Relaying techniques for enhancing the physical layer secrecy in cooperative networks with multiple eavesdroppers

Physical layer security has recently attracted considerable attention in the context of information-theoretic point of view. In this paper, we investigate relay selection schemes for security-constrained half-duplex cooperative wireless networks with multiple eavesdroppers, which have the ability to cooperate to overhear the source transmission. The proposed techniques select a trusted decode-and-forward relay to assist the source transmission and maximize the achievable secure rate for different eavesdropper policies (cooperation or not); for the two cases, we assume that the channel is always available. In addition, a jamming method that selects two relay nodes to create an intentional interference at both phases of the decode-and-forward protocol to confound the eavesdropper nodes is also considered. Both the source-destination and source-eavesdroppers links are taken into account in the proposed analysis. Secrecy rate and secrecy outage probability are the two performance metrics that are used to verify the effectiveness of the proposed schemes while asymptotic approximations of the secrecy outage probability are also derived. Simulation and analytical results demonstrate the performance improvement of the proposed schemes. Copyright (c) 2012 John Wiley & Sons, Ltd.