Multi-UAV Aided LEO Satellite Communication Network Analysis Based on Stochastic Geometry

The non-terrestrial networks, which include low earth orbit (LEO) satellites and unmanned aerial vehicles (UAVs), have gained important attention for next-generation networks. In this paper, we propose a multi-relay selection scheme for UAV-aided LEO networks in order to improve the coverage performance. Based on stochastic geometry, the binomial point process and Poisson point process are utilized to determine the 3D locations of LEO satellites and UAVs, respectively. The coverage probability analysis considering the interference effect due to the multiple UAVs is derived theoretically and verified by simulations. Also, the simulation results are compared with the Walker-based constellation, which is a practical constellation for LEO satellites. It is represented that the stochastic geometry-based results and Walker-based simulation results are very compatible with each other. Moreover, the effects of the UAV altitude, channel conditions, and the amount of UAVs that are utilized for cooperative communication are analyzed to obtain the comprehensive performance results. It is shown that the coverage performance is better in the case of UAV cooperation with more number of UAVs, while the coverage performance is worse in both sparse and dense UAV network deployments.