TD-LTE原理及常见优化案例分析.ppt

Soc Classification level 1? Nokia worksPresentation / Author / Date Physical LayerSoc Classification level 2? Nokia worksPresentation / Author / Date Introduction?It provides the basic bit transmissionfunctionality over air?LTE physical layer based on OFDMA downlink and SC-FDMA inuplink direction–This is the same for both FDD and TDD mode of operation ? No need of RNC like functional element –Everything radio related can be terminated in the eNodeB?System is reuse 1, single work operation is feasible–No frequency planning required?There are no dedicated physical (neither transport) channels anymore, as all resource mapping is dynamically driven by the schedulerSoc Classification level 3? Nokia worksPresentation / Author / Date 帧结构概述无线帧结构1:FDD模式?无线帧长度为10ms,包含20个时隙,共10个子帧。?每个子帧长度为1ms,由相邻两个时隙构成,。?任何一个子帧即可以作为上行,也可以作为下行。无线帧结构2:TDD模式?每个10ms无线帧包括两个时长为5ms的半帧,每个半帧由4个数据子帧和一个特殊子帧组成。?支持5ms和10ms上下行切换点?子帧0和子帧5以及DwPTS永远预留为下行传输。?在5ms切换周期情况下,UpPTS、子帧2和子帧7预留为上行传输。?在10ms切换周期情况下,UpPTS、子帧2预留为上行传输,子帧7和子帧9预留为下行传输。Soc Classification level 4? Nokia worksPresentation / Author / Date TDD帧结构?Subframes 1, 6为特殊子帧,包含DwPTS 、GP、UpPTS三个特殊区域。这三个特殊区域总时长为1ms,各自的时长可灵活配置。?常规CP(循环前缀),每个子帧有14个符号组成,扩展CP有12个符号组成。DwPTS: Downlink Pilot time SlotUpPTS: Uplink Pilot Time SlotGP: Guard Period to separate between UL/DLMore info: - (03/09)Soc Classification level 5? Nokia worksPresentation / Author / Date 特殊子帧传输内容1、DwPTS(下行链路导频时隙)–类似于较短的下行链路子帧,传送下行控制信息–传送下行参考信号–也可以传送下行数据–PSS(主同步信道)固定位于第3个符号2、UpPTS(上行导频时隙)–传送SRS探测参考信号或短RACH信号3、GP(保护周期)–用于上下行转换–GP长度决定了最大可支持的小区覆盖范围More info: - (03/09)SUBFRAME 1Soc Classification level 6? Nokia worksPresentation / Author / Date 上下行时隙配比?LTE TDD支持5ms和10ms的上下行子帧切换周期,可支持7种不同的上、下行时间配比。上下行时间配比是TDD区别于FDD的一个显著特点。?为避免在传输方向间的干扰,全网小区上下行时隙配比设置应一致?NSNs第一个TD版本(RL15TD)仅支持Configuration1和2。Configuration1提供上下行时隙配比2DL:2UL。Configuration2 提供上下行时隙配比3DL:1ULSoc Classification level 7? Nokia worksPresentation / Author / Date 资源分组More info: - (03/09)信道类型