RIS-Assisted Cooperative NOMA With SWIPT

Abstract

This letter proposes a two-stage reconfigurable intelligent surface (RIS)-assisted transmission scheme for cooperative non-orthogonal multiple access networks with simultaneous wireless information and power transfer. We focus on improving the achievable rate of the strong user with guaranteed weak user's quality of service by jointly optimizing power splitting factors, beamforming coefficients, and RIS reflection coefficients in two transmission stages. To tackle this challenging problem, we first use the alternating optimization framework to transform it into three subproblems, and then apply the penalty-based arithmetic-geometric mean approximation algorithm and the successive convex approximation-based method to solve them. Numerical results verify the superiority of the proposed algorithm over the baseline schemes.