Research on Gamma–Gamma Turbulence Channel Modeling Algorithm Based on Atmospheric Coherence Length Correction

Atmospheric turbulence is an important factor affecting the application of the free-space optical communication (FSOC) system in the atmospheric environment. The scintillation effect caused by turbulence distorts the phase and amplitude of the optical signal, which significantly reduces the performance of laser communication. In particular, the actual atmospheric environment is complex and changeable when long-distance optical transmission occurs, and the test is difficult and the conditions are limited. Therefore, developing accurate numerical simulation models in the laboratory serves as a critical testing method for the design of atmospheric laser communication systems. In this paper, we introduce an empirical parameter mapping based on the equivalent atmospheric coherence length into the existing framework for generating Gamma–Gamma stochastic differential equations (SDE), and evaluate its statistical performance using received power data from a single 13 km horizontal link coupled via 200 μm multimode fiber. The equivalent coherence length was derived from the statistics of received power flicker and was not measured independently. The results show that the correction effect depends on the fluctuation conditions and evaluation metrics: under low-fluctuation conditions, both the scintillation-index error and the KS distance increase; under medium-fluctuation conditions, the scintillation-index error decreases, but the KS distance increases; under high-fluctuation conditions, the relative error of the average scintillation index decreases from 18.71% to 11.03%, and the KS distance decreases from 0.0433 to 0.0277. These findings provide a reference for statistical modeling of received power under the tested link and reception configurations; however, their applicability to other paths, propagation geometries, and reception configurations requires further verification.