Research On Physical Layer Security Technology In Large-scale Array Antenna System

In the future 5G mobile communication,greater throughput and faster transmission rate are an important requirement,but the security of wireless communication is also a key issue that users are concerned about.In the conventional wireless communication system,information security mainly relies on upper-layer encryption technology.And physical layer security solves the security problem of wireless broadcast communication by making use of the normal randomness of the wireless communication channel to ensure that the information is transmitted to the desired persons while ensuring that the correct signal can not be extracted by the undesired direction,which fundamentally solve the security issues of wireless broadcast communications.Firstly,this paper proposes an antenna selection security scheme based on switching phased array in a large-scale antenna array system.The antenna array is randomly switched by selecting the antenna structure from the antenna codebook at each transmission symbol interval,so as to disturb the constellation of the eavesdropper in the undesired direction,making it impossible to demodulate the signal,and the desired direction constellation has no influence.On this basis,an antenna selection algorithm based on iterative FFT to select low-side-lobe antenna array codebook is also proposed.Secondly,this paper extends the scheme of secure transmission from one-dimensional linear array to two-dimensional planar array.By utilizing the beam control ability of planar array in the vertical direction,this paper solve the shortcoming that the linear array can not disturb the eavesdropper constellation in the elevation direction,and further enhance the practical application scenario of the solution.At the same time,the iterative FFT algorithm is generalized from the linear array to the planar array.The antennas used to yield the low sidelobes in the plane array are selected to form a codebook,which is used for antenna switching.Finally,this paper studys the hybrid precoding in massive mimo antenna array and millimeterwave system,and proposes a hybrid precoding and artificial noise security scheme based on RF subarrays structure.The lower bound of the hybrid precoding secrecy rate under this structure is given.Then,this paper combines artificial noise in hybrid precoding and designs a hybrid precoder to maximize the lower bound of the secrecy rate,thereby improving the safe transmission performance in millimeter wave hybrid precoding.