Secrecy Outage Probability of Optimal Relay Selection for Secure AnF Cooperative Networks

For cooperative systems, in which an eavesdropper overhears source information through relays' transmission, an optimal relay selection (ORS) scheme has recently been proposed to improve the system secrecy performance. In this letter, we evaluate the secrecy outage probability (SOP) of the ORS scheme with an amplify-and-forward system over independent and non-identically distributed Rayleigh fading. More specifically, we derive a tight approximation on the SOP. Thereafter, by analyzing asymptotic behaviour of the derived approximation, novel insights are revealed. The derivations are confirmed through Monte Carlo simulations.