Performance Analysis of Free-Space Optical Systems in Gamma-Gamma Fading

Atmospheric turbulence induced fading is one of the main impairments affecting free-space optics (FSO). Gamma-gamma fading has become the dominant fading model for FSO links because of its excellent agreement with measurement data for a wide range of turbulence conditions. In this paper, we express the bit error rate of intensity modulated FSO with direct detection in single-input single-output and multiple-input multiple-output gamma-gamma fading channels as generalized infinite power series with respect to the signal-to- noise ratio. For fast numerical evaluation these power series are truncated to a finite number of terms and an upper bound for the associated approximation error is provided. Another contribution of this paper is the extension of the well-known RF concepts of diversity and combining gain to FSO and gamma-gamma fading.