Research On Physical Layer Security Communication Based On Relay Selection And Cooperative Jamming

The background to the fifth-generation mobile communications and big data,the total amount of communication data has grown exponentially.It can be some sensitive data,which needs to be transmitted in an extremely secure environment.Due to the rapidly development of computer processing capability,the information encryption method of traditional cryptography is no longer absolutely reliable.As an effective supplement to the traditional upper layer encryption method,physical layer security utilizes the physical characteristics of wireless channels to ensure communication security,which has been one of the research hotspots in the field of wireless communication.Aiming at relay cooperative secure communication network,this paper studies the secure transmission performance under environment of passive eavesdropper or adaptive eavesdropper based on the relay selection strategy and the cooperative jamming strategy.The main research contents are as follows:On the one hand,the secure transmission performance of the system is studied in communication environment with passive eavesdropper.Two relay selection strategy is adopted,and the channel state information of the legitimate user and eavesdropper is considered comprehensively.Firstly,an optimal relay is selected from decoding set that can successfully decode source information,which is regarded as relay forwarding node to assist source node forwarding the message.Then,another relay is selected from remaining relay nodes as the jammer based on the above-mentioned relay selection,which is used to send the artificial noise to.The performance of the security outage probability for two relay selection schemes are analyzed and compared.Finally,the simulation result proves that the relay selection strategy can effectively improve the secure transmission performance.On the other hand,the secure transmission performance of the system is studied in the communication environment with an adaptive eavesdropper.Compared with passive eavesdropper,the adaptive eavesdropper is smarter,which can intelligently switch between the passive eavesdropping mode or active jamming mode based on the quality of the eavesdropping link.It will further increase the difficulty of information security transmission.Based on the cooperative jamming strategy,it is assumed that the channel quality between source node and all relay nodes is good,which means all relays can successfully decode the source information.One relay node is selected before the source information transmission,which is used to assist the source node to forward information,and the remaining relays transmit jamming cooperatively in two transmission phases to confuse the eavesdropper.Firstly,the asymptotic closed-formed expression of ergodic achievable security rate is derived under equally power allocation condition.Then,the performance of system security outage probability is further analyzed under different power allocation condition.Finally,simulations verify the correctness of analysis for the performance of ergodic achievable security rate,and the impact of each power allocation factor parameter on system security outage probability.