Research On Physical Layer Security Transmission Mechanism Based On Time Reversal

The coming 5G Wireless mobile communication system will face massive terminal access,and information security transmission will be the focus of many scientific research institutions.Wireless channel has unique spatial,time domain and frequency domain diversity,which provides research space for establishing a more secure physical layer confidential communication.Time reversal is an electromagnetic science developed in recent years,which can improve the security of wireless transmission by using the characteristics of wireless channel combined with its own electromagnetic characteristics.The introduction of time reversal technology into the physical layer to improve the transmission performance of information security will be the research hotspot of wireless communication in the future.At present,some researchers have proposed a secrecy scheme using time reversal technology under the classical eavesdropping model,and carried out the safety performance evaluation.The advantages of time reversal technology in physical layer have not been fully excavated,and need further research.Based on this,the main work of this thesis is:Firstly,aiming at how to improve the legal channel capacity under traditional time reversal technology,an equalized time reversal technique for improving the security performance of indoor frequency selective fading channel is proposed.First,the equalizer is configured with the time inversion mirror at the signal sending end,and all transmitting antennas share the equalizer.Second,the equalizer is designed by time reversal equivalent channel information to deal with the channel equalization of indoor wireless channels,and to reduce the interference components between the legitimate receiving end codes in order to increase the secrecy SINR.At last,the secrecy performance of the system is deduced by mathematical analysis.Theoretical analysis and simulation results show that compared with the traditional time inversion technology,the secrecy SINR,the secrecy capacity of the equalized time reversal is higher,and the error rate of the legal receiving user is lower.Secondly,aiming at the eavesdropping problem of eavesdropping users using high channel correlation,a secure transmission method using artificial noise assisted time reversal is proposed.First,the system model is modeled as MIMO eavesdropping channel model,and the time reversal technique is adopted to ensure the security in the process of information transmission.Second,the artificial noise is designed according to the MIMO equivalent channel of time reversal,so that the noise interferes with the eavesdropper and does not affect the legal end.At last,based on the mathematical derivation of this method,the closed expression of SINR and secrecy capacity of confidential letter is obtained.Simulation results show that the use of time reversal technology at the same time,the distribution of a certain power of noise can improve the security performance of the system.