On the modeling of scattering mechanisms of rough surfaces at the terahertz band: invited paper.

Looking to 2030 and beyond, revolutionary enhancement of transmission rates in the sixth-generation mobile communication (6G) is required to meet the challenge of increasing communication traffic. The terahertz (THz) band providing ultra-wide bandwidth is promising to address the spectrum scarcity and capacity limitations of current wireless systems. However, when the frequency increases to the THz band, a surface that is considered smooth at low frequencies will become rough for THz waves. Then, scattering on rough surfaces is more dominant for wave propagation. The directive scattering (DS) model is widely used to characterize the scattering mechanism. Nevertheless, the DS model can only characterize the shape of the scattering lobe and cannot portray the effect of microstructures. Given the limitations of the existing DS model, there is an urgent need for an enhanced model to characterize the scattering mechanism in the THz band. In this paper,we first use the full-wave simulation method to obtain extensive data to support the modeling of the scattering mechanism. Then, based on full-wave simulations and the DS model, we propose a modified DS model to reconstruct the scattering distribution in the incidence plane. The modified DS model characterizes the scattering of rough surfaces and shows good agreement with the simulation results. In the future, the modified DS model, which only applies to the incidence plane in this paper, will be extended to a three-dimensional (3D) model with the magnitude, phase, and polarization incorporated. Finally, the modified 3D DS model will be integrated into ray-tracing simulation methods and further support the standardization of THz channel modeling.