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ID:36641992
大小:212.92 KB
页数:3页
时间:2019-05-13
《LTELayer2协议分析002-MAC层协议设计概述》由会员上传分享,免费在线阅读,更多相关内容在学术论文-天天文库。
1、LTELayer2协议分析002——MAC层协议设计概述本文主要从三个方面分析MAC层协议的设计:MAC层提供的功能、MAC层的信道映射和MAC层的相关处理过程。A.MAC层提供的功能MAC层主要提供以下功能:-Mappingbetweenlogicalchannelsandtransportchannels;-Multiplexing/demultiplexingofMACSDUsbelongingtooneordifferentlogicalchannelsinto/fromtransportblocks(TB)de
2、liveredto/fromthephysicallayerontransportchannels;-schedulinginformationreporting;-ErrorcorrectionthroughHARQ;-PriorityhandlingbetweenlogicalchannelsofoneUE;-PriorityhandlingbetweenUEsbymeansofdynamicscheduling;-MBMSserviceidentification;-Transportformatselection
3、;-Padding.为力求准确,此处直接应用TS36.300,6.1.1小节的英文描述,从中可以看出,MAC层提供的功能可以分为用户面和控制面:用户面包括信道映射、复用解复用、MBMS业务发送、HARQ纠错和padding等功能;控制面主要是调度功能,包括优先级的维护、UE的调度请求等。需要特别注意的是,在TS36.321中,没有关于padding功能的描述,这是不妥的。其中这些功能的分布如下表所示(TS36.321,Table4.4-1,根据该表修改而成),MACfunctionUE_DownlinkeNB_Downl
4、inkUE_UplinkeNB_UplinkMappingbetweenlogicalXXXXchannelsandtransportchannelsMultiplexingXXDemultiplexingXXErrorcorrectionthroughHARQXXXXTransportFormatSelectionXXPriorityhandlingbetweenUEsXXPriorityhandlingbetweenlogicalXXchannelsofoneUELogicalChannelprioritisatio
5、nXSchedulinginformationreportingXB.MAC层的信道映射MAC层对上层提供的逻辑信道分为控制用信道(Controlchannel)和传输用信道(Trafficchannel)两类(这里的传输用信道与逻辑信道映射到的传输信道是不同的),如下表(源于TS36.321,Table4.5.2-1,增加一列用作解释其传输数据用途),LogicalchannelnameAcronymUsageControlTrafficchannelchannelBroadcastControlChannelBCCH
6、FortransmittingsystemXcontrolinformationPagingControlChannelPCCHFortransmittingpagingXinformationandsysteminformationchangenotificationCommonControlChannelCCCHFortransmittingcontrolXinformationbetweenueandnetworkwhenthereisnoRRCconnectionDedicatedControlChannelDC
7、CHFortransmittingcontrolXinformationbetweenueandnetworkwhenthereisRRCconnectionMulticastControlChannelMCCHFortransmittingMBMSXcontrolinformationDedicatedTrafficChannelDTCHFortransmittinguserXinformationinthecaseofunicastMulticastTrafficChannelMTCHFortransmittingu
8、serXinformationinthecaseofmulticast(MBMS)物理层向MAC层的传输信道(Transportchannel)分为上行和下行两类,其中每一类还可以根据传输格式在做划分,主要包含如下信道(TS36.321,Table4.5.1-1,增加一列用作解释其传输数据用途),Transportc
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