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1、附录Ⅰ外文翻译(原文)RESEARCHOFCELLULARWIRELESSCOMMUNATIONSYSTEMAbstract1897,Marconidemonstratesthefirstpracticalapplicationofthemobileradiocommunication,openingupaprecedentofmobilecommunication,wirelesscommunicationinthemodernsensewasborn.Fromthatdayonwards,thewirelesscommunicationtechnology
2、iscommittedtoachievingbettercommunicationquality,lowerpowerconsumption,smallersizeandcheaperprice.Inthenext60years,anumberoflandmarktechnologicalbreakthroughstopromotethefurtherdevelopmentofmobilecommunications.Knowtheearly1980s,withtheestablishmentofacellularmobilecommunicationsyst
3、ems,mobilecommunicationsystemhasnowenteredaperiodofprosperityanddevelopment.Thecellularsystemhasexperiencedrapidexponentialgrowth,clearlyshowingthatwirelesscommunicationhasabrightfuture.Cellularcommunicationsystemsallowalargenumberofmobileuserstoseamlesslyandsimultaneouslycommunicat
4、etowirelessmodemsatfixedbasestationsusingalimitedamountofradiofrequency(RF)spectrum.TheRFtransmissionsreceivedatthebasestationsfromeachmobilearetranslatedtobaseband,ortoawidebandmicrowavelink,andrelayedtomobileswitchingcenters(MSC),whichconnectthemobiletransmissionswiththePublicSwit
5、chedTelephoneNetwork(PSTN).Similarly,communicationsfromthePSTNaresenttothebasestation,wheretheyaretransmittedtothemobile.Cellularsystemsemployeitherfrequencydivisionmultipleaccess(FDMA),timedivisionmultipleaccess(TDMA),codedivisionmultipleaccess(CDMA),orspatialdivisionmultipleaccess
6、(SDMA).1IntroductionAwidevarietyofwirelesscommunicationsystemshavebeendevelopedtoprovideaccesstothecommunicationsinfrastructureformobileorfixedusersinamyriadofoperatingenvironments.CellularmobilecommunicationsystembytheexchangeofNetworkSubsystem(NSS),thewirelessbasestationsubsystem(
7、BSS)andmobilestation(MS)hasthreemajorcomponents.Switchednetworksubsystem(NSS)completionoftheexchangefunctionalandcustomerdata,andmobilitymanagement,securitymanagementdatabasefunctionalityMostoftoday’swirelesssystemsarebasedonthecellularradioconcept.Cellularcommunicationsystemsallowa
8、largenumberofmobile
