不完美反馈自适应多天线跨层系统的性能分析

摘要

为提高网络无线通信的频谱利用率,提出一种自适应闭环多输入多输出（MIMO）跨层设计方案。该方案是融合物理层的自适应调制技术（AM）和数据链路层的自动重传技术（ARQ）;发射端利用反馈信息,自适应选择调制模式和发射权矢量,并自动重传数据,形成三重反馈的闭环MIMO跨层系统。推导了不完美反馈下的系统频谱效率和中断概率闭合表达式,分析了时延对跨层系统性能的影响。仿真结果表明：对比单发/单收（SISO）跨层系统以及开环MIMO跨层系统,自适应闭环MIMO跨层系统的性能有明显提高。%Adaptive closed-loop multipleinput multiple output（MIMO） cross-layer scheme is proposed to improve wireless communication network spectral efficiency.The scheme is scheduled through combining adaptive modulation（AM） at physical layer with automatic repeat request protocol（ARQ） at data link layer.By utilizing feedback information,the transmitter updates the modulation mode adaptively,chooses optimal transmitter beam-steering vector and retransmitted data automatically,to form the three-feedback.The paper presents close-form expressions of the spectral efficiencies and the probability of outage under imperfect feedback,and analyzs the effects of delayed feedback on the system performance gains.The simulation results show that compared to single input single output（SISO）cross-layersystem and open-loop MIMO cross-layer system,the performance of the adaptiveclosed-loop MIMO cross-layer system is observably enhanced.