Energy-Efficient Resource Allocation for UAV-Enabled Information and Power Transfer with NOMA

This paper investigates the energy efficiency optimization in a wireless communication network in which an unmanned aerial vehicle (UAV) deploys information and power transfer towards co-located information and energy receivers to enable downlink and uplink data transmission through nonorthogonal multiple access (NOMA). Using a constructed closed-form expression for the energy efficiency, a resource allocation mechanism aiming at maximizing the energy efficiency of the system is developed. To this end, an algorithm which jointly takes into account the downlink and uplink stages is proposed, using Lagrangian optimization and gradient decent methods. Numerical results and comparisons are provided. In particular, the results show an enhancement in energy efficiency for the NOMA scheme compared with OMA, and that less wireless power transfer time will be needed from the UAV to simultaneously charge energy receivers when using NOMA.