  Current statistical channel models for Terahertz (THz) wireless communication
primarily concentrate on the sub-THz band, mostly with $\alpha$-$\mu$ and
Gaussian mixture fading distributions for short-term fading and deterministic
modeling for atmospheric absorption. In this paper, we develop a generalized
statistical model for signal propagation at THz frequencies considering random
path-loss employing Gamma distribution for the molecular absorption
coefficient, short-term fading characterized by the
$\alpha$-$\eta$-$\kappa$-$\mu$ distribution, antenna misalignment errors, and
transceiver hardware impairments. The proposed model can handle various
propagation scenarios, including indoor and outdoor environments,
backhaul/fronthaul situations, and complex urban settings. Using Fox's
H-functions, we present the probability density function (PDF) and cumulative
distribution function (CDF) that capture the combined statistical effects of
channel impairments. We analyze the outage probability of a THz link to
demonstrate the analytical tractability of the proposed generalized model. We
present computer simulations to demonstrate the efficacy of the proposed model
for performance assessment with the statistical effect of atmospheric
absorption.
