Research On Physical Layer Security Technology Of Millimeter Wave MIMO Communication System

After 5G technology enters the commercial stage,the demand for speed is becoming more and more urgent,which requires the characteristics of broadband and ultra-high speed in the millimeter wave band.Due to the small array size and large spatial scale decline,millimeter wave frequency bands are usually used with massive MIMO antennas,and the continuous development of new air interfaces puts forward new requirements for 5G communication security technology research.There is information that the US military is developing electronic warfare equipment in the millimeter wave band(40-100GHz).Due to the broadcast and superposition of the wireless channel,the wireless communication system is more vulnerable to attacks by other users,and the advantages of security concealment and strong anti-interference of millimeter wave communication will also face challenges in the future,and ensuring the information security of the millimeter wave frequency band has become a problem that cannot be ignored.At present,the air interface security of millimeter wave communication systems still adopts traditional information security schemes above the network layer such as symmetric and asymmetric encryption systems,and with the emergence of high-computing computers such as quantum computers,this security based on computational complexity is no longer reliable.The emergence of physical layer security technology is to solve the above problems in essence.Shannon first proposed the idea of "complete confidentiality" from the perspective of information theory in 1949.Wyner subsequently introduced the Wire Tap channel model,and with the development of multi input multi output systems,physical layer security technologies such as using spatial degrees of freedom of the air channel for precoding matrix design or utilizing the inherent randomness of noise to transmit artificial noise have emerged.This article mainly focuses on the research of channel estimation and air port transmission in millimeter wave communication systems using this technology,combined with 5G communication scenarios.The main work and achievements are as follows:This dissertation studies the physical layer security technology in the channel estimation phase of the millimeter wave MIMO communication system,and discusses whether the channel is a reciprocal channel in two cases.In view of the fact that the reverse channel of the reciprocal channel is prone to pilot spoofing attack(PSA)attacks,a "hybrid pilot-based attack detection algorithm" is proposed.The simulation results show that the energy of the pilot attack is very small(-5 dBm),When the length of the pilot sequence is 64,the accuracy of this method can reach 98%,and the detection process of PSA can be realized by only one reverse channel estimation process,which simplifies the number of transmissions and reduces the transmission power.A "differential channel estimation algorithm based on secondary two-way feedback" is proposed for non-reciprocal channels.Through simulation,it can be seen that this algorithm can provide accurate channel estimation for the target node in the nonreciprocal channel scenario,and achieve the purpose that the eavesdropping node cannot use any pilot information.For MIMO communication system,the common physical layer security scheme in the data transmission stage is to use beamforming technology/precoding technology to carry out spatial orientation of security information,or use spatial freedom to send artificial noise.In the millimeter wave band,in view of the application status of analogdigital hybrid beamforming architecture,a design scheme of analog-digital hybrid secure beamforming filter based on alternative optimization is proposed.The simulation data shows that this scheme can reduce the computational complexity while ensuring the safe transmission rate of the system.On this basis,aiming at the overall energy consumption of the communication system,a beamforming scheme that can effectively reduce confidential information and reduce artificial noise is explored.From the simulation data,it can be seen that compared with traditional zero forcing algorithms,this algorithm effectively reduces the total transmission power by about 50%while ensuring transmission performance.Based on the requirements of mobile operations and emergency communications in the context of the future information battlefield,the application of UAV as the airbased relay platform is also increasingly popular.In this dissertation,we study the physical layer security scheme and its performance evaluation in the case of traditional multi-antenna relay node and RIS-based relay node.This dissertation proposes a PLS communication method in which the main station(origin station)and the relay station(secondary station)jointly transmit artificial interference signals.Through the analysis of experimental data,it is proved that the security of this new communication method on the channel is more than double that of the conventional communication method.Furthermore,the relationship between the size of adjustable elements and the correlation matrix of RIS reflection space is studied,and the safety interruption probability index SOP of the relay safety communication system with RIS is further studied.The simulation data shows that because RIS changes the amplitude and phase parameters of the reflected electromagnetic wave and thus realizes the spatial isolation of the eavesdropping node,the performance of SOP is more than twice that of the traditional multi-antenna relay security communication system.