Research On Electric Field Intensity Calculation Method By FDTD In Indoor Environment Based On 3D Point Cloud

With the rapid development of mobile communication technology,the market scale of wireless network equipment in indoor scenes is expanding day by day.The requirements for indoor signal coverage quality are also getting higher and higher.Calculating and studying the field intensity distribution of indoor signals is of great significance for analyzing the propagation characteristics and signal coverage of indoor signals.The Finite Difference Time Domain method is widely used in electromagnetic field.Compared with other electromagnetic field solution methods,its calculation time is shorter and can meet the needs of practical application.To calculate the field intensity distribution of indoor environment,it is necessary to obtain the geometric information of indoor environment as the boundary of the field intensity calculation area.Traditional geometric information acquisition methods take up much manpower and time,with low modeling efficiency.The development of computer vision provides convenience for acquiring geometric information based on three-dimensional point cloud images.In this paper,the FDTD indoor field intensity calculation method based on threedimensional point cloud is deeply studied.Firstly,the research status of field strength calculation method and geometric information acquisition method at home and abroad is analyzed.Secondly,the basic theory of FDTD and the acquisition method of point cloud are studied.In addition,this paper has mainly completed the following research work for obtaining indoor geometric information and FDTD field intensity calculation method based on three-dimensional point cloud images:(1)Aiming at the problems of heavy workload and long modeling time in the process of obtaining indoor environment geometric information by manual measurement method,a method of obtaining indoor environment geometric information based on threedimensional point cloud image is proposed.In this method,the Random Sampling Consensus algorithm is used to divide the three-dimensional point cloud into planes.The points on the plane point cloud map are extracted from each boundary according to the degree of uniformity of distribution in the neighborhood of the points.The frequency histogram is solved for the three-dimensional coordinates of the boundary point cloud picture,and the geometric information of the point cloud is finally calculated.This method can effectively reduce the workload and labor cost in modeling the indoor environment and improve the modeling speed.(2)Aiming at the problem of high modeling complexity in the process of building indoor environment propagation model,a method of modeling indoor environment geometric information and electromagnetic parameter information based on structural array is proposed.The method effectively reduces the modeling complexity and improves the modeling speed.The FDTD method is used to calculate the field strength of indoor environment,analyze the performance of FDTD method,and study the influence of excitation source on the distribution of indoor field strength.The FDTD method is used to calculate the field strength when there are errors in the geometric information of the indoor propagation model,and compared with the standard data,the influence of geometric information errors on the field strength calculation results is analyzed.Finally,the method proposed in this paper is verified by simulation experiments.Extensive analysis has shown that the average error between the calculated value of geometric information and the standard value obtained by the method based on threedimensional point cloud images is about 0.08 m.The modeling method based on the structural array can build a propagation model consistent with the indoor environment.FDTD calculation results show that the geometric information error of the indoor environment has relatively large influence on the field strength calculation results in the area near the excitation source in the propagation model,and has little influence on the field strength calculation results in the area far away from the excitation source.