Secrecy Outage Probability of Multiuser Untrusted Amplify-and-Forward Relay Networks

This paper investigates the effect of untrusted relay on the secrecy outage probability of amplify- and-forward relay networks with the help of direct links and multiple users. We consider three selection criteria which are based on the direct and relaying link. The impacts of both the direct and relaying links on SOP performance is studied by deriving the closed-form analytical SOP as well as the asymptotic expressions. Simulation results are provided to confirm the theoretical analysis. It can be found that the diversity order of optimal selection criterion is equal to the number of users, while the diversity order of the sub-optimal criterion based on relaying links is equal to one.