28 GHz Millimeter-Wave Channel Models in Urban Microcell Environment Using Three-Dimensional Ray Tracing

The millimeter-wave (mmWave) band has attracted great attention as promising spectrum for the next-generation cellular systems. However, mmWave communication systems have encountered several challenges because of different electromagnetic characteristics compared with existing spectrum below-6 GHz systems. In order to evaluate the technical feasibility of mmWave provision, 28 GHz mmWave band channel models were presented by developing an efficient three-dimensional (3-D) ray-tracing simulation. The accuracy of 3-D ray-tracing simulation was verified by comparing its results with actual measurements. The path loss (PL) agreed well in both line-of-sight (LOS) and non-line-of-sight (NLOS) regions, whereas the shadowing factor exhibited differences in the NLOS regions. The contributions of this work include confirmation of the applicability of single- and dual-slope LOS and NLOS PL models with different threshold distances for NLOS regions with low root-mean-square errors.