Research On Physical Layer Security Communications In Cooperative Cognitive Radio Networks

As one of the effective means to solve the shortage of spectrum resources,cognitive radio technology has become a research hotspot in wireless communication.Due to the broadcast characteristics of the transmission channel itself,the security threats faced by wireless communications are more severe in cognitive networks.Utilizing the characteristics of wireless channel fading and superposition,through channel coding and signal processing,the physical layer security,which can achieve secure transmission from the physical layer,has been considered as an effective communication method that is capable of achieving absolute secure communication.Cooperative relaying and cooperative jamming technologies can well resist eavesdropping nodes and improve the security performance of wireless systems.Therefore,this paper studies the secure transmission performance for cooperative cognitive radio networks based on cooperative relaying and cooperative jamming technologies.Firstly,the basic theory of physical layer security is introduced,and several performance indicators of physical layer security are further explained.Finally,the cooperative relaying and cooperative jamming technologies in physical layer security are introduced.Secondly,non-orthogonal multiple access(NOMA)technology is applied to cognitive wireless networks,and an underlay cognitive NOMA system model based on relay cooperation is proposed.Under a Rayleigh fading channel,consider a two-hop communication network.The relay node receives signals from the primary and secondary network transmitters simultaneously,and uses successive interference cancellation strategy to decode and forward the received signals.The secondary network obtains the opportunity to access the authorized frequency band by providing relay services for the primary network.The primary network provides the authorized frequency band for the secondary network in exchange for the opportunity of secondary network cooperative communication,and also obtains the highest priority decoding right to ensure the primary network communication reliability.The closed-form expressions of the outage probability of each destination node of the system model are derived,and MATLAB simulations are performed.Simulation results show that the use of cooperative relaying can effectively improve the outage probability performance of cognitive NOMA networks.Finally,a new cooperative communication mode between the primary network and the secondary network is proposed.The source node and the destination node of the secondary network are regarded as two additional relay nodes of the primary network.The two nodes provide cooperative relaying and cooperative jamming services along with the relay of the primary network to improve the physical layer secure transmission performance of the primary network.In return for cooperation,secondary users can access authorized frequency bands of the primary network to complete secondary communication,and the primary relay provides relay services for secondary user communication.Due to the division of time slots,the secondary network communication under this system will not interfere with the primary network.The reachable rate and outage probability of the secondary network,the reachable safe rate and outage probability of the primary network were analyzed,and Monte-Carlo simulation verification was performed.The outage probability and ergodic capacity of the secondary network,the secrecy outage probability and ergodic secrecy capacity of the primary network were analyzed,and MATLAB simulations were performed.The numerical results show that compared with the traditional non-cooperative mode,the cooperative relaying and cooperative jamming strategy can effectively improve the physical layer security performance of the system.This paper uses cooperative relaying and cooperative jamming technology to model and analyze the physical layer security performance of cooperative cognitive radio network,and obtains the relationship between system secrecy performance and provides necessary reference value for the design and deployment of cognitive radio network.