Investigating cooperative strategies for security-reliability trade-off in full-duplex relay wireless networks

In this paper, we present a comprehensive investigation on security-reliability trade-off (SRT) in cooperative wireless networks in which full-duplex intermediate nodes act as jammer and/or relay. Various cooperative schemes named as opportunistic relay selection (ORS), opportunistic jammer selection (OJS), hybrid relay-jammer selection (HRJS), and joint relay-jammer selection (JRJS) are considered. In these schemes, relay and jammer sets are distinguished by comparing the instantaneous and average fading properties of the main and wiretap links, respectively. So that, one or two helpers from these sets are opportunistically employed for cooperation regarding the applied scheme. We analyze the outage and intercept probabilities and derive closed-form expressions for the SRT of the considered schemes. The results show that the cooperative schemes deliver different behaviors by varying parameters such as number of helpers, link quality and data rate. In details, ORS outperforms the other schemes for high main to eavesdropper ratio (MER), whereas JRJS delivers better performance for lower MERs. By improving the relay-to-destination link compared to source-to-destination, both HRJS and JRJS outperform the ORS while HRJS delivers better SRT than JRJS. Moreover, HRJS outperforms JRJS at higher data rates. The results also indicate that SRT of all schemes is improved by increasing the number of helpers.