Site-Specific Ray-Tracing and Experimental Validation for THz Channel Characterization

Terahertz (THz) technology is seen as a key component of the upcoming 6G networks due to the huge untapped spectrum. Accurate channel models are crucial for the design and development of such THz communication and sensing systems. As the THz channel exhibits unique features including high propagation loss, sparsity, and near-field properties (with ultramassive multiple-input multiple-output systems), deterministic ray-tracing (RT), which can simulate wireless channels in a site-specific manner based on the high-frequency approximation of Maxwell's equation, is considered suitable for THz channel modeling. However, a thorough analysis of RT-based THz channel modeling and its extensive experimental validation (especially at 300 GHz) is still missing in the literature. In this article, we develop an RT modeling framework tailored for THz channels, which incorporates processes of environment reconstruction and electromagnetic calculation, material calibration, and acceleration. Then, three measurements with 14 locations ranging from 3 to 58 m covering frequency bands at 300 and 100 GHz are used to validate the developed RT framework. It is observed that there is an excellent match for the dominant paths between the real-world measurements and the RT results, and the near-field characteristics are realistically and accurately captured in the modeling. Furthermore, the validated RT framework is employed to enable an in-depth THz channel characterization at 300 GHz in an indoor hall scenario. This analysis is rooted in extensive channel data across 30 locations, consisting of experimental data at 12 locations in the first measurement and RT-simulated data for another 18 locations. The developed RT framework and the channel characterization aim to provide insights for future THz channel modeling and standardization studies.