Distributed Coalition Formation of Relay and Friendly Jammers for Secure Cooperative Networks

In this paper, we investigate cooperation of conventional relays and friendly jammers subject to secrecy constraints for cooperative networks consisting of one source node, one corresponding destination node, one malicious eavesdropper node, and several intermediate nodes. In order to obtain a higher secrecy rate, the source selects one conventional relay and several friendly jammers from the intermediate nodes to assist message transmission, and in return, it needs to make a payment. Each intermediate node here has two possible identities to choose, i.e., to be a conventional relay or a friendly jammer, which results in a direct impact on the final utility of the intermediate node. After the intermediate nodes determine their identities, they seek to find optimal partners forming coalitions, which improves their chances to be selected by the source and thus to obtain the payoffs in the end. We formulate this cooperation as a coalitional game with transferable utility and also study its properties. Furthermore, we define a Max-Pareto order for comparison of the coalition value, based on which we employ the merge-and-split rules. We also construct a distributed merge-and-split coalition formation algorithm for the defined coalition formation game. The simulation results verify the efficiency of the proposed coalition formation algorithm.