Impact of Facade Details on Radio Propagation at 28 GHz

Channel modeling tools, such as ray-tracers, require geometrical information of the environment. Usually, this geometrical information consists of smooth 3D models. These models are obtained by extruding building footprints from commercially available digital maps. However, with the evolution of mobile networks and the use of higher frequencies, small-scale geometric details are becoming increasingly important. This contribution investigates if the typically used Lambertian diffuse scattering model is sufficient to mimic these small-scale geometric variations or if more detailed geometrical models are needed. A raytracing tool is used to simulate the channel with a 3D model of various levels of details. Comparison between simulations and corresponding measurements indicate that typically used diffuse scattering models mimic scattering from facades not well enough. More details, such as windows, should be included in the 3D models or an improved facade scattering model is required to more realistically model the scattering observed from a facade.