  Following recent advances in terahertz (THz) technology, there is a consensus
among multiple research initiatives on the essential role of THz communications
in the sixth generation of wireless communication systems and beyond. Aiming at
catalyzing THz communications research, we propose TeraMIMO, an accurate MATLAB
simulator of statistical THz channels. We simulate ultra-massive multiple-input
multiple-output antenna configurations as critical infrastructure enablers that
overcome the limitation in THz communications distances. We consider both
line-of-sight and multipath components and propose frequency- and delay-domain
implementations for single- and multi-carrier paradigms in both time-invariant
and time-variant scenarios. We implement exhaustive molecular absorption
computations based on radiative transfer theory alongside alternative sub-THz
approximations. We further model THz-specific constraints, including wideband
beam split effects, spherical wave propagation, and misalignment fading. We
verify TeraMIMO by analogy with measurement-based channel models in the
literature, and we introduce a graphical user interface.
