Performance Analysis of Urban Satellite-Terrestrial Networks with 3D Blockage Effects: A Stochastic Geometry Approach

Urban satellite networks are affected by large-scale blockages, especially at higher frequencies. However, their effects in analysis are either ignored or described by oversimplified models. This paper introduces a systematic framework to model blockages and analyze their effect in urban Low Earth Orbit (LEO) satellite networks. By leveraging random shape theory concepts, the model captures the dynamic attributes of the user's environment, while stochastic geometry characterizes blockages and LEO satellite locations to identify the visible satellites to the user. A non-uniform distribution is observed for the visible satellites, with intensity varying with constellation size, altitude, blockage dimensions, and density. An adaptive association policy is proposed to enhance connection reliability. Under the proposed framework, we derive the line-of-sight probability, central angle distribution of the nearest visible satellite, and coverage probability under Rician fading. The proposed blockage model includes the unobstructed scenario as a special case. Compared to our theoretical analysis, simulation results show an excellent match. A detailed study of the effect of blockages and the different network parameters on its behavior is conducted and compared to the typical case with no blockages. The results underscore the need to account for blockage effects in the design of future communication systems.