Sum Rate Optimization for RIS-Assisted NOMA SWIPT System with Joint Beamforming and Phase Shift Design

Simultaneous wireless information and power transfer (SWIPT) and non-orthogonal multiple access (NOMA) enable efficient data-power transfer and massive connectivity but suffer from channel limitations. To overcome this, we integrate Reconfigurable Intelligent Surfaces (RIS) into SWIPT-NOMA systems, leveraging RIS’s programmable reflection to enhance channel conditions. In the proposed setup, a base station simultaneously serves two distinct user groups (information and energy) via RIS assistance. We develop an alternating optimization (AO) algorithm to maximize the sum rate, subject to transmit power and energy harvesting constraints, by jointly designing active beamforming and RIS phase shifts. Addressing the non-convex constraints, we apply successive convex approximation (SCA) and solve the reformulated problem iteratively. Simulations validate the scheme’s effectiveness.