`
`Mercedes EX1021
`U.S. Patent No. 10,965,512
`
`
`
`Multicarrier Techniques for 4G Mobile
`Communications
`
`
`
`The Artech House Universal Personal
`Communications Series
`Ramjee Prasad, Series Editor
`CDMA for Wireless Personal Communications, Ramjee Prasad
`IP/ATM Mobile Satellite Networks, John Farserotu and Ramjee Prasad
`Multicarrier Techniques for 4G Mobile Communications, Shinsuke Hara
`and Ramjee Prasad
`OFDM for Wireless Multimedia Communications, Richard van Nee and
`Ramjee Prasad
`Radio over Fiber Technologies for Mobile Communications Networks,
`Hamed Al-Raweshidy and Shozo Komaki, editors
`Simulation and Software Radio for Mobile Communications,
`Hiroshi Harada and Ramjee Prasad
`TDD-CDMA for Wireless Communications, Riaz Esmailzadeh and
`Masao Nakagawa
`Technology Trends in Wireless Communications, Ramjee Prasad and
`Marina Ruggieri
`Third Generation Mobile Communication Systems, Ramjee Prasad,
`Werner Mohr, and Walter Konha¨user, editors
`Towards a Global 3G System: Advanced Mobile Communications in Europe,
`Volume 1, Ramjee Prasad, editor
`Towards a Global 3G System: Advanced Mobile Communications in Europe,
`Volume 2, Ramjee Prasad, editor
`Universal Wireless Personal Communications, Ramjee Prasad
`WCDMA: Towards IP Mobility and Mobile Internet, Tero Ojanpera¨ and
`Ramjee Prasad, editors
`Wideband CDMA for Third Generation Mobile Communications,
`Tero Ojanpera¨ and Ramjee Prasad, editors
`Wireless IP and Building the Mobile Internet, Sudhir Dixit and
`Ramjee Prasad, editors
`WLAN Systems and Wireless IP for Next Generation Communications,
`Neeli Prasad and Anand Prasad, editors
`WLANs and WPANs towards 4G Wireless, Ramjee Prasad and Luis Mun˜oz
`
`
`
`Multicarrier Techniques for 4G Mobile
`Communications
`
`Shinsuke Hara
`Ramjee Prasad
`
`Artech House
`Boston • London
`www.artechhouse.com
`
`
`
`Library of Congress Cataloging-in-Publication Data
`Hara, Shinsuke.
`Multicarrier techniques for 4G mobile communications / Shinsuke Hara, Ramjee
`Prasad.
`p. cm. — (Artech House universal personal communications series)
`Includes bibliographical references and index.
`ISBN 1-58053-482-1 (alk. paper)
`1. Universal Mobile Telecommunications System.
`I. Prasad, Ramjee.
`II. Title.
`III. Series.
`TK5103.4883.H37
`2003
`621.382—dc21
`
`2. Carrier waves.
`
`2003048095
`
`British Library Cataloguing in Publication Data
`Hara, Shinsuke
`Multicarrier techniques for 4G mobile communications. — (Artech House universal
`personal communications series)
`1. Mobile communication systems
`I. Title
`II. Prasad, Ramjee
`621.3’8456
`
`ISBN 1-58053-482-1
`
`Cover design by Igor Valdman
`
`© 2003 Shinsuke Hara and Ramjee Prasad.
`All rights reserved.
`
`All rights reserved. Printed and bound in the United States of America. No part of this book
`may be reproduced or utilized in any form or by any means, electronic or mechanical,
`including photocopying, recording, or by any information storage and retrieval system, without
`permission in writing from the publisher.
`All terms mentioned in this book that are known to be trademarks or service marks have
`been appropriately capitalized. Artech House cannot attest to the accuracy of this information.
`Use of a term in this book should not be regarded as affecting the validity of any trademark
`or service mark.
`
`International Standard Book Number: 1-58053-482-1
`Library of Congress Catalog Card Number: 2003048095
`
`10 9 8 7 6 5 4 3 2 1
`
`
`
`To my parents Kokichi and Kazuko, to my wife Yoshimi, and to our sons
`Tomoyuki and Tomoharu
`
`—Shinsuke Hara
`
`To my wife Jyoti, to our daughter Neeli, to our sons Anand and Rajeev,
`and to our granddaughters Sneha and Ruchika
`—Ramjee Prasad
`
`
`
`
`
`Contents
`
`Preface
`
`Acknowledgments
`
`Introduction
`
`Mobile Communications Systems: Past,
`Present, and Future
`
`Toward 4G Systems
`
`Multicarrier Techniques for 4G Systems
`
`Preview of the Book
`References
`
`Characteristics of Multipath Fading
`Channels
`
`Introduction
`
`Rayleigh and Ricean Fading Channels
`
`Multipath Delay Profile
`
`vii
`
`1
`
`1.1
`
`1.2
`
`1.3
`
`1.4
`
`2
`
`2.1
`
`2.2
`
`2.3
`
`xv
`
`xvii
`
`1
`
`1
`
`2
`
`7
`
`8
`10
`
`13
`
`13
`
`14
`
`18
`
`
`
`viii
`
`Multicarrier Techniques for 4G Mobile Communications
`
`2.4
`
`2.5
`
`2.6
`
`2.7
`
`3
`
`3.1
`
`3.2
`
`3.3
`
`3.4
`
`3.5
`
`4
`
`4.1
`
`4.2
`
`4.3
`
`4.4
`
`Frequency Selective and Frequency
`Nonselective Fading Channels
`
`Spaced-Time Correlation Function
`
`Time Selective and Time Nonselective Fading
`Channels
`
`Examples of Multipath Fading Channels
`References
`
`Principle and History of MCM/OFDM
`
`Introduction
`
`Origin of OFDM
`
`Use of Discrete Fourier Transform
`
`Insertion of Cyclic Prefix for Current Form of
`OFDM
`
`Conclusions
`References
`
`OFDM Characteristics
`
`Introduction
`
`Radio Channel Model
`
`Bit Error Rate in AWGN Channel
`
`Bit Error Rate of CPSK-Based OFDM System
`in Rayleigh Fading Channels
`
`4.5
`
`Bit Error Rate of DPSK-Based OFDM
`System in Rayleigh Fading Channels
`4.5.1 Theoretical Bit Error Rate Analysis
`
`19
`
`20
`
`21
`
`22
`26
`
`27
`
`27
`
`27
`
`30
`
`33
`
`39
`41
`
`43
`
`43
`
`44
`
`46
`
`49
`
`49
`50
`
`
`
`Contents
`
`4.5.2
`
`Bit Error Rate in Frequency Selective and
`Time Selective Rayleigh Fading Channels
`4.5.3 Optimum Number of Subcarriers and
`Optimum Length of Guard Interval
`4.5.4 Numerical Results and Discussions
`
`4.6
`
`Robustness Against Frequency Selective
`Fading
`
`Robustness Against Man-Made Noises
`4.7
`4.7.1 Generalized Shot Noise Channel
`4.7.2
`Bit Error Rate of SCM in GSN Channel
`4.7.3
`Bit Error Rate of OFDM in GSN Channel
`4.7.4 Numerical Results and Discussions
`
`4.8
`4.8.1
`
`Sensitivity to Frequency Offset
`Bit Error Rate in Frequency Selective and
`Time Selective Rayleigh Fading Channel with
`Frequency Offset
`4.8.2 Numerical Results and Discussions
`
`Sensitivity to Nonlinear Amplification
`4.9
`Simbo’s Method
`4.9.1
`4.9.2 Numerical Results and Discussions
`
`4.10
`
`Sensitivity to A/D and D/A Resolutions
`
`4.11
`
`Conclusions
`References
`
`Appendix 4A
`Reference
`
`Appendix 4B
`
`5
`
`Pilot-Assisted DFT Window Timing/
`Frequency Offset Synchronization and
`Subcarrier Recovery
`
`5.1
`
`Introduction
`
`ix
`
`52
`
`56
`59
`
`61
`
`63
`64
`65
`67
`69
`
`72
`
`74
`77
`
`79
`79
`82
`
`86
`
`88
`93
`
`95
`96
`
`96
`
`99
`
`99
`
`
`
`x
`
`Multicarrier Techniques for 4G Mobile Communications
`
`Pilot-Assisted DFT Window Timing/
`101
`Frequency Offset Estimation Method
`Principle of DFT Window Timing Estimation 101
`Principle of Frequency Offset Estimation
`105
`Spectral Property of Pilot Symbol
`106
`Performance of DFT Window Timing
`Estimator
`Performance of Frequency Offset Estimator
`
`107
`110
`
`5.2
`
`5.2.1
`5.2.2
`5.2.3
`5.2.4
`
`5.2.5
`
`5.3
`
`5.3.2
`
`111
`
`111
`
`115
`116
`
`121
`
`123
`125
`
`127
`
`127
`
`128
`
`129
`
`134
`
`135
`139
`
`TEAMFLY
`
`Pilot-Assisted DFT Window Timing
`Synchronization and Subcarrier Recovery
`Method
`5.3.1 Time Domain Pilot-Assisted DFT Window
`Timing Synchronization and Subcarrier
`Recovery Method
`Frequency Domain Pilot-Assisted Subcarrier
`Recovery Method
`5.3.3 Numerical Results and Discussions
`
`5.4
`
`5.5
`
`6
`
`6.1
`
`6.2
`
`6.3
`
`6.4
`
`6.5
`
`Chaotic Pilot Symbol Generation Method
`
`Conclusions
`References
`
`Blind Maximum Likelihood-Based Joint DFT
`Window Timing/Frequency Offset/ DFT
`Window Width Estimation
`
`Introduction
`
`System Model
`
`Maximum Likelihood Parameter Estimation
`for Cyclostationary Signal
`
`Numerical Results and Discussions
`
`Conclusions
`References
`
`Team-Fly®
`
`
`
`Contents
`
`Coded OFDM Scheme to Gain Frequency
`Diversity Effect
`
`Introduction
`
`Convolutional Encoding/Viterbi Decoding
`
`Symbol Interleaved Coded OFDM Scheme
`
`Bit Interleaved Coded OFDM Scheme
`
`Numerical Results and Discussions
`
`Conclusions
`References
`
`7
`
`7.1
`
`7.2
`
`7.3
`
`7.4
`
`7.5
`
`7.6
`
`8
`
`Applications of OFDM
`
`8.1
`
`Introduction
`
`Digital Broadcasting
`8.2
`8.2.1 Digital Audio Broadcasting
`8.2.2 Terrestrial Digital Video Broadcasting
`8.2.3 Terrestrial Integrated Services Digital
`Broadcasting
`
`8.3
`
`5 GHz-Band Wireless LANs
`
`8.4
`8.4.1
`8.4.2
`8.4.3
`
`Others
`IEEE 802.11g
`IEEE 802.11h
`IEEE 802.16a
`
`8.5
`
`9
`
`9.1
`
`9.2
`
`Conclusions
`References
`
`Combination of OFDM and CDMA
`
`Introduction
`
`Channel Model
`
`xi
`
`141
`
`141
`
`142
`
`143
`
`146
`
`149
`
`156
`158
`
`159
`
`159
`
`159
`159
`160
`
`161
`
`162
`
`165
`165
`165
`166
`
`167
`167
`
`169
`
`169
`
`170
`
`
`
`xii
`
`Multicarrier Techniques for 4G Mobile Communications
`
`DS-CDMA System
`9.3
`9.3.1 DS-CDMA Transmitter
`9.3.2 DS-CDMA Receiver
`9.3.3
`Bit Error Rate Analysis
`
`MC-CDMA System
`9.4
`9.4.1 MC-CDMA Transmitter
`9.4.2 MC-CDMA Receiver
`9.4.3
`Bit Error Rate Analysis
`9.4.4 Design of MC-CDMA System
`9.4.5 Head/Tail Guard Interval Insertion Method
`9.4.6
`Bit Error Rate of MC-CDMA System
`9.4.7
`Sliding DFT-Based Subcarrier Recovery
`Method
`
`9.5
`
`Conclusions
`References
`
`10
`
`Future Research Directions
`
`10.1
`
`Introduction
`
`10.2 Where Will 4G Systems Come From?
`
`Variants Based on MC-CDMA Scheme
`10.3
`10.3.1 OFCDM System
`10.3.2 Other Variant Based on MC-CDMA Scheme
`
`10.4 OFDM Adaptive Array Antennas
`10.4.1 Principle of Adaptive Array Antenna
`10.4.2 Post-FFT and Pre-FFT Type OFDM
`Adaptive Array Antennas
`10.4.3 Weight-Per-User and Weight-Per-Path Type
`OFDM Adaptive Array Antennas
`
`10.5 MIMO-OFDM
`
`171
`171
`173
`175
`
`176
`176
`179
`183
`186
`188
`191
`
`194
`
`200
`200
`
`203
`
`203
`
`204
`
`204
`204
`209
`
`211
`211
`
`211
`
`213
`
`215
`
`
`
`10.6
`
`10.7
`
`Contents
`
`Linear Amplification of OFDM Signal with
`Nonlinear Components
`
`Conclusions
`References
`
`List of Acronyms
`
`About the Authors
`
`Index
`
`xiii
`
`216
`
`218
`220
`
`223
`
`227
`
`231
`
`
`
`
`
`Preface
`
`yada¯ samharate ca¯yam
`ku¯rmo ′nga¯nı¯va sarvas´ah
`indriya¯nı¯ndriya¯rthebhyas
`tasya prajn˜a¯ pratisthita¯
`
`‘‘One who is able to withdraw his senses from sense objects, as the
`tortoise draws its limbs within the shell, is firmly fixed in perfect
`consciousness.’’
`
`—The Bhagvad Gita (2.58)
`
`At recent major international conferences on wireless communications,
`there have been several sessions on beyond third generation (3G) or fourth
`generation (4G) mobile communications systems, where modulation/demod-
`ulation and multiplexing/multiple access schemes related to multicarrier
`techniques have drawn a lot of attention. We often met at the conference
`venues and realized that no book covered the basics of multicarrier techniques
`to recent applications aiming at the 4G systems. Therefore, we decided to
`write a book on multicarrier techniques for 4G mobile communications
`systems.
`
`xv
`
`
`
`xvi
`
`Multicarrier Techniques for 4G Mobile Communications
`
`Figure P.1 illustrates the coverage of the book.
`This book provides a comprehensive introduction to multicarrier tech-
`niques including orthogonal frequency division multiplexing (OFDM), put-
`ting much emphasis on the analytical aspects by introducing basic equations
`with derivations.
`This book will help solve many problems encountered in research and
`development of multicarrier-based wireless systems. We have tried our best
`to make each chapter comprehensive. We cannot claim that this book is
`errorless. Therefore, we would really appreciate it if readers would provide
`us with any comments to improve the text and correct any errors.
`
`Figure P.1 Illustration of the coverage of the book. The number in branches denotes the
`chapter of the book.
`
`
`
`Acknowledgments
`
`The material in this book is based on research activities at Osaka University
`in Japan, the Department of Communication Technology at Aalborg Univer-
`sity in Denmark, and Delft University of Technology in the Netherlands. The
`authors would like to thank Professor Norihiko Morinaga (Osaka University),
`who gave Shinsuke a chance to work with Ramjee in the Netherlands in
`1995–1996. They also wish to thank Dr. Jean-Paul Linnartz (Philips National
`Laboratory), who also gave Shinsuke a chance to do research in the Nether-
`lands. Their heartfelt gratitude also goes to Professors Seiichi Sampei and
`Shinichi Miyamoto (Osaka University), who kindly took care of Shinsuke’s
`students during his absence.
`They are deeply indebted to Professor Minoru Okada (Nara Institute
`of Science and Technology in Japan) and Dr. Yoshitaka Hara (Information
`Technology R&D Center at Mitsubishi Electric Corporation in Japan) for
`their discussion, interaction, and friendship with Shinsuke over the years.
`The material in this book has benefited greatly from the inputs of the
`following many brilliant students who have worked with us on the topic:
`Kazuyasu Yamane, Kiyoshi Fukui, Ikuo Yamashita, Masutada Mouri, Tai
`Hin Lee, Frans Kleer, Daichi Imamura, Masaya Nakanomori, Shuichi Hane,
`Shigehiko Tsumura, and Montee Budsabathon.
`Last but not the least, the authors would like to express their apprecia-
`tion for the support Junko Prasad provided in finishing the book.
`
`xvii
`
`
`
`
`
`1 I
`
`ntroduction
`
`1.1 Mobile Communications Systems: Past, Present, and
`Future
`
`There has been a paradigm shift in mobile communications systems every
`decade. The first generation (1G) systems in the 1980s were based on analog
`technologies, and the second generation (2G) systems in the 1990s, such as
`Global Systems for Mobile Telecommunications (GSM) [1], Personal Digital
`Cellular (PDC) [2], and Interim Standard (IS)-95 [3], on digital technologies
`for voice-oriented traffic. The 3G systems are also based on digital technolo-
`gies for mixed voice, data, and multimedia traffic and mixed-circuit and
`packet-switched network [4, 5]. The first 3G system was introduced in
`October 2001 in Japan [6].
`Figure 1.1 shows a rough sketch of present and future mobile communi-
`cations systems. As an evolutional form of mobile phone systems, Interna-
`tional Mobile Telecommunications (IMT)-2000 [4, 5], which corresponds
`to 3G systems, aims to support a wide range of multimedia services from
`voice and low-rate to high-rate data with up to at least 144 Kbps in vehicular,
`384 Kbps in outdoor-to-indoor, and 2 Mbps in indoor and picocell environ-
`ments. It provides continuous service coverage in 2-GHz band with code
`division multiplexing/code division multiple access (CDM/CDMA) scheme
`and supports both circuit-switched and packet-oriented services. Further-
`more, high data rate (HDR), which supports a maximum 2.4-Mbps downlink
`packet transmission, is proposed [7], and high-speed downlink packet access
`(HSDPA), which also aims for more than 2-Mbps throughput, is under
`
`1
`
`
`
`2
`
`Multicarrier Techniques for 4G Mobile Communications
`
`TEAMFLY
`
`Figure 1.1 A rough sketch of present and future mobile communications systems.
`
`standardization in the Third Generation Partnership Project (3GPP) [8].
`Both HDR and HSDPA are categorized into enhanced IMT-2000 systems,
`which correspond to 3.5G systems.
`As a progressive form of wireless local area networks (LANs), high-
`rate wireless LANs [9] such as IEEE802.11a [10], high-performance radio
`LAN type two (HIPERLAN/2) [11], and multimedia mobile access commu-
`nication (MMAC) [12, 13], which are all based on the OFDM technique,
`provide data transmission up to 54 Mbps in 5-GHz band. They are mainly
`intended for communications between computers in an indoor environment,
`although they can support real-time audio and video transmission, and users
`are allowed some mobility [14].
`
`1.2 Toward 4G Systems
`Long-term researches and developments are usually required to lead a com-
`mercial service to success. Now, just coming into the new century, it might
`
`Team-Fly®
`
`
`
`Introduction
`
`3
`
`be a good time to start discussions on 4G systems, which may be put in
`service around 2010. Indeed, since the beginning of this century, we have
`often seen the words ‘‘future generation,’’ ‘‘beyond 3G’’ or ‘‘4G’’ in magazines
`on wireless communications [15–19].
`According to the Vision Preliminary Draft of New Recommendation
`(DNR) of ITU-R WP8F [20, 21], there will be a steady and continuous
`evolution of IMT-2000 to support new applications, products, and services.
`For example, the capacities of some of the IMT-2000 terrestrial radio inter-
`faces are already being extended up to 10 Mbps, and it is anticipated that
`these will be extended even further, up to approximately 30 Mbps, by 2005,
`although these data rates will be limited only under optimum signal and traffic
`conditions. For systems beyond 3G [beyond IMT-2000 in the International
`Telecommunication Union (ITU)], there may be a requirement for a new
`wireless access technology for the terrestrial component around 2010. This
`will complement the enhanced IMT-2000 systems and the other radio sys-
`tems with which there is an interrelationship. It is envisaged that these
`potential new radio interfaces will support up to approximately 100 Mbps
`for high mobility and up to approximately 1 Gbps for low mobility such
`as nomadic/local wireless access by around 2010.
`The data rate figures are targets for research and investigation on the
`basic technologies necessary to implement the vision. The future system
`specification and design will be based on the results of the research and
`investigations. Due to the high data rate requirements, additional spectrum
`will be needed for these new capabilities of systems beyond IMT-2000. The
`data rate targets consider advances in technology, and these values are expected
`to be feasible from a technology perspective in the time frame of investigation
`and development of the new capabilities of systems beyond IMT-2000.
`In conjunction with the future development of IMT-2000 and systems
`beyond IMT-2000, there will be an increasing relationship between radio
`access and communication systems, such as wireless personal area networks
`(PANs), LANs, digital broadcast, and fixed wireless access.
`Based on today’s envisaged service requirements, traffic expectations,
`and radio access technologies, ITU-R is working on a potential system
`architecture, according to Figures 1.2 through 1.4.
`In this context, low mobility covers pedestrian speed (≈3km/h), medium
`mobility corresponds to limited speed as for cars within cities (≈50-60 km/h),
`high mobility covers high speed as on highways or with fast trains (≈60
`km/h to 250 km/h, or even more). The degree of mobility is basically linked
`to the cell size in a cellular system, as well as to system capacity. In general,
`the cell size in a cellular system has to be greater for a higher degree of
`mobility in order to limit the handover load in the network.
`
`
`
`4
`
`Multicarrier Techniques for 4G Mobile Communications
`
`Figure 1.2 System capabilities for systems beyond third generation. (After: [20].)
`
`Figure 1.3 Seamless future network, including a variety of interworking access systems.
`(After: [20].)
`
`
`
`Introduction
`
`5
`
`Figure1.4Layeredstructureofseamlessfuturenetworkwithprimarilyallocatedsystems.(After:[20].)
`
`
`
`6
`
`Multicarrier Techniques for 4G Mobile Communications
`
`Different complementary access schemes will be part of systems beyond
`IMT-2000. The different access systems are cooperating in terms of vertical
`handover and seamless service provision. Reconfigurable terminal devices
`and network infrastructure will be an essential part of such architecture.
`Such a concept of heterogeneous networks enables a migration and evolution
`path for network operators from today’s networks to systems beyond IMT-
`2000 by reusing deployed investment. New access components can be added
`where and when needed from economic reasons. This ensures the requested
`scalability of the system according to Figure 1.5.
`Possible new radio interface components are part of the concept. The
`different access systems will use already-allocated and identified frequency
`bands and potential new frequency bands for the new elements. Therefore,
`no direct interference between different technologies has to be expected. All
`access systems will be connected to an Internet Protocol (IP)-based network.
`Discussions are ongoing as to whether there should be a distinction between
`radio access and core network in the future.
`From today’s perspective, ITU-R expects the start of system standardiza-
`tion after WRC’07 with respect to identified spectrum bands and an initial
`deployment of systems beyond IMT-2000 after 2010.
`The future system will comprise available and evolving access technolo-
`gies. In addition, new radio access technologies with high carrier data rate
`for the wireless nomadic case with low mobility and for the cellular case
`with high mobility are envisaged. The data rate requirement for the cellular
`case is a big challenge from the technological perspective and with respect
`to the availability of sufficient future spectrum. Figure 1.6 shows the time
`plan for the systems beyond IMT-2000.
`
`Figure 1.5 Inhomogeneous traffic or system capacity demand in deployment area.
`(After: [20].)
`
`
`
`Introduction
`
`7
`
`Figure 1.6 Timelines. (After: [21].)
`
`1.3 Multicarrier Techniques for 4G Systems
`
`Figure 1.7 shows the evolution of mobile communications systems. In discus-
`sions about 2G systems in the 1980s, two candidates for the radio access
`technique existed, time division multiple access (TDMA) and CDMA
`schemes. Finally, the TDMA scheme was adopted as the standard. On the
`other hand, in the discussions about 3G systems in the 1990s, there were
`also two candidates, the CDMA scheme, which was adopted in the one-
`generation older systems, and the OFDM-based multiple access scheme called
`band division multiple access (BDMA) [22]. CDMA was finally adopted as
`the standard. If history is repeated, namely, if the radio access technique
`that was once not adopted can become a standard in new generation systems,
`then the OFDM-based technique looks promising as a 4G standard.
`This book presents multicarrier techniques, including OFDM, and we
`believe that readers can easily understand the reason why it is suited for 4G
`
`
`
`8
`
`Multicarrier Techniques for 4G Mobile Communications
`
`Figure 1.7 History of mobile communications systems in terms of adopted radio access
`technique.
`
`systems when they finish reading. The following provides some of our
`justifications:
`
`1. Multicarrier techniques can combat hostile frequency selective fad-
`ing encountered in mobile communications. The robustness against
`frequency selective fading is very attractive, especially for high-speed
`data transmission [15].
`2. OFDM scheme has been well matured through research and devel-
`opment for high-rate wireless LANs and terrestrial digital video
`broadcasting. We have developed a lot of know-how on OFDM.
`3. By combining OFDM with CDMA, we can have synergistic effects,
`such as enhancement of robustness against frequency selective fading
`and high scalability in possible data transmission rate.
`
`Figure 1.8 shows the advantages of multicarrier techniques.
`
`1.4 Preview of the Book
`
`This book is composed of 10 chapters. It covers all the necessary elements
`to understand multicarrier-based techniques. Chapter 2 briefly shows the
`characteristics of radio channels. It is the prerequisite knowledge for readers
`to understand the phenomena in the radio channels and is essential to carry
`
`
`
`Introduction
`
`9
`
`Figure 1.8 Advantages of multicarrier techniques for 4G systems.
`
`out theoretical analysis and performance evaluation on multicarrier technique
`in radio channels.
`Chapter 3 shows the history and principle of multicarrier technique,
`including the OFDM scheme. It includes the history from the origin to the
`current form.
`Chapter 4 discusses the characteristics of the OFDM scheme. It puts
`much emphasis on the theoretical analysis and discusses advantages and
`disadvantages of OFDM, including robustness against frequency selective
`fading and impulsive noises and sensitivity to frequency offset and nonlinear
`amplification.
`Synchronization of carrier frequency and discrete Fourier transform
`(DFT) window timing is a very important task for an OFDM receiver. Two
`chapters are devoted to this topic; Chapter 5 shows several pilot-assisted
`approaches on the synchronization, whereas Chapter 6 deals with a pilotless
`approach.
`To obtain diversity effect in fading channels, channel coding/decoding
`scheme is essential. Chapter 7 shows the frequency diversity effect in the
`performance of coded OFDM scheme. It discusses symbol- and bit-interleav-
`ing depth to obtain a full frequency diversity effect.
`
`
`
`10
`
`Multicarrier Techniques for 4G Mobile Communications
`
`Chapter 8 shows several systems where OFDM was successful. It
`includes digital audio broadcasting (DAB), terrestrial digital video broadcast-
`ing (DVB-T), terrestrial integrated services digital broadcasting (ISDB-T),
`IEEE 802.11a, HIPERLAN/2, MMAC, IEEE 802.11g, IEEE 802.11h, and
`IEEE 802.16a.
`Chapter 9 discusses a combination of OFDM and CDMA. One combi-
`nation is called multicarrier code division multiple access (MC-CDMA).
`Since it was born in 1993, intensive research has been conducted on this
`interesting new access scheme, and it is now considered suitable for a radio
`access technique in 4G systems. This chapter shows the principle and perfor-
`mance of the MC-CDMA.
`Finally, Chapter 10 presents some recent (2000–2002) interesting
`research topics related to multicarrier technologies for future research.
`
`References
`
`[4]
`
`[1] Mouly, M., and M. B. Pautet, ‘‘Current Evolution of the GSM,’’ IEEE Personal
`Commun. Mag., Vol. 2, No. 5, October 1995, pp. 9–19.
`[2] Kinoshita, K., and M. Nakagawa, ‘‘Japanese Cellular Standard,’’ The Mobile Communi-
`cations Handbook, J. D. Gipson (ed.), Boca Raton, FL: CRC Press, pp. 449–461,
`1996.
`[3] Ross, A. H. M., and K. L. Gilhousen, ‘‘CDMA Technology and the IS-95 North
`American Standard,’’ The Mobile Communications Handbook, J. D. Gipson (ed.), Boca
`Raton, FL: CRC Press, pp. 430–448, 1996.
`Prasad, R., CDMA for Wireless Personal Communications, Norwood, MA: Artech House,
`1996.
`[5] Ojanpera, T., and R. Prasad, (eds.), Wideband CDMA for Third Generation Mobile
`Communications, Norwood, MA: Artech House, 1998.
`[6] Ohmori, S., Y. Yamao, and N. Nakajima, ‘‘The Future Generations of Mobile Commu-
`nications Based on Broadband Access Technologies,’’ IEEE Commun. Mag., Vol. 38,
`No. 12, December 2000, pp.134–142.
`[7] Bender, P., et al., ‘‘CDMA/HDR: A Bandwidth-Efficient High-Speed Wireless Data
`Services for Nomadic Users,’’ IEEE Commun. Mag., Vol. 38, No. 7, July 2000,
`pp. 70–77.
`3 GPP, 3G TR25.848, V.0.6.0, May 2000.
`van Nee, R., et al., ‘‘New High-Rate Wireless LAN Standards,’’ IEEE Commun. Mag.,
`Vol. 37, No. 12, December 1999, pp. 82–88.
`IEEE Std. 802.11a, ‘‘Wireless Medium Access Control (MAC) and Physical Layer
`(PHY) Specifications: High-speed Physical Layer Extension in the 5-GHz Band,’’
`IEEE, 1999.
`
`[8]
`[9]
`
`[10]
`
`
`
`Introduction
`
`11
`
`[14]
`
`[11] ETSI TR 101 475, ‘‘Broadband Radio Access Networks (BRAN); HIPERLAN Type2;
`Physical (PHY) Layer,’’ ETSI BRAN, 2000.
`[12] ARIB STD-T70, ‘‘Lower Power Data Communication Systems Broadband Mobile
`Access Communication System (CSMA),’’ ARIB, December 2000.
`[13] ARIB STD-T70, ‘‘Lower Power Data Communication Systems Broadband Mobile
`Access Communication System (HiSWANa),’’ ARIB, December 2000.
`van Nee, R., and R. Prasad, OFDM for Wireless Multimedia Communications, Norwood,
`MA: Artech House, 2000.
`[15] Chuang, J., and N. Sollenberger, ‘‘Beyond 3G: Wideband Wireless Data Access Based
`on OFDM and Dynamic Packet Assignment,’’ IEEE Commun. Mag., Vol. 38,
`No. 7, July 2000, pp. 78–87.
`‘‘Fourth Generation Wireless Networks and Interconnecting Standards,’’ IEEE Personal
`Commun. Mag., (special issue), Vol. 8, No. 5, October 2001.
`‘‘European R&D on Fourth-Generation Mobile and Wireless IP Networks,’’ IEEE
`Personal Commun. Mag., (special issue), Vol. 8, No. 6, December 2001.
`‘‘Mobile Initiatives and Technologies,’’ IEEE Commun. Mag., (special issue), Vol. 40,
`No. 3, March 2002.
`‘‘Technologies for 4G Mobile,’’ IEEE Wireless Commun., Vol. 9, No. 2, April 2002.
`[19]
`[20] Mohr, W., ‘‘Heterogeneous Networks to Support User Needs with Major Challenges
`for New Wideband Access Systems,’’ Wireless Personal Communications (Kluwer),
`Vol. 22, No. 2, August 2002, pp. 109–137.
`[21] Nakagawa, H., ‘‘Vision in WP8F and Activity in Japan for Future Mobile Communica-
`tion System,’’ Strategic Workshop 2002 Unified Global Infrastructure, Prague, Czech
`Republic, September 6–7, 2002.
`[22] ARIB FPLMTS Study Committee, ‘‘Report on FPLMTS Radio Transmission Tech-
`nology Special Group (Round 2 activity report),’’ Draft v.E1.1, January 1997.
`
`[16]
`
`[17]
`
`[18]
`
`
`
`TEAMFLY
`
`Team-Fly®
`
`
`
`2 C
`
`haracteristics of Multipath Fading
`Channels
`
`2.1 Introduction
`
`Radio propagation characterization is the bread and butter of communica-
`tions engineers. Without knowledge of radio propagation, a wireless system
`could never be developed. Radio engineers have to acquire full knowledge
`of the channel if they want to be successful in designing a good radio
`communication system [1]. Therefore, knowledge of radio propagation char-
`acteristics is a prerequisite for designing radio communication systems.
`A lot of measurements have been done to obtain information concerning
`multipath fading channels. Reference [2] has presented a good overview of
`this topic. Detailed discussions on characteristics of multipath fading channels
`can be found in [3–8]. This chapter shows the essence in the literature.
`This chapter is organized as follows. Multipath fading is due to
`multipath reflections of a transmitted wave by local scatterers such as houses,
`buildings, and man-made structures, or natural objects such as forest sur-
`rounding a mobile unit. The probability density function of the received
`signal follows a Rayleigh or Ricean distribution. Section 2.2 presents the
`Rayleigh and Ricean fading channels, and multipath delay profile is discussed
`in Section 2.3. The wireless channel is defined as a link between a transmitter
`and a receiver and classified considering the coherence bandwidth and coher-
`ence time. Accordingly, a wireless channel can be frequency selective or
`frequency nonselective (explained in Section 2.4) and time selective or time
`
`13
`
`
`
`14
`
`Multicarrier Techniques for 4G Mobile Communications
`
`nonselective (described in Section 2.6). Section 2.5 briefly introduces the
`spaced-time correlation function.
`
`2.2 Rayleigh and Ricean Fading Channels
`
`Figure 2.1 shows a typical multipath fading channel often encountered in
`wireless communications, where there are L paths. Assume the transmitted
`signal is given by
`
`x (t ) = Re [s (t ) e j2f C t ]
`
`(2.1)
`
`where s (t ) is the equivalent baseband form of x (t ) and f C is a carrier frequency.
`In addition, Re [*] denotes the real part of * (Im [*] denotes the imaginary
`part of *).
`Through the multipath fading channel,
`written as
`
`the received signal
`
`is
`
`y (t ) = ∑L
`␣l (t ) x (t − l (t ))
`l =1
`= Re冤∑L
`
`␣l (t ) e
`
`l =1
`
`(2.2)
`
`(t) s (t − l (t )) e j2f C t冥
`
`l
`
`−j2f C
`
`where ␣l (t ) and l (t ) are the complex-valued channel loss (or gain) and
`real-valued time delay for the l th path, both of which can be modeled as
`
`Figure 2.1 Example of a multipath fading channel.
`
`
`
`Characteristics of Multipath Fading Channels
`
`15
`
`stochastic processes. Then,
`written as
`
`the equivalent baseband form of y (t )
`
`is
`
`(2.3)
`
`(t) s (t − l (t ))
`
`l
`
`−j2f C
`
`␣l (t ) e
`
`h (; t ) s (t − ) d
`
`r (t ) = ∑L
`l =1
`= 冕+∞
`
`−∞
`
`where h (; t ) is the equivalent baseband impulse response of the multipath
`fading channel at instant t , which is given by
`h (; t ) = ∑L
`l =1
`
`(t) ␦(t − l (t ))
`
`(2.4)
`
`l
`
`−j2f C
`
`␣l (t ) e
`
`Assume that the transmitted signal is a continuous wave (CW) with
`frequency of f C . In this case, if setting s (t ) = 1 in (2.3), the received signal
`is written as
`
`(2.5)
`
`(2.6)
`
`(t)
`
`l
`
`−j2f C
`
`␣l (t ) e
`
`l (t )
`
`r (t ) = ∑L
`l =1
`= ∑L
`l =1
`
`(t)
`
`l
`
`−j2f C
`
`l (t ) = ␣l (t ) e
`
`where l (t ) is a complex-valued stochastic process.
`Equation (2.5) clearly shows that the received signal is the sum of
`stochastic processes, so when there are a large number of paths, the central
`limiting theorem can be applied. That is, r (t ) can be modeled as a complex-
`valued Gaussian stochastic process with its average and variance given by
`
`r = 1
`avr = E [r (t )], 2
`2
`
`E [r *(t ) r (t )]
`
`(2.7)
`
`therefore, the probability density function (p.d.f.) of r = r (t ) is given by
`
`
`
`16
`
`Multicarrier Techniques for 4G Mobile Communications
`
`p (r ) =
`
`1
`22
`r
`
`e
`
`− (r − avr )*(r − avr )
`22
`r
`
`Furthermore, defining the envelope and phase of r (t ) as
`(t ) = | r (t )| , (t ) = arg r (t )
`
`the joint p.d.f. of = (t ) and = (t ) is given by
`
`(2.8)
`
`(2.9)
`
`p (, ) =
`22
`r
`=
`22
`r
`
`e
`
`e
`
`− 1
`22
`r
`
`[(cos − aI )2 + (sin − aQ )2 ]
`
`(2.10)
`
`− 2 + A 2
`22
`r
`
`(aI cos + aQ sin )
`22
`r
`
`e
`
`where
`
`aI = Re [avr ], aQ = Im [avr ]
`A = | avr |
`
`Averaging (2.10) in terms of , the p.d.f. of is given by
`
`p() = 冕2
`
`p(, ) d
`
`0
`=
`2
`r
`
`I0冉A
`
`2
`r
`
`冊 e
`
`− 2 + A 2
`, (> 0)
`22
`r
`
`(2.11)
`
`(2.12)
`
`(2.13)
`
`where I0 (x ) is the zero th order modified Bessel function of the first kind,
`which is defined as
`
`2冕2
`
`I0 (x ) = 1
`
`0
`
`e x cos d
`
`(2.14)
`
`The p.d.f. of the envelope given by (2.13) is called the Rice distribution
`[3]. Especially, in (2.13),
`
`
`
`Characteristics of Multipath Fading Channels
`
`17
`
`K = A 2
`22
`r
`
`(2.15)
`
`is called ‘‘the Ricean K factor.’’
`When r (t ) can be modeled as a zero average complex-valued Gaussian
`stochastic process, that is, A = 0 in (2.13), the p.d.f. of is given by
`− 2
`r , (> 0)
`22