Research On Physical Layer Security Technology Based On Large Scale Antenna Array

In this thesis,the physical layer related security technology of the millimeter-wave MIMO system equipped with a large-scale antenna array at the base station is studied.In a millimeter-wave MIMO system,a large number of antennas are arranged at the base station.Due to system hardware cost limitations,a cost-controllable precoding scheme needs to be sought,and at the same time,the performance of a full digital precoding system can be approximated,ie,a baseband radio frequency mixed precoding scheme.(1)In the scenario of a single-user system,the receiver is equipped with multiple antennas,and a hybrid precoding scheme with optimized spectral efficiency is proposed,and energy efficiency is analyzed.The traditional MIMO single-user system model and millimeter-wave MIMO single-user system model were established respectively,and a Cluster-Ray channel model suitable for millimeter-wave channels was introduced.The optimization objectives and constraints for maximizing spectrum efficiency are introduced.Based on the traditional orthogonal matching pursuit algorithm,the proposed improved hybrid precoding scheme is described in detail.The simulation results show that the performance of the proposed TOMP algorithm is much better than the OMP algorithm.And close to the optimal all-digital precoding scheme.Finally,the effects of different precoding schemes on energy efficiency performance are analyzed from two aspects: signal-to-noise ratio and radio frequency.(2)The physical layer security problem in the MISO system is introduced,and the definition of the security capacity and the system model of the eavesdropper in the communication system are given.The traditional zero-forcing precoding scheme and artificial noise-assisted precoding scheme are analyzed and simulated.In the pre-coding scheme with artificial noise added,beamforming and artificial noise were jointly optimized.Simulation results show that adding artificial noise can improve system performance.(3)In the multi-user system scenario,each receiver is equipped with a single antenna,and a precoding scheme for a millimeter-wave MIMO system is studied.The traditional multiuser MIMO system model and multiuser millimeter wave MIMO system model are introduced.The millimeter wave channel model is introduced.The optimization objectives and constraints of the hybrid precoding design at the transmitter are introduced.A phase-controlled zero-forcing hybrid precoding scheme is analyzed.Based on the limitations of the scheme,a new precoding matrix construction scheme is proposed.Simulation results show that the proposed scheme has wider applicability than phase-controlled ZF scheme.Spectrum efficiency is better.Intuitive analysis of the traditional maximum-transmission precoding and zero-forcing precoding effects was finally verified by simulation.