Tuning Ray Tracing for Mm-wave Coverage Prediction in Outdoor Urban Scenarios

Abstract

Propagation characteristics at 26, 28, and 38 GHz (Ka band) in outdoor environments are analyzed through path loss measurements in two different urban scenarios and used to tune a ray-tracing model, with specific focus on nonspecular scattering and vegetation attenuation. The contribution from nonspecular components in non-line-of-sight conditions is shown to be much more important than expected even for narrowband prediction, differently to what was found in previous studies at lower frequencies. Attenuation through vegetation is also very important and can be described using vegetation polygons and a simple linear attenuation model. When these effects are modeled inside the ray-tracing tool, prediction accuracy is good. However, scattering from vehicles and other cluttering objects is shown to give a relevant contribution in deep non-line-of-sight locations, and further work is needed to systematically model such effects into the ray-tracing engine.