Sum Rate Maximization in STAR-RIS Assisted D2D Communications

This paper investigates wireless communication based on a simultaneous transmission and reflection of a re-configurable intelligent surface (STAR-RIS), in which device-to-device communication is established using STAR-RIS near cellular users. The sum rate of multicast downlink communication is calculated using the STAR-RIS transmission and reflection coefficients (TARCs). In order to maximize the sum rate while fulfilling the minimum quality-of-service requirements, the nonconvex optimization problem is investigated. The successive convex approximation technique and iterative approach are utilized to transform the optimization problem into a convex problem. Finally, numerical results are presented to demonstrate how increasing the size of STAR-RIS and optimizing its TARCs elements affects the system's sum-rate.