RIS辅助的MISO系统安全鲁棒波束赋形算法

Secure and Robust Beamforming Algorithm for RIS Assisted MISO Systems

为解决无线信道开放性导致的信息传输安全及信道估计误差等不确定性带来的系统传输性能恶化问题,该文提出一种存在用户窃听的可重构智能超表面(RIS)辅助多输入单输出(MISO)系统的Charnes-Cooper鲁棒波束赋形算法。针对窃听用户建立有界信道不确定性模型,并通过约束最大发射功率以及RIS相移,联合优化基站波束和RIS相移来最大化用户保密率。为求解该非凸问题,首先通过变量替换、Charnes-Cooper方法和S-procedure方法将其转换为凸优化问题,进而采用间接交替优化耦合变量来获得鲁棒波束赋形矩阵和RIS相移。仿真结果表明,该文提出的基于RIS的联合优化算法具有更好的用户保密率和鲁棒性。

To solve the problem of information transmission security caused by wireless channel openness and system transmission performance deterioration caused by channel estimation error,a Charnes-Cooper robust beamforming algorithm is proposed for Reconfigurable Intelligent Surface(RIS)assisted Multiple-Input Single-Output(MISO)systems with eavesdroppers.A bounded channel uncertainty model is established for the eavesdropper,and the base station beamforming and RIS phase shift are jointly optimized to maximize user secrecy rate based on the constraints of maximum transmit power and RIS phase shifts.To solve the nonconvex problem,it is first converted to a convex optimization problem by variable substitution,Charnes-Cooper method and S-procedure method,and then the coupling variables are indirectly and alternately optimized to obtain robust beamforming matrix and RIS phase shifts.Simulation results show that the proposed RIS-based joint optimization algorithm has better user confidentiality and robustness.