Speed ​​up The Calculation Of Multi-image Method For Irregular Urban Environment Electromagnetic Radiation

The communication is the industry which is developing the most rapidly in the information age. Thousands upon thousands of people are getting close touch with the mobile communication in their daily life. For fulfilling the request for the increasing mobile communication, it requires increasing the cover area of microcell mobile communication system.To keep the environment people live in, we should restrict or prevent many kinds of pollution, which includes electromagnetic radiation pollution.While we are considering setting up base station or evaluating the electromagnetism pollution of environment, we can measure on the spot. To save time, hard work and cost taken by measuring on spot, it is necessary to calculate and analyze the electromagnetic wave propagation in urban area.The research of electromagnetic wave propagation prediction has had 30 many years. And along with the development of mobile communication, the prediction model of large area turns to the prediction model of microcells area naturally. Of the available models, the computational results of ray tracing method are comparatively accurate. In the various document data more electromagnetic wave propagation forecasts aimed at the urban area that the buildings were regularly arranged and the detailed datum that the forecasts aimed at the urban area that the buildings were regular arranged were not seen. A kind of method - accelerative multi-images method is given to the electromagnetic wave propagation prediction to the irregular urban area of this article. Because the mirror image method is basing on the point-to-point ray tracing method, the computational solution precision is higher. As for the building wall face is the plane, it is feasible to use multi-mirror images method. But when the building is not only the rectangle (being the polyhedron) and the buildings is not merely justified parallel, sheltering tests and mirror image source's finding are fairly more complicatedly, and the calculation amount is great.For raising the capacity, this method has used the ray acceleration technology, including that the back gathers and the partition algorithm in binary space and decreasing dimensions. These algorithms make the intersection test quantity reduces greatly, and calculation capacity is corresponding and reduces greatly, and has economized CPU's time. This method is first to establish the mirror image tree - tree shape data structure includes all levels mirror image sources and their visible facets and diffractive edges, then according to same method to establish the field tree of only one layer- tree shape data structure includes the field point's (observation point) visible facets and diffractive edges, then by the traversal of mirror image tree and inquiring about field tree we can find out all rays arrive field point. Thus we can calculate the electric field intensity value and the path loss.Input radiant point's coordinate and various property, building's coordinate and various property, we can calculate the given field point's electric field intensity value and the path loss.This text has counted the electric wave propagation path loss of street in one kind of typical rule range urban area, and reaches calculation data fairly with the measured data in the document. Then calculate and analyze electric wave propagation's characteristic in urban area. Finally give an electric wave propagation prediction application example of this model.