hsdpa技术简介和分析.pptxVIP

ContentOverviewTechnical Details（Including Characteristic， Performance and Complexity）AMC，H-ARQ，FCS ……Impacts on R99（Including radio protocols， UE，NodeB，RNC， MAC，Interfate Iub Iur）ConclusionsWhat is HSDPA?HSDPA is abbreviation of High Speed downlink packet access.It can apply to UTRA in order to provide very high speed downlink packet access. HSDPA is extending UTRA with a new transport channel HS-DSCH (High Speed Downlink Shared Channel). Why Introduced HSDPA?Use of HS-DSCH will enhance the UTRA support for interactive, background, and, to some extent, streaming services, in terms of Higher peak data rates Improved overall cell throughput [kbps/MHz/cell] Reduced delay HS-DSCH L1 Structure in Code Domain SharingTechnologies to support HSDPAAdaptive Modulation and CodingHybrid ARQFast Cell SelectionMultiple Input Multiple Output Antenna techniquesStand alone DSCHAMC（Adaptive Modulation and Coding）Why introduce AMC? 无线链路的信道质量是时变的，任何对链路变化进行的适应都有易于接收信号的质量。Link adapation FunctionPower controlAMC AMC Basic PrinciplePrinciple of changing MCSusers in favorable positions e.g. users close to the cell site are typically assigned higher order modulation with higher code rates (e.g. 64 QAM with R=3/4 Turbo Codes) users in unfavorable positions e.g. users close to the cell boundary, are assigned lower order modulation with lower code rates (e.g. QPSK with R=1/2 Turbo Codes) MCS（Modulation and Coding Scheme）MCS LevelInfo Rate（Mbps）Code RateModulation710.83/464QAM67.23/416QAM54.81/216QAM45.43/48PSK33.63/4QPSK22.41/2QPSK11.21/4QPSKAMC Physical Layer StructureAMC benefitsMain benefits处于有利位置的用户可以得到更高的数据速率，提高小区平均吞吐量； 链路自适应基于改变调制编码方案代替改变发射功率减小干扰， AMC在不使用快速下行功率控制的条件下允许达到较高的频谱利用率和高的数据速率。选择MCS的方法 MCS的选择基于下行信道的质量。根据UE的反馈信息 UE对下行信道质量进行测量，有两种可能：UE估计/预测下行信道质量并计算合适的传输格式报告给Node-B； UE估计/预测下行信道质量并报告给Node-B； 不根据UE的反馈信息Node-B不通过来自UE的反馈决定传输格式，而通过其他信息估计下行信道质量。 下行信道质量估计基于C/I方法：使用CPICH RSCP/ISCP测量下行信道质量。缺点：公共导频问题 ，不知道如何和自适应天线和波束成形很好的一起工作 。基于TPC方法：使用下行DPCH的TPC估计下行信道质量。优点：不增加UE的复杂度，DPCH和HS-DSCH采用同一个波束 。