Active RIS-Assisted Transmission Design for Wireless Secrecy Network with Energy Harvesting

We investigated the secrecy transmission design in a simultaneous wireless information and power transfer (SWIPT) system, where an active reconfigurable intelligent surface (RIS) is utilized to enhance the secure information transmission as well as the wireless energy transmission. Specifically, we studied the fairness secrecy rate maximization by jointly optimizing the transmit beamformer and the reflecting coefficients, subject to the transmit power constraint and the nonlinear energy harvesting constraint. To solve the formulated nonconvex problem, we utilize the successive convex approximation to reformulate the problem and then propose an alternating optimization to address the approximated problem. The simulation result showed the performance of the proposed design as well as the superiority of active RIS when compared with other benchmarks.