FDTD-Based Diffuse Scattering and Transmission Models for Ray Tracing of Millimeter-Wave Communication Systems

At millimeter-wave (mm-wave) frequencies, diffuse scattering (DS) from rough surfaces is an important propagation mechanism. Including this mechanism in radio propagation modeling tools, such as ray tracing (RT), is a key step toward realizing accurate propagation models for 5G and beyond systems. We propose a two-stage solution to this problem. First, we model reflection and transmission through rough slabs, such as doors, walls, and windows with the FDTD method. Our results indicate the influence of roughness and whether this influence is measurable, either reducing the magnitude of the reflected and transmitted waves or (most importantly) generating DS components. In the latter case, the surface effectively acts as a secondary source, whose pattern is computed by full-wave analysis. Then, this pattern is embedded in a ray tracer, enabling the computation and tracing of DS field components. We demonstrate this approach in the RT analysis of a 28 GHz indoor environment.