Refracting RIS-Aided Hybrid Satellite-Terrestrial Relay Networks: Joint Beamforming Design and Optimization

Reconfigurable intelligent surface (RIS) has been viewed as a promising solution in constructing reconfigurable radio environment of the propagation channel and boosting received signal power by smartly coordinating passive elements’ phase shifts at RIS. Inspired this emerging technique, article focuses on joint beamforming design optimization for RIS-aided hybrid satellite-terrestrial relay networks, where links from satellite base station (BS) to multiple users are blocked. Specifically, refracting RIS cooperates with BS, latter operates half-duplex decode-and-forward relay, order strengthen desired signals blocked users. Considering limited onboard resource, objective is minimize total transmit both BS while guaranteeing rate requirements Since optimized weight vectors shifters coupled, leading mathematically intractable problem, we propose an alternating scheme utilizing singular value decomposition uplink–downlink duality optimize vectors, using Taylor expansion penalty function methods iteratively. Finally, simulation results provided verify superiority proposed compared benchmark schemes.