Energy Efficiency for STAR‐RIS Aided Multi‐User MISO Networks

ABSTRACT This letter focuses on a multi‐user multi‐input single‐output downlink wireless communication network aided by a simultaneous transmission and reflection reconfigurable intelligent surface (STAR‐RIS). To enhance the energy efficiency (EE) of this network under energy splitting protocol at STAR‐RIS, an efficient alternating optimisation algorithm in combination with successive convex approximation, semi‐definite relaxation and the Dinkelbach method is proposed to efficiently design the transmit beamforming for the base station and phase shifts for the STAR‐RIS. Simulation results indicate that the proposed algorithm with energy splitting protocol can achieve superior EE performance than both the model selection and time switching protocols when there is enough transmit power.