Secrecy outage performance for partial relay selection schemes in cooperative systems

In this study, secrecy outage performance is studied for partial relay selection (PRS) schemes in cooperative systems over Rayleigh fading channels. In the considered systems, there are one source (S), one destination (D), one eavesdropper, one jammer that can send interference to the eavesdropper, and N (N > 1) relay candidates, one of which is selected as the relay (R). By considering the practical scenarios and to protect the transmitted information over R-D link from being eavesdropped, the authors propose a new transmission scheme: let D send random information to R while S sending information to R. Then, R processes the messages from S and D by XOR operation in order to prevent the eavesdropper´s interception while the information is delivered between R and D. They study the secrecy outage performance for two PRS schemes: (i) the optimal source-relay link (OSRL) scheme; and (ii) the optimal source-relay-destination link (OSRDL) scheme. The closed-form expressions for the secrecy outage probability (SOP) of the two PRS schemes are derived, as well as the closed-form upper bound for SOP under OSRL scheme and the lower bound for SOP under OSRDL scheme. Finally, simulation results are given to verify the presented analytical models and the proposed transmission scheme.