  In this paper, a pervasive wireless channel modeling theory is first
proposed, which uses a unified channel modeling method and a unified equation
of channel impulse response (CIR), and can integrate important channel
characteristics at different frequency bands and scenarios. Then, we apply the
proposed theory to a three dimensional (3D) space-time-frequency (STF)
non-stationary geometry-based stochastic model (GBSM) for the sixth generation
(6G) wireless communication systems. The proposed 6G pervasive channel model
(6GPCM) can characterize statistical properties of channels at all frequency
bands from sub-6 GHz to visible light communication (VLC) bands and all
scenarios such as unmanned aerial vehicle (UAV), maritime, (ultra-)massive
multiple-input multiple-output (MIMO), reconfigurable intelligent surface
(RIS), and industry Internet of things (IIoT) scenarios. By adjusting channel
model parameters, the 6GPCM can be reduced to various simplified channel models
for specific frequency bands and scenarios. Also, it includes standard fifth
generation (5G) channel models as special cases. In addition, key statistical
properties of the proposed 6GPCM are derived, simulated, and verified by
various channel measurement results, which clearly demonstrates its accuracy,
pervasiveness, and applicability.
