Trajectory Optimization of a UAV Following Moving Targets in Wireless Communication Network

In this paper, we study the problem of determining the optimal flight trajectory of an Unmanned Aerial Vehicle (UAV) serving as a mobile base station to provide wireless coverage to moving aerial targets in a cellular network. The investigation of this problem is motivated by the need to improve UAV-assisted wireless communication for dynamic aerial targets, in contrast to the focus on primarily static targets in current literature. Our goal is to achieve the desired Signal-to-Noise Ratio (SNR) level for these targets with predefined priorities through UAV-assisted wireless connectivity during the mission. We consider three different cases, wherein the broadcasting UAV may have an (a) isotropic antenna, (b) omnidirectional antenna, and (c) a directional antenna. For each of these cases, we formulate the SNR optimization problem as a nonlinear optimal control problem leading to the Hamilton-Jacobi-Bellman (HJB) equation. We explore the problem from a guidance aspect, and apply the Successive Galerkin Approximation method to solve the HJB equation and derive the optimal guidance law. Simulation results are presented.