Research On Pilot Spoofing Attack Detection And Secure Transmission Technology In Wireless Communication Systems

With the rapid development of wireless communication technology,the problem of information security have become more and more serious.The traditional security solution mainly depends on the high complexity encryption algorithm.However,with the rapid development of computing power of the devices,the encryption technology which depends on computational complexity has the risk of being deciphered.Physical layer security technology uses the random characteristics of wireless channel and combines coding and signal processing technology to achieve secure communication.Compared with traditiona encryption technology,it has the advantages of lower computational complexity and no key interaction,with which it has attracted extensive attention in the industry.Physical layer security uses the physical characteristics of wireless channel to achieve secure transmission of information,so accurate channel estimation is the prerequisite for realizing the physical layer security.The transmitter usually uses the pilot sequence to estimate the channel state information(CSI),but this process is vulnerable to the pilot spoofing attack(PSA)of eavesdropping users,which affects the accuracy of channel estimation and leads to the leakage of confidential information during the transmission process.Therefore,PSA poses a serious security threat to data transmission.The transmitter uses beamforming technology to transmit data after it has obtained CSI.However,due to the openness of the wireless channel,the transmitted data faces the risk of eavesdropping.Therefore,it is of great significance to study the secure transmission scheme of confidential data and analyze the security performance of the system theoretically,so as to improve the security performance of wireless communication system.This paper studies the security risks from "channel estimation stage"to "data transmission stage".Firstly,the PSA detection scheme based on spatial spectrum is studied,and the location information of legitimate users is obtained.On this basis,the spatial location information of legitimate user and eavesdropping user is used to design an optimization model to realize the secure transmission of data,Finally,the security performance of the system is analyzed theoretically.The main research contents and contributions of this paper are summarized as follows:(1)Aiming at the problem of pilot spoofing attacks,the paper studies and proposes a pilot two-way training and detection scheme based on spatial spectrum.The scheme first uses the spatial spectrum information of the received pilot signal to detect pilot spoofing attacks.Further,when the pilot spoofing attack occurs,the asymmetry of the estimated spatial spectrum peaks in the uplink training process and the downlink pilot training process is used to identify the eavesdropping user,and estimates the directions of arrival(DOAs)of the legitimate user and the eavesdropping user.On this basis,the corresponding beamforming transimission scheme is designed.The simulation results show that the pilot two-way training scheme based on the spatial spectrum has better detection performance in the case of low signal-to-noise ratio,and the beamforming transmission scheme can realize the secure transmission of confidential information in the presence of eavesdropping user.(2)Aiming at the scenario where a single eavesdropping user exists in the Multi-Input Single-Output(MISO)system,this paper constructs a Spatial Secrcy Outage Probability(SSOP)model based on Insecure Region and deduces the upper bound of SSOP.Aiming at the problem of secure transmission in wireless communication system,a secure transmission scheme is proposed to maximize the system security throughout under the constraints of SSOP and legal channel rate.Simulation results show that the scheme can obtain the optimal legal channel transmission rate by maximizing the system security throughput.(3)Aiming at the eavesdropping scene where there are multiple eavesdropping users in the MISO system,this paper models the eavesdropping users based on the Poisson point process and the random geometry theory,and studies and proposes a secure transmission scheme in this scene.The transmission scheme takes maximizing the minimum value of the average Secrecy Rate(SR)as the optimization goal,taking the Secrecy Outage Probability(SOP)as the constraint condition,and through strict mathematical analysis,it is proved that the objective function has the maximum value.Through strict mathematical analysis,it is proved that the objective function has the maximum value.The simulation results show that the scheme can obtain the optimal transmission power by maximizing the average security rate of the system.(4)Aiming at the eavesdropping scenario where there are multiple eavesdropping users in the MISO system,this paper models the eavesdropping users based on the Poisson point process,studies and analyzes the spatial interruption probability under Nakagami-m channel fading,and deduces its closed expression of upper bound.This paper further analyzes the relationship between confidential throughput and confidential rate,as well as the secure and non-secure areas under the constraint of confidential outage probability.