Channel Modeling for UAV-Aided LEO Satellite Communication

In satellite communication, to solve the problem that it is impossible to deploy ground base stations in some special scenarios to realize normal communication, this paper introduces Unmanned Aerial Vehicles (UAV) as relay base stations in Low Earth Orbit (LEO) satellite communication system to construct space-air-ground integrated communication link, and proposes a Three-Dimensional Multiple Input Multiple Output (3D MIMO) channel model based on regular geometry. In this model, a hemispherical model is used to describe the distribution of terminal scatterers. Since the elevation and azimuth angles of the scatterers in the hemispherical model are combined, the effective scatterer distribution is represented by the von Mises Fisher (VMF) function. The statistical properties such as the local Space-Time Correlation Function (S-TCF), Doppler Power Spectral Density (DPSD), Level Crossing Rate (LCR), and Average Fading Duration (AFD) of the channel model are deduced, and the influencing factors of the channel properties are studied and analyzed. The results show that the UAV’s moving direction, antenna direction, and initial angle all affect the statistical properties of the model. The simulation results verify the accuracy of the model, and the second-order statistical properties confirm the effectiveness of the model. The proposed model expands the research and application of the satellite communication channel model.