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1、大学题目蜂窝无线通信系统的研究学生迪专业班级通信工程学号P01114073院（系）电子信息工程学院指导教师（职称）洋RESEARCHOFCELLULARWIRELESSCOMMUNATIONSYSTEM一：ConceptionAbstractCellularsystemsisalsocalledthe"village"system.Isalltheareascoveredbydividedintoseveralvillage,eachdistricttheradiusofthevisualuserd
2、istributiondensityin1~10kmorso.Setupabasestationineverycommunityserviceforuserswithinthescopeofthisarea.Andthroughthedistrictdivisiontofurtherimprovethesystemcapacity.Thissystembymobileservicesswitchingcenter(MSC),basestation(BS)equipmentandmobilestati
3、on(MS)(theuserequipment)andtheexchangecentertothebasestationofatransmissionline,asshowninthefigurebelow.Atpresentintheoperationofthe900MHZ(TACS)firstgenerationmobilecommunicationsystemsimulationsystemandthesecondgenerationmobilecommunication(GSM)digita
4、lsystembelongtothiscategory.Isthemovementofthemobilestationexchangecenterandthepublictelephonenetwork(PSTN)iswhatweusuallycalltelephonenetworkislinkedtogether,betweenthemobileswitchingcenterisresponsiblefortheconnectionbetweenthebasestationcommunicatio
5、n,callprocess,themobilestation(suchasmobilephones)andsubordinatetothebasestationtoestablishcontact,bythebasestationconnectedtothemobileswitchingcenteragain,finallyaccesstothepublictelephonenetwork.Cellularcommunicationsystemsallowalargenumberofmobileus
6、erstoseamlesslyandsimultaneouslycommunicatetowirelessmodemsatfixedbasestationsusingalimitedamountofradiofrequency(RF)spectrum.TheRFtransmissionsreceivedatthebasestationsfromeachmobilearetranslatedtobaseband,ortoawidebandmicrowavelink,andrelayedtomobile
7、switchingcenters(MSC),whichconnectthemobiletransmissionswiththePublicSwitchedTelephoneNetwork(PSTN).Similarly,communicationsfromthePSTNaresenttothebasestation,wheretheyaretransmittedtothemobile.Cellularsystemsemployeitherfrequencydivisionmultipleaccess
8、(FDMA),timedivisionmultipleaccess(TDMA),codedivisionmultipleaccess(CDMA),orspatialdivisionmultipleaccess(SDMA).二：IntroductionAwidevarietyofwirelesscommunicationsystemshavebeendevelopedtoprovideaccesstothecommunicationsinfrastructureform
