Energy-Aware Self-Sustaining Solar-Powered UAV Swarm in Dense Urban 6G Networks With Laser WPT

Abstract

This paper addresses the self-sustainable operation of unmanned aerial vehicle (UAV) swarms in dense urban 6G networks, where both communication reliability and energy replenishment are strongly affected by building-induced blockage. Although solar harvesting and laser wireless power transfer (WPT) can extend UAV operation, they are tightly coupled with UAV mobility: a communication-favorable position may not be feasible for laser charging, while a charging-oriented position may degrade ground node (GN) service. To capture this coupling, we develop a blockage-aware self-sustaining UAV swarm framework that integrates communication, solar harvesting, safety-compliant laser WPT, and UAV mobility under urban blockage. In the proposed model, buildings serve as common geometric constraints that determine both UAV–GN line-of-sight (LoS) connectivity and laser charging feasibility. We formulate a joint optimization problem of user association, UAV trajectory, laser charging decisions, and battery states to maximize the minimum spectral efficiency among GNs while ensuring sustainable energy operation. To address the resulting nonconvex mixed-integer nonlinear problem, we develop a tailored convexification framework for the coupled communication–charging–mobility design. Simulation results reveal that UAVs adapt their mobility according to solar availability: they prioritize short-range LoS communication when solar energy is sufficient, while moving toward safety-compliant and blockage-free laser charging regions under limited solar harvesting. These results highlight the need for joint mobility control that balances communication service and energy replenishment under building-induced blockage.