LTE-NB-IOT-协议介绍

NB-IOTprotocolcollection1.NB-IOT基本概念Improvedindoorcoverage,supportformassivenumberoflowthroughputdevices,lowdelaysensitivity,ultralowdevicecast,lowdevicepowerconsumptionNB-IOTshouldsupport3differentmodesofoperation：‘Stand-aloneoperation’utilizingforexamplethespectrumcurrentlybeingusedbyGERANsystemsasareplacementofoneormoreGSMcarriers,aswellasscatteredspectrumforpotentialIoTdeployment.‘Guardbandoperation’utilizingtheunusedresourceblockswithinaLTEcarrier’sguard-band‘In-bandoperation’utilizingresourceblockswithinanormalLTEcarrier180kHzUERFbandwidthforbothdownlinkanduplink上行支持15kHz和3.75kHz两种subcarrierspacing；下行仅支持15kHz的sub-carrierspacing3.75kHz只支持single-Tone；可以提供更大的覆盖，CP较长，对timing要求放松了；更小的功耗仅支持type-Bhalf-duplexFDDoperation(type-B定义参考3GPP36.211R13chapter6.2.5)NB-IOTvseMTCvslegacyLTELTER9NB-IoT系统带宽1.4M/3M/5M/10M/15M/20M200kHz工作模式fullduplexFDD/TDDhalf-duplexFDD最大传输速率DL:150Mbps;UL50MbpsDL/UL:200kbps频带部署方式LTE授权频段带内，带外，保护带三种部署方式覆盖范围(MCL)~145dB164dB子载波间隔DL/UL:15kHzDL:15kHz,UL:15kHzor3.75kHz传输模式TM1-TM9TM1/TM2(单天线或双天线发送分集)同步信号PSS/SSSNPSS/NSSS，构造以及相对间隔都与R9PSS/SSS不同随机接入Preamble/RAR/MSG3/MSG4NPRACH/NPDSCH解调信号DL:CRSUL:DMRSDL:NRSUL:NDMRS上下行信道探测下行CSI，上行SRS没有CSI，没有SRS下行数据信道PDSCHNPDSCHQPSK,16QAM,64QAMPQPSK1/3turbocoding1/3Tailbitingconvolutionalcoding单子帧传输一个传输块单个或多个子帧传输一个传输块下行控制信道PDCCHNPDCCH和PDSCH在同一个子帧，占用前几个OS占用单独的下行子帧，类似于EPDCCHDCIFormat0/1/1A/2/2A/3/3A…DCIFormatN0/N1/N2上行数据信道PUSCHNPUSCH15kHzsub-carrierspacing15kHzor3.75kHzsub-carrierspacing1/3turbocoding1/3turbocoding单子帧传输一个传输块以ResourceUnit(可以跨多个子帧)作为传输块的传输单位UL-SCH和UCI在同一个子帧发送UL-SCH和UCI在不同子帧发送省电技术DRXPSM,eDRXeMTCcanonlybedeployedwithinLTEsystem,whileNB-IoThasmoreflexibilityasitcanbedeployedin-band,guardbandandstandalone.NB-IoTcansupportupto200kdevicespercellper200kHzTheNB-IoTuplinktransmission(3.75kHz,15kHz)ismuchmoreefficientthaneMTCwidebanduplinktransmissionNB-IoThasabout6.3dBbettercoveragethaneMTCIn-Band操作的一些特殊处理？？？SymbolsandabbreviationsULslotsNNumberofconsecutiveslotsinanULresourceunitforNB-IoT2.36.211-d202.1Uplink(10.1)2.1.1UplinkPhysicalchannelsandsignals(10.1.1.1)Thefollowingnarrowbandphysicalchannelsaredefined:-NarrowbandPhysicalUplinkSharedChannel,NPUSCH-NarrowbandPhysicalRandomAccessChannel,NPRACHThefollowinguplinknarrowbandphysicalsignalsaredefined:-NarrowbanddemodulationreferencesignalComment:新增上行信道NPUSCH和NPRACH，新增上行信号NDMRS；2.1.2Uplinkslotstructureandphysicalresources(10.1.2.1)TheuplinkbandwidthintermsofsubcarriersULscN,andtheslotdurationslotTaregiveninTable10.1.2.1-1.Table10.1.2.1-1:NB-IoTparameters.SubcarrierspacingULscNslotTkHz75.3f48s61440TkHz15f12s15360TAsingleantennaport0pisusedforalluplinktransmissions.Comment:上行有两种时隙结构，一种是针对子载波间隔15kHz的，和legacyLTE的时隙结构相同；一种是针对子载波间隔3.75kHz的，一个RB内包含的子载波数是48，是legacyLTE的4倍。同时时隙长度是2ms，是legacyLTE的4倍。一个无线帧只包含5个Slots。所以一个无线帧仍然是10ms。NB-IOT上行总是使用p=0的单天线发送。2.1.2.1Uplinkresourceunit(10.1.2.3)ResourceunitsareusedtodescribethemappingoftheNPUSCHtoresourceelements.AresourceunitisdefinedasULslotsULsymbNNconsecutiveSC-FDMAsymbolsinthetimedomainandRUscNconsecutivesubcarriersinthefrequencydomain,whereRUscNandULsymbNaregivenbyTable10.1.2.3-1.Table10.1.2.3-1:SupportedcombinationsofRUscN,ULslotsN,andULsymbN.NPUSCHformatfRUscNULslotsNULsymbN13.75kHz116715kHz116386412223.75kHz1415kHz14Comment:NPUSCH资源分配的基本单位称之为ResourceUnit。一个ResourceUnit定义为ULslotsULsymbNN个连续的SC-FDMAsymbols以及RUscN个连续子载波。2.1.3Narrowbandphysicaluplinksharedchannel(10.1.3)Thenarrowbandphysicaluplinksharedchannelsupportstwoformats:-NPUSCHformat1,usedtocarrytheUL-SCH-NPUSCHformat2,usedtocarryuplinkcontrolinformationComment:NPUSCH包含两种format，Format1用于传输UL-SCH，Format2用于传输UCI。不存在同时传输UL-SCH和UCI的NPUSCH。2.1.3.1NPUSCHscrambling(10.1.3.1)Scramblingshallbedoneaccordingtoclause5.3.1.ThescramblingsequencegeneratorshallbeinitialisedwithNcellID9s1314RNTIinit2222mod2Nnnncfwheresnisthefirstslotofthetransmissionofthecodeword.IncaseofNPUSCHrepetitions,thescramblingsequencereinitialisedaccordingtotheaboveformulaaftereveryNPUSCHidenticalMtransmissionsofthecodewordwithwithsnandfnsettothefirstslotandtheframe,respectively,usedforthetransmissionoftherepetition.ThequantityNPUSCHidenticalMisgivenbyclause10.1.3.6.Comment:NPUSCH和legacyPUSCH一样，在调制之前需要做加扰。由于NPUSCH资源映射的单元包含最多16个Slots，因此加扰使用的初始参数需要使用第一个Slotindex。如果NPUSCH有重传，那么在重传范围内，每NPUSCHidenticalM次传输重新初始化一次扰码，使用该次重传中首个无线帧号和时隙号做初始化。因此在NPUSCHidenticalM次重传范围内可以做解调前的数据合并，增加解调信噪比。具体可以参考4.42.1.3.2NPUSCHmodulation(10.1.3.2)Table10.1.3.2-1:NPUSCHmodulationschemesNPUSCHformatRUscNModulationscheme11BPSK,QPSK1QPSK21BPSK2.1.3.3NPUSCHlayermappingandprecodingComment:NPUSCH仅支持单天线发送。2.1.3.4NPUSCHmappingtophysicalresources(10.1.3.6)NPUSCHcanbemappedtooneormorethanoneresourceunits,RUN,asgivenbyclause16.5.1.2of3GPPTS36.213[4],eachofwhichshallbetransmittedNPUSCHrepMtimes.AftermappingtoslotsNslots,theslotsNslotsshallberepeated1NPUSCHidenticalMadditionaltimes,beforecontinuingthemappingof)(ztothefollowingslot,where1114,2/minRUscRUscNPUSCHrepNPUSCHidenticalNNMMkHz152kHz75.31slotsffNThemappingof)1(),...,0(apsymbMzzisthenrepeateduntil