Security-reliability tradeoff analysis for jamming aided decode-and-forward relay networks

In this paper, we explore a cooperative decode-and-forward (DF) relay network comprised of a source, a relay, and a destination in the presence of an eavesdropper. To improve physical-layer security of the relay system, we propose a jamming aided decode-and-forward relay (JDFR) scheme combining the use of artificial noise and DF relaying which requires two stages to transmit a packet. Specifically, in stage one, the source sends confidential message to the relay while the destination acts as a friendly jammer and transmits artificial noise to confound the eavesdropper. In stage two, the relay forwards its re-encoded message to the destination while the source emits artificial noise to confuse the eavesdropper. In addition, we analyze the security-reliability tradeoff (SRT) performance of the proposed JDFR scheme, where security and reliability are evaluated by deriving intercept probability (IP) and outage probability (OP), respectively. For the purpose of comparison, SRT of the traditional decode-and-forward relay (TDFR) scheme is also analyzed. Numerical results show that the SRT performance of the proposed JDFR scheme is better than that of the TDFR scheme. Also, it is shown that for the JDFR scheme, a better SRT performance can be obtained by the optimal power allocation (OPA) between the friendly jammer and user.