Parsons, DSc Eng, FREng, FIEE Emeritus Professor of Electrical Engineering University of Liverpool, UK JOHN WILEY & SONS LTD Chichester ´ New York ´ Weinheim ´ Brisbane ´ Singapore ´ Tor
Trang 1The Mobile Radio Propagation Channel
Copyright & 2000 John Wiley & Sons Ltd Print ISBN 0-471-98857-X Online ISBN 0-470-84152-4
Trang 2The Mobile Radio
Propagation Channel
Second Edition
J D Parsons, DSc (Eng), FREng, FIEE
Emeritus Professor of Electrical Engineering
University of Liverpool, UK
JOHN WILEY & SONS LTD
Chichester ´ New York ´ Weinheim ´ Brisbane ´ Singapore ´ Toronto
The Mobile Radio Propagation Channel Second Edition J D Parsons
Copyright & 2000 John Wiley & Sons Ltd Print ISBN 0-471-98857-X Online ISBN 0-470-84152-4
Trang 3First Edition published in 1992 by Pentech Press
Copyright & 2000 by John Wiley & Sons, Ltd
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Library of Congress Cataloging-in-Publication Data
Parsons, J.D (John David)
The mobile radio propagation channel/J.D Parsons ± 2nd ed.
p cm.
Includes bibliographical references and index.
ISBN 0-471-98857-X (alk paper)
1 Mobile radio stations 2 Radio ± Transmitters and transmission 3 Radio wave
propagation I Title
TK6570.M6 P38 2000
621.3845 ± dc21 00-032482
British Library Cataloguing in Publication Data
A catalogue record for this book is available from the British Library
ISBN 0 471 98857 X
Typeset in 10/12pt Times by Dobbie Typesetting Limited, Devon
Printed and bound in Great Britain by Bookcraft (Bath) Ltd.
This book is printed on acid-free paper responsibly manufactured from sustaintable forestry,
in which at least two trees are planted for each one used for paper production.
Copyright & 2000 John Wiley & Sons Ltd Print ISBN 0-471-98857-X Online ISBN 0-470-84152-4
Trang 4To my wife, Mary
and in memory of my parents
Doris and Oswald
The Mobile Radio Propagation Channel Second Edition J D Parsons
Copyright & 2000 John Wiley & Sons Ltd Print ISBN 0-471-98857-X Online ISBN 0-470-84152-4
Trang 5Preface xv
Preface to the ®rst edition xvii
1 Introduction 1
1.1 Background 1
1.2 Frequency bands 4
1.2.1 VLF 5
1.2.2 LF and MF 5
1.2.3 HF 6
1.2.4 VHF and UHF 6
1.2.5SHF 6
1.2.6 EHF 7
1.3 Mobile radio frequencies 8
1.3.1 Radio links 9
1.3.2 Area coverage 10
1.4 Postscript 13
References 14
2 Fundamentals of VHF and UHF Propagation 15
2.1 Introduction 15
2.2 Propagation in free space 16
2.3 Propagation over a re¯ecting surface 18
2.3.1 The re¯ection coecient of the Earth 18
2.3.2 Propagation over a curved re¯ecting surface 21
2.3.3 Propagation over a plane re¯ecting surface 22
2.4 Ground roughness 24
2.5The eect of the atmosphere 26
2.5.1 Atmospheric ducting and non-standard refraction 29
References 31
3 Propagation over Irregular Terrain 32
3.1 Introduction 32
3.2 Huygens' principle 33
3.3 Diraction over terrain obstacles 34
Copyright & 2000 John Wiley & Sons Ltd Print ISBN 0-471-98857-X Online ISBN 0-470-84152-4
Trang 63.3.1 Fresnel-zone ellipsoids 36
3.3.2 Diraction losses 37
3.4 Diraction over real obstacles 41
3.4.1 The uniform theory of diraction 42
3.5Multiple knife-edge diraction 46
3.5.1 Bullington's equivalent knife-edge 47
3.5.2 The Epstein±Peterson method 47
3.5.3 The Japanese method 49
3.5.4 The Deygout method 5 0 3.5.5 Comparison 5 0 3.6 Path loss prediction models 5 2 3.6.1 The Egli model 5 3 3.6.2 The JRC method 5 4 3.6.3 The Blomquist±Ladell model 5 6 3.6.4 The Longley±Rice models 5 6 3.6.5CCIR methods 60
3.6.6 Other methods 62
3.7 Discussion 64
References 68
4 Propagation in Built-up Areas 71
4.1 Introduction 71
4.2 Built-up areas: a classi®cation problem 72
4.2.1 A classi®cation approach 73
4.2.2 Classi®cation methods: a brief review 74
4.3 Propagation prediction techniques 77
4.3.1 Young's measurements 77
4.3.2 Allsebrook's method 79
4.3.3 The Okumura method 81
4.3.4 The Ibrahim and Parsons method 88
4.3.5The Wal®sch±Bertoni method 91
4.3.6 Other models 95
4.4 Microcellular systems 101
4.4.1 Microwave measurements 102
4.4.2 UHF measurements 105
4.4.3 Microcellular modelling 107
4.5Discussion 110
References 111
5Characterisation of Multipath Phenomena 114
5.1 Introduction 114
5.2 The nature of multipath propagation 116
5.3 Short-term fading 119
5.3.1 The scattering model 120
5.4 Angle of arrival and signal spectra 122
5.5 The received signal envelope 125
5.6 The received signal phase 127
Trang 75.7 Baseband power spectrum 128
5 8 LCR and AFD 130
5.9 The PDF of phase dierence 134
5.10 Random FM 136
5.11 Rician fading 139
5.12 Spatial correlation of ®eld components 140
5.12.1 Cross-correlation 142
5.13 The signal received at the base station 144
5.13.1 Vertically separated antennas 146
5.13.2 Horizontally separated antennas 147
5.14 The magnetic ®eld components 15 0 5.15 Signal variability 15 2 5.15.1 Statistics of the fast fading 15 3 5.15.2 Statistics of the local mean 15 5 5.15.3 Large area statistics 15 5 References 162
6 Wideband Channel Characterisation 164
6.1 Introduction 164
6.2 Frequency-selective fading 165
6.2.1 Channel characterisation 166
6.3 Characterisation of deterministic channels 167
6.3.1 The time domain function 168
6.3.2 The frequency domain function 169
6.3.3 The time-variant transfer function 169
6.3.4 The delay/Doppler-spread function 170
6.3.5Relationships between system functions 171
6.4 Randomly time-variant linear channels 172
6.4.1 Channel correlation functions 172
6.4.2 Relationships between the functions 173
6.5Classi®cation of practical channels 174
6.5.1 The wide-sense stationary channel 174
6.5.2 The uncorrelated scattering channel 175
6.5.3 The WSSUS channel 177
6.6 Channel characterisation using the scattering function 178
6.6.1 The point scatterer description 179
6.6.2 Statistical point scatterer model 180
6.6.3 The scattering function 181
6.7 Mobile radio channel characterisation 184
6.7.1 Small-scale channel characterisation 185
6.7.2 Large-scale channel characterisation 188
References 189
7 Other Mobile Radio Channels 190
7.1 Introduction 190
7.2 Radio propagation into buildings 191
7.3 Propagation inside buildings 195
Trang 87.3.1 Propagation characteristics 196
7.3.2 Wideband measurements 199
7.4 Ray tracing: a deterministic approach 203
7.5Radio propagation in tunnels 210
7.6 Propagation in rural areas 211
7.6.1 Introduction 211
7.6.2 Signal statistics 212
7.6.3 Small-scale signal variations: statistical modelling 215
References 218
8 Sounding, Sampling and Simulation 221
8.1 Channel sounding 221
8.2 Narrowband channel sounding 221
8.2.1 A practical narrowband channel sounder 223
8.3 Signal sampling 226
8.4 Sampled distributions 227
8.4.1 Sampling to obtain the local mean value 228
8.4.2 Sampling a Rayleigh-distributed variable 229
8.5Mean signal strength 229
8.5.1 Con®dence interval 230
8.6 Normalisation revisited 232
8.7 Wideband channel sounding 233
8.8 Wideband sounding techniques 234
8.8.1 Periodic pulse sounding 234
8.8.2 Pulse compression 235
8.8.3 Convolution matched-®lter 236
8.8.4 Swept time-delay cross-correlation 237
8.9 System requirements 239
8.9.1 Accuracy of frequency standards 241
8.9.2 Phase noise in signal sources 242
8.10 A practical sounder design 242
8.10.1 Data processing 243
8.11 Experimental data processing 246
8.11.1 Frequency domain characterisation 247
8.11.2 Large-scale characterisation 248
8.11.3 Summary 248
8.12 Radio channel simulation 248
8.12.1 Hardware simulation of narrowband channels 249
8.13 Wideband channels 25 3 8.13.1 Software simulation 25 3 8.13.2 Hardware simulation 25 7 References 261
9 Man-made Noise and Interference 263
9.1 Introduction 263
9.2 Characterisation of pulses 265
9.2.1 Spectrum amplitude of a rectangular pulse 265
Trang 99.2.2 Impulse generators 267
9.3 Characterisation of impulsive noise 267
9.3.1 Measurement parameters 267
9.4 Measuring equipment 270
9.4.1 Bandwidth 273
9.4.2 Dynamic range 273
9.4.3 Receiver sensitivity and noise ®gure 274
9.4.4 Impulse response 274
9.5Practical measuring systems 275
9.5.1 Measurement of amplitude probability distribution 276
9.5.2 Measurement of noise amplitude distribution 278
9.6 Impulsive noise measurements 280
9.7 Discussion 286
9.8 Performance prediction techniques 287
9.8.1 Assessment of receiver performance using APD 288
9.8.2 Assessment of receiver performance using NAD 289
9.9 Interference 295
9.9.1 Single interferer 298
9.9.2 Multiple interferers 299
References 304
10 Mitigation of Multipath Eects 307
10.1 Introduction 307
10.2 Diversity reception 307
10.3 Basic diversity methods 308
10.3.1 Selection diversity 311
10.3.2 Maximal ratio combining 312
10.3.3 Equal-gain combining 313
10.4 Improvements from diversity 315
10.4.1 Envelope probability distributions 315
10.4.2 LCR and AFD 317
10.4.3 Random FM 320
10.5Switched diversity 321
10.6 The eect of diversity on data systems 322
10.7 Practical diversity systems 325
10.8 Post-detection diversity 325
10.8.1 Uni®ed analysis 328
10.9 Time diversity 328
10.10 Diversity on hand-portable equipment 330
10.11 Discussion and conclusions 335
10.12 Interleaving 335
10.13 Channel equalisation 337
10.13.1 Adaptive equalisers 337
10.14 Non-linear equalisers 338
10.14.1 Decision feedback equalisers 339
10.14.2 MLSE Viterbi equaliser 339
10.15Channel coding 341
Trang 1010.15.1 Linear block codes 342
10.15.2 Convolutional codes 344
10.16 Codes for fading channels 344
10.16.1 Performance of codes in fading channels 345
10.17 Speech coding 347
10.17.1 Sub-band coders 347
10.17.2 Pulse-excited coders 348
10.18 The RAKE receiver 348
10.19 Smart antennas 35 0 10.19.1 Considerations and possibilities 35 1 10.20 Wideband modulation: the alternative 35 5 10.20.1 Mitigation bandwidth 35 6 References 35 9 11 Planning Radio Networks 362
11.1 Introduction 362
11.2 Cellular systems 363
11.2.1 Interference considerations 366
11.3 Radio coverage 369
11.3.1 Coverage of a small area 369
11.3.2 Coverage area of a base station 371
11.4 Planning tools 373
11.4.1 Self-regulating networks 379
11.5A modelling and survey analysis module 379
11.5.1 Data preparation 380
11.5.2 Model calibration 380
11.5.3 Developing a model 382
11.5.4 Limits on coecients 384
11.5.5 Microcell model 384
11.6 Grade of service 384
11.6.1 Milli-erlangs per subscriber 385
11.7 Summary and review 386
11.7.1 Cell site dimensioning 386
11.7.2 Base station site planning 388
11.7.3 Frequency planning 388
11.7.4 Outputs of planning 392
11.7.5Conclusion 392
11.8 A design example 392
11.9 The future 395
11.9.1 A UMTS planning tool 396
11.9.2 Ray tracing models 399
References 401
Appendices 403
A Rayleigh Graph Paper and Receiver Noise Figure 403
B Rayleigh Distribution (dB) and CNR in a Rayleigh Fading Environment 405
Trang 11C Deriving PDFs for Variables in Logarithmic Units 407
D Eective Signal Envelope 411Index 413
Trang 12Some time ago it became apparent that the ®rst edition of this book was rapidlyapproaching its sell-by date, since many aspects needed revision There were twoobvious courses of action: to forget the whole thing and concentrate my energies onother pursuits such as golf or ®shing, or to embark on a new edition For severalreasons I was persuaded that a new edition was a worthwhile endeavour;manypeople had made complimentary remarks or written complimentary letters about the
®rst edition and I understood that it had become a recommended text for severalpostgraduate courses The independent reviewers who had been contacted by thepublisher were also very kind;they were unanimous in their opinion that thestructure of the book should remain unchanged and that its appeal might bejeopardised by attempting to make it much more system oriented This is not to say,
of course, that there was no need for updating and the inclusion of some newmaterial This was very much in line with my own thinking, so I was happy to acceptthat advice And so, work began
Soon after I started, it became obvious that major scrutiny, rather than minorattention, was needed Of course there were some sections covering basic and well-established theory which only needed small amendments, but I have revisited everyparagraph of the original book to correct errors, to improve the explanation and toprovide further clari®cation In most of the chapters I have updated parts that were
in need of such action and I have added several new sections, particularly in Chapter
4 A section on ray tracing has been added to Chapter 7, and in Chapter 8 I haveextensively revised the sections describing practical channel sounders The emphasis
in Chapter 9 has changed;I have considerably shortened the sections on man-madenoise measurements and I have extended the sections on how to predict systemperformance in the presence of man-made noise At one stage I was tempted to be farmore ruthless in cutting this chapter, since noise is not the limiting factor in cellularradio systems, but in the end I decided to stick to my original theme and not beconstrained by considerations of one type of system, important though it may be.The really major change, however, is the addition of two new chapters at the end
of the book I realised that throughout the ®rst edition I had emphasised the waymultipath in¯uences system performance yet I had not described how to mitigate itsdeleterious eects Chapter 10 is an attempt to correct that omission, withoutstraying too far from the main theme and getting very system-speci®c Again, having
The Mobile Radio Propagation Channel Second Edition J D Parsons
Copyright & 2000 John Wiley & Sons Ltd Print ISBN 0-471-98857-X Online ISBN 0-470-84152-4
Trang 13said that cellular systems are not the whole of mobile radio, it is dicult tooveremphasise their importance in the modern world, and this led to Chapter 11 onsystem planning Much of Chapter 11 is applicable beyond cellular radio-telephonesystems, so I hope it will prove useful I have been considerably constrained by myown thoughts about the total length of the book, so again I have gone into detailonly on those aspects of planning connected with the main theme.
Once again there are several people who have contributed to the book, directly orindirectly To those mentioned in the preface to the ®rst edition I must add severalnew names Andrew Arowojolu, formerly at the University of Liverpool, but now atFresh®eld Communications, has been most helpful He, and my friend AdelTurkmani, devoted many hours to a discussion of radio planning tools and providedboth information and sound advice The same must be said for Robin Potter andClaes Malmberg of MSI plc;they willingly gave of their time and expertise,particularly in connection with 3D propagation modelling and UMTS planning.George Tsoulos has been extremely helpful with regard to smart antennas, and onDS/SS signalling and associated concepts there is nobody better to contact thanFrank Amoroso My former students Chi Nche and Gary Davies designed and builtchannel sounders for their own research work and I am pleased to acknowledge theircontribution Paul Leather wrote an award-winning doctoral thesis on diversity forhand-portable equipment and was pleased to allow a brief extract from that work to
be included The assistance of all these people has considerably enhanced the book inmany ways Jane Bainbridge and Alison Reid were enormously helpful with theillustrations and typing new sections of the manuscript;I am in their debt
My greatest thanks, however, must go to my wife, Mary, whose love,encouragement and understanding have been constant and unwavering She has,once again, put up with my `eat and run' existence for several months when, in allhonesty, following my retirement from the university, she might have hoped for, andcertainly deserved, something better Never mind ± there's always tomorrow!
David Parsons
Trang 14Preface to the First Edition
Although the demand for mobile radio services has continued to increase for manyyears, research into mobile radio, as distinct from the development of systems tomeet speci®c operational and economic requirements, was a minority activity on aninternational scale until the mid-1960s However, about that time it became apparentthat the contribution that civil land mobile radio could make to national economieswas very large Furthermore it was obvious that existing systems had reached thelimits of development that could be supported by the relatively unsophisticatedtechnology of the day These factors, amongst others, made it obvious that a majorstrategic research eort was justi®ed and the results of that research are nowapparent in all the developed countries of the world Policemen, taxi-drivers andsecurity guards all have individual pocket radios, the general public have access toworld-wide telephone services via hand-held and vehicle-borne cellular radiotransceivers and pan-European digital systems using wideband TDMA techniquesare but a year or two away
Of all the research activities that have taken place over the years, those involvingcharacterisation and modelling of the radio propagation channel are amongst themost important and fundamental The propagation channel is the principalcontributor to many of the problems and limitations that beset mobile radiosystems One obvious example is multipath propagation which is a majorcharacteristic of mobile radio channels It is caused by diraction and scatteringfrom terrain features and buildings; it leads to distortion in analogue communicationsystems and severely aects the performance of digital systems by reducing thecarrier-to-noise and carrier-to-interference ratios A physical understanding andconsequent mathematical modelling of the channel is very important because itfacilitates a more accurate prediction of system performance and provides themechanism to test and evaluate methods for mitigating deleterious eects caused bythe radio channel
This book is an attempt to bring together basic information about the mobileradio channel, some of which has hitherto only been available in published technicalpapers The initial concept was that of a fairly slim volume but as the workprogressed, so it grew Even so, the eventual decisions that had to be made weremore concerned with what to leave out rather than what to include!
The Mobile Radio Propagation Channel Second Edition J D Parsons
Copyright & 2000 John Wiley & Sons Ltd Print ISBN 0-471-98857-X Online ISBN 0-470-84152-4
Trang 15The ®rst two chapters are introductory in nature and attempt to establish thecontext in which the subject is to be treated We then move on to propagation overirregular terrain in Chapter 3 and introduce some of the well-known path-lossprediction models Chapter 4 deals with the problem of urban areas and introduces anumber of prediction models that have been speci®cally developed with the urbanarea in mind.
Multipath has already been mentioned as a principal feature of mobile radiochannels and the characterisation of multipath phenomena is a central topic.Chapter 5 deals with so-called narrowband channels although it must be emphasisedthat it is the signal that is narrowband, not the channel! In truth, Chapter 5 provides
a characterisation which is adequate when frequency-selective fading is not aproblem, whilst frequency-selective (wideband) channels are the subject of Chapter
6 Mathematically speaking, these are the `heaviest' chapters although I haveattempted to emphasise physical understanding rather than mathematic rigour.The conventional elevated base station communicating with vehicle-borne radiotransceivers is, nowadays, not the only radio scenario of importance Hand-portableequipment is commonplace and can be taken into buildings and Chapter 7 is whereproblems such as this are addressed
Chapter 8 is exactly what it's title says At one stage in the writing process itseemed to be in danger of becoming a `rag-bag' of unrelated topics, but I hope thatultimately it will prove to be useful Several more practical issues are discussed,without which the treatment would be incomplete Finally, Chapter 9 covers noiseand interference, the latter being a very important topic in the context of current andfuture cellular systems where frequency re-use is a premier consideration
There are several people who have contributed directly or indirectly to the writing
of this book My own interest in mobile communications was ®rst aroused byProfessor Ramsay Shearman, over 20 years ago and he has been a source of constantencouragement, particularly so in the early part of my academic career My ownresearch students have taught me much (`teachers teach and students learn' is a half-truth) and in the context of this book it is appropriate for me to mention AnwarBajwa, Mohamed Ibrahim, Andy Demery and Tumu Kafaru who have allowed me
to draw freely on their work The same can be said for my colleague and friend AdelTurkmani who has, in addition, given generously of his time and expertise He hasadvised with regard to content, order of presentation and depth of treatment; I amtruly in his debt Likewise I owe much to my secretary Mrs Brenda Lussey who hastyped the manuscript (several times) and has incorporated modi®cations, secondthoughts and other alterations in her usual cheerful manner without so much as afrown of frustration or disapproval
Finally, this work would never have been completed without the encouragement,understanding and love of my wife, Mary She has put up, uncomplainingly, with myseemingly unending periods in my study both during the evenings and at weekends.She has been an unpaid coee-maker and proof-reader who relieved me of many ofthe less interesting jobs that befall the aspiring author Will Sundays ever be the sameagain?
David Parsons