Downlink Analysis and Evaluation of Multi-Beam LEO Satellite Communication in Shadowed Rician Channels

A multi-beam low-earth orbit (LEO) satellite delivers widespread coverage by forming spot beams that tessellate cells on the surface of the Earth. In doing so, co-channel interference manifests between cells when reusing frequency spectrum across spot beams. To permit forecasting of such multi-beam satellite communication system performance, this work characterizes desired and interference signal powers under the Shadowed Rician (SR) sky-to-ground channel model, along with SNR, INR, SIR, and SINR. Specifically, we present a framework for analyzing system performance by capitalizing on the fact that the desired and interfering signals travel along almost the same path in such multi-beam satellite systems. We then introduce a minor approximation on the fading order of SR channels that significantly simplifies the probability distribution function and cumulative distribution function of these quantities and facilitates performance analyses of LEO satellite systems. We conclude this article with an evaluation of multi-beam LEO satellite communication in SR channels of varying intensity with shadowing parameters fitted from existing measurements. Our numerical results highlight the effect satellite elevation angle has on SNR, INR, and SINR, which brings attention to the variability in system state and potential performance as a satellite traverses across the sky along its orbit.