Signal Processing Applications in CDMA Communications (Artech House Mobile Communications Series)

210 Pages·2000·8.43 MB·English

by  Hui Liu

Signal Processing Applications
in CDMA Communications
For a listing of recent titles in the Artech House Mobile Communications Series,
turn to the back of this book.
Signal Processing Applications
in CDMA Communications
Hui Liu
Artech House
Boston London
Library of Congress Cataloging-in-Publication Data
Liu, Hui.
Signal processing applications in CDMA communications / Hui Liu.
p. cm. - (Artech House mobile communications series)
Includes bibliographical references and index.
ISBN 1-58053-042-7 (alk. paper)
1. Code division multiple access. 2. Signal processing. 3. Broadband
communication systems. 4. Mobile communication systems. I. Title. 11. Series.
TK5 103.452. L58 2000 99-0895 13
621.3845-dc21 CIP
British Library Cataloguing in Publication Data
Liu, Hui
Signal processing applications in CDMA communications. -
(Artech House mobile communications series)
1. Code division multiple access 2. Wireless communication
systems 3. Signal processing
I. Title
621.3’845
ISBN 1-58053-042-7
Cover design by Jennifer Stuart
0 2000 ARTECH HOUSE, INC.
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Norwood, MA 02062
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International Standard Book Number: 1-58053-042-7
Library of Congress Catalog Card Number: 99-0895 13
10987654321
Contents
Preface ix
1 CDMA Fundamentals 1
1.1 Spread Spectrum . . . . . . . . . . . . . . . . . . . . . . 3
1.1.1 Direct-Sequence Spread Spectrum . . . . . . . . 3
1.1.2 Frequency-Hopping Spread Spectrum . . . . . . 6
1.2 Code-Division Multiple- Access (CDMA) . . . . . . . . . 7
1.2.1 CDMA Receivers . . . . . . . . . . . . . . . . . . 11
1.3 Classifications . . . . . . . . . . . . . . . . . . . . . . . . 12
1.3.1 Short Codes Versus Long Codes . . . . . . . . . 13
1.3.2 Narrowband Versus Wideband . . . . . . . . . . 14
1.4 Spatial Diversity . . . . . . . . . . . . . . . . . . . . . . 19
1.5 Scope of This Book . . . . . . . . . . . . . . . . . . . . . 21
2 CDMA With Short Codes: Direct Approaches 25
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.2 Constrained Optimization . . . . . . . . . . . . . . . . . 27
2.3 Decorrelating RAKE Receivers . . . . . . . . . . . . . . 32
2.3.1 Constrained MOE . . . . . . . . . . . . . . . . . 33
2.3.2 Adaptive Implementation . . . . . . . . . . . . . 37
2.4 Performance Analysis . . . . . . . . . . . . . . . . . . . 38
2.4.1 Receiver Optimality . . . . . . . . . . . . . . . . 38
2.4.2 Steady-State Behavior . . . . . . . . . . . . . . . 41
2.5 Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 42
2.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . 46
V
vi Signal Processing Applications in CDMA Communications
3 CDMA With Short Codes: Indirect Approaches 49
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 49
3.2 Channel Parameter Estimation . . . . . . . . . . . . . . 51
3.2.1 Subspace Concept . . . . . . . . . . . . . . . . . 52
3.2.2 Closed-Form Estimation . . . . . . . . . . . . . . 53
3.2.3 Overloaded Systems . . . . . . . . . . . . . . . . 55
3.2.4 Performance Analysis . . . . . . . . . . . . . . . 56
3.3 Joint Channel and Carrier Estimation . . . . . . . . . . 61
3.3.1 Problem Reformulation . . . . . . . . . . . . . . 63
3.3.2 Decoupling and Closed-Form Solution . . . . . . 66
3.3.3 Perforniance Analysis . . . . . . . . . . . . . . . 69
3.4 Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 72
3.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . 73
Appendix 3A: The Existence and Calculation of G(x) . . . . 76
Appendix 3B: First and Second Order Derivatives of the
J(4,h,U ,) . . . . . . . . . . . . . . . . . . . . . . . . . 78
4 CDMA With Long Codes: Space-Time Processing 81
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 81
4.2 Uplink . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
4.2.1 Space-Time Receivers . . . . . . . . . . . . . . . 85
4.2.2 Blind 2D Reception . . . . . . . . . . . . . . . . 90
4.2.3 Examples . . . . . . . . . . . . . . . . . . . . . . 93
4.3 Downlink . . . . . . . . . . . . . . . . . . . . . . . . . . 101
4.3.1 Constrained Equalization . . . . . . . . . . . . . 1 03
4.3.2 Adaptive Implementation . . . . . . . . . . . . . 1 07
4.3.3 Examples . . . . . . . . . . . . . . . . . . . . . . 112
4.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . 117
5 Multicarrier CDMA 121
5.1 MC-CDMA Overview . . . . . . . . . . . . . . . . . . . 1 22
5.1.1 Multicarrier and OFDM . . . . . . . . . . . . . . 1 22
5.1.2 MC-CDMA . . . . . . . . . . . . . . . . . . . . . 126
5.1.3 MC Direct-Sequence CDMA . . . . . . . . . . . 1 30
5.1.4 Multitone-CDMA . . . . . . . . . . . . . . . . . 1 34
5.2 Channel and Carrier Offset Estimation . . . . . . . . . . 1 34
Con tents vii
5.3 Enabling Codes in MC-DS-CDMA . . . . . . . . . . . .1 37
5.4 Carrier Sensitivity Analysis . . . . . . . . . . . . . . . .1 41
5.4.1 SINR Degradation . . . . . . . . . . . . . . . . .1 43
5.5 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 148
5.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . 156
6 Space-Division Multiple- Access 161
6.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . 162
6.2 Antenna Array Packet Networks . . . . . . . . . . . . . 1 64
6.2.1 Conventional Spatial-Division Multiple-Access . 166
6.3 Scheduling Protocol . . . . . . . . . . . . . . . . . . . . 170
6.3.1 Terminal Allocation . . . . . . . . . . . . . . . . 1 70
6.3.2 Slot Adjustment . . . . . . . . . . . . . . . . . . 173
6.4 Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
6.4.1 Upper-Bound and Lower-Bound . . . . . . . . . 1 76
6.4.2 Asymptotic Optimality . . . . . . . . . . . . . . 1 78
6.5 Performance Evaluation . . . . . . . . . . . . . . . . . . 1 81
6.5.1 Finite Population With Bursty Traffic . . . . . . 1 81
6.5.2 Infinite Population With Poisson Traffic . . . . . 1 84
6.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . 186
About the Author 189
Index 191
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Preface
An ideal wireless system provides a unified bandwidt h-on-demand
platform to support a high user population with mixed traffic and dif-
ferent quality-of-service requirements. Code-division mult iple-access
(CDMA) is seen as one of the generic signal-access strategies for wire-
less communications. In addition to many existing applications in
mobile telephony, wireless local loops (WLL), and wireless local-area
networks (WLAN), CDMA is also positioning itself to become a ma-
jor player for t hird-generation personal communication services (PCS)
mobile systems.
Signal processing plays a central role in solving many key problems
in CDMA, such as diversity combining, multiuser detection, channel
estimation, and carrier synchronization. Advances in these areas have
received increasing attention in both the wireless communication and
signal processing communities. This book is a result of several R&D
projects I have been involved in during the past few years. The sig-
nal processing methodologies described here target generic wideband
CDMA problems in a mobile fading environment. With many books
on CDMA focusing on the IS-95 standard, this one should have appeal.
The book consists of six chapters. Chapter 1 provides a preamble
that puts the material in subsequent chapters in perspective. Spread
spectrum, multiple-access, and different classes of CDMA are included.
The chapter highlights some well-known CDMA schemes and discusses
their advantages and drawbacks. Readers with a good background on
CDMA can skip this part. The chapter also lays the groundwork for
subsequent chapters by discussing fading channels, diversity, interfer-
ence, and other critical issues in CDMA communications. A unified
ix