Sub-Connected Active RIS Assisted Secrecy Communications

This letter proposes a sub-connected active reconfigurable intelligent surface (RIS)-aided downlink wireless communication scheme for the physical layer security (PLS). In the proposed scheme, the statistics CSI error is considered and the secrecy rate (SR) of the system is maximized by jointly designing the beamforming vectors of the base station and the reflecting coefficients of the sub-connected active RIS. Besides, fractional programming (FP) and successive convex approximation (SCA) methods are applied to convert the original optimization problem into three subproblems. A penalty-based alternating optimization (AO) framework is employed to solve the optimization problem. Simulation results verify the efficiency and robustness of the proposed sub-connected active RIS-assisted PLS scheme.