802.11ac-测试规范

2014-8-11Agenda一、IEEE802.11acKeyFeatures二、IEEE802.11acModulation三、IEEE802.11acTX測試規範及定義四、IEEE802.11acRx測試規範及定義2014-8-11一、IEEE802.11acKeyFeatures•5GHzRFBandonly(幹擾更少)•WiderChannelBandwidth–Mandatory80MHzchannelbandwidth•DoublesPHYrateatnegligiblecostincrease–Optional160MHzchannelbandwidth•Contiguousor80+80MHznoncontiguous•EnhancedConstellationMapping(速率上升33%)–Optional256QAM3/4and5/6codingrates–Usedforboth802.11ac80MHzand160MHz•EnhancedMiMoFeatures–“Multi-User”MiMocapabilities(多使用者的MIMO)–Basedonspatialmultiplexingofmultiplestreams(高達8個空間流，802.11n最多4個)2014-8-11一、IEEE802.11acKeyFeatures2014-8-11一、IEEE802.11acKeyFeatures2014-8-11二、IEEE802.11acModulationTDFT=DFT/IFDFTSymbolPeriod(符號周期)=3.2μsTSYMS=ShortGIsymbolinterval(短防護符號間隔)=3.6μsTSYML=LongGIsymbolinterval(長防護符號間隔)=4.0μsNDPSC=Numberofdatabitspersubcarrier(各組子載波的資料bit數)強化調制方式BitPerSymbol=log2(ModulationOrder)Ndpsc=BitsPerSymbol*空间流数*NumberofDataSubcarriers*CodeRateDataRate=Ndbps*SymbolRate*Tdft/TsymSpatialStreams(Note1)MCSIndexModulationtypeCodingrateDataRate(Mb/s)20MHz40MHz80MHz160MHzGuardIntervalGuardIntervalGuardIntervalGuardInterval800ns400ns800ns400ns800ns400ns800ns400ns10BPSK1/26.57.213.51529.332.558.5651QPSK1/21314.4273058.5651171302QPSK3/419.521.740.54587.897.5175.5195316-QAM1/22628.95460117130234260416-QAM3/43943.38190175.5195351390564-QAM2/35257.8108120234260468520664-QAM3/458.565121.5135263.3292.5526.5585764-QAM5/66572.2135150292.53255856508256-QAM3/47886.71621803513907027809256-QAM5/6N/AN/A180200390433.3780866.720BPSK1/21314.4273058.6651171301QPSK1/22628.854601171302342602QPSK3/43943.48190175.6195351390316-QAM1/25257.8108120234260468520416-QAM3/47886.6162180351390702780564-QAM2/3104115.62162404685209361040664-QAM3/4117130243270526.658510531170764-QAM5/6130144.4270300585650117013008256-QAM3/4156173.4324360702780140415609256-QAM5/6N/AN/A360400780866.615601733.430BPSK1/219.521.640.54587.997.5175.51951QPSK1/23943.28190175.51953513902QPSK3/458.565.1121.5135263.4292.5526.5585316-QAM1/27886.7162180351390702780416-QAM3/4117129.9243270526.558510531170564-QAM2/3156173.432436070278014041560664-QAM3/4175.5195364.5405789.9877.51579.51755764-QAM5/6195216.6405450877.5975175519508256-QAM3/4234260.148654010531170210623409256-QAM5/6N/AN/A54060011701299.923402600.12014-8-11二、IEEE802.11acModulation通道頻寬空間串流調變方式子載波間距編碼率子載波總數資料子載波數Ndpsc最大資料率20MHZ1256-QAM312.5KHZ3/4645231286.7Mbps40MHZ2256-QAM312.5KHZ5/61281081440400Mbps80MHZ4256-QAM312.5KHZ5/625623462401.7333Gbps160MHZ8256-QAM312.5KHZ5/6512468249606.933Gbps子載波間距既符碼率（symbol-rate）一定的情況下，通道頻寬越高，子載波總數越大Eg：80MHZ，3個空間流，5/6編碼率，短防護間隔的DataRate：8*234*5/6*3*312500*3.2/3.6=1300,000,000bps2014-8-11二、IEEE802.11acModulationEVMRequirement2014-8-11二、IEEE802.11acModulation•256-QAM訊號在不同SNR環境中的星座圖2014-8-11一、IEEE802.11acKeyFeaturesMU-MIMOMulti-userMIMO是一種新的技術，其優點在於多個終端設備同時連上AP時，每個裝置可獨立使用不同的空間流(SpatialStreams)傳輸資料，進而減少競爭2014-8-11二、IEEE802.11acModulationFRAMFORMAT•Framebodyincreasefrom7955to11426octets(11454MPDUlength-28)•VHT-SIG-A…replaceHT-SIGfields2014-8-11二、IEEE802.11acModulationVHT-SIG-A•ThenextfieldsinthepacketbeginningwithVHTarenewto11ac.(VHT=11acandstandsforVeryHighwrought.)TheVHT-SIG-AfieldcontainstwoOFDMsymbols.•ThefirstsymbolismodulatedusingBPSK,soany11ndevicelisteningwillthinkthatthepacketisan11a.Thesecondsymbolusesa90degreerotatedBPSKwhichallowstheVHTdevicetoknowthatthisisan11acpacket.•Importantinformationiscontainedinthebitsofthesetwosymbolssuchasbandwidthmode,MCS(ModulationandCodingScheme)forthesingleusercase,numberofspacetimestreams,etc.2014-8-11二、IEEE802.11acModulationVHT-STFandVHT-LTFTheVHTSTF(ShortTrainingField)isusedtoimprovetheAGC（automaticgaincontrol（:自动增益控制）inaMIMOtransmission.TheVHTLTF(longtrainingfields)areusedbythereceivertoestimatetheMIMOchannelandequalizethereceivedsignal.ThenumberofLTFsymbolssentinapacketdependsonthenumberofspacetimestreams:oneLTFforonespacetimestream,twoLTFsfortwospacetimestreams...eightLTFsforsevenoreightspacetimestreams.2014-8-11二、IEEE802.11acModulationVHT-SIG-BTheVHT-SIG-BfollowstheVHT-LTF.ItisonesymbolthatisBPSKmodulatedandcontains26bitsina20MHzpacket,27bitsina40MHzpacketand29bitsinan80MHz,160MHz,or80+80MHzpacket.TheformatfortheVHTSIG-BdependsonwhetherthepacketisforaSU-MIMOorforaMU-MIMOasshowninFigure8.(TheMCSforsingleusercaseistransmittedinVHT-SIG-A.)2014-8-11二、IEEE802.11acModulation802.11nFRAMFORMAT2014-8-11二、IEEE802.11acModulationMCS2014-8-11二、IEEE802.11acModulation2014-8-11•802.11acTxMeasurementsConfiguration三、IEEE802.11acTx測試規範及定義DUTSplitterShieldingBoxGPIBCableConsoleCable/NetworkCable/PCIECardNetworkCable50OhmCable50OhmCable2014-8-11三、IEEE802.11acTx測試規範及定義RBW(分析帶寬)=100KHz,VBW(觀測帶寬)=30KHz2014-8-11三、IEEE802.11acTx測試規範及定義2014-8-11三、IEEE802.11acTx測試規範及定義模板包絡門限可通過下表計算得到2014-8-11三、IEEE802.11acTx測試規範及定義•TransmitSpectralFlatness2014-8-11三、IEEE802.11acTx測試規範及定義•TransmitCenterFrequencyandSymbolClockTolerancethetoleranceshallbewithin20ppm(0.002%)2014-8-11三、IEEE802.11acTx測試規範及定義•TransmitterModulationAccuracy1.TransmitterCenterFrenquencyLeaka.Thecenterfrequencyleakageismeasuredusinga312.5KHzRBW(Resolu