3D ray-tracing model including effect of inhomogeneous building surface for characterization of wireless communication channel

A ray-tracing method in conjunction with UTD (uniform theory of diffraction) has been widely used to characterize a wireless communication channel. Due to the complexity of the real situation, the ray-tracing method generally assumes buildings have homogeneous and smooth surfaces. However, in a real case, the building surface consists of many heterogeneous materials, whose shapes are also various. Hence, the scattering by the surface is much different from a homogeneous surface, which will affect the final accuracy of the ray-tracing method. In UTD, scattering mechanism by an object is mainly decomposed into two groups: reflection and diffraction. In general, the reflection in the specular direction is important, but the inhomogeneity may reduce the specular reflection drastically. In this paper, to consider the reduction of the specular reflection, we formulate the effective specular reflection based on PO (physical optics) approximation, and include the reflection in a 3D ray-tracing code. Then, we investigate the inhomogeneity effect on the final path-loss.