Optimal Wireless Information and Energy Transmissions for UAV-Enabled Cognitive Communication Systems

This paper considers a novel UAV-enabled cognitive communication system, where a battery-powered UAV hovers above a radio frequency (RF) energy harvesting enabled ground terminal (GT), and opportunistically accesses the licensed spectrum of the primary user (PU), to adaptively perform wireless information transfer (WIT) and/or wireless energy transfer (WET) to the GT. We formulate the UAV’s optimal WIT and WET design as a constrained Markov decision process (MDP) problem to maximize the sum-throughput in the downlink over a finite time horizon. However, this problem is shown to have high complexity to solve. We then propose an efficient suboptimal policy with low complexity by studying the optimal policy structure. Numerical results show that the proposed suboptimal policy can significantly improve the sum-throughput in the downlink over the benchmark.