Multi-Frequency Wireless Channel Measurements and Characterization in Indoor Industrial Scenario

Millimeter-wave (mmWave) and Terahertz (THz) communication technologies have great application prospects in the Industrial Internet of Things (IIoT). However, the channels in industrial scenarios have not been fully investigated at multi-frequency bands and in multi-scenarios by using the same channel configurations, especially for the frequency ranges from mmWave to THz. In this paper, channel measurements are conducted at 28 GHz, 38 GHz, 132 GHz, and 220 GHz in four industrial scenarios. The channel characteristics are extracted and modeled, including path loss, K factor, root mean square (RMS) delay spread and angular spread (AS), and the correlation between K factor, RMS AS and distance across the different frequencies in different scenarios. Specifically, we have extended the close-in path loss model to depict the excess loss caused by metal scatterers and modified AS model in the 3rd Generation Partnership Project (3GPP). Furthermore, cluster-level parameters at different frequencies are presented in our work. The results demonstrate that channel characteristics exhibit frequency dependence under the same measurement configuration. This study provides valuable guidance for the design and optimization of IIoT and contributes to the standardization process of 3GPP.