When Satellites Work as Eavesdroppers

TL;DR

This paper analyzes the secrecy performance of uplink satellite communication systems with randomly distributed eavesdropping satellites, deriving closed-form expressions for SNR distributions, secrecy capacities, and outage probabilities, verified by simulations.

Contribution

It provides a comprehensive analytical framework for evaluating satellite secrecy performance considering non-colluding eavesdroppers with directional beamforming.

Findings

Closed-form SNR distribution expressions at satellites.

Derived ergodic and outage secrecy capacities.

Validated analytical results with Monte-Carlo simulations.

Abstract

This paper considers satellite eavesdroppers in uplink satellite communication systems where the eavesdroppers are randomly distributed at arbitrary altitudes according to homogeneous binomial point processes and attempt to overhear signals that a ground terminal transmits to a serving satellite. Non-colluding eavesdropping satellites are assumed, i.e., they do not cooperate with each other, so that their received signals are not combined but are decoded individually. Directional beamforming with two types of antennas: fixed- and steerable-beam antennas, is adopted at the eavesdropping satellites. The possible distribution cases for the eavesdropping satellites and the distributions of the distances between the terminal and the satellites are analyzed. The distributions of the signal-to-noise ratios (SNRs) at both the serving satellite and the most detrimental eavesdropping satellite are derived as closed-form expressions. The ergodic and outage secrecy capacities of the systems are derived with the secrecy outage probability using the SNR distributions. Simpler approximate expressions for the secrecy performance are obtained based on the Poisson limit theorem, and asymptotic analyses are also carried out in the high-SNR regime. Monte-Carlo simulations verify the analytical results for the secrecy performance. The analytical results are expected to be used to evaluate the secrecy performance and design secure satellite constellations by considering the impact of potential threats from malicious satellite eavesdroppers.