cellular mobile radio systems (wiley)外语英文电子书

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1、CellularMobileRadioSystems:DesigningSystemsforCapacityOptimizationHusniHammudaCopyright©1997byJohnWiley&SonsLtdPrintISBN0-471-95641-4ElectronicISBN0-470-84254-9CellularMobileRadioSystems:DesigningSystemsforCapacityOptimizationHusniHammudaCopyright©1997byJohn

2、Wiley&SonsLtdPrintISBN0-471-95641-4ElectronicISBN0-470-84254-9CellularMobileRadioSystems:DesigningSystemsforCapacityOptimizationHusniHammudaCopyright#1997byJohnWiley&SonsLtdPrintISBN0±471±95641±4ElectronicISBN0±470±84254±91IntroductionThepotentialofcommunica

3、tingwithmovingvehicleswithouttheuseofwirewassoonrecognizedfollowingtheinventionofradioequipmentbytheendofthenineteenthcenturyanditsdevelopmentinthebeginningofthetwentiethcentury[1.1,1.2].However,itisonlytheavailabilityofcompactandrelativelycheapradioequipmen

4、twhichhasledtotherapidexpansionintheuseoflandmobileradiosystems.Landmobileradiosystemsarenowbecomingsopopular,forbothbusinessanddomesticuse,thattheavailablefrequencybandsarebecomingsaturatedwithoutmeetingevenafractionoftheincreasingdemand.Togiveanexample,the

5、estimatednumberofmobileradiosinusein1984wasabout540000withagrowthrateofabout10%perannumintheUK;estimatesofgrowthratesupto20%havebeenmadeforotherEuropeancountries[1.3].Usingthesefiguresleadstoestimatesofapproximately2.5millionUKusersbytheendofthiscentury.Agro

6、wthrateof20%annuallywouldleadtomorethan13millionusersworldwidebytheyear2000.Suchafigureiscomparabletothe11millionbusinessand18millionresidentialfixedtelephoneinuseatpresent[1.3].IntroductionSolutionstospectralcongestioninthelandmobileradioenviron-mentcanbeen

7、visagedinthefollowingways.0a)TheCellularConceptIncellularsystems,spectralefficiencyisachievedbyemployingspatialfrequencyre-usetechniquesonaninterference-limitedbasis.Frequencyre-usereferstotheuseofradiochannelsonthesamecarrierfrequencytocoverdifferentareaswh

8、ichareseparatedfromoneanotherbyasufficientdistancesothatco-channelinterferenceisnotobjectionable[1.4].Thisisachievedbydividingtheserviceareaintosmaller`cells',ideallywithnogapsoroverlaps,eachcel