Evaluating the Beamforming Impact on Channel Dispersion Characterization Using Multi-Scenario Sub-THz Channel Measurements

To provide substantially high capacity, future 6G networks will be able to operate in higher frequency bands than current 5G networks. However, owing to the significant differences in channel characteristics between lower bands (< 100 GHz) and sub-terahertz (sub-THz) band (i.e., 100-300 GHz), novel waveform and air interface design for sub-THz systems need to account for the radio channels observed by practical beam patterns. In this paper, we investigate the beamforming impact on the characterization of angular and time dispersion based on extensive measured channel data at 142 GHz across multiple scenarios. A post-processing method for analysis of beamforming impact on channel dispersion is proposed using measured propagation channel data. Since sub-THz radio links necessitate high antenna gains, we first find the potential beam directions from beamformed channels and then form single- and multi-beam patterns towards desired directions under practical constraints. The angular spread of the beamformed channels observed by steered beams will be widened especially in line-of-sight scenarios. The beam-weighted radio channel is considered as the basis of calculating time dispersion parameters, i.e., beam gains are multiplied by the measured propagation path gains before the analysis. Preliminary results show that the reduction of delay spread and maximum excess delay depends mainly on scenario, link distance, and used beamwidth, and partly on sidelobe level.