LTE Downlink Transport Channel
21
LTE Downlink Physical Channels
22
LTE Downlink Physical Channels
23
LTE Uplink Channels
Random Access Channel
CQI report
Physical Uplink Shared Channel
Physical Radio Access Channel
24
LTE Uplink Logical Channels
25
LTE Uplink Transport Channel
26
LTE Uplink Physical Channels
27
LTE Release 8 Key Features (1/2)



High spectral efficiency
 OFDM in Downlink
 Single‐Carrier FDMA in Uplink
Very low latency
 Short setup time & Short transfer delay
 Short hand over latency and interruption time
Support of variable bandwidth
 1.4, 3, 5, 10, 15 and 20 MHz
28
LTE Release 8 Key Features (2/2)



Compatibility and interworking with earlier
3GPP
FDD and TDD within a single radio access
technology
Efficient Multicast/Broadcast
29
Evolution of LTE-Advanced





Asymmetric transmission bandwidth
Layered OFDMA
Advanced Multi-cell Transmission/Reception
Techniques
Enhanced Multi-antenna Transmission Techniques
Support of Larger Bandwidth in LTE-Advanced
30
Asymmetric Transmission
Bandwidth

Symmetric transmission


Voice transmission: UE to UE
Asymmetric transmission

Streaming video : the server to the UE (the downlink)
31
Layered OFDMA


The bandwidth of basic frequency block is, 15 - 20
MHz
Layered OFDMA comprises layered transmission
bandwidth assignment (bandwidth is assigned to
match the required data rate), a layered control
signaling structure, and support for layered
environments for both the downlink and uplink.
32
Coordinated Multi-Point
Transmission/Reception (CoMP)

The CoMP is one of the candidate techniques for
LTE-Advanced systems to increase the average cell
throughput and cell edge user throughput in the
both uplink and downlink.
33
Enhanced Multi-Antenna
Transmission Techniques


In LTE-A, the MIMO scheme has to be further improved
in the area of spectrum efficiency, average cell through
put and cell edge performances
In LTE-A the antenna configurations of 8x8 in DL and
4x4 in UL are planned
34
Enhanced Techniques to Extend
Coverage Area

Remote Radio Requirements (RREs) using optical
fiber should be used in LTE-A as effective
technique to extend cell coverage
35
Support of Larger Bandwidth in
LTE-Advanced

Peak data rates up to 1Gbps are expected from
bandwidths of 100MHz. OFDM adds additional
sub-carrier to increase bandwidth
36
LTE vs. LTE-Advanced
37
Conclusion


LTE-A helps in integrating the existing networks,
new networks, services and terminals to suit the
escalating user demands
LTE-Advanced will be standardized in the 3GPP
specification Release 10 (LTE-A) and will be
designed to meet the 4G requirements as defined
by ITU
38