实现MIMO系统定向干扰抑制的迭代MLD方案

An Iterative MLD Scheme for Directional Interference Suppression in MIMO System

收发多天线(Multiple Input Multiple Output,MIMO)空时分组编码(Space-Time Block Codes,STBC)系统中存在定向干扰,特别是军用通信环境下存在强定向干扰时,需进行有效的干扰抑制以避免性能恶化.本文提出了一种迭代最大似然解码(Maximum-Likelihood Decoding,MLD)方案.该方案通过噪声子空间投影实现了强干扰下的有效信道估计,利用等效信道矩阵的估计值代替真实信道矩阵的估计值实现干扰抑制和解码;并在似然函数中引入了信道估计误差以减小其对解码性能的不良影响,通过迭代累积代价函数的增量,实现了按分组进行解码,大大减少了搜索计算量.仿真结果表明该方案可有效抑制干扰,且其性能对导频长度的变化不敏感,更具适用性.

For multiple input multiple output（MIMO） system using space-time block codes（STBC） with directional interferences,especially with strong directional interferences in military communication scenario,effective interference suppression is necessary to avoid system performance degradation.An iterative maximum-likelihood decoding（MLD） scheme is presented.The proposed scheme estimates equivalent channel matrix instead of real channel matrix to perform interference suppression and decoding through noise subspace projection;reduces bad effect of channel estimation error on decoding performance,and realizes MLD of STBC block by block instead of frame by frame with less searching calculations by accumulating the increment of cost function iteratively.Simulation results show that the proposed scheme is valid to suppress interference and less sensitive to the length of pilot symbols,which is more flexible in practical applications.