Coverage Analysis for Cellular-Connected Random 3D Mobile UAVs with Directional Antennas

TL;DR

This paper develops an analytical model to evaluate coverage and handover performance of cellular-connected 3D mobile UAVs with directional antennas, considering factors like antenna beamwidth, mobility, and base station density.

Contribution

It introduces a stochastic geometry-based framework for analyzing UAV coverage with directional antennas and mobility, highlighting optimal antenna beamwidth and association strategies.

Findings

Optimal UAV antenna beamwidth decreases with GBS density.

Omnidirectional antennas are better in sparse networks.

Strongest average RSS association's advantage diminishes as GBS density increases.

Abstract

This letter proposes an analytical framework to evaluate the coverage performance of a cellular-connected unmanned aerial vehicle (UAV) network in which UAV user equipments (UAV-UEs) are equipped with directional antennas and move according to a three-dimensional (3D) mobility model. The ground base stations (GBSs) equipped with practical down-tilted antennas are distributed according to a Poisson point process (PPP). With tools from stochastic geometry, we derive the handover probability and coverage probability of a random UAV-UE under the strongest average received signal strength (RSS) association strategy. The proposed analytical framework allows to investigate the effect of UAV-UE antenna beamwidth, mobility speed, cell association, and vertical motions on both the handover probability and coverage probability. We conclude that the optimal UAV-UE antenna beamwidth decreases with the GBS density, and the omnidirectional antenna model is preferred in the sparse network scenario. What's more, the superiority of the strongest average RSS association over the nearest association diminishes with the increment of GBS density.