Abstract

This study investigates the secrecy performance of a satellite–backscatter device communication system in the presence of a potential eavesdropper. In the considered setup, a satellite transmits signals to a backscatter device, which reflects the modulated information back to the satellite while being subject to interception by an eavesdropper. To capture the practical wireless environment, the analysis is conducted over correlated Nakagami-$m$ fading channels, where the coupling among the forward, backscatter, and wiretap links is explicitly taken into account. We derive exact closed-form analytical expressions for key secrecy metrics, namely the secrecy outage probability (SOP), the ergodic secrecy capacity (ESC), and the symbol error rate (SER), which provide comprehensive insights into the secure operation of the system. Furthermore, asymptotic expressions are obtained for the SOP, enabling a deeper understanding of the secrecy diversity order under high signal-to-noise ratio (SNR) regimes. The impacts of critical channel and system parameters, such as fading severity, correlation, user power, and eavesdropper power, on the SOP, ESC, and SER are thoroughly examined. Monte Carlo simulations are also performed to validate the accuracy of the theoretical analysis.

Key words: Backscatter communication; secrecy outage probability; ergodic secrecy capacity; symbol error rate; physical layer security.