  Millimeter-wave (mmWave) and Terahertz (THz) will be used in the
sixth-generation (6G) wireless systems, especially for indoor scenarios. This
paper presents an indoor three-dimensional (3-D) statistical channel model for
mmWave and sub-THz frequencies, which is developed from extensive channel
propagation measurements conducted in an office building at 28 GHz and 140 GHz
in 2014 and 2019. Over 15,000 power delay profiles (PDPs) were recorded to
study channel statistics such as the number of time clusters, cluster delays,
and cluster powers. All the parameters required in the channel generation
procedure are derived from empirical measurement data for 28 GHz and 140 GHz
line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios. The channel model
is validated by showing that the simulated root mean square (RMS) delay spread
and RMS angular spread yield good agreements with measured values. An indoor
channel simulation software is built upon the popular NYUSIM outdoor channel
simulator, which can generate realistic channel impulse response, PDP, and
power angular spectrum.
