Increasing the information-theoretic secrecy by cooperative relaying and jamming

The use of cooperation to increase the information-theoretic secrecy in a decentralized ad-hoc wireless network is investigated. In particular, four cases of cooperative relaying are analyzed and compared. These cases include the no-cooperation case, the case with single-hop cooperation with multiple relays, the case with single-hop cooperation with the strongest relay, and finally the case of multi-hop cooperation with the strongest relay. From the results, it is seen that cooperation increases the probability of a positive secrecy rate between two nodes in a network with friendly (cooperative) nodes and eavesdropping nodes. The improved information-theoretic secrecy increases the probability that two nodes can share a secret message with perfect secrecy using a multi-hop route of trusted nodes. Cooperative jamming is also studied, and it is observed that very often it is more beneficial to use friendly nodes for cooperative jamming than cooperative relaying. Finally, a combination of cooperative relaying and jamming is considered.