On the second order statistics of N-hop FSO communications over N-gamma-gamma turbulence induced fading channels

The paper explores N-hop FSO communications assisted by amplify-and-forward relays (AFRs) over N-gamma-gamma (N-gg) turbulence induced (TI) fading channels. We model TI signal as the product of independent but not necessarily identically distributed (i.n.i.d) N number gg random processes (RPs) in order to address AFR moderate strong conditions. closed form statistical measures such as: probability density function (PDF), cumulative distribution (CDF), average level crossing rate (LCR) and fade duration (AFD) approximated general Laplace integration formula (LIF) exponential LIF are derived. CDF AFD derived expressions terms finite sums valid only for an integer value parameter related small-scale atmospheric cells first link system. numerical examples conditions well various hops proposed systems presented discussed. Moreover, approximate results compared with evaluated from exact integral observed system parameters.