Table Of Content

Understanding Cellular Radio Understanding Cellular Radio William Webb Artech House Boston • London LibraryofCongressCataloging-in-PublicationData Webb,William,Dr. Understandingcellularradio/WilliamWebb. p. cm.—(ArtechHousemobilecommunicationslibrary) Includesbibliographicalreferencesandindex. ISBN0-89006-994-8 (alk.paper) 1.Cellularradio. I.Title. II.Series. TK6570.M6W43 1998 621.3845’6—dc21 98-2921 CIP BritishLibraryCataloguinginPublicationData Webb,William Understandingcellularradio—(ArtechHousemobilecommunicationslibrary) 1.Cellularradio I.Title 621.3’8456 ISBN0-89006-994-8 CoverillustrationbyEliCedrone ©1998ARTECHHOUSE,INC. 685CantonStreet Norwood,MA02062 Allrightsreserved.PrintedandboundintheUnitedStatesofAmerica.Nopartofthisbook may be reproduced or utilized in any form or by any means, electronic or mechanical, in- cludingphotocopying,recording,orbyanyinformationstorageandretrievalsystem,with- outpermissioninwritingfromthepublisher. Alltermsmentionedinthisbookthatareknowntobetrademarksorservicemarkshave beenappropriatelycapitalized.ArtechHousecannotattesttotheaccuracyofthisinforma- tion.Useofaterminthisbookshouldnotberegardedasaffectingthevalidityofanytrade- markorservicemark. InternationalStandardBookNumber:0-89006-994-8 LibraryofCongressCatalogCardNumber:98-2921 10987654321 Contents Preface xi Objectives xi Acknowledgments xii Part I Wireless Communications Systems 1 1 Introduction 3 1.1 Whyabooksimplyexplainingtechnicalaspects? 3 1.2 Scopeofmaterialcovered 4 1.3 Acronyms,abbreviations,andotherwaystomakeit 1.3 complicated 4 1.4 Howtoreadthisbook 5 1.5 Furtherreading 6 v vi Understanding Cellular Radio 2 Overview of a Cellular System 7 2.1 Introduction 7 2.2 Whyitiscalledcellular? 7 2.3 Systemoverview 9 3 Basic Cellular System Design 21 3.1 Introduction 21 3.2 Thescarcityofradiospectrum 22 3.3 Theuseofcellsasameanstoconservespectrum 27 3.4 Whyonechannelcanservemanyusers 31 3.5 Basicnetworkdesignprinciples 35 3.6 Connectingupthenetwork 41 3.6.1 Leasedlink 42 3.6.2 Microwavelinks 43 3.6.3 Satellitelinks 46 Part II Getting Calls to Moving Subscribers 49 4 Keeping Track of Where the Users Are 51 4.1 Introduction 51 4.2 Theconceptoflocationareas 51 4.3 Attachanddetach 53 4.4 Periodiclocationupdating 54 4.5 Themobileinacall 55 5 How Calls are Made Between Two Users 57 5.1 Introduction 57 5.2 Paging 57 5.3 Respondingtoapagingmessage 59 6 Hand-off 69 6.1 Themobileinacall 69 6.2 Handingthemobiletoanothercell 69 Contents vii 6.3 Cellselectioninidlemode 71 7 Network Management, Roaming, and Authentication 73 7.1 Networkmanagement 73 7.1.1 Monitoringthecorrectworkingofthenetwork 74 7.1.2 Deliveringnetworkstatistics 74 7.1.3 Changingnetworkconfiguration 75 7.1.4 Addinganddeletingsubscribers 75 7.1.5 Generatingbills 76 7.1.6 Monitoringfraud 77 7.1.7 Providingcustomercare 77 7.2 Internationalroaming 78 7.3 Authenticationandciphering 79 7.4 Callrouting 82 Part III Transmitting the Signal 85 8 Radio Propagation 87 8.1 Introduction 87 8.1.1 Distance-relatedattenuation 89 8.1.2 Slowfading 91 8.1.3 Fastfading 91 8.2 Widebandchannels 94 8.3 Predictingcellularcoverage 95 8.4 Sectorization 96 8.5 Microcellsandunderlay/overlaynetworks 98 9 Radio Systems 101 9.1 Fromspeechtoradiowaves 101 9.2 Speechcoding 102 9.3 Errorcorrectioncodingandinterleaving 106 9.4 Interleaving 110 9.5 Modulation 111 viii Understanding Cellular Radio 9.6 Frequencyhopping 112 9.6.1 Overcomingfading 112 9.6.2 Reducinginterference 114 9.7 Equalization 116 9.8 Multipleaccess 118 9.8.1 FDMA 120 9.8.2 TDMA 121 9.8.3 CDMA 123 9.8.4 CDMApowercontrol 132 9.9 Packetandcircuitswitching 133 10 TDMA or CDMA 137 10.1 Introductiontothedebate 137 10.2 AmoregenerallookatCDMAversusTDMA 138 10.2.1 Divisionofthefrequencies 140 10.2.2 Distributingtheinterference 140 10.2.3 MakingTDMAinterferencemoreeven 141 10.3 Comparisonofadvantagesanddisadvantages 142 10.3.1 Capacity 142 10.3.2 Greaterrange 143 10.3.3 Sectorization 143 10.3.4 Nofrequencyplanning 145 10.3.5 Macrocell/microcell 145 10.3.6 Risk 147 10.3.7 Cost 147 10.3.8 Bandwidthflexibility 147 10.3.9 Frequencyhoppingversusdirectsequence 147 10.4 Summary 148 Part IV Specific Radio Systems 151 11 Cellular Systems 153 11.1 Thedifferencebetweenanaloganddigitalcellular 153 Contents ix 11.2 Cellularsystemsinoverview 155 11.3 GSM 160 11.3.1 Framingformat 160 11.3.2 Howmobilesmeasureadjacentcells 174 11.3.3 Numberingscheme 175 11.3.4 Spectrumefficiency 176 11.4 CDMAone 177 11.4.1 Softhand-off 181 12 Cordless Systems 183 12.1 Overviewofcordless 183 12.2 DECT 185 12.3 PHS 187 13 Overview of Wireless Local Loop Systems 191 13.1 Introduction 191 13.2 Accesstechnologies 194 13.3 TheattractionofWLLsystems 197 13.4 CurrentstatusofWLL 200 13.5 ThedifferencesbetweenWLLandcellular 201 13.6 WLLpropagation 201 13.6.1 Fastfading 203 13.6.2 Newobstructions 204 13.6.3 Rainfall 204 14 WLL Technologies 207 14.1 Introduction 207 14.2 TheLucentAirLoopWLLsystem 208 14.2.1 Localexchange(termedaswitchinGSM) 211 14.2.2 CATU(termedabasestationcontrollerinGSM) 211 14.2.3 CTRU(termedabasestationinGSM) 212 14.2.4 Thesubscriberunit(mobileinGSM) 212 14.3 DECTasaWLLtechnology 212 x Understanding Cellular Radio 15 The Future of WLL 217 15.1 Introduction 217 15.2 TechnicaladvancesinWLL 218 15.3 Technicaladvancesinotheraccesstechniques 219 15.4 Changinguserdemand 220 15.5 PredictionsforWLL 222 16 Satellite Systems 225 16.1 Whyusesatellites? 225 16.2 Howsatellitesystemswork 226 16.3 Willsatellitesystemsbesuccessful? 227 17 The Future of Cellular 231 17.1 Whatcouldbebetterthancurrentsystems? 231 17.2 Thethird-generationideal 232 17.2.1 GSMevolution 235 17.3 Mobile/fixedconvergence 237 17.4 Thelongertermfuture 238 Bibliography 241 Model Answers 247 Glossary 257 About The Author 271 Index 273 Preface Objectives As I have increasingly moved away from the world of research and into thatofmanagementandbusiness,ithasbecomeapparenttomethatthere are many people from a nontechnical background who need to under- standcellularsystemsinmoredetailinordertobeabletoperformtheir job,beitanalyzingfinancialinvestments,runningcallcenters,ormarket- ingcellularservices.Theproblemisthatcellularandwirelesslocalloop systems have become increasingly complex over the years and under- standingthesesystemsisbecomingdifficultevenforengineers.Indeed,I doubt whether there is anyone in the world who can really claim to understandfullyallthepartsoftheGlobalSystemforMobileCommunications (GSM)indetail—somewillbeexpertsinspeechcoders,othersinerror correctors, security algorithms, or network protocols. The complexity of these systems, coupled with the dramatic growth of cellular and the resultant influx of people into the industry, has resulted in increasingly xi