Research On Full-Duplex Jamming Physical Layer Security Technology

With the advent of the fifth-generation(5G)wireless communication technology,the wireless information transmission rate has been rapidly increased.At the same time,the number of mobile terminals has also gradually increased.This will take into account that the security and reliability of the user's confidential information in the transmission process,which has become a particularly important issue in the wireless transmission systems.Within traditional cryptography systems that are based on the secrecy key method,information is always encrypted and transmitted directly to ensure the security of the intended information.However,due to the advancement of semiconductor material technology,computer processing capabilities have been rapidly developed,resulting that the traditional encryption algorithm may be easily cracked,which will greatly threaten the security of wireless transmission systems.In view of the above,the physical layer security technology has received extensive attention in the academic community,and the cooperative relay network technology has the advantages of extending signal coverage and increasing network capacity.Therefore,by combining the cooperative relaying,cooperative jamming,and antenna selection technologies,meanwhile by using the time-varying and spatial characteristics of the wireless channel,it is possible to ensure the secure and reliable transmission of information directly at the physical layer.In untrusted relay networks,this dissertation studies the secure and reliable transmission performance of the multi-antenna full-duplex destination jamming,the half-duplex destination jamming,and the half-duplex non-jamming strategies,respectively.In order to improve the security and reliability of the three strategies,an optimal antenna selection scheme based on the switchable separate antenna deployment is proposed.In Rayleigh fading channel,for the three strategies under the optimal antenna selection method,the exact closed-form expressions of the ergodic achievable secrecy rate,the outage probability and the intercept probability are respectively derived in the case of any value of antenna number.Moreover,in the case of large-scale antenna array,the approximate closed-form expressions of the ergodic achievable secrecy rate and the asymptotic expressions of secrecy outage probability are derived,respectively.For the fixed transmission power in each time slot,the optimal power allocation scheme is given.The simulation results on the MATLAB platform show that,the theoretical analysis curves match well with the Monte Carlo simulation results.Through the comparison and analysis of the performance of the three strategies,the superior reliability of the full-duplex destination jamming strategy is highlighted.The research results show that,the three strategies under the optimal antenna selection method designed in this dissertation can significantly improve the security transmission performance of untrusted relay systems.In untrusted relay networks,cooperative jamming and antenna selection techniques can be used to effectively prevent internal eavesdropping systems from intercepting confidential information.In addition,the full-duplex jamming technology and optimal power allocation scheme are proposed to further improve the system's security and reliability performance.Under the optimal antenna selection,the secrecy diversity order of the full-duplex destination jamming strategy is proportional to the number of antennas,and the full antenna diversity gain can be achieved.With the increase of the antennas number,the security and reliability trade-off performance of the system is getting better,and under the largescale antenna array,the closed-form expression of the optimal power allocation factor for the full-duplex destination jamming strategy can be obtained,which can guide the design of the practical system efficiently.