Aerial RIS-Enabled Wireless Coverage Enhancement Under UAV Jitter

Reconfigurable intelligent surface (RIS), as a promising technology for coverage enhancement, has been widely combined with unmanned aerial vehicles (UAVs) which can be flexibly deployed and enable preferable line-of-sight (LoS) propagation. However, unavoidable jitter effect at the UAV may degrade the coverage performance of the RIS. In this context, we consider a UAV-RIS system for enhancing regional coverage. Aiming at maximizing the worst signal-to-noise ratio (wSNR) in the target area, we jointly optimize the position of the UAV and the phases of the RIS elements under a practical UAV jitter model. For the ease of manipulation, the original problem is decoupled into two sub-problems: First, for a given UAV position, we propose a robust design of the RIS phases under UAV jitter, to ensure the coverage of the target area; after that, based on the proposed phases designing strategy, the feasible deploying positions of UAV is scanned via line search, to identify the optimal UAV position that maximizes the wSNR in the area. Simulation results show that the proposed RIS designing method effectively compensates for the coverage gain loss caused by UAV jitter, while the coverage performance of the target area is further improved by the joint UAV position optimization.