Optical scintillations and fade statistics for FSO communications through moderate-to-strong non-Kolmogorov turbulence

It is known that free space optical (FSO) communications is highly vulnerable to atmospheric turbulence. In this paper, by use of a generalized modified atmospheric spectrum that features inner scale parameter and high wave number “bump” for non-Kolmogorov atmospheric turbulence, tractable expressions are developed for the scintillation index (SI) of a plane wave and a spherical wave that are valid under moderate-to-strong irradiance fluctuations. With the derived SI and the gamma–gamma distribution, fade probabilities and mean fade time for FSO systems are investigated. The presented numerical results reveal some new details about how the inner scale and spectrum exponent values influence the SI and the associated fade statistics.

► The scintillation index in moderate-to-strong non-Kolmogorov turbulence is studied.
► Inner-scale effects are considered by the generalized modified atmospheric spectrum.
► The scintillation behavior in non-Kolmogorov turbulence is analyzed.
► The corresponding fade statistics are investigated.