Stochastic Channel Models for Satellite Mega-Constellations

TL;DR

This paper introduces a stochastic satellite channel model for LEO mega-constellations, capturing the effects of satellite positions, movement, and propagation characteristics to improve communication system analysis.

Contribution

It develops a novel stochastic channel model based on a marked NBPP, accurately representing satellite positions, delays, Doppler shifts, and scattering effects for mega-constellations.

Findings

Channel parameters match realistic orbit simulations

Derived scattering function characterizes delay-Doppler spread

Global parameters like path loss are accurately modeled

Abstract

A general satellite channel model is proposed for communications between a rapidly moving low Earth orbit (LEO) satellite in a mega-constellation and a stationary user on Earth. The channel uses a non-homogeneous binomial point process (NBPP) for modelling the satellite positions, marked with an ascending/descending binary random variable for modelling the satellite directions. Using the marked NBPP, we derive the probability distributions of power gain, propagation delay, and Doppler shift, resulting in a stochastic signal propagation model for the mega-constellation geometry in isolation of other effects. This forms the basis for our proposed channel model as a randomly time-varying channel. The scattering function of this channel is derived to characterise how the received power is spread in the delay-Doppler domain. Global channel parameters such as path loss and channel spread are analysed in terms of the scattering function. The channel statistics and the global channel parameters closely match realistic orbit simulations of the Starlink constellation.