Research On The Artificial-noise Aided Physical Layer Secure Transmission Of Multi-antenna MmWave Communication

Mm Wave communication owns a very high bandwidth,which provides a good solution to satisfy the capacity demand of the 5G wireless network.However,the characteristics of free propagation of electromagnetic waves and the openness of wireless channels provide natural conditions for attackers to carry out malicious attack interference or eavesdropping.Mmwave system faces severe secure problems of communication,so it is significant to consider the security of wireless transmission when designing the communication system.Physical layer security can effectively improve the security of wireless communication.It utilizes the diversified time-variability of wireless channels,the uniqueness,and reciprocity of channels between legitimate communication parties,and the objective transmission law of wireless signal to discover the secure characteristics of wireless channels,and promote the integration of security and communication.At present,remarkable achievements have been made in studies of secure transmission technologies in the physical layer of mm Wave systems,including utilizing channel fading,artificial noise interference,beamforming,and secure precoding.All above studies have solved problems of physical layer security in mm Wave systems to varying degrees,but there are relatively strict limitations in the research scenarios and technologies mentioned.Some studies assume that the system knows the number,spatial location,and channel state information of eavesdroppers,which is unrealistic in actual eavesdropping scenarios.Although the multi-antenna technology can effectively enhance the main-lobe gain of confidential signal and reduce the beam width,however,it enhances the gain of side-lobe and raises the risk of side-lobe information leakage as well,which is ignored by many studies.Besides,the propagation of mm Wave is more sensitive to the randomly blocking effect,and the fading statistical characteristics in line-of-sight transmission and non-line-of-sight transmission are different as well,which seriously affects the performance of mm Wave systems.Thus,the influence of random distribution of eavesdroppers,randomly blocking effects on mm Wave,and the influence of small-scale fading on the secrecy performance of the system should be seriously considered when designing the secure transmission mechanism of mm Wave.According to the gaps and deficiencies in the current research of the secure transmission technology of mm Wave systems,this thesis designs the artificial noise-aided secure transmission mechanism in the mm Wave multi-antenna systems with considering the unique propagation characteristics and channel fading characteristics of mm Wave.When communicating,the transmitter emits artificial noise in the side-lobe area outside the main signal area to resist the eavesdropper for enhancing the secrecy performance of the system.The thesis studies the secrecy performance of the system in different random eavesdropper scenarios respectively,including communication connection probability,secrecy outage probability,and secrecy capacity of the system.The main research works are as follows(1)The communication connection reliability and security of the mm Wave MISO system under a non-colluding randomly eavesdropping scenario are studied and analyzed,and the corresponding artificial-noise aided secrecy transmission mechanism is designed to suppress side-lobe eavesdropping,so as to enhance the security performance of the system.On this basis,the closed-form expressions of communication connection probability and secrecy outage probability of the system are derived,with further theoretical analysis,simulation,and validation.In the case of Lo S communication links,the influence of total transmitting power and the number of antennas on the optimal power allocation and the corresponding secrecy outage probability is analyzed,and the variation rule is summarized.(2)The communication connection reliability and security of the mm Wave MIMO system under a non-colluding randomly eavesdropping scenario are studied and analyzed,and the corresponding artificial-noise aided secrecy transmission mechanism is utilized to suppress side-lobe eavesdropping,so as to enhance the security performance of the system.On this basis,the closed-form expressions of communication connection probability and secrecy outage probability of the system are derived,with further theoretical analysis,simulation,and validation.In the case of Lo S and NLo S communication links,the influence of total transmitting power,communication distance,random blockages,and the number of antennas on the optimal power allocation and the corresponding secrecy outage probability is analyzed,and the variation rule is summarized.For Lo S links,the influence of communication distance and the number of antennas on the system secrecy capacity is explored.(3)The communication security of the mm Wave MIMO system is studied and analyzed under the colluding randomly eavesdropping scenario,where the artificial-noise jamming aided secure transmission mechanism is utilized to suppress side-lobe eavesdropping for enhancing the security performance of the system.On this basis,the low bound expression of secrecy outage probability with AN and the closed-form expression of secrecy outage probability without AN aided are derived,theoretically analyzed,and validated.In addition,the influence of the total transmitting power on the secrecy capacity of the system is investigated.