Permittivity Effect of Building Materials on 28 GHz mmWave Channel Using 3D Ray Tracing Simulation

Abstract

To evaluate the technical feasibility of the millimeter-wave (mmWave) band for cellular network, several channel measurement experiments have been performed in recent years. To reduce the burden of repetitive channel measurement campaigns, ray tracing simulations have been widely utilized to evaluate the characteristics of wireless propagation channels for outdoor environments. However, existing simulation studies have not addressed the permittivity effects of building materials on the mmWave band propagation channel because it is difficult to precisely model the overall building surfaces. In this paper, we investigate the variation of a propagation channel at non-line of sight (NLOS) points in urban micro-cell environments at the 28 GHz mmWave band using a three- dimensional (3D) ray tracing tool. The simulation results are compared with actual field measurement data. It is demonstrated that the path loss and channel impulse responses in the NLOS region fluctuate approximately 10-20 dB in urban environments owing to high-rise building blocks. Further, the impulse responses of the NLOS points indicate an increasing trend of the number of multipath components and the received signal strength as the permittivity increases. Therefore, the dielectric models of building materials must be considered for simulation analysis on mmWave channel properties such as path loss, mean excess delay, and delay spread.