Relay Selection for Enhancing Wireless Secrecy Against Eavesdropping

Abstract

In this chapter, we consider a wireless network consisting of a source and a destination with the aid of multiple relay nodes, where an eavesdropper is assumed with an intention to tap the confidential transmission from the source to destination. Considering multiple relays available, we present a relay selection scheme to protect the source-destination transmission against eavesdropping, where only the single “best” relay is selected to help the source transmit the signal to the destination. For comparison purposes, we also consider the conventional direct transmission and random relay selection as benchmark schemes. As the name implies, the direct transmission allows the source to directly transmit its signal to the destination without relying on the relays. By contrast, in the random relay selection, a relay is randomly selected to assist the source-destination transmission. Closed-form intercept probability expressions are derived for the conventional direct transmission and random relay selection as well as the proposed relay selection schemes over Rayleigh fading channels. We also present the secrecy diversity analysis of these there schemes and show that the proposed relay selection obtains the full secrecy diversity, whereas the direct transmission and random relay selection methods achieve the secrecy diversity order of only one. Numerical results demonstrate that the proposed relay selection performs better than both the direct transmission and random relay selection in terms of the intercept probability. Finally, as the number of relays increases, the intercept performance of the proposed relay selection improves significantly, showing the security benefits of exploiting the relay selection to defend against eavesdropping.