Joint characterization of fog, turbulence, and adaptive amplification in a 4-channel WDM-FSO communication system

Abstract

This paper investigates the joint effects of fog, atmospheric turbulence, pointing error, modulation, receiver filtering, and optical amplification in a four-channel WDM-FSO system operating at 1,550 nm with 10 Gbps per channel. OptiSystem simulations are performed using Kim’s fog model, Gamma–Gamma turbulence, and the Farid–Hranilovic pointing-error model. Fixed and adaptive EDFA schemes are compared, and a closed-loop PI controller is evaluated for dynamic fog compensation. An analytical Gamma–Gamma BER model is also used to assess qualitative agreement with the simulated turbulence response. Results show that receiver noise dominates under weak turbulence, while turbulence becomes the major limitation near C ² _n  = 10 ⁻¹³  m ^−2/3 . Adaptive EDFA provides its greatest improvement under moderate fog, whereas dense fog exceeds practical amplifier gain limits. RZ-OOK and the RC matched filter provide the best performance among the investigated configurations. Pointing-error results indicate a significant reduction in jitter tolerance as turbulence increases. The PI-controlled EDFA further demonstrates improved received-power recovery during fog transients. These results highlight the importance of jointly considering atmospheric and system impairments for reliable high-capacity WDM-FSO deployment.