A Generalized GBSM for Free-Space Optical Channel Modeling

Free space optical (FSO) communication is a promising technology for sixth-generation (6G) networks, offering high bandwidth and immunity to electromagnetic interference. However, its performance is severely degraded by atmospheric impairments such as fog, rain, and atmospheric turbulence. To mitigate these effects, the development of accurate and comprehensive channel models that closely emulate real-world conditions is essential. This paper proposes a novel geometry-based stochastic model (GBSM) that unifies the deterministic attenuations of fog extinction, rain scattering, and beam divergence with turbulence-induced stochastic fading. The model incorporates the refractive index structure parameterC2n, which is dependent on temperature and wind, to precisely characterize environmental dynamics. Simulations and experiments demonstrate that the proposed model accurately reproduces the temporal fluctuations and statistical distributions of the received optical power under composite atmospheric conditions.