Multi-RISs Assisted UAV-Enabled Wireless Sensor Network

To fully take advantage of unmanned aerial vehicle (UAV)’s flight freedom in three-dimensional (3D) space, and enhance the capability of reconfigurable intelligent surface (RIS) for providing better communication services with multiple ground sensors, we design a multi-RISs assisted UAV-supported wireless sensor network (WSN). The target is to achieve the highest minimum average data collection rate by optimizing the communication scheduling of ground sensors, multi-RISs’ phase-shift coefficients, and the UAV’s 3D trajectory. This paper offers an iterative theorem that effectively obtains the high-quality suboptimal solution to the non-convex problem by utilizing successive convex approximation (SCA), alternating optimization (AO), and semidefinite relaxation (SDR) techniques. The results verify that the designed algorithm has significant improvement in data collection rate, and the practical significance of deploying multi-RISs and designing 3D UAV trajectory.