Primary Privacy Preserving with Joint Wireless Power and Information Transfer for Cognitive Radio Networks

In order to provide information privacy for the primary network and support the secondary quality-of-service (QoS) requirement, we design a cooperative primary preserving strategy which simultaneously transfers information and power in cognitive radio networks. In this strategy, the secondary network provides information security for the primary information transmission in three phases and obtains some licensed spectrum for the secondary information transmission. Specifically, in the first phase, a fraction of the primary transmitter's power is allocated for the primary privacy transmission, and the remaining power is utilized to beamform the energy signal for energy harvesting. After receiving the privacy signal, two secondary users cooperatively forward the privacy information under jamming protection. In the last phase, the secondary user occupies the licensed spectrum for the secondary information transmission. We first analyze the transmission reliability and secrecy performances of the primary network, and then the primary transmit power and the time slot are optimally allocated such that the secondary transmission rate is maximized under the requirements of the primary information reliability and security. Additionally, we also investigate the primary power and time slot allocation problem for the asymptotic scenario. Numerical results are presented to show the performance improvement of the proposed scheme about the secondary average rate under the primary performance requirements.