Security-reliability tradeoff for relay selection in cooperative amplify-and-forward relay networks

In this paper, we consider a cooperative amplify-and-forward (AF) relay network comprised of a source node, multiple AF relay nodes, and a destination node, in which an eavesdropper appears to intercept data communications from the source to destination via AF relays. In order to protect the source-destination transmissions against eavesdropping, we propose the best-relay selection scheme, where the “best” relay is chosen to assist the source-destination transmission. Intercept probability and outage probability are analyzed for characterizing the security-reliability tradeoff (SRT) of the best-relay selection. We also consider the SRT performance of direct transmission for the purpose of comparison with the proposed relay selection scheme. The SRT of the best-relay selection scheme is shown to be better than that of the direct transmission. In addition, as the number of AF relays increases, the SRT of the proposed scheme improves notably.