Centimeter- and Millimeter-Wave Channel Modeling Using Ray-Tracing for 5G Communications

A ray-tracing tool, including specular reflection, diffraction and attenuation by foliage, is experimentally validated at 12 and 30 GHz in a suburban environment. The tool is then applied to double directional channel modeling at 30 GHz in a real-world urban area in downtown Brussels. Azimuth-, elevation- and delay-spread are computed and analyzed on a stochastic viewpoint. It is found that elevation spreads remain limited (below 3 degrees), while azimuth-spreads are on average similar at both sides of the link (with a mean value of 12 degrees). Delay-spreads vary significantly over the user´s locations, with a mean value of 45 nanoseconds. They are positively correlated with the directional spreads at the base station. Finally, an investigation about the impact of microscopic surface roughness is conducted: it is found that it is mostly negligible at millimeter waves, unless extremely narrow beamwidth antennas are used.