LTE Radio Interface

Introduction

LTE Radio Interface?› Different from other technologies

› New structures

› Some similarities

eNBeNB ?

Scope and objectives

› Describe OFDM/OFDMA› Describe SC-FDMA› Explain Flexible Spectrum Usage› Explain Hybrid ARQ (HARQ)› Present Radio Interface Structure› Describe Channel Structure

Objectives

Scope

› Downlink and Uplink Transmission Technique

› Flexible Spectrum Usage› HARQ› Radio Interface and Channel Structure

Pre-Test

Pre-test

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Overview

LTE Radio Interface› Interface between UE and

eNodeB

› Hybrid ARQ

› Multi Antenna Possibility

› Flexible spectrum usage

processHARQ process

3210 4 …

eNBeNB

LTE Radio Interface

Downlink transmission technique

Flexible bandwidth operation Different regions Different frequency bands & bandwidths

eNBeNB

OFDM/OFDMA

OFDM

Datastream

Subcarrier

frequency

time1 ms

User #2 scheduledUser #1 scheduled

User #3 scheduled

OFDMA

SC-FDMA

time

frequency

Uplink transmission technique

Intra-cellorthogonality

eNBeNB

SC-FDMA

110 RB (20 MHz)

Bandwidth flexibility

20 MHz151031.4 5

1.4 MHz

fDL

fUL

FDDfDL

fUL

Half-duplex FDDfDL/UL

TDD

Time-domain structure

- more overhead and latency+ radio channel reciprocity+ simpler to deploy in limited

available spectrum

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Multi Antenna Possibilities

RXRX

MIMO

Segmentation, ARQ

Ciphering

Header Compr.

Hybrid ARQHybrid ARQ

MAC multiplexing

Antenna and resrouce mapping

Coding + RM

Data modulation

Antenna and resource mapping

Coding

Modulation

User #1 User #2

Concatenation, ARQ

Deciphering

Header Compr.

Hybrid ARQHybrid ARQ

MAC demultiplexing

Antenna and resrouce mapping

Coding + RM

Data modulation

Antenna and resource demapping

Decoding

Demodulation

eNodeB UE

EPS bearers

E-UTRA Radio Bearers

Logical Channels

Transport Channels

Physical Channels

Radio interface structure

MAC MAC

RLC#1

PHY

RLC

PHY

PDCP#1

PDCP

PHYMACRLC

PDCPRRC

UE

PHYMACRLC

PDCP

eNB

RRCNAS NAS

Control PlaneMME

S1-CP

Radio interface – Control Signaling

Receiver process Receiver process

Demultiplexed and forwarded to RLC

Receiver process

Receiver process

processHARQ process

3 7 2 6 1 5 9

Datastream

0 4 8

The HARQ Principle

processHARQ process

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Control

Channel structure

PHY

MAC

RLC

Logical Channels

Transport Channels

Physical Channels/ Signals

Traffic

Summary

Summary

› OFDM/OFDMA in DL› SC-FDMA in UL› Six different bandwidths› FDD, TDD and Half-duplex FDD› Multiple antenna solutions› Layered interface structure

eNBeNB

OFDM/OFDMA

SC-FDMA

Quiz

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