Sajad Poursajadi - Electronic and Computer engineering Malek-Ashtar University of Technology, Iran
Mohammad Hossein Madani - Electronic and Computer engineering Malek-Ashtar University of Technology, Iran

In this paper we investigate a feedback-based cooperative scenario, i.e. the incremental-best-relay selection (IBRS), to improve the physical layer security of multiple relay wireless networks. A realistic situation is considered in which there is direct links between source node and both destination and eavesdropper nodes, and also no knowledge of eavesdropper channel state information is available. We investigate the secrecy outage probability of the system. Simulation results are presented which indicate the desired secrecy performance provided by the IBRS scheme. In detail, it is shown that the IRBS scheme can improve secrecy capacity and secrecy outage probability compared to other common transmission scheme such as non-cooperative, and best relay selection (BRS). In fact, as the IBRS scheme avoids from retransmission in unnecessary cases, it can improve the spectral efficiency along with providing tradeoff between reliability and leakage of information to the eavesdropper. Clearly, this improvement is provided in the cost of applying limited feedback from the destination, i.e. log۲(I+۱) bits for a cooperative system with I relays

Physical layer security; cooperative communications; relay selection; incremental relaying;