  Terahertz (THz) communication is envisioned as one of the possible
technologies for the sixth-generation (6G) communication system due to its rich
spectrum. To evaluate the performance of THz communication, it is essential to
propose THz channel models within the common framework of the geometry-based
stochastic model (GBSM) in the 3rd Generation Partnership Project (3GPP). This
paper focuses on THz channel modeling and simulation by a 3GPP-like GBSM, based
on channel measurements. We first present channel measurements at 100 GHz in an
indoor office scenario and 132 GHz in an urban microcellular scenario.
Subsequently, channel characteristics such as path loss, delay spread, angle
spread, K-factor, cluster characteristic, cross-correlations, and correlation
distances are obtained and analyzed based on channel measurement. Additionally,
the channel characteristics are modeled by the statistical distribution of 3GPP
channel models, which can be used to reconstruct the channel impulse response
(CIR). Furthermore, these obtained distributions are studied referring to the
default models in the 3GPP, revealing the channel sparsity in the THz channel.
For instance, in the case of line-of-sight links in the indoor office, the mean
of the measured cluster number is 4 while the default value is 15. Finally, we
propose the THz channel model and its simulation framework to reconstruct CIRs
based on the obtained models, which aim at characterizing the sparser THz
channels. The obvious channel sparsity is characterized in both scenarios, as
the Gini factors obtained by the proposed model only have the maximum deviation
of 0.04 for those of the measurement. Overall, these findings are helpful in
understanding and modeling the THz channel, facilitating the application of THz
communication techniques for 6G.
