Sum Rate Maximization in STAR-RIS Assisted Full-Duplex Communication Systems

The sum rate performance of simultaneous transmitting and reflecting reconfigurable intelligent surface (STAR- RIS) assisted full-duplex (FD) communication systems is investigated. The reflection and transmission coefficients of STAR- RIS elements are optimized for the energy splitting and mode switching protocols to maximize the weighted sum rate of the system. The underlying optimization problems are non-convex, and hence, the successive convex approximation technique has been employed to develop efficient algorithms to obtain suboptimal solutions. Thereby, the maximum average weighted sum rate and corresponding coefficients at the STAR-RIS subject to predefined threshold rates and unit-modulus constraints are quantified. The performance of the proposed system design is compared with the conventional reflecting/transmitting-only RISs and half-duplex counterparts via simulations where it is observed that STAR-RIS can boost the performance of FD systems.