3 GPP Long Term Evolution LTE Outline n

3 GPP Long Term Evolution (LTE)

Outline n n n History of 3 GPP LTE Basic Concepts of LTE Introduction of LTE Protocol Comparison of LTE and LTE-Advanced Conclusion 2

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

Evolution of Radio Access Technologies 802. 16 m 802. 16 d/e n n LTE (3. 9 G) : 3 GPP release 8~9 LTE-Advanced : 3 GPP release 10+ 4

LTE Basic Concepts n LTE employs Orthogonal Frequency Division Multiple Access (OFDMA) for downlink data transmission and Single Carrier FDMA (SC-FDMA) for uplink transmission 5

Multipath-Induced Time Delays Result in Inter-Symbol Interference (ISI) βS(t-m) S(t) y(t) : output signal S(t) : input signal S(t-m) : delayed m time input signal n(t) : noise y(t) 6

Equalizers in Receiver n Against Frequency Selective Fading n Channel transform function Hc(f) n Equalizers transfer function, Heq(f) (Receiver) 7

Frequency Selective Fading n Coherence bandwidth of the channel is smaller than the bandwidth of the signal Frequency Correlation > 0. 9 Bc = 1 / 50α α is r. m. s. delay spread It may be useless even in increasing transmission power 8

Cyclic Prefixes against multipath 9

FDM vs. OFDM 10

LTE-Downlink (OFDM) n n n Improved spectral efficiency Reduce ISI effect by cyclic prefix Against frequency selective fading 11

LTE Uplink (SC-FDMA) n SC-FDMA is a new single carrier multiple access technique which has similar structure and same performance to OFDMA A salient advantage of SCFDMA over OFDM is low to Peak to Average Power Ratio (PAPR) : Increasing battery life 12

Multi-antenna techniques 13

Generic Frame Structure n Allocation of physical resource blocks (PRBs) is handled by a scheduling function at the 3 GPP base station (e. Node. B) Frame 0 and frame 5 (always downlink) 14

Resource block One frame is 10 ms 10 subframes 20 slots n One subframe is 1 ms 2 slots n One slot is 0. 5 ms N resource blocks [ 6 < N < 110] n One resource block is 0. 5 ms and contains 12 subcarriers from each OFDM symbol n 15

LTE spectrum (bandwidth and duplex) flexibility 16

LTE Release 8 Key Features (1/2) n n n High spectral efficiency n OFDM in Downlink n Single‐Carrier FDMA in Uplink Very low latency n Short setup time & Short transfer delay n Short hand over latency and interruption time Support of variable bandwidth n 1. 4, 3, 5, 10, 15 and 20 MHz Compatibility and interworking with earlier 3 GPP Releases FDD and TDD within a single radio access technology Efficient Multicast/Broadcast 17

Evolution of LTE-Advanced n n n Asymmetric transmission bandwidth Layered OFDMA Advanced Multi-cell Transmission/Reception Techniques Enhanced Multi-antenna Transmission Techniques Support of Larger Bandwidth in LTEAdvanced 18

Asymmetric transmission bandwidth n Symmetric transmission n n voice transmission : UE to UE Asymmetric transmission n streaming video : the server to the UE (the downlink) 19

Layered OFDMA n n 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 20

Advanced Multi-cell Transmission/Reception Techniques n In LTE-A, the advanced multi-cell transmission/reception processes helps in increasing frequency efficiency and cell edge user throughput n n Estimation unit Calculation unit Determination unit Feedback unit 21

Enhanced Multi-antenna Transmission Techniques n n 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 8 x 8 in DL and 4 x 4 in UL are planned 22

Enhanced Techniques to Extend Coverage Area n Remote Radio Requirements (RREs) using optical fiber should be used in LTE-A as effective technique to extend cell coverage 23

Support of Larger Bandwidth in LTE-Advanced n Peak data rates up to 1 Gbps are expected from bandwidths of 100 MHz. OFDM adds additional sub-carrier to increase bandwidth 24

LTE vs. LTE-Advanced 25

Conclusion n n 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 3 GPP specification Release 10 (LTE-A) and will be designed to meet the 4 G requirements as defined by ITU 26