On the Secrecy Analysis of Satellite-Terrestrial Communication Link over Gamma–shadowed Ricean Fading Channels

This paper deals with the physical layer security for the satellite-terrestrial communication system in the presence of an eavesdropper. In the analysis, the satellite has no knowledge of the eavesdropper’s channel state information referring to the passive eavesdropping scenario. The main, as well as the wiretap link, are both characterized as gamma-shadowed Ricean fading channels. The analytical expressions for the secrecy outage probability and the probability of strictly positive secrecy capacity are derived. The secrecy diversity order is also determined. The impact of the fading/shadowing parameters and the average signal-to-noise ratios of the legitimate/illegitimate channels on the aforementioned secrecy metrics is investigated. The results illustrate that specific, either main or wiretap channel nature can enhance system security at the physical layer.