Physical layer security is proposed to solve the security problem in which the secrecy principle is based on the exploitation of the physical characteristics of the wireless channel. At this time, a SU has the right to use the licensed band, but the SU does not know the artifice of PUs which PUs want to eavesdrop on the information of the SU.ĭue to the broadcast characteristic of the wireless environment, the secrecy of data transmissions is very important. In this scheme, the PU leases a part of the licensed band to the SU to increase the QoS of the primary network as well as the spectrum access capacity of the secondary network.

When the quality of service (QoS) of the primary network is very high, the transmission of the secondary network depends on the cooperative request of the PU. To do this, SUs always opportunistically sense the presence or absence of the licensed bands to make a transmission decision. In cognitive radio networks, unlicensed users, which are known as secondary users (SUs), only access the licensed bands without causing interference to licensed users, which are known as primary users (PUs). In addition, the secure performance of the secondary network, as expressed by the outage secrecy probability and the average secrecy capacity, is maintained under the eavesdropping of the primary transmitter.Ĭognitive radio (CR) is a concept that enhances the utilization efficiency of the licensed frequency spectrum in that wireless devices are continuously developed for modern applications, but the spectrum bands are limited. The numerical and simulative results show that the system performance of the primary network in the cooperative scheme is improved in terms of the outage probability and the symbol error rate and is compared with that in the direct transmission scheme. Physical layer security is applied to evaluate the cooperative efficiency in terms of the data transmission and data security. On the other hand, the SU owns important data and may mistrust the intention of a primary transmitter. Hence, the SU helps the PU in transmitting primary signals and has an opportunity to access the frequency spectrum.

In this scheme, a secondary user (SU) accepts a lease of a part of the licensed band according to a cooperative request of a primary user (PU). In this paper, we propose a cooperative scheme between primary and secondary networks.

F secure spectrum