Improving Wireless Security for Bidirectional Communication Scenarios

In this paper, we study how to improve wireless security for bidirectional communications. For the scenario with single-antenna nodes, effective criteria for relay and jamming node selection are developed to ensure that the probability to have nonzero secrecy rates is approaching one, given sufficient relays. For the scenario with multiple-antenna nodes, effective precoding is proposed to ensure that the mutual information obtained at the eavesdropper decreases to zero when there is a sufficient number of relays.