Optimal Joint Design on Continuous Trajectory and Power Control for UAV-Assisted Energy Constrained Communications

IEEE Transactions on Vehicular Technology, vol. 73, pp. 13060–13075

Abstract

In unmanned aerial vehicle (UAV)-assisted wireless networks, the continuous UAV trajectory designs generally suffer from the infinite variable number and the inherent trajectory continuity. In this paper, we aim at addressing the trajectory continuity and achieving a globally optimal joint design on the continuous trajectory and resource allocation. In particular, we consider a UAV-assisted wireless network serving a ground deployed user and focus on the energy-constrained communication. Taking the practical power control capability into account, we target at maximizing the overall throughput and formulate a joint power control and UAV trajectory design problem. However, the practically discrete choices for the realization of power control have also lead the optimization problem highly intractable. In this work, we start with the ideal power control case and propose a methodology with high extensibility for obtaining the optimal joint solution, which avoids the unexpected trajectory approximation in conventional design strategy. More specifically, via dual analysis, we first characterize the optimal power control as a function of a dual variable and the UAV position, such that the dual function can be transformed to pure trajectory design problems and the joint power control design is integrated in optimizing the dual variable. Inspired by a novel mechanical equivalence idea, we convert the formulated pure trajectory design problems into a series of equivalent mechanical rope equilibrium problems with adaptively defined potential field, which can then be solved optimally via physical principles. Based on that, an efficient algorithm is proposed for obtaining the optimal dual solution, from which the optimal joint solution is recovered as a closed-form solution according to the proved strong duality. Afterwards, the extensibility of the proposed design methodology is examined in the scenario with practical discrete power control and corresponding optimal joint design is eventually achieved. Finally, compared with a benchmark, the optimality and low design complexity in our obtained closedform solution are verified via numerical results. The necessity of considering practical discrete power control is also highlighted in simulations.

Authors 3

1. Xiaopeng Yuan Aachen Chair of Information Theory and Data Analytics

   RWTH Aachen University · Wuhan University

   Affiliation as printed

   Electronic Information School, Wuhan University, Wuhan, China

   Chair of Information Theory and Data Analytics, RWTH Aachen University, Germany

2. Yulin Hu

   Wuhan University

   Affiliation as printed

   Electronic Information School, Wuhan University, Wuhan, China

3. Anke Schmeink Aachen Chair of Information Theory and Data Analytics

   RWTH Aachen University

   Affiliation as printed

   Chair of Information Theory and Data Analytics, RWTH Aachen University, Aachen, Germany