Energy-Efficient Design of STAR-RIS Aided MIMO-NOMA Networks

Simultaneous transmission and reflection-reconfigurable intelligent surface (STAR-RIS) can provide expanded coverage compared with the conventional reflection-only RIS. This paper exploits energy efficient potential of STAR-RIS in a multiple-input multiple-output (MIMO) enabled non-orthogonal multiple access (NOMA) system. Specifically, we mainly focus on energy-efficient resource allocation MIMO technology assisted NOMA network. To maximize system efficiency, propose an algorithm to optimize transmit beamforming phases low-cost passive elements alternatively until convergence. first decompose formulated efficiency problem into phase shift optimization problems. efficiently address non-convex problem, exploit signal alignment zero-forcing precoding methods each user pair MIMO-NOMA channels single-antenna channels. Then, Dinkelbach approach dual decomposition are utilized vectors. In order solve successive convex approximation (SCA) based method obtain optimized STAR-RIS. Simulation results demonstrate that proposed yield superior performance over orthogonal (OMA) scheme random scheme.