Physical Layer Security Improvement for Hybrid RIS-Assisted MIMO Communications

This letter studies the physical-layer security (PLS) improvement in wireless communication systems, where a hybrid reconfigurable intelligent surfaces (RISs) is deployed between the transmitter and legitimate receiver to enhance the communication security. To achieve a tradeoff between the secrecy capacity and power consumption, the element on-off mechanism is considered firstly to represent the connection relationship between the RIS elements and power amplifier. To address this non-convex problem, two-stage cyclic iterative technique is utilized to the considered optimization problem by iteratively optimizing the transmit beamformingreflection coeffcient and amplifcation coeffcient. Simulation results demonstrate that the proposed algorithm can effectively improve the performance gains compared with existing solutions.