Energy-Efficient Resource Allocation For Uav-Enabled Wireless Powered Communications

This paper investigates the energy efficiency optimization in a wireless communication network where devices are wirelessly powered via unmanned aerial vehicle (UAV) to enable uplink data transmission. First, the path loss of the air-to-ground channels is minimized by optimizing the position of the UAV depending on the ground nodes' service demands. Then, using the optimized positioning and a closed-form expression for the energy efficiency, a resource allocation aiming at maximizing the energy efficiency is developed. To this end, two algorithms are proposed, using Lagrangian optimization and gradient decent methods. Numerical results and comparisons are provided. In particular, the results show an enhancement in energy efficiency and reduced wireless power charging time when the ground nodes' demands are taken into consideration.