Unmanned aerial vehicles (UAVs) are expected to play an important role in future wireless networks, serving as communication relays, computing servers, and flying infrastructure for ground users when ground-based infrastructure is congested or inaccessible. However, typical UAVs are powered by on-board batteries, which results in limited battery lifetime and poses a major restriction for UAV applications in communications. To overcome this, we propose a consistent and cost-aware energy procurement framework for a UAV powered concurrently by laser beams, emitted from locally deployed laser beam directors, and local renewable energy (RE) sources. The UAV intends to lower its overall energy cost for a certain operation cycle by optimizing the quantities of energy obtained from its battery as well as laser beams at each time period. Given the optimization results, we also propose a cost-aware UAV placement strategy with the ultimate goal of ensuring quality communication-energy links for the UAV, ground devices (GDs) and users. In addition, we assess the amount of additional procured RE that can be transferred via wireless power transfer to charge a set of distributed GDs. The simulations provide interesting insights into the efficiency of the proposed framework.
