AN INTRODUCTION TO LTE LTE, LTE-ADVANCED, SAE AND 4G MOBILE COMMUNICATIONS Christopher Cox Director, Chris Cox Communications Ltd, UK A John Wiley & Sons, Ltd., Publication This edition first published 2012 © 2012 John Wiley & Sons Ltd Registered office John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, United Kingdom For details of our global editorial offices, for customer services and for information about how to apply for permission to reuse the copyright material in this book please see our website at www.wiley.com. The right of the author to be identified as the author of this work has been asserted in accordance with the Copyright, Designs and Patents Act 1988. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher. Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic books. Designations used by companies to distinguish their products are often claimed as trademarks. All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners. The publisher is not associated with any product or vendor mentioned in this book. This publication is designed to provide accurate and authoritative information in regard to the subject matter covered. It is sold on the understanding that the publisher is not engaged in rendering professional services. If professional advice or other expert assistance is required, the services of a competent professional should be sought. Library of Congress Cataloging-in-Publication Data Cox, Christopher (Christopher Ian), 1965- An introduction to LTE : LTE, LTE-advanced, SAE and 4G mobile communications / Christopher Cox. p. cm. Includes bibliographical references and index. ISBN 978-1-119-97038-5 (cloth) 1. Long-Term Evolution (Telecommunications) 2. Mobile communication systems – Standards. I. Title. TK5103.48325.C693 2012 621.3845’6 – dc23 2011047216 A catalogue record for this book is available from the British Library. Print ISBN: 9781119970385 Set in 10/12 Times by Laserwords Private Limited, Chennai, India To my nieces, Louise and Zoe Contents Preface xvii Acknowledgements xix List of Abbreviations xxi 1 Introduction 1 1.1 Architectural Review of UMTS and GSM 1 1.1.1 High Level Architecture 1 1.1.2 Architecture of the Radio Access Network 2 1.1.3 Architecture of the Core Network 4 1.1.4 Communication Protocols 4 1.2 History of Mobile Telecommunication Systems 6 1.2.1 From 1G to 3G 6 1.2.2 Third Generation Systems 7 1.3 The Need for LTE 8 1.3.1 The Growth of Mobile Data 8 1.3.2 Capacity of a Mobile Telecommunication System 10 1.3.3 Increasing the System Capacity 11 1.3.4 Additional Motivations 11 1.4 From UMTS to LTE 11 1.4.1 High Level Architecture of LTE 11 1.4.2 Long Term Evolution 12 1.4.3 System Architecture Evolution 13 1.5 From LTE to LTE-Advanced 15 1.5.1 The ITU Requirements for 4G 15 1.5.2 Requirements of LTE-Advanced 15 1.5.3 4G Communication Systems 15 1.5.4 The Meaning of 4G 16 1.6 The 3GPP Specifications for LTE 16 References 18 2 System Architecture Evolution 21 2.1 Architecture of LTE 21 2.1.1 High Level Architecture 21 2.1.2 User Equipment 21 2.1.3 Evolved UMTS Terrestrial Radio Access Network 23 viii Contents 2.1.4 Evolved Packet Core 24 2.1.5 Roaming Architecture 25 2.1.6 Network Areas 26 2.1.7 Numbering, Addressing and Identification 27 2.2 Communication Protocols 28 2.2.1 Protocol Model 28 2.2.2 Air Interface Transport Protocols 29 2.2.3 Fixed Network Transport Protocols 30 2.2.4 User Plane Protocols 31 2.2.5 Signalling Protocols 31 2.3 Example Information Flows 33 2.3.1 Access Stratum Signalling 33 2.3.2 Non Access Stratum Signalling 33 2.3.3 Data Transport 35 2.4 Bearer Management 36 2.4.1 The EPS Bearer 36 2.4.2 Tunnelling Using GTP 37 2.4.3 Tunnelling Using GRE and PMIP 38 2.4.4 Signalling Radio Bearers 39 2.5 State Diagrams 40 2.5.1 EPS Mobility Management 40 2.5.2 EPS Connection Management 40 2.5.3 Radio Resource Control 41 2.6 Spectrum Allocation 42 References 44 3 Digital Wireless Communications 47 3.1 Radio Transmission and Reception 47 3.1.1 Signal Transmission 47 3.1.2 Signal Reception 49 3.1.3 Channel Estimation 50 3.1.4 Multiple Access Techniques 51 3.1.5 FDD and TDD Modes 52 3.2 Multipath, Fading and Inter-Symbol Interference 53 3.2.1 Multipath and Fading 53 3.2.2 Inter-Symbol Interference 55 3.3 Error Management 56 3.3.1 Forward Error Correction 56 3.3.2 Automatic Repeat Request 57 3.3.3 Hybrid ARQ 58 References 60 4 Orthogonal Frequency Division Multiple Access 61 4.1 Orthogonal Frequency Division Multiplexing 61 4.1.1 Reduction of Inter-Symbol Interference using OFDM 61 4.1.2 The OFDM Transmitter 62 4.1.3 Initial Block Diagram 65 Contents ix 4.2 OFDMA in a Mobile Cellular Network 66 4.2.1 Multiple Access 66 4.2.2 Fractional Frequency Re-Use 67 4.2.3 Channel Estimation 68 4.2.4 Cyclic Prefix Insertion 69 4.2.5 Use of the Frequency Domain 70 4.2.6 Choice of Sub-Carrier Spacing 72 4.3 Single Carrier Frequency Division Multiple Access 72 4.3.1 Power Variations from OFDMA 72 4.3.2 Block Diagram of SC-FDMA 73 References 76 5 Multiple Antenna Techniques 77 5.1 Diversity Processing 77 5.1.1 Receive Diversity 77 5.1.2 Closed Loop Transmit Diversity 78 5.1.3 Open Loop Transmit Diversity 79 5.2 Spatial Multiplexing 80 5.2.1 Principles of Operation 80 5.2.2 Open Loop Spatial Multiplexing 82 5.2.3 Closed Loop Spatial Multiplexing 84 5.2.4 Matrix Representation 85 5.2.5 Implementation Issues 88 5.2.6 Multiple User MIMO 88 5.3 Beamforming 90 5.3.1 Principles of Operation 90 5.3.2 Beam Steering 91 5.3.3 Dual Layer Beamforming 92 5.3.4 Downlink Multiple User MIMO Revisited 93 References 94 6 Architecture of the LTE Air Interface 95 6.1 Air Interface Protocol Stack 95 6.2 Logical, Transport and Physical Channels 97 6.2.1 Logical Channels 97 6.2.2 Transport Channels 97 6.2.3 Physical Data Channels 98 6.2.4 Control Information 99 6.2.5 Physical Control Channels 100 6.2.6 Physical Signals 100 6.2.7 Information Flows 101 6.3 The Resource Grid 101 6.3.1 Slot Structure 101 6.3.2 Frame Structure 103 6.3.3 Uplink Timing Advance 105 6.3.4 Resource Grid Structure 106 6.3.5 Bandwidth Options 106 x Contents 6.4 Multiple Antenna Transmission 107 6.4.1 Downlink Antenna Ports 107 6.4.2 Downlink Transmission Modes 107 6.5 Resource Element Mapping 109 6.5.1 Downlink Resource Element Mapping 109 6.5.2 Uplink Resource Element Mapping 109 References 112 7 Cell Acquisition 113 7.1 Acquisition Procedure 113 7.2 Synchronization Signals 114 7.2.1 Physical Cell Identity 114 7.2.2 Primary Synchronization Signal 115 7.2.3 Secondary Synchronization Signal 116 7.3 Downlink Reference Signals 116 7.4 Physical Broadcast Channel 117 7.5 Physical Control Format Indicator Channel 118 7.6 System Information 119 7.6.1 Organization of the System Information 119 7.6.2 Transmission and Reception of the System Information 121 7.7 Procedures After Acquisition 121 References 122 8 Data Transmission and Reception 123 8.1 Data Transmission Procedures 123 8.1.1 Downlink Transmission and Reception 123 8.1.2 Uplink Transmission and Reception 125 8.1.3 Semi Persistent Scheduling 126 8.2 Transmission of Scheduling Messages on the PDCCH 127 8.2.1 Downlink Control Information 127 8.2.2 Resource Allocation 128 8.2.3 Example: DCI Format 1 129 8.2.4 Radio Network Temporary Identifiers 130 8.2.5 Transmission and Reception of the PDCCH 131 8.3 Data Transmission on the PDSCH and PUSCH 132 8.3.1 Transport Channel Processing 132 8.3.2 Physical Channel Processing 133 8.4 Transmission of Hybrid ARQ Indicators on the PHICH 135 8.4.1 Introduction 135 8.4.2 Resource Element Mapping of the PHICH 136 8.4.3 Physical Channel Processing of the PHICH 136 8.5 Uplink Control Information 137 8.5.1 Hybrid ARQ Acknowledgements 137 8.5.2 Channel Quality Indicator 137 8.5.3 Rank Indication 138 8.5.4 Precoding Matrix Indicator 139 Contents xi 8.5.5 Channel State Reporting Mechanisms 139 8.5.6 Scheduling Requests 140 8.6 Transmission of Uplink Control Information on the PUCCH 140 8.6.1 PUCCH Formats 140 8.6.2 PUCCH Resources 142 8.6.3 Physical Channel Processing of the PUCCH 142 8.7 Uplink Reference Signals 143 8.7.1 Demodulation Reference Signal 143 8.7.2 Sounding Reference Signal 144 8.8 Uplink Power Control 145 8.8.1 Uplink Power Calculation 145 8.8.2 Uplink Power Control Commands 146 8.9 Discontinuous Reception 146 8.9.1 Discontinuous Reception and Paging in RRC_IDLE 146 8.9.2 Discontinuous Reception in RRC_CONNECTED 147 References 148 9 Random Access 151 9.1 Transmission of Random Access Preambles on the PRACH 151 9.1.1 Resource Element Mapping 151 9.1.2 Preamble Sequence Generation 153 9.1.3 Signal Transmission 153 9.2 Non Contention Based Procedure 154 9.3 Contention Based Procedure 155 References 156 10 Air Interface Layer 2 159 10.1 Medium Access Control Protocol 159 10.1.1 Protocol Architecture 159 10.1.2 Timing Advance Commands 160 10.1.3 Buffer Status Reporting 161 10.1.4 Power Headroom Reporting 162 10.1.5 Multiplexing and De-Multiplexing 162 10.1.6 Logical Channel Prioritization 163 10.1.7 Scheduling of Transmissions on the Air Interface 163 10.2 Radio Link Control Protocol 164 10.2.1 Protocol Architecture 164 10.2.2 Transparent Mode 165 10.2.3 Unacknowledged Mode 165 10.2.4 Acknowledged