LAUSR

—To compensate for severe blockages and achieve flexible and pervasive network access, UAV-mounted RISs have recently attracted research interest. In this work, a solar-powered UAV-mounted RIS (SUR) system is investigated, where solar cells are utilized to provide supplementary propulsion power. To maximize the energy efficiency of the SUR system, the optimal joint active and passive beamforming, as well as the energy- constrained UAV trajectory, i.e., its velocity and placement, are derived in closed form. Furthermore, subject to the size, weight, and power limitations of the UAV, the number of reflecting elements, the flying and hovering time of the SUR system are also optimized. Finally, simulations are provided to demonstrate the effectiveness of the proposed SUR system.