Channel Measurements and Multipath Characterization for Indoor Sub-Terahertz Communication

Sub-terahertz (THz) (100–300 GHz) has attracted huge interest in recent years as a promising candidate band for applications in the future sixth-generation wireless networks. However, when extending to higher sub-THz band, the problems of scarce measurement data and incomplete channel characteristics become increasingly evident, hindering the establishment of sub-THz communications. This paper presents the measurements of small-scale fading (SSF) channel characterization and sparsity analysis based on the vector network analyzer in typical indoor scenarios at 215–225 GHz. The directional scanning scheme is adopted to identify the multipath components (MPCs) in a three-dimensional space. The MPC-level parameters, including power, delay, azimuth and elevation angles are estimated based on the power angular delay profiles and then processed with the multipath component distance-based density-based spatial clustering of applications with noise algorithm. Modeling of MPC-level and cluster-level temporal-spatial characteristics are presented. With the correlation matrix of sub-THz MPC-level SSF characteristics, the Gini index, root mean square delay spread, azimuth spread of arrival and elevation spread of arrival are firstly used to comprehensively evaluate the sparsity of the sub-THz channel. In addition, the key factors affecting sub-THz channel sparsity are explored. The numerical results indicate the strong sparsity of the channel at sub-THz band. Specifically, in empty and closed scenarios, the sparse channel characteristics are less pronounced, and there is a notable reduction in sparsity from line-of-sight (LoS) channel to non-LoS channel. The channel characterization extracted from the sub-THz channels in this paper is instrumental in the development of channel modeling, system design and performance assessment of sub-THz communication systems.