多RIS辅助的多用户上行MIMO系统信号检测算法

Signal detection algorithm for multi-user uplink MIMO systemsassisted by multi-RIS

面对未来无线通信系统对通信质量的更高要求,针对多个可重构智能表面(reconfigurable intelligent surfaces,RIS)辅助的多用户上行多输入多输出(multiple-input multiple-output,MIMO)系统,通过联合优化设计接收矩阵和RIS相移系数,提出一种有效的信号检测算法。以最大化系统和速率为目标,构建一非凸优化问题;基于拉格朗日对偶变换,将该非凸问题等价为对偶问题;基于交替优化算法,将联合优化拆分为2个子问题来交替求解,利用二次变换技术处理多比率分式规划(fractional programming,FP)问题,利用半定松弛(semi-definite relaxation,SDR)算法处理RIS相移优化子问题。仿真结果表明,与对比算法相比,提出的信号检测算法可显著提高系统误码率,当RIS相移量化比特数为5时,可取得趋近于全精度RIS相移的性能。

Facing the higher requirements of communication quality for future wireless communication systems,we propose an effective signal detection algorithm for multiple reconfigurable intelligent surfaces(RIS)-assisted multi-user uplink multiple-input multiple-output(MIMO)systems through the joint optimization of the design of receive matrix and RIS phase shift coefficients.In the algorithm,a non-convex optimization problem is constructed with the goal of maximizing the sum rate of the system.Based on the Lagrange dual transformation,the non-convex problem is equivalent to its dual problem.Next,based on the alternating optimization algorithm,the joint optimization problem is split into two subproblems to solve alternately.Among them,the quadratic transform technique is used to deal with the multi-ratio fractional programming(FP)problem,while the semi-definite relaxation(SDR)algorithm is used to deal with the RIS phase shift optimization sub-problem.Simulation results show that compared with the comparison algorithm,the proposed signal detection algorithm can significantly improve the performance of the system bit error rate.At the same time,when the number of RIS phase shift quantization bits is 5,the performance close to the full precision RIS phase shift can be obtained.