Improving physical layer security in two-way cooperative networks with multiple eavesdroppers

In this paper, three different relay and jammers selection schemes are presented to improve the physical layer security of two-way cooperative networks in the presence of multiple cooperating and non-cooperating eavesdroppers. The presented selection schemes are; optimal selection scheme without jamming, optimal selection scheme with conventional jamming, and optimal selection scheme with controlled jamming. The proposed schemes select three intermediate nodes during two communication phases. In the first phase, a friendly jammer is selected to create intentional interference at the eavesdroppers´ nodes. In the second phase, two relay nodes are selected; one node is selected to operate as a conventional relay and assists the sources to deliver their data to the corresponding destinations via a Decode-and-Forward (DF) strategy. While the other node behaves as a jammer node in order to confuse the eavesdroppers in this phase. The proposed schemes are analyzed in terms of ergodic secrecy rate and secrecy outage probability. The obtained results show that the jamming schemes outperform the non-jamming schemes in the eavesdroppers´ environment. Moreover, cooperating eavesdroppers´ further degrade system´s secrecy performance than the non-cooperating ones. Finally, a comparison between relay and jammers selection schemes in both one-way and two-way cooperative networks is given in terms of both ergodic secrecy rate and secrecy outage probability metrics.