On the Impact of Orbital Motion on Handoff and Coverage in Multi-antenna LEO Satellite Systems

As fast-moving low Earth orbit (LEO) satellite communication systems gain increasing prominence, the significance of analytical performance models that account for mobility becomes more crucial than ever. Additionally, while considerable progress has been made in modeling the coverage performance of single-antenna LEO satellites, there is a noticeable gap when it comes to considering multi-antenna satellites. This paper presents a novel stochastic geometry framework to characterize the user coverage probability in a downlink LEO satellite network in the presence of multi-antenna satellites, handoffs (HOs), and the Shadowed-Rician fading model. We first determine the distribution of the desired and interfering channel power gains under zero-forcing beamforming. Then, we characterize the HO probability per unit time referred to as the HO rate under distance-based association. Next, we derive the handoff-aware coverage probability expression, and we validate our findings through numerical results obtained from Monte-Carlo simulations, offering insights into the effects of HO and multi-antenna processing on user coverage probability.