Closed Trajectory Optimization for Aerial Base Station: An Energy Efficiency Design

Abstract

By optimizing the energy-efficient flight trajectory of unmanned aerial vehicles (UAVs), UAV-based aerial base stations (BSs) can provide longer communication services to more ground nodes (GNs) under the UAV battery limitation. Path discretization method and successive convex approximation (SCA) algorithm have been shown to be effective techniques in the design of the energy-aware UAV one-way trajectory along a few GNs. Compared with current studies, this paper designed and compared different optimal closed UAV trajectories among multiple GNs under a wide range of changing communication requirements. Meanwhile, a more complex and realistic scenario is considered where the UAV visits the ground nodes sequentially without repetition from a centrally located terrestrial base station and returns to the starting point in the end. To thoroughly analyze this problem, two UAV trajectory designs are proposed in this paper. One is to use the fly-hover-communicate protocol as a benchmark for comparison, and the other is to require that the UAV should fly and communicate with ground nodes simultaneously, named the fly-over scheme. The simulation results show that, in general, the proposed fly-over scheme outperforms the benchmark results, while in the case of high and low communication demands, the energy-saving performance of both is very similar. Therefore, advice can be given on the design of the UAV trajectory depending on different situations.