Beamforming Design for Double-RIS Assisted UAV Communication with Limited Feedback in Disaster Scenarios

Reconfigurable intelligent surfaces (RIS) assisted unmanned aerial vehicle (UAV) communication can enhance wireless communication in disaster scenarios. However, the critical challenge lies in improving the communication throughput under the joint design of channel acquisition and beamforming with limited percision codebook. In this paper, we consider using cascaded double-RIS assisted UAV of multi-hop communications with limited feedback multiple-input single-output (MISO). And the steepest descent method (SDM) based beamforming design scheme and a codebook based channel quantization feedback mechanism were proposed. Then, we establish an optimization problem of maximizing the system throughput to realize the design of beamforming, with the constraints of transmission power and RISs phase-shift. The SDM based alternating iterative optimization algorithm is proposed to solve this problem with low complexity. The final simulation results show that our proposed optimization algorithm can improve the system throughput.