Effects of Atmospheric Gases and Rain Intensity on Terahertz Wave Propagation in 6G Wireless Networks

Terahertz (THz) (0.1–10 THz) communication is a promising technology for sixth-generation wireless networks due to its ultrahigh data rates and low latency. This study investigates the impact of atmospheric gases on signal attenuation and path loss in the frequency range of 300–400 GHz and a path distance of 1 Km in the outdoor environment. The large-scale path loss models: Close-In (CI) free space, Alpha–Beta–Gamma (ABG), and Close-In Frequency dependence (CIF), are summarized and are used to estimate the path loss and optimized path loss model in an atmospheric absorption environment. Additionally, the impact of rain intensity on THz channel performance is examined with raindrop size distribution (DSD) models. Simulation results reveal that rainfall intensity, water vapor and dry air significantly affect THz signal propagation. At 380 GHz and 800 m path difference, the CI path model yields the highest path loss of 632 dB, primarily due to significant attenuation from rain, water vapor, and dry air. In contrast, the ABG model exhibits the lowest path loss of 196 dB at 300 GHz over a 100 m distance under the same environmental conditions. These results shows that the dynamic variations in rain intensity, rain drop size distribution, water vapor, and dry air absorption leads to substantial fluctuations in path loss, even when the rain rate remains constant. THz frequency band of 300–400 GHz range is the usable band for 6G wireless communications except 380 GHz band.Therefore, the CI and CIF models are identified as the most suitable models for optimized path loss estimation in 6G wireless networks.