Energy-Efficient Primary Security Provisioning for the Full-Duplex Cognitive Radio Networks

In order to protect the primary information and provide some licensed spectrum for the secondary system, we propose a secure transmission scheme, where the primary privacy information is protected by a full-duplex secondary system. In the proposed scheme, the secondary receiver utilizes one antenna to receive the secondary information, and the remaining antennas will be utilized to jamming the eavesdropper. In addition, the secondary system allocates a fraction of the transmit power for the secondary transmission and the remaining power will be allocated for jamming protection in the null space of both the primary and secondary transmission links. For the proposed scheme, we first analyze the primary secrecy outage probability and the secondary transmission rare as well as the energy-efficiency. Moreover, we optimally allocate the secondary transmit power such that the primary average secrecy rate is maximized under the requirements of the secondary transmission rate and energy-efficiency. Numerical results have been given to show the performance improvement of the proposed scheme about both the primary and secondary performances.