Towards secure communications in cooperative cognitive radio networks

In this paper, a cooperative cognitive radio networking framework, which enhances the security of communications for the primary users (PUs) and provides transmission opportunities to secondary users (SUs), is proposed. Particularly, a PU selects two cooperating SUs, a relay SU and a jammer SU, for improving communication secrecy and grants a fraction of the bandwidth resource as a reward to the SUs, in which the cooperating SUs transmit their own data simultaneously using quadrature signaling. The objective of the cooperation is to maximize the secrecy rate of the primary link while satisfy the transmission rate requirements of SUs. To this end, the PU selects the best cooperating SUs and allocates the bandwidth optimally, while the relay and jammer SUs determine the optimal transmit power. Numerical results demonstrate that, with the proposed cooperative framework, the PU can achieve the maximum secrecy rate through cooperation with the selected SUs.