Time-correlated Geometrical Radio Propagation Model for LEO-to-Ground Satellite Systems

Low-Earth orbit (LEO)-based satellite communication systems are envisioned to be the next-generation key asset for telecom industry due to their potential to deliver global and seamless mobile broadband services. The high-speed mobility relative to Earth, that characterizes LEO orbits, will pose time-varying propagation conditions impacting the system performance in terms of mobility, availability and user throughput. Therefore, in LEO systems, it is fundamental to understand accurately the signal variations between mobile satellites and users on the ground. This paper presents a radio propagation model able to describe realistically the time variations of the LEO satellite-to-ground path loss, including the line-of-sight changes and the impact of the surrounding built-up structures. We propose a low-complexity geometrical approach based on intelligent raytracing that considers the general dependencies on the elevation angle. The resulting model has been validated for a suburban scenario, exhibiting an overall root mean square error of 1.1 dB. Furthermore, the time-correlated geometry-based model is suitable for system-level radio mobility simulations with LEO-to-Ground satellite systems.