Multibeam scintillation cumulative distribution function.

The gamma-gamma probability density function is commonly used to model the scintillation of a single laser beam propagating through atmospheric turbulence. One method proposed to reduce scintillation at the receiver plane involves the use of multiple channels propagating through independent paths, resulting in a sum of independent gamma-gamma random variables. Recently, a novel approach for an accurate, closed-form approximation for the sum of independent, identically distributed gamma-gamma random variables was introduced by Chatzidiamantis et al. [GLOBECOM 2009--2009 IEEE Global Telecommunications Conference (2009)]. Using this approximation, we present the first analytic model for the distribution of irradiance due to propagating multiple independent beams. This model compares favorably to wave-optics simulations.