Joint Wireless Power and Information Transfer for Primary Secure Transmission

For the sake of supplying information privacy to the primary network and supporting the secondary quality-of-service (QoS) requirement, we design a cooperative primary preserving strategy which simultaneously transfers power and information in cognitive radio networks. In this strategy, the secondary network offers information security to the primary information in three phases and obtains needed licensed spectrum for the secondary transmission. Specifically, in the first phase, a small part of the primary transmitter's power is allocated for the primary privacy transmission, meanwhile, 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, SR will occupy the licensed spectrum for the secondary information. For our proposed scheme, we research the transmission reliability and secrecy performances of the primary network and derive their closed -form expressions. Numerical results display the performance improvement of our scheme about the secondary average rate under the primary performance requirements.