3D-Trajectory design for outage minimization in UAV-assisted 5G communication system

Abstract

In this paper, we study and optimize the trajectory for unmanned aerial vehicle (UAV) to provide fifth-generation (5G) cellular service to users in a given area. We consider a single UAV launched from the fixed initial to the final location, during which it serves the ground users that are distributed in a circular field. We introduced an optimization problem to minimize the average outage probability of the system by optimizing the threedimensional (3D) trajectory of the UAV. As this problem is nonconvex, we proposed an efficient approach that involves two steps, firstly it frames a new problem to obtain a globally optimal location in 3D space for minimal average outage probability. This problem is shown to be conditionally convex and an efficient algorithm is proposed to obtain a globally optimal location within an acceptable tolerance. Thereafter, a sub-optimal solution is proposed for the original problem. Simulation results provide useful insights into the sub-optimal trajectory of UAV and show that our proposed approach on an average provides 24% outage improvement over the benchmark scheme. This improvement is further enhanced with the increase in the velocity of UAV.