Mitigation of Turbulence-Induced Scintillation Noise in Free-Space Optical Communication Links Using Kalman Filter

Atmospheric turbulence causes fluctuation of the received light signal in free-space optical (FSO) communication links through atmosphere, impairing link performance. The propagation of light wave in atmospheric turbulence was studied, and the received signal was modeled. Then the optimum decision threshold model was derived for FSO communication links using intensity modulation with direct detection (IM/DD). The turbulence-induced signal fluctuation, i.e. scintillation noise, was modeled as multiplicative noise in the received signal. In order to mitigate the scintillation noise, an adaptive Kalman filter was used to predict the value of received signal and turbulence statistics. Based on the Kalman filter, the detection with adaptive decision threshold was realized. Finally, the performance of Kalman filter was calculated, and the results show the error between optimum decision threshold and adaptive decision threshold is smaller than 0.48%. Kalman filter is an effective tool to combat turbulence-induced scintillation noise.