Random 3D Mobile UAV Networks: Mobility Modeling and Coverage Probability

In this paper, we investigate the coverage performance of a reference user equipment (UE) in a finite network of multiple three-dimensional (3D) mobile unmanned aerial vehicles (UAVs). Specifically, following the general theory on mobile ad hoc networks (MANETs), we propose a mixed mobility (MM) model which characterizes the movement process of a UAV in the 3D cylindrical region. In this paper, we invoke the random waypoint mobility (RWPM) and uniform mobility (UM) models to represent the movement of a UAV in vertical and spatial directions, respectively. By employing this MM model, we analyze the coverage probability of a reference UE in a finite network of multiple UAVs under the uniform UAV association and closest UAV association policies in one snapshot. According to the former policy, the UE connects to a random UAV while in the latter policy it connects to the closest UAV. Furthermore, all the non-serving UAVs act as the interferers to UE. To facilitate coverage probability analysis, we determine the serving and interfering UAVs-to-UE distance distributions under two association policies for Nakagami-m fading. We quantify the coverage performance of UE for various system and mobility parameters to exemplify the closest UAV association policy. Moreover, the analytical results are verified through simulations.