具有不完全信道状态信息的MIMO广播信道预编码

摘要

多用户MIMO系统中,基站已知具有有限误差的信道状态信息时,基于信干噪比限制下的广播信道预编码的鲁棒性设计可行性差,为此提出基于信漏噪比限制下的预编码设计方案.将信漏噪比限制下的最小化发射总功率的设计转化为一组半正定优化的问题进行求解,并依据各个用户当前信道条件动态指定每个用户的信漏噪比的要求,从而增强了采用凸优化方法进行设计的可行性.针对信道状态信息误差较大的情况,提出使用一个基于最小均方误差准则的信道矫正矩阵来减少误差矩阵的范数,从而更有效地使用提出的预编码设计方案.仿真结果显示,本方案的误码率性能对信道信息误差具有鲁棒性,与基于信干噪比的类似方案相比较,本方案可获得最优解的概率更高,有更好的误码性能.%When the base station knows imperfect channel state information (CSI) with limited estimation erroiB, the robust preceding scheme based on signal to interference plus noise ratio (SINR) constraints is less feasible. In this paper, a precoding scheme based on signal to leakage plus noise ratio (SLNR) is proposed for MIMO downlinks. By solving a series of semidefinite program (SDP) problems, the proposed design minimizes the total transmitted power under each user's SLNR constraint. At the same time, it can dynamically allocate each user's SLNR threshold according to their channel states, so it is more feasible than the similar SINR-based precoding scheme. In the case of having higher estimation errors for CSI, a channel modification matrix based on the minimum mean square error (MMSE) is used to increase feasibility of the proposed precoding method. Simulation results show that the proposed precoding scheme is robust to channel estimation errors, and can achieve optimal solutions with higher probability. Moreover, it has a better bit error rate performance than similar SINR-based precoding.