A Simple Statistical Model for Turbulence-Induced Fading in Free-Space Optical Systems

In this paper, we propose the Inverse Gaussian (IG) distribution, as a less complex alternative to Log-normal (LN), to describe turbulence-induced fading in free-space optical (FSO) systems operating in weak turbulence conditions and/or in the presence of a large amount of aperture averaging. By conducting goodness of fit tests, we define the range of values of the scintillation index, where the two distributions approximate each other, with a certain significance level. The efficiency of the new model is pointed out by deriving analytical expressions for the calculation of the bit-error rate of two typical FSO systems; an intensity-modulation/direct detection FSO system with M-ary pulse position modulation and a heterodyne FSO system with differential phase shift keying. Numerical examples are provided to clearly illustrate the accuracy of the proposed approach in the weak turbulence regime.