On Sum Rate Maximization of STAR-RIS Assisted Underlay D2D-NOMA System with Energy Harvesting

In the recent years, simultaneous transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) has garnered significant research attention due to its ability to overcome the half-space coverage limitations of the conventional RIS. In this paper, we investigate a STAR-RIS and non-orthogonal multiple access (NOMA) assisted device-to-device (D2D) communication system underlaying a cellular network with a multi-antenna base station (BS). Additionally, the D2D transmitter functions in full-duplex (FD) mode and employs simultaneous wireless information and power transfer (SWIPT) to harvest energy from the BS. For the considered system model, we address the optimization problem aimed at maximizing the sum rate of the D2D receivers, taking into account practical scenarios such as non-linear energy harvesting and residual self-interference (RSI). The particle swarm optimization (PSO) has gained attention to solve this type of optimization problem of wireless communication. The results demonstrate performance improvements over conventional RIS, orthogonal multiple access (OMA) techniques, and other baseline optimization algorithms such as multi-armed bandit and deep Q-networks. Additionally, various other system design insights are provided.