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1 Ultra Wideband Signals and Systems in Communication Engineering M. Ghavami King s College London, UK L. B. Michael Japan R. Kohno Yokohama National University, Japan John Wiley & Sons, Ltd

3 Ultra Wideband Signals and Systems in Communication Engineering

5 Ultra Wideband Signals and Systems in Communication Engineering M. Ghavami King s College London, UK L. B. Michael Japan R. Kohno Yokohama National University, Japan John Wiley & Sons, Ltd

6 Copyright 2004 John Wiley & Sons, Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, England Telephone (for orders and customer service enquiries): Visit our Home Page on or 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, scanning or otherwise, except under the terms of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London W1T 4LP, UK, without the permission in writing of the Publisher. Requests to the Publisher should be addressed to the Permissions Department, John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, England, or ed to permreq@wiley.co.uk, or faxed to (+44) This publication is designed to provide accurate and authoritative information in regard to the subject matter covered. It is sold with 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. Other Wiley Editorial Offices John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, USA Jossey-Bass, 989 Market Street, San Francisco, CA , USA Wiley-VCH Verlag GmbH, Boschstr. 12, D Weinheim, Germany John Wiley & Sons Australia Ltd, 33 Park Road, Milton, Queensland 4064, Australia John Wiley & Sons (Asia) Pte Ltd, 2 Clementi Loop #02-01, Jin Xing Distripark, Singapore John Wiley & Sons (Canada) Ltd, 22 Worcester Road, Etobicoke, Rexdale, Ontario, Canada M9W 1L1 Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic books. British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library ISBN Typeset by the author using LaTex Software. Printed and bound in Great Britain by Antony Rowe, Chippenham, Wiltshire. This book is printed on acid-free paper responsibly manufactured from sustainable forestry in which at least two trees are planted for each one used for paper production.

7 Contents Preface xiii Acknowledgments xvii List of Figures xix List of Tables xxvii Introduction 1 I.1 Ultra wideband overview 1 I.2 A note on terminology 2 I.3 Historical development of UWB 2 I.4 Key benefits of UWB 3 I.5 UWB and Shannon s theory 4 I.6 Challenges for ultra wideband 5 I.7 Summary 6 1 Basic properties of UWB signals and systems Introduction Power spectral density Pulse shape 9 v

8 vi CONTENTS 1.4 Pulse trains Spectral masks Multipath Penetration characteristics Spatial and spectral capacities Speed of data transmission Cost Size Power consumption Summary 22 2 Generation of ultra wideband waveforms Introduction Damped sine waves Gaussian waveforms Orthogonal waveforms and Hermite pulses Hermite polynomials Orthogonal modified Hermite pulses Modulated and modified Hermite pulses Orthogonal prolate spheroidal wave functions Introduction Fundamentals of PSWF PSWF pulse generator Designing waveforms for specific spectral masks Introduction Multi-band modulation Practical constraints and effects of imperfections Summary 59 3 Signal-processing techniques for UWB systems The effects of lossy medium on an UWB transmitted signal Time domain analysis Classification of signals Some useful functions Some useful operations Classification of systems 76

9 CONTENTS vii Impulse response Distortionless transmission Frequency domain techniques Fourier transforms Frequency response approaches Transfer function Laplace transform z-transform The relationship between the Laplace transform, the Fourier transform, and the z-transform UWB signal-processing issues and algorithms Detection and amplification Summary 93 4 Ultra wideband channel modeling A simplified UWB multipath channel model Number of resolvable multipath components Multipath delay spread Multipath intensity profile Multipath amplitude-fading distribution Multipath arrival times Path loss model Free space loss Refraction Reflection Diffraction Wave clutter Aperture-medium coupling loss Absorption Example of free space path loss model Two-ray UWB propagation model Two-ray path loss Two-ray path loss model Impact of path loss frequency selectivity on UWB transmission 117

10 viii CONTENTS 4.4 Frequency domain autoregressive model Poles of the AR model Summary Ultra wideband communications Introduction UWB modulation methods Pulse position modulation Bi-phase modulation Other modulation methods Orthogonal pulse modulation Pulse amplitude modulation On-off keying Summary of UWB modulation methods Pulse trains Gaussian pulse train PN channel coding Time-hopping PPM UWB system UWB transmitter UWB receiver Detection Pulse integration Tracking Rake receivers Multiple access techniques in UWB Frequency division multiple access UWB Time division multiple access Code division multiple access Orthogonal pulse multiple access system Capacity of UWB systems Comparison of UWB with other wideband communication systems CDMA Comparison of UWB with DSSS and FHSS Orthogonal frequency division multiplexing Interference Wireless local area networks 154

11 CONTENTS ix Bluetooth GPS Cellular systems Summary Ultra wideband antennas and arrays Antenna fundamentals Maxwell s equations for free space Wavelength Antenna duality Impedance matching VSWR and reflected power Antenna bandwidth Directivity and gain Antenna field regions Antenna directional pattern Beamwidth Antenna radiation for UWB signals Dispersion due to near-field effects Suitability of conventional antennas for the UWB system Resonant antennas Nonresonant antennas Difficulties with UWB antenna design Impulse antennas Conical antenna Monopole antenna D-dot probe antenna TEM horn antenna Conclusion Beamforming for UWB signals Basic concepts A simple delay-line transmitter wideband array Radar UWB array systems Summary 191

12 x CONTENTS 7 Position and location with ultra wideband signals Wireless positioning and location Types of wireless positioning systems Wireless distance measurement Microwave positioning systems Global positioning system techniques Differential GPS (DGPS) GPS tracking modes GPS error sources Positioning techniques Introduction Network-based techniques Handset-based techniques Hybrid techniques Other techniques Time resolution issues Narrowband systems Wideband systems Super-resolution techniques Ultra wideband systems UWB positioning and communications Potential user scenarios Potential applications Summary Applications using ultra wideband systems Military applications Precision asset location system Commercial applications Time Domain PulsON Time Domain UWB signal generator XtremeSpectrum Intel corporation Motorola Communication Research Laboratory General atomics Wisair 228

13 CONTENTS xi Home networking and home electronics Precision asset location system Summary 233 References 235 Index 242

15 Preface In this book we focus on the basic signal processing that underlies current and future ultra wideband systems. By looking at signal processing in this way we hope this text will be useful even as UWB applications mature and change or regulations regarding ultra wideband systems are modified. The current UWB field is extremely dynamic, with new techniques and ideas being presented at every communications and signal-processing conference. The basic signal-processing techniques presented in this text though will not change for some time to come. Thus, we have taken a somewhat theoretical approach, which we believe is longer lasting and more useful to the reader in the long term than an up-to-the-minute summary that is out of date as soon as it is published. We restrict our discussion in general to ultra wideband communication, looking in particular at consumer communication. What we mean by this is that although there are many and varied specialized applications for UWB, particularly for the military, we assume that the majority of readers will either be in academia or in industry. In any case, as this is a basic text aimed primarily at the undergraduate or graduate student, these basics should stand readers in good stead in their efforts to understand more advanced papers and make a contribution in this field for themselves. We are painfully aware of the depth and breadth of this field and, regretfully, pass on interesting topics, such as UWB radar, including groundpenetrating radar, and most military applications. For the former there is already a great deal of information available, while for the latter most material is classified. xiii

Ultra Wideband Signals and Systems in Communication Engineering

Ultra Wideband Signals and Systems in Communication Engineering Second Edition M. Ghavami King's College London, UK L. B. Michael Japan R. Kohno Yokohama National University, Japan BICENTENNIAL 3 I CE