This letter provides a comparison of indoor radio propagation measurements
and corresponding channel statistics at 28, 73, and 140 GHz, based on extensive
measurements from 2014-2020 in an indoor office environment. Side-by-side
comparisons of propagation characteristics (e.g., large-scale path loss and
multipath time dispersion) across a wide range of frequencies from the low
millimeter wave band of 28 GHz to the sub-THz band of 140 GHz illustrate the
key similarities and differences in indoor wireless channels. The measurements
and models show remarkably similar path loss exponents over frequencies in both
line-of-sight (LOS) and non-LOS (NLOS) scenarios, when using a one meter free
space reference distance, while the multipath time dispersion becomes smaller
at higher frequencies. The 3GPP indoor channel model overestimates the
large-scale path loss and has unrealistic large numbers of clusters and
multipath components per cluster compared to the measured channel statistics in
this letter.

本文研究了室内办公环境中的无线信道在不同频段（28 GHz、73 GHz 和 140 GHz）下的特性，结果显示无论是直射信道（LOS）还是非直射信道（NLOS），在一米自由空间参考距离下路径损耗均具有相似的指数。此外，多径时延随着频率的提高而减小，而作者的测量数据还表明，3GPP 室内信道模型对于大尺度的路径损耗有所高估，且聚簇数量过多。