现代电信交换1

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1、SWITCHINGANDTRAFFICTHEORYFORINTEGRATEDBROADBANDNETWORKSJosephY.HuiChapter1IntegratedBroadbandServicesandNetworks---AnIntroduction1.1Communicationnetworking1.2Broadbandtechnologies1.3Broadbandservices1.4Tointegrateornotintegrate1.5OutlineoftheBookInrecentyears,significantadvanceshaveb

2、eenmadeintheareasofcommunicationandcomputationtechnologies.Theadvancesincommunicationtechnologiesaremostlyintheareaoftransmissionandswitchingdevices.Broadband:1Mb/s~100Mb/s1.1CommunicationnetworkingTwokindsofsolutiontointerconnecttelephones,figure1.Localaccessnetwork,figure1TrunksExc

3、hangenetwork,figure2Longdistancenetwork,figure3Fromlocalaccessnetworkandexchangenetworktolongdistancenetwork,ahierarchicalnetworkiscreated.Networkinginvolvesatradeoffbetweentransmissioncostandswitchingcostateachlevelofthenetworkhierarchy.Thistradeoffbetweentransmissioncostandswitchin

4、gcostsdependsstronglyonthetechnologiesforbuildingtransmissionandswitchingfacilities.1.2BroadbandtechnologiesTheadvancesofswitching:ManualattendantswitchingStep-by-stepmechanicalswitch,Electroniccrossbarswitch,Storedprogramcontrol,Spacedivisionswitch,Timedivisionswitch.Withtheadoption

5、ofmulti-stageswitchingandstoredprogramcontrol,largeelectronicswitchingsystemsforlocalandlongdistanceswitchingemerged.Multiplexingschemes:FDM:frequencydivisionmultiplexingTDM:timedivisionmultiplexingInfact,timedivisionmultiplexingismorethanjustamultiplexingandtransmissionmechanism;itc

6、analsobeusedasaswitchingmechanism.TimedivisionswitchTimemultiplexedspacedivisionswitchOpticalspacedivisionswitchTheadvancesoftransmission:Transmissionspeedincreasedexponentiallyintheeightieswiththedevelopmentoffiberandlasertechnologies.Fortheexchangenetwork,thisextremeeconomyofshared

7、transmissionmaysimplifythenetworkstructure.Itmaybemoreeconomicaltoconsolidatetheexchangenetworkintoahubbingarchitecture,whichconnectslocalswitchingcentersinanexchangenetworktoahubswitchingcenterusinghighcapacityopticaltransmissionlines.1.3BroadbandservicesThesenewcommunicationservice

8、sdepartfromt