The Study Of Radio Wave Propagation Characteristics In The Hilly Terrain On The Basis Of The Ray Tracing Method

Hilly terrain is widely distributed in China as one of the five kinds of world land topography, so the study of wave propagation characteristics under this topography is of great significance in the design and plan of wireless communication network in hilly areas. The landform of hilly areas is usually irregular,in the past,the study of wave propagation characteristics of hilly areas basically uses the field measurements and empirical model prediction methods which are always time-consuming and taxing, additionally, with the development of wireless mobile communications,these methods have been far can not meet the requirements of the actual network planning in terms of efficiency or precision.This article aims to use ray tracing methods and geographic information technologies to establish a deterministic model of wave propagation over hilly environment to study the influence of irregular hilly terrain environment to the radio propagation characteristics.The main contents of this article are:(1) The electronic map of the study hilly area was made to establish the corresponding DEM elevation model.the electronic map was used as a data source, in the VB environment,Mapobjects(MO) which is one kind of the component-based development tools was used to build geographic information systems(GIS). By analysis and processing the data of the map, the original data of the path profile was analyzed by interpolation algorithm to get the profile function of sending and receiving ends, the deterministic research model was established by the function of sending and receiving ends.(2) The path profile function was approximately processed as split type.The image method of ray tracing method was used to analysis the path profile after the approximation,the main algorithmic process of direct rays module, reflected rays module,diffracted rays module as well as the mixed-ray module.The calculation of related wireless channel parameters was completed by the combination of the ray-tracing method and GTD/UTD method.(3) The simulation of this ray-tracing model was done under the VB and Matlab environment to study the influence of the irregular terrain to the radio propagation path loss when the receiving antenna height was different,the comparison between the simulation results,the previous experimental data in the literature and the prediction of empirical model was done to verify the correctness and accuracy of the model.At last,depending on the the simulation results of some path,some improvements of this model were made by studying the influence of the electricalparameters of the ground to wave propagation path loss predictions.