Physical Layer Security In Full-Duplex Millimeter Wave Communication Systems

In order to meet the needs of wider bandwidth and higher speed in the new generation of wireless communication systems,it is inevitable that the carrier frequency will develop towards the higher frequency millimeter wave frequency band.The wireless propagation characteristics of electromagnetic waves and the openness of wireless channels make wireless communication systems vulnerable to eavesdropping.Therefore,the millimeter-wave wireless communication system faces severe communication security problems.Wireless physical layer security can effectively improve wireless communication security,and is an effective method to improve the security performance of wireless communication systems.At present,the physical layer security technology in mm Wave communication has achieved remarkable results.Some studies propagate artificial noise into the null space of legal channels,but transmitting artificial noise will occupy a certain transmit power and is only feasible with multi-antenna transmitters.Therefore,artificial noise schemes are not suitable for situations with low power constraints or single-antenna transmitters.Some studies use external relays to provide jamming signals to confuse eavesdroppers.Although it can help improve the security performance to a certain extent,it also brings the trust of external relays and the problem of difficulty in synchronization.Full-duplex technology can realize the switching of artificial noise emission from the transmitter to the receiver,which provides a promising solution to the above problems.In this thesis,aiming at the research gaps and deficiencies of the security performance of the full-duplex system in the above-mentioned millimeter-wave frequency band,considering the unique propagation characteristics and channel attenuation characteristics of the millimeterwave,the security of the millimeter-wave full-duplex communication system based on interference blocking is designed.mechanism.During communication,full-duplex jamming receivers generate jamming signals to interfere with eavesdroppers to protect confidential information.In this thesis,we choose security rate and security throughput as the indicators to characterize security performance,and design the physical layer security transmission mechanism of millimeter-wave MISO(Multi Input Single Output)and MIMO(Multi Input Single Output)communication systems in the eavesdropping scenarios where the eavesdropper’s CSI(Channel State Information)is known or unknown,respectively.Specifically,in this thesis,beamforming is jointly designed at the transmitter and receiver to maximize the security performance.The maximum secrecy rate and secrecy throughput can be further obtained by jointly optimizing the power distribution ratio between the transmitter and the receiver,and the constraint of secrecy interruption probability.The thesis also derives that the optimal hybrid beamforming matrix for interfering signals is a rank-1 matrix.Since the beamforming of the interfering signal is fully designed,the confidentiality of the full-duplex mm Wave system is no longer constrained by self-interference in the case of multiple antennas.Simulation results show that our designed secure transmission scheme with a full-duplex jamming receiver outperforms the traditional half-duplex method even considering residual self-interference.Furthermore,our simulation results also show that,given a fixed transmit power,there is always an optimal pair of power allocation ratio and secrecy outage probability constraints to maximize secrecy throughput.Therefore,the designed security transmission mechanism can effectively improve the security performance of the millimeter communication system.