lte空口l2协议课件

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1、LTE空中接口L2(层2)协议介绍主要内容MAC层RLC层PDCP层LTE架构和协议概述LTE整体架构LTE用户面协议栈LTE控制面协议栈UuS1接口协议栈L2协议L2协议总览RB承载逻辑信道传输信道物理信道MAC层RLC层PDCP层LTE架构和协议概述PDCP所处位置ThePacketDataConvergenceProtocol(PDCP)layerThislayerprocessesRadioResourceControl(RRC)messagesinthecontrolplaneandInternetProtocol(IP)pa

2、cketsintheuserplane.Dependingontheradiobearer,themainfunctionsofthePDCPlayerareheadercompression,security(integrityprotectionandciphering),andsupportforreorderingandretransmissionduringhandover.ThereisonePDCPentityperradiobearer.PDCPfunctionHeadercompressionanddecompress

3、ionforuserplanedata.Securityfunctions:–cipheringanddecipheringforuserplaneandcontrolplanedata;–integrityprotectionandverificationforcontrolplanedata.PDCPfunction(cont.)Handoversupportfunctions:–in-sequencedeliveryandreorderingofPDUsforthelayeraboveathandover;–losslesshan

4、doverforuserplanedatamappedonRLCAcknowledgedModeUserPlanePDCPControlPlanePDCPPDCPPDUFormatsPDCPPDUsforuserplanedatacomprisea‘D/C’fieldinordertodistinguishDataandControlPDUsPDCPPDUPDCPDataPDUforcontrolplanedataandforuserplanedata.--Controlplanedata:RRCmessage--Userplaneda

5、ta:VoIP、wapPDCPControlPDUonlyhastwotypes--ROHCfeedback--PDCPStatusReportMAC层RLC层PDCP层LTE架构和协议概述RLC层所处位置TheRadioLinkControl(RLC)layerThemainfunctionsoftheRLClayeraresegmentationandreassemblyofupperlayerpacketsinordertoadaptthemtothesizewhichcanactuallybetransmittedoverthe

6、radiointerface.Forradiobearerswhichneederror-freetransmission,theRLClayeralsoperformsretransmissiontorecoverfrompacketlosses.Additionally,theRLClayerperformsreorderingtocompensateforout-of-orderreceptionduetoHybridAutomaticRepeatreQuest(HARQ)operationinthelayerbelow.Ther

7、eisoneRLCentityperradiobearer.Segmentation/ConcatenationRe-segmentationRe-segmentation就是重分段，LTE中它只在AM实体的发送侧执行。RLCAM实体支持ARQ重传，当重传的RLCPDU无法适配到由MAC层指示的总的RLCPDU大小时，RLC层就会根据此情况对重传的RLCPDU执行分段操作，让生成的RLCPDU分段能适配进去RLC的丢包功能当收到高层丢弃指示命令丢弃特定的RLCSDU时，UM或AMRLC实体的发送端应该丢弃指示的RLCSDU(只有在该SD

8、U还没有被映射到RLC数据PDU中)RLCEntitiesTransparentMode(TM)RLCEntityUnacknowledgedMode(UM)RLCEntityAcknowledgedMod