Joint Beamforming and Reconfigurable Intelligent Surface Design for Two-Way Relay Networks

In this paper, we consider a reconfigurable intelligent surface (RIS)-assisted two-way relay network, in which two users exchange information through the base station (BS) with help of an RIS. By jointly designing phase shifts at RIS and beamforming matrix BS, our objective is to maximize minimum signal-to-noise ratio (SNR) users, under transmit power constraint BS. We first single-antenna BS case, propose algorithms design amplification parameter, namely SNR-upper-bound-maximization (SUM) method, genetic-SNR-maximization (GSM) method. When there are multiple antennas optimization problem can be approximately addressed by successively solving decoupled subproblems, one optimize shifts, other matrix. The subproblem solved using SUM or GSM while second optimized maximum-ratio-beamforming proposed have been verified numerical results computational complexity analysis.