DTECM: Digital Twin Enabled Channel Measurement and Modeling in Terahertz Urban Macrocell

TL;DR

This paper addresses the challenge of accurate THz outdoor channel modeling for urban macrocell environments by conducting an extensive measurement campaign at 220 GHz and developing the digital twin enabled channel model (DTECM). The model combines deterministic ray-tracing and computer-vision derived foliage information with statistical MPC generation to achieve high fidelity with lower computational complexity. DTECM significantly improves path-loss accuracy over traditional statistical models, reducing RMSE from about 14 dB to around 4 dB, and provides insights into delay/angle spreads and coverage in THz UMa. The results indicate that while THz UMa is feasible, it requires high-gain antennas and coverage-extension techniques (e.g., IRS/NIRS) to achieve reliable, wide-area connectivity.

Abstract

In this work, in the THz UMa, extensive channel measurements are conducted and an accurate channel model is developed by combining ray-tracing, computer vision (CV), and statistical methods. Specifically, substantial channel measurement campaigns with distances up to 410~m are conducted at 220~GHz, with nanosecond-level absolute time synchronization. Based on the measurement results, the propagation phenomena are analyzed in detail and the channel characteristics are calculated and statistically modeled. Furthermore, a digital twin enabled channel model (DTECM) is proposed, which generates THz channel responses in a hybrid manner. Specifically, the dominant paths are generated deterministically by using the ray-tracing technique and CV methods. Apart from the path gains determined by ray-tracing, the additional foliage loss is accurately modeled based on foliage information extracted from panoramic pictures. To maintain a low computational complexity for the DTECM, non-dominant paths are then generated statistically. Numeric results reveal that compared to the traditional statistical channel models, the DTECM reduces the path loss modeling error from 14~dB to 4~dB, showing its great superiority. Furthermore, a preliminary link performance evaluation using the DTECM indicates that THz UMa is feasible, though requiring high antenna gains and coverage extension techniques to achieve high spectral efficiencies and wide coverage.

Figures (17)

• Figure 1: Correlation-based time-domain channel sounder.
• Figure 2: The measurement deployment in the UMa scenario. Rx positions are labeled with colored dots. Orange dots represent Rx positions with LoS propagation, while green dots and blue dots are those in OLoS and NLoS conditions.
• Figure 3: The link budget analysis considering the measurement setup in this work. Note that the Rx gains are omitted here as they affect both the signal and noise and thus cause no influence on the SNR.
• Figure 4: The time drifts between the Tx and Rx.
• Figure 5: The propagation analysis in the THz UMa. PDPs measured in different Rx locations are shown in (a) and (b), while the objects affecting the THz propagation are shown in (c) and (d).