Discrete Markov chain model for transition analysis of optical scintillation in reflection-assisted free space optical links

Abstract

In this work, a novel technique of estimating turbulence state information (TSI) for characterizing the strength of the channel induced laser beam scintillation in a reflection assisted free space optical link is introduced. The consistency of the proposed TSI estimation technique is then substantiated through scintillation index analysis in FSO test-bed link with non-uniform temperature induced turbulent channel over a beam propagation distance of 7.5 m. Based on the experimental results, we statistically investigate the BER performance and the scintillation transition probability matrix of the FSO link for Gamma–Gamma distributed turbulent channel. A finite state Markov chain (FSMC) model is then developed for analyzing the fading behavior of the turbulent FSO channel over the long run of link operation. We further adopt the Eigen analysis of the statistically generated transition probability matrix for evaluating the limiting transition probability of the beam scintillation. Additionally, the scintillation rate in the test bed link is estimated from the Eigen analysis technique and is observed to be 4.09%.