Energy Minimization in RIS-Assisted UAV-Enabled Wireless Power Transfer Systems

Unmanned aerial vehicle (UAV)-enabled wireless power transfer (WPT) systems offer significant advantages in coverage and deployment flexibility, but suffer from endurance limitations due to the limited onboard energy. This article proposes improve energy efficiency of UAV-enabled WPT with multiple ground sensors by utilizing reconfigurable intelligent surface (RIS). Specifically, total consumption UAV is minimized, while meeting requirement each sensor. First, we consider a fly-hover-broadcast (FHB) protocol, which radiates radio-frequency (RF) signals only at several hovering locations. The minimization problem formulated jointly optimize UAV’s trajectory, time, RIS’s reflection coefficients. To solve this complex nonconvex problem, propose an efficient algorithm. successive convex approximation (SCA) framework adopted trajectory minorization–maximization (MM) algorithm that maximizes minimum charged all provided update Then, investigate general scenario RF are radiated during flight, aiming minimize optimizing flight By applying path discretization (PD) optimization finite number variables. A high-quality solution for more challenging obtained. Finally, our simulation results demonstrate effectiveness proposed benefits RIS saving.