Research On Physical Layer Security Mechanism Of Wireless Network Based On Cooperative Communication

In the current era,with the amazing development speed of wireless networks and the popularity of wireless devices,wireless networks have become an important means for people to share information,the amount of information transmitted on the wireless channel has exploded.However,due to the broadcast characteristics of wireless channel,data transmitted on wireless networks is extremely vulnerable to eavesdropping by illegitimate users,leading to information leakage.Traditional cryptography-based schemes use the key encryption to transmit information,but they have the disadvantages of complex key management and inability to cope with brute force attacks.The physical layer security(PLS)exploits the physical characteristics of the wireless channel to achieve secure communication.It is simple to operate and does not require complex encryption and decryption algorithms.Thus,it is a promising technology to solve the security problems of wireless networks,and has become a research hotspot in the field of wireless network communication security.In addition,cooperative communication utilizes cooperative relay to assist transmission,which not only expands the coverage of the network,but also effectively improves the signal quality at the receiver and the transmission reliability of the system.The combination of cooperative communication and PLS can bring the diversity increment of cooperative node into PLS,making the channel quality of the legitimate link better than the channel quality of the eavesdropping link,thus ensuring the secure and reliable transmission of information.Nevertheless,the cooperative relay may be untrustworthy in some cases,which means that the relay can act as an eavesdropper to eavesdrop on messages from the source node.Therefore,in order to solve the problem of secure communication in wireless networks,combined with the relevant technologies of cooperative communication and PLS,this paper studies the PLS schemes in the trusted relay and untrusted relay cooperative communication scenarios,respectively.The specific research contents are as follows:(1)In the case of the trusted relay cooperative communication scenario,the security performance of relay and jammer selection schemes under the condition of different channel state information(CSI)of eavesdropping links is studied.For the case in which the statistical CSI of eavesdropping channels is known,the security performance of two kinds of relay and jammer selection schemes based on maximizing secrecy capacity is discussed,namely the relay-only selection scheme and the joint relay and jammer selection scheme.The selection results and the asymptotic expressions of the secrecy outage probability are given under the conditions of cooperative and non-cooperative eavesdroppers.For the case in which the CSI of the eavesdropping channels is unknown,a relay selection scheme with cooperative jamming is proposed,where multiple jammers are selected to cooperate to prevent eavesdropping by eavesdroppers,and the best forwarding relay is obtained by maximizing the capacity at the destination.Simulation results show that proper jamming contributes to improve the security performance of the system.When the number of eavesdroppers increases,compared with the scheme of selecting only one jammer,the relay selection scheme with multiple cooperative jammers has better security.(2)In the case of the untrusted relay cooperative communication scenario,in order to prevent the untrusted relay and the eavesdropper at the same time,the full-duplex technology is introduced,and the beamforming and cooperative jamming scheme is proposed.The source node uses the zero-forcing beamforming strategy to send messages,and the destination sends jamming signal while receiving messages.The closed-form expressions of the average achievable secrecy rate and secrecy outage probability of this scheme are derived.Simulation results show that the proposed scheme can achieve higher security performance and is superior to the half-duplex scheme.This paper investigates the PLS schemes under different relay roles to improve the security performance of wireless networks and provides some insights for the secure transmission of information in next generation networks.