sdh传输体制与pdh传输体制的

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1、SDH传输体制与PDH传输体制的ThedifferencebetweentheSDHtransmissionsystemandthePDHtransmissionsystemOpticalfibercommunicationinthetelecommunicationsnetworkhasalargescopeofapplicationofitsapplicationshasbeenfromlongdistaneecommunication,relaycommunicationbetweencentralofficetotheuseraccessnetwork・

2、Thecheapequipmentusedbyfibre-opticcommunicationsanditsexcellentbroadbandfeaturemakeittheprimarymeansoftransmissionintelecommunicationsnetworks・However,withthedevelopmentofthetelecommunicationnetworkandtheimprovementofuserrequirements,thequasi-synchronousdigitalsystem(PDH)inopticalfib

3、ercommunicationisexposingsomeinherentweaknesses:Thereisnoworldwidesta.ndardfortheregionaldigitalsignalspeedandframestructurestandards・Thereisnoworldwidestandardopticalinterfacespecification,leadingtotheproliferationofdedicatedopticalinterfacesdevelopedbyvendorsthemselves・Thesededicat

4、edopticalinterfacesarenotavailableonthelightpath,therebylimitingtheflexibilityofnetworkingapplicationsandincreasingthecomplexityandoperatingcostsofthenetwork.3.Thereuseofquasi-synchronizationsystemstructurewithafewlowratelevelsignalusingsynchronousreuse,mostothergradesofasynchronousm

5、ultiplexingsignalwasadopted,namelybystuffingsomeextrathanenvoysignalswithvariousloopsandreuseintohigh-speedsignalmultiplexingequipmentsynchronizalion.Thisapproachmakesitdifficulttoidentifyandextractlow-speedsignalsfromhigh-speedsignals・Toupanddownthecircuit,andtheonlywayistothehigh-s

6、peedlinesusedstepbysteppointstotakeoutthebranchlevelsignalsatlowspeed,andbranchaftersignal,thenstepbystepmultiplexingsignalistransmittedtothehigh-speedlines・Themultiplexingstructureisnotonlycomplicated,butalsolackstheflexibility,thehardwarequantity,thehighcostofthebusiness,therealiza

7、tionofthedigitalcrossfunctionisverycomplicated.3.Thetraditionalquasi-synchronizationsystemoperation,managementandmaintenanceofnetworkmainlybyartificialdigitalsignalcrossconnectionandstopbusinesstest,thusreusesignalframestructuredoesnotneedtoarrangealotofthe0AMbitsfornetwork・4.Duetoth

8、ereuseofbase