An Introduction of 3GPP Long Term Evolution (LTE)
SpeakerTsung-Yin Lee
Reference
http://www.tcs.com LTE-Advanced: Future of Mobile Broadband, TATA Consultancy Services Takehiro Nakamura ,Proposal for Candidate Radio Interface Technol ogies for IMTAdvanced Bas d on LTE Release 10 and Beyond, 3GPP TSGRAN 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 Astly, Erik Dahlman, Anders Furuskr, Ylva Jading, Magnus Lindstrm, and Stefan Parkvall, Ericsson Research, LTE: The Evolution of Mobile Broadband , IEEE Communications Magazine, April 2009
Outline
History of 3GPP LTE Basic Concepts of LTE Introduction of LTE Protocol Compare with LTE and LTE-Advanced Conclusion
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
Evolution of Radio Access Technologies
802.16m 802.16d/e
LTE (3.9G) : 3GPP release 8~9 LTE-Advanced : 3GPP release 10+
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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
Multipath-Induced Time Delays Result in Inter-Symbol Interference (ISI)
y(t ) S (t ) S (t m) n(t )
y(t) : output signal S(t) : input signal S(t-m) : delayed m time input signal n(t) : noise
y(t) S(t-m) S(t)
Equalizers in Receiver
Against Frequency Selective Fading
Channel transform function Hc(f)
y(t ) S (t ) S (t m)
H c ( f ) 1 e j 2fm
Equalizers transform function Heq(f) (Receiver)
1 1 Hc ( f ) H c ( f ) 1 e j 2fm
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Frequency Selective Fading
the coherence bandwidth of the channel is smaller than the bandwidth of the signal
Frequency Correlation > 0.9 Bc = 1 / 50 is r.m.s. delay spread
It may be useless for increasing transmission power
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 SCFDMA over OFDM is low to Peak to Average Power Ratio (PAPR) : Increasing battery life 13
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 Control Channel
Paging Channel
Physical Downlink Shared Channel
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LTE Uplink Channels
Random Access Channel
CQI report
Physical Uplink Shared Channel Physical Radio Access Channel
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LTE Release 8 Key Features (1/2)
High spectral efficiency
OFDM in Downlink SingleCarrier FDMA in Uplink Short setup time & Short transfer delay Short hand over latency and interruption time 1.4, 3, 5, 10, 15 and 20 MHz
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Very low latency
Support of variable bandwidth
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 LTEAdvanced
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Asymmetric transmission bandwidth
Symmetric transmission
voice transmission : UE to UE streaming video : the server to the UE (the downlink)
Asymmetric transmission
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Layered OFDMA
The bandwidth of basic frequency block is, 1520 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
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