Research on Large‐Scale Channel Model for Satellite–Terrestrial Communication Based on GBSM and NHMP

With the rapid development of LEO satellite communication systems, satellite–terrestrial integrated networks have become a crucial component of future 6G communication systems. However, the high‐speed relative motion between satellites and terrestrial terminals forms a complex dual‐dynamic communication scenario, which endows the channel with prominent time variability and nonstationarity, thus posing great challenges to the accurate modeling of large‐scale fading. To address this problem, this paper proposes an integrated propagation probability calculation model that combines the GBSM with the NHMP. First, based on the Fresnel zone diffraction principle and stochastic geometry theory, this paper models urban buildings with Poisson and Rayleigh distributions and analytically derives the time‐varying probability expressions for LOS propagation and reflected propagation. On this basis, aiming at the nonstationary switching of links among different propagation states, the NHMP model is constructed and the corresponding state transition matrix is derived, with the time‐varying probability of integrated effective propagation solved by the forward Kolmogorov equation. The accuracy of the proposed model is verified via Monte Carlo simulation, which provides a universal large‐scale channel modeling method for the satellite–terrestrial link budget in dual‐dynamic scenarios.