Analysis of Handover Probability Based on Equivalent Model for 3D UAV Networks

The unmanned aerial vehicle (UAV) communication has become a promising technology to enhance network coverage thanks to the high mobility and flexibility of UAV. However, the dense deployment of UAVs and the time-varying aerial environment will introduce frequent handovers. This paper proposes a tractable equivalent model for 3D UAV networks, and derives compact expressions of the user association probability and the handover probability through stochastic geometry analysis. Modeling the 3D wireless network of UAVs as a multi-tier network where the locations of UAVs in each tier follow a Poisson point process (PPP), the equivalent horizontal distance is introduced to eliminate the information loss brought by the projective process. Based on the proposed model, the per-tier user association probability is first derived with the maximum average received power criterion. Furthermore, taking advantage of the equivalent model, handover probability between UAVs with different altitudes is analyzed. The results show that there is an optimal density in the 3D UAV networks for minimal handover probability, and the handover probability decreases as the deployment altitude increases.