Energy Efficient Rate Splitting Multiple Access (RSMA) with Reconfigurable Intelligent Surface

Abstract

This paper investigates the problem of resource allocation for reconfigurable intelligent surface (RIS)-assisted wireless communication system with rate splitting multiple access (RSMA). In this network, the energy efficiency of the network is maximized by controlling the phase shifts of the RIS and beamforming of the base station. This problem is posed as a joint optimization problem of transmit beamforming and RIS control, whose goal is to maximize the energy efficiency under minimum rate constraints of the users. To solve this problem, an iterative algorithm is proposed through solving the phase optimization subproblem and beamforming optimization subproblem, iteratively. For the subproblem of phase optimization or beamforming optimization, we use the successive convex approximation (SCA) method to obtain a suboptimal solution. Simulation results show that the RSMA can achieve higher energy efficiency compared to non-orthogonal multiple access (NOMA) and orthogonal frequency-division multiple access (OFDMA).