SHDSL

1©GlobespanVirataInc.2003ThisdocumentcontainsproprietaryinformationG.SHDSLandG.SHDSL.BisSystemandTechnologiesFengOuyang,Ph.D.欧阳峰GlobespanVirata100SchulzDrive,RedBank,NJ07701,[e-mail]2©GlobespanVirataInc.2003ThisdocumentcontainsproprietaryinformationAgendaSHDSL—Single-pairhigh-speeddigitalsubscriberlineG.SHDSL—ITU-TRecommendationG.991.2•G.SHDSLOverview•TCBlockDescriptions•PMDBlockDescriptions•PerformanceStandard•G.SHDSLBis•Summary3©GlobespanVirataInc.2003ThisdocumentcontainsproprietaryinformationG.SHDSLOverview•G.SHDSLOverview–TechnologyandApplications–RegionalStandards•TCBlockDescriptions•PMDBlockDescriptions•LineProbing:RateAdaptation•PerformanceStandardandImprovement•G.SHDSLBis•Summary4©GlobespanVirataInc.2003ThisdocumentcontainsproprietaryinformationHistoryofSymmetricDSLSymmetricDSLStandards•Improvementover2B1Q:advancedchannelcoding(TC-PAM)•ImprovementoverHDSL-2:ITUstandard,moreframersupports,variableratesDSLLineCode#ofPairsPayloadperPairStandardsHDSL2B1QorCAP1,2or3776,1160or2312kbpsETSITS101135ITUG.991.1ANSIT1.4-TR28SDSL2B1QorCAP1128to2304kbpsProprietaryHDSL-2TC-PAM11544kbpsANSIT1.418HDSL-4TC-PAM2776kbpsANSIT1.418SHDSLTC-PAM1or2192to2312kbpsITUG.991.2ETSITS102524T1.4225©GlobespanVirataInc.2003ThisdocumentcontainsproprietaryinformationPerformanceComparisonNote:thesearenominaldatapubliclyavailable.GlobespanVirataproductsexceedtheseperformancefigures.6©GlobespanVirataInc.2003ThisdocumentcontainsproprietaryinformationSpectralCompatibility•G.SHDSLusesdifferentspectrumfordifferentratesandlengths,tobecompatiblewithotherservices•G.SHDSLdoesnotexcludePOTSband,asADSLdoes•Bothdirectionssharethesamespectrum(fullduplex)7©GlobespanVirataInc.2003ThisdocumentcontainsproprietaryinformationRate-scaledPSDRate-scaledPSD8©GlobespanVirataInc.2003ThisdocumentcontainsproprietaryinformationApplications:MultipleSections9©GlobespanVirataInc.2003ThisdocumentcontainsproprietaryinformationApplications:TransmissionAlternatives•E1/T1Replacement–Muchlowercost–Supportsrepeaters,butrequiresless–Fractionalratespossible•AlternativetoFiber–Canbebondedforhigherrate10©GlobespanVirataInc.2003ThisdocumentcontainsproprietaryinformationApplications:BusinessandHome•Business–Multi-lineVoDSL–Videoconferencing–VPNandRemoteLAN•Residential–InternetAccess(longerreachthanADSL)–InteractiveMultimedia(requiringhighUSrates)–Peer-to-peerorserverapplications11©GlobespanVirataInc.2003ThisdocumentcontainsproprietaryinformationRegionalStandards•Differentregionshaveslightlydifferentparameters–Performancerequirementsandtestingmethods–PSDdefinitions(especiallyasymmetric)–Modulationparameters–Supporteddatarates–Otherslightchanges•CurrentlyU.S.(AnnexA)andEurope(AnnexB)aredefined,JapanwithTCM-ISDN(AnnexC)iscross-referencedtoAnnexHofADSLforTDDoperations12©GlobespanVirataInc.2003ThisdocumentcontainsproprietaryinformationSHDSL概述•SHDSL是最新的对称DSL标准•SHDSL在技术和功能上优于以往标准•SHDSL可应用于多种通讯系统中•SHDSL采用与数据速率成正比的频宽，兼顾频谱相容，实施便利和性能•SHDSL是完全双工的系统13©GlobespanVirataInc.2003ThisdocumentcontainsproprietaryinformationTCBlockDescriptions•G.SHDSLOverview•TCBlockDescriptions–SHDSLframestructureandframer–FrameProcessing•PMDBlockDescriptions•PerformanceStandard•G.SHDSLBis•Summary14©GlobespanVirataInc.2003ThisdocumentcontainsproprietaryinformationSHDSLFramer•Generateandprocessoverheadbits•CheckandreportCRC•Generateandseparatesynchronizationandstuffingbits•Performcustomerframeinputandoutput15©GlobespanVirataInc.2003ThisdocumentcontainsproprietaryinformationThreemainframetypescustomermodemmodemcustomerlinesignalpayloadpayloadbufferavailabledataavailableClearchannelcustomermodemmodemcustomerlinesignalpayloadpayloadbitclockbitclockTDM(oneoftheclockconfigurations)customermodemmodemcustomerlinesignalpayloadpayloadbufferoverflowbufferoverflowbufferavailabledataavailableATM16©GlobespanVirataInc.2003Thisdocumentcontainsproprietaryinformation帧处理•帧处理模块形成和拆散SHDSL数据帧，处理有关控制数位–完成客户接口功能•实现与客户的数据时钟同步17©GlobespanVirataInc.2003ThisdocumentcontainsproprietaryinformationPMDBlockDescriptions•G.SHDSLOverview•TCBlockDescriptions•PMD(PhysicalMediaDependent)BlockDescriptions–TCMChannelCoding–TrainingPhaseTxandRx–DataPhase:precoding–AnalogueFrontEnd–PerformanceTuningExample•PerformanceStandard•G.SHDSLBis•Summary18©GlobespanVirataInc.2003ThisdocumentcontainsproprietaryinformationTCMImplementationOverviewTCMencoderprecoderTxfilterAnalogFrontEndloopDigitaldecimatorequalizerSymboltimingrecoverySlicer/decoderEchocanceler19©GlobespanVirataInc.2003ThisdocumentcontainsproprietaryinformationTCMChannelCoding:Encoder•Introducesredundancytoprotectmorecloselyspacedconstellationpoints•Thereceiverspecifiesthecode,althoughknowngoodcodeiscommonlyused•Maximumcodinggainisabout5dB20©GlobespanVirataInc.2003ThisdocumentcontainsproprietaryinformationTCMChannelCoding:Decoder•Viterbidecoder,withEuclideandistanceascostfunction•Tracebacklength:compromisebetweenperformanceandmemoryrequirement21©GlobespanVirataInc.2003ThisdocumentcontainsproprietaryinformationDecisionFeedbackEqualizer(DFE)1/2LinearEqualizerSlicer/Decode