An Introduction of3GPP Long Term Evolution (LTE)

Speaker ： Tsung-Yin Lee

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Reference http://www.tcs.com “LTE-Advanced: Future of Mobile Broadband,”

TATA Consultancy Services Takehiro Nakamura ,“Proposal for Candidate Radio Interface Technol

ogies for IMT‐Advanced Bas d on LTE Release 10 and Beyond,” 3GPP TSG‐RAN Chairman

“3GPP LTE Channels and MAC Layer,” EventHelix.com Inc. 2009 Ahmed Hamza, Network Systems Laboratory Simon Fraser

University, “Long Term Evolution (LTE) - A Tutorial,” October 13, 2009

Jim Zyren, “Overview of the 3GPP Long Term Evolution Physical Layer,” Document Number: 3GPP EVOLUTIONWP Rev0 07/2007

David Astély, Erik Dahlman, Anders Furuskär, Ylva Jading, Magnus Lindström, and Stefan Parkvall, Ericsson Research, “LTE: The Evolution of Mobile Broadband” , IEEE Communications Magazine, April 2009

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Outline

History of 3GPP LTE Basic Concepts of LTE Introduction of LTE Protocol Compare with LTE and LTE-Advanced Conclusion

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What is LTE ?

In Nov. 2004, 3GPP began a project to define the long-term evolution (LTE) of Universal Mobile Telecommunications System (UMTS) cellular technology Higher performance Backwards compatible Wide application

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Evolution of Radio Access Technologies

LTE (3.9G) : 3GPP release 8~9

LTE-Advanced :3GPP release 10+

802.16d/e

802.16m

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LTE Basic Concepts

LTE employs Orthogonal Frequency Division Multiple Access (OFDMA) for downlink data transmission and Single Carrier FDMA (SC-FDMA) for uplink transmission

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Multipath-Induced Time Delays Result in Inter-Symbol Interference (ISI)

)()()()( tnmtStSty

y(t) : output signalS(t) : input signalS(t-m) : delayed m time input signaln(t) : noise

y(t)

βS(t-m)

S(t)

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Equalizers in Receiver

Against Frequency Selective Fading Channel transform function Hc(f)

Equalizers transform function Heq(f) (Receiver)

fmjc efH 21)(

fmjc

c efHfH 21

1

)(

1)(

)()()( mtStSty

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Frequency Selective Fading

the coherence bandwidth of the channel is smaller than the bandwidth of the signal

It may be useless for increasing transmission power

Frequency Correlation > 0.9Bc = 1 / 50α α is r.m.s. delay spread

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Cyclic Prefixes

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FDM vs. OFDM

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LTE-Downlink (OFDM)

Improved spectral efficiency

Reduce ISI effect by multipath

Against frequency selective fading

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LTE Uplink (SC-FDMA) 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 low to Peak to Average Power Ratio (PAPR) :

Increasing battery life

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Multi-antenna techniques

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Generic Frame Structure

Allocation of physical resource blocks (PRBs) is handled by a scheduling function at the 3GPP base station (eNodeB)

Frame 0 and frame 5 (always downlink)

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Resource Grid

One frame is 10ms 10 subframes

One subframe is 1ms 2 slots

One slot is 0.5ms N resource blocks[ 6 < N < 110]

One resource block is 0.5ms and contains 12 subcarriers from each OFDM symbol

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LTE spectrum (bandwidth and duplex) flexibility

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LTE Downlink Channels

Paging Channel

Paging Control Channel

Physical Downlink Shared Channel

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LTE Uplink Channels

Random Access Channel

Physical Radio Access Channel

Physical Uplink Shared Channel

CQI report

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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

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LTE Release 8 Key Features (2/2)

Compatibility and interworking with earlier 3GPP Releases

FDD and TDD within a single radio access  technology

Efficient Multicast/Broadcast

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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

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Asymmetric transmission bandwidth Symmetric transmission

voice transmission : UE to UE Asymmetric transmission

streaming video : the server to the UE (the downlink)

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Layered OFDMA

The bandwidth of basic frequency block is, 15–20 MHz

Layered OFDMA radio access scheme in LTE-A will have layered transmission bandwidth, support of layered environments and control signal formats

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Advanced Multi-cell Transmission/Reception Techniques

In LTE-A, the advanced multi-cell transmission/reception processes helps in increasing frequency efficiency and cell edge user throughput Estimation unit Calculation unit Determination unit Feedback unit

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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

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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

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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

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LTE vs. LTE-Advanced

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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

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Backup

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LTE Downlink Logical Channels

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LTE Downlink Logical Channels

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LTE Downlink Transport Channel

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LTE Downlink Transport Channel

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LTE Downlink Physical Channels

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LTE Downlink Physical Channels

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LTE Uplink Logical Channels

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LTE Uplink Transport Channel

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LTE Uplink Physical Channels