Performance Analysis of LEO Satellite Networks

Abstract

As the demand for ubiquitous connectivity increases, the necessity for extensive coverage becomes paramount. Satellite networks are increasingly recognized as a vi- able solution for providing seamless global connectivity across various applications. With their low latency and broad coverage, low Earth orbit (LEO) satellite networks are considered essential infrastructure for a wide array of applications. Despite their advantages, LEO satellite networks encounter several challenges. The dense deploy- ment of hundreds or thousands of satellites increases the probability of inter-satellite interference, exacerbated by the wide beam diameters that can overlap with those of neighboring satellites. Security vulnerabilities are also a significant concern, as the broad coverage of LEO satellites heightens the risk of signals being intercepted by unauthorized users. The broadcast nature of satellite communications makes them susceptible to eavesdropping and jamming attacks. Additionally, the growing demand for broadband services has led to the sharing of satellite frequencies with terrestrial networks, causing potential in-band and out-of-band interference. In this dissertation, I investigate the performance of LEO satellite networks considering these three critical scenarios. Using stochastic geometry tools to analytically characterize the performance, I begin by investigating the coverage performance of downlink satellite networks em- ploying dynamic coordinated beamforming. My approach involves modeling the spa- tial arrangement of satellites and users using Poisson point processes (PPPs) situated on concentric spheres. Then, I derive an analytical expression for the coverage prob- ability which is formulated in terms of various parameters, including the number of antennas per satellite, satellite density, fading characteristics, and path-loss exponent. I also present a secrecy rate analysis for downlink LEO satellite networks by model- ing the spatial distribution of satellites, users, and potential eavesdroppers as homoge- neous PPPs on concentric spheres. Lastly, the analytical expressions for the ergodic spectral efficiency of uplink and downlink satellite networks are derived, considering the spectrum sharing with terrestrial networks.