Abstract:In the previous research on performance analysis of heterogeneous network, the distributions of base stations (BSs) and users are usually modeled as the horizontal distributions, which are not suitable for hyper-density network surrounded by dense buildings. Meanwhile, the physical layer security of the heterogeneous network is directly affected by the eavesdroppers on the vertical dimension. To address this problem, the vertical dimension of the base station antenna was adjusted, the signal-to-interference-plus-noise ratio (SINR) and the cumulative distribution function (CDF) of legitimate users and eavesdroppers was obtained by using the tilt angle, the spatial distribution of base stations and users, and the physical layer security performance of heterogeneous network was analyzed. An adjustment in three-dimensional heterogeneous network was proposed that the vertical dimension of the base station full dimension antenna is controlled.The SINR of the legitimate users and the eavesdroppers with the tilt angle of the BS antenna available were formulated, and the cumulative distribution functions of SINR were deduced according to spatial random Poisson point process distribution of the BSs and the users. Finally, the closed expressions of average secret rates of the heterogeneous network were obtained. The simulation results validated the correctness of the closed expression among the density of the small cells, the down tilt angles and the average security rates. The feasibility of the physical layer security can be improved by adjusting the vertical tilt angle. Meanwhile the reasonability of the distribution of small cells was validated.