# RSSI Probability Density Functions Comparison Using Jensen-Shannon Divergence and Pearson Distribution

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Information and Telecommunications Department, University of Peloponnese, 22131 Tripoli, Greece

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Section of Electronic Physics and Systems, Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, 15784 Athens, Greece

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Division of Combat Systems, Naval Operations, Sea Sciences, Νavigation, Electronics & Telecommunications Sector, Hellenic Naval Academy, 15561 Athens, Greece

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Author to whom correspondence should be addressed.

Academic Editor: Gwanggil Jeon

Received: 18 March 2021 / Revised: 1 April 2021 / Accepted: 5 April 2021 / Published: 8 April 2021

The performance of a free-space optical (FSO) communications link suffers from the deleterious effects of weather conditions and atmospheric turbulence. In order to better estimate the reliability and availability of an FSO link, a suitable distribution needs to be employed. The accuracy of this model depends strongly on the atmospheric turbulence strength which causes the scintillation effect. To this end, a variety of probability density functions were utilized to model the optical channel according to the strength of the refractive index structure parameter. Although many theoretical models have shown satisfactory performance, in reality they can significantly differ. This work employs an information theoretic method, namely the so-called Jensen–Shannon divergence, a symmetrization of the Kullback–Leibler divergence, to measure the similarity between different probability distributions. In doing so, a large experimental dataset of received signal strength measurements from a real FSO link is utilized. Additionally, the Pearson family of continuous probability distributions is also employed to determine the best fit according to the mean, standard deviation, skewness and kurtosis of the modeled data.