Joint Beamforming and Resource Allocation Design for STAR-RIS Aided RSMA-BiBC System

A novel framework of simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS)-aided rate-splitting multiple access (RSMA)-enabled bistatic backscatter communication (BiBC) is proposed in this letter, considering double reflections and transmissions at STAR-RIS. An optimization problem is formulated to maximize the sum rate at the reader by the joint design of beamforming at the STAR-RIS and power allocation at the tag, guaranteeing the targeted rate requirement and energy harvesting constraint of each tag. To solve the coupling non-convex problem, an alternating optimization (AO) algorithm based on the successive convex approximation (SCA) and sequential rank-one constraint relaxation (SROCR) is presented. Simulation results reveal that the proposed framework provides ~61 % and ~40 % gains in system sum rate over benchmarks and achieves better trade-off between harvested energy and data rate.