Distributed Interference Alignment in Cognitive Radio Networks

In this paper, we investigate the problem of incorporating two advanced physical layer technologies, i.e., multiple-input and multiple- output (MIMO) and distributed interference alignment, in cognitive radio (CR) networks. We present a cooperative spectrum leasing scheme for primary and secondary users to trade off between data transmission and revenue collection/payment. A Stackelberg game is formulated, where the primary user is the leader and the secondary users are followers. With backward induction, we derive the unique Stackelberg Equilibrium, where no player can gain by unilaterally changing strategy, as well as the optimal strategies. We find spectrum leasing is always beneficial to enhance the utilities of primary and secondary users. The proposed scheme outperforms a no-spectrum-leasing scheme and a cooperative scheme presented in the literature with considerable gains, which demonstrate the benefits of spectrum leasing and distributed interference alignment and validate the efficacy of the proposed scheme.