Cooperative Jamming in a Two-Hop Relay Wireless Network with Buffer-Aided Relays

In this paper, we consider a two-hop relay wireless network with one source, one destination, one eavesdropper and multiple half-duplex (HD) relays each having a finite buffer. We assume two cases of the eavesdropper's channel state information (CSI), i.e., the perfect CSI case where the instantaneous CSI of the eavesdropper channels are available, and the partial CSI case where only the average CSI of the eavesdropper channels are available. Cooperative jamming schemes are proposed for both eavesdropper's CSI cases, where two relays are selected in each hop, one is selected as a message relay and another as a jammer to transmit jamming signals to degrade the eavesdropper channel. The security performance in terms of the secrecy outage probability (SOP) is analyzed by simulation. We also make comparison between our proposed cooperative jamming schemes with the random jammer selection scheme. Results show that the proposed cooperative jamming scheme outperforms the random jammer selection scheme and the joint consideration of the buffer-aided relay selection and jamming can achieve better security performance.