Secrecy Performance Analysis of Hybrid RF-FSO Cooperative Satellite-Aerial-Terrestrial Networks with imperfect CSI

This study examines the secrecy outage performance of uplink transmission within a hybrid cooperative satellite-aerial-terrestrial network (SATN) that integrates radio-frequency (RF) and free-space optical (FSO) technologies. Specifically, in the proposed cooperative SATN, a terrestrial source (S) conveys its information to a satellite receiver (D) with the assistance of an aerial relay (R), while a group of eavesdropping aerial terminals (Eves) attempts to intercept the confidential data. RF and FSO transmission methods are employed over the S-R and R-D links, respectively, both subject to imperfect channel state information (CSI). By considering the randomness of R, D, and Eves, and utilizing a stochastic geometry framework, we investigate the secrecy outage performance of the considered SATN. A closed-form analytical expression for the end-to-end secrecy outage probability is derived. Finally, simulations are conducted to validate the accuracy of the analysis.

I. Introduction

The hybrid cooperative satellite-aerial-terrestrial network (SATN) has gained significant attention for its inherent features, such as seamless connectivity and extensive coverage [1]. Recently, it has emerged as a vital enhancement for sixth-generation (6G) systems, which are designed to meet the rapidly increasing global demand for data and accommodate a diverse range of users. The versatility of satellite communication makes it particularly suitable for applications such as mass broadcasting, internet access, military communication, weather monitoring, aviation and navigation [2], [3].