Improve secure communications in cognitive two-way relay networks using sequential second price auction

In this paper, we consider a cognitive radio network in which multiple pairs of secondary users (SUs) exchange their information over two-way relay orthogonal channels with the existence of an eavesdropper. The SU pairs share the same frequency band with a primary user (PU) by satisfying the interference power constraint, and the eavesdropper can listen to all the frequency bands. Our goal is to maximize the sum secrecy rate of the SU pairs and meanwhile preserve fairness by suitably allocating the power of the relay station (RS). We introduce a sequential second price auction as the mechanism. Specifically, the total power of the RS is divided into several homogeneous units and auctioned off in sequence, with each round a typical second price auction. First, we formulate the value of each power unit for each SU pair, which is fundamental in the proposed auction, and then based on this auction we construct an efficient searching algorithm, which leads to only one equilibrium. Simulation results show that the proposed game achieves promising performance in the total secrecy rate, total revenue, and fairness under randomness of terminal location and the time-varying nature of wireless channels.