MIMO系统中基于信道状态信息提高性能的改进算法

准正交空时分组码能够全速率传输信号,但由于降低了部分天线间发送信号的正交性,所以在分集增益性能上有所下降。针对这个问题,提出了一种发送天线选择方法,并将其应用到准正交空时分组码。该方法基于相位旋转空时分组码(R-QO-STBC),将准正交空时码序列映射到合适的发送天线,传输信号根据信道状态信息交错选择天线发送,接收端根据信道状态信息反馈能获得分集增益。分析了不同天线发送方案的性能。仿真结果显示:如果采用最小均方误差方法接收,本方案能获得近似理想的性能,与开环方案相比,本方案在分集增益上大约提高4~5 dB。

Advanced Algorithm Based on Channel State Information in MIMO system

Quasi-Orthogonal Space-Time Block Codes(QOSTBCs) made space-time sequences transmiting with full rate,however,this encodeing method losed partly diversity performance for lowering the orthogonality between antennas.In order to solve to this problem,a transmiting antenna selection scheme for QOSTBCs was proposed.The method was based on R-QO-STBC,by adaptively mapping the space-time sequences of the QO-STBC to the appropriate transmiting antennas depending on the channel condition.The proposed scheme could improve its transmiting diversity with limited feedback information.The performance of the scheme with various numbers of antennas selection patterns was also analyzed.The bit error probability of the schemes was evaluated by simulations.It was demonstrated that with the linear zero-forcing(ZF) and the minimum mean squared error(MMSE) receivers,the closed-loop QO-STBC using two feedback bits can achieve almost the same performance as the ideal 4-path diversity and it is about 4~5 dB better than the open loop schemes.