A Study And Implementation Of A Ray Tracing Method For Radio Wave Predictions

Ray tracing technique can analyze and predict the characters of large scale and wide range radio wave propagation. Based on geometrical optics, ray tracing technique considers direct, reflection, transmission mechanism. When the geometrical optics ray encounters with obstacles, ray can’t enter the shadow area, but the field in reality is not equal to zero attributed to diffraction. Therefore, using geometrical optics and uniform geometric theory of diffraction can analyze diffraction so as to improve the precision of field.In this thesis, the main contents and contributions are as follows,(1) This thesis explores the ray tracing technique with space meshing, and implements the three-dimensional general algorithm program. The subdivision of electromagnetic environment in this article is generated using a mesh generator. In ray tracing method, the 3-dimensional scenario space is divided into seamless and non-overlapping tetrahedrons. We analyze the trajectory of ray that moves in each tetrahedron, and can obtain all the trajectory of rays in whole environment. The tracing algorithm does not need intersection tests between rays and object facets that can improve the efficiency of calculation.(2) Ray tracing technique with space meshing is improved on the basis of predecessors. Previous tracing algorithms only consider the influence of direct and reflected rays while ignore the diffracted rays. Based on geometric diffraction and uniform geometric theory of diffraction, this thesis proposes the diffraction tracing algorithm that combined with ray tracing technique based on space meshing. The proposed algorithm can improve the efficiency of calculation while guarantee the accuracy of the results.(3) In the aspect of implementation technology, the information of diffracted rays are encapsulated and independent with each other using the custom defining data types. Finally, the indoor and outdoor non line-of-sight geometric models are established, and the geometric models are computed by the proposed technique. Thus the efficiency and accuracy is validated by the results.