Research On Physical Layer Security Communication Technology In Millimeter Wave

With its rich spectrum,millimeter wave communication has become a key technology to alleviate the high congestion of frequency resources,so as to meet the needs of high data rate communication and play an important role in future wireless communication systems.Therefore,millimeter wave communication technology has attracted the attention of many researchers.However,due to the openness of wireless systems,the security of wireless systems faces severe challenges.The traditional method realizes secure communication by using the key encryption technology at the network layer and above,but with the improvement of computing power,the traditional technology based on the key encryption technology is always facing the risk of being cracked.The physical layer security technology does not depend on the key and moves the security gate forward,so it becomes an important potential solution to solve the problem of wireless security communication in the future.Traditional physical layer security techniques use artificial noise,directional modulation,beamforming and other techniques to degrade the eavesdropper's channel and securely transmit confidential information to legitimate receivers.Different from the previous research on millimeter wave physical layer security technology,this thesis mainly studies the physical layer security communication technology in millimeter wave communication system based on the unique propagation characteristics and large broadband characteristics of millimeter wave.Starting from the propagation characteristics of millimeter waves,this thesis proposes three secure transmission schemes based on the discrete angle domain channel model to combat non-cooperative and cooperative eavesdropping.Starting from the large bandwidth of millimeter-wave communication,this thesis proposes a large-scale MIMO(Multiple Input Multiple Output)suitable for high-bandwidth millimeter wave in view of the SWE(Spatial Wideband Effect)caused by the high bandwidth of large-scale antenna arrays.A secure transmission scheme for MIMO communication systems.First,by modeling randomly distributed eavesdroppers in space as a Poisson point process,this thesis takes advantage of the sparsity of mm Wave transmission to model the mm Wave channel as a discrete angle domain channel model,which divides the transmitter channel into multiple independent orthogonal spatial subchannels.This thesis assumes that eavesdroppers can obtain feedback from historical eavesdropping results and improve eavesdropping strategies accordingly.In order to deal with such eavesdroppers,this thesis first proposes a secure transmission strategy based on dynamic path selection to deal with non-cooperative eavesdroppers;in order to deal with cooperative eavesdroppers,this thesis proposes a security transmission strategy based on parity check codes.The transmission scheme ensures that the eavesdropper cannot obtain any confidential information when only part of the path is eavesdropped.The simulation analysis of the secure rate and the eavesdropper's bit error rate shows that the secure transmission strategy proposed in this thesis can effectively deteriorate the eavesdropper's receiving performance and achieve the purpose of secure communication.In a large-scale antenna array millimeter-wave communication system,the SWE caused by the signal delay difference of different antennas exceeding the symbol period poses a challenge to the robustness of the system and the compatibility with narrowband systems.Affected by SWE,the signal received by the receiver will suffer from severe inter-symbol interference.Most of the previous studies have focused on how to eliminate SWE and improve the transmission reliability of the system.Here,by adjusting the angle of the antenna array of the transmitter,the legitimate ones are not affected by the SWE,while the eavesdroppers in other directions are affected by the SWE,and the reception performance deteriorates sharply.Thereby,safety performance is improved in both antenna gain and inter-symbol interference.