Holographic Beamforming for LEO Satellites

Low-earth-orbit (LEO) satellite communication networks are expected to provide global massive connectivity and high-speed data services for terrestrial users. Reconfigurable holographic surfaces (RHSs) can fulfill such vision by achieving holographic beamforming with low power consumption and hardware cost. In this letter, we consider an RHS-aided LEO satellite communication system, where a satellite equipped with an RHS broadcasts to multiple user terminals via holographic beamforming. To derive the minimum number of elements for RHS that can guarantee the system performance, we first develop a holographic beamforming optimization algorithm to maximize the sum rate, based on which the closed-form expression of the maximum sum rate is obtained. By comparing the RHS-aided system with the phased array-aided system, we then discuss the conditions when the RHS can achieve a higher sum rate than the phased array. Simulation results validate the theoretical analysis and show the RHS can meet the sum rate requirement of the LEO satellite communication system with low hardware cost.