[信息与通信]camel in gprs prepaid service

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1、1CAMELinGPRSprepaidserviceghlee@alumni.csie.nctu.edu.tw2OutlineEvolutionofINGPRSoverviewCAMELinGPRSDiscussion3PlainOldTelephoneServiceServicelogicwerehardwiredinswitchingsystems.Networkoperatorsdiscussservicescustomersrequiredwithswitchvendors.(nostandard)Onceserviceswereimplemented,they

2、werenoteasilymodified.servicelogichardwired4StoredProgramControlInthemid-1960s,storedprogramcontrol(SPC)switchingsystemswereintroduced.Asaresult,itwaseasiertointroducenewservices.Servicelogicwasnotmodular.servicelogicprogrammable5CommonChannelSignalingInthemid-1970s,commonchannelsignalin

3、gnetwork(CCSN)wasintroduced.Signalingsystemnumber7(SS7)istheprotocolthatrunsovertheCCSN.SS7networkseparatesthecallsetupinformationandtalkpathfromthecommontrunkthatrunsbetweenswitchingsystems.6SS7networkcomponentssignalswitchingpoints(SSPs)—SSPsaretelephoneswitchesequippedwithSS7-capables

4、oftwareandterminatingsignalinglinks.Theygenerallyoriginate,terminate,orswitchcalls.signaltransferpoints(STPs)—STPsarethepacketswitchesoftheSS7network.Theyreceiveandrouteincomingsignalingmessagestodestination.signalcontrolpoints(SCPs)—SCPsaredatabasesprovidinginformationnecessaryforadvanc

5、edcall-processingcapabilities7SS7network8TheIntroductionofINDuringthemid-1980s,TelcordiaTechnologiesrespondedtoRBOCs’srequestanddevelopedtheconceptofIntelligentNetwork1(IN/1).Servicelogicsplitsfromswitchingsystem,nowresidesinservicecontrolpoints(SCP).servicelogicnowhere9CallModelPICsrepr

6、esentswitchingsystemstatesthatacallgoesthroughfromoriginationtotermination.SSPscheckTDPstoseeifthereareanyactivetriggers.Ifanactivetriggerisdetected,normalswitchingsystemcallprocessingissuspendeduntiltheSSPandSCPcompletecommunications.SSPsuspended,andaskSCPwhattodoinnextstep10GPRSlogical

7、architecture11Transmissionplanein2.5GFramerelayRadiodepRadioindepMultiplexinglayer12Signalingplanein2.5G13MultiplexingofnetworkprotocolsIP/X.25TransmissionplaneSignalingplane14Userplanein3GATM15Controlplanein3G16CAMELarchitecture17MAP/CAPprotocolstackCAPhasthesameunderlyi