Optimal Power Allocation and Passive Beamforming of Double Active RIS-Aided Communication with AF Relay

Reconfigurable Intelligent Surfaces (RIS) is a promising technology for 6G. RISs can configure their phase shifts to enhance the rate in multi-user scenarios. Besides the RIS ability to enhance the performance, power control and beamforming are also important factors. In this paper, we investigate the optimal power allocation and passive beamforming at the base station for an uplink scenario where two active RISs and an intermediate amplify and forward (AF) relay are deployed to aid the wireless communication. Simulation results show that only power optimization have significant results on the sum-rate maximization meanwhile beamforming only reduces noise and has limited effect on the sum-rate.