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Abstract. This paper works with the simulation of T-CONT

This paper is devoted to the analysis of environmental influences in the optical transmission medium and their impacts on multilevel modulation formats. An attention is focused on main features and characteristics of environmental negative influences of optical fibers. Consequently, principles for appropriate multilevel modulation formats are introduced together with block schemes representing their main functionalities. The created Simulink model for technologies and communications is verified for real conditions in the optical transmission medium. It can allow executing requested analysis for environmental influences on advanced multilevel modulation formats at the signal transmission. Finally, a comparison of considered multilevel modulations is introduced, using constellation diagrams, signal characteristics, eye diagrams and waterfall curves of individual signals.

The Fisher-Snedecor F distribution has been recently proposed as an experimentally verified and tractable turbulence induced fading model (TIFM) for free space optical (FSO) communications. This paper provides outage probability (OP) and higher-order (HO) performance analysis of the product of N independent but not identically distributed (i.n.i.d) Fisher-Snedecor F random variates (RVs). Accurate and closed-form (C-F) expressions for cumulative distribution function (CDF), level crossing rate (LCR) and average fade duration (AFD) of N-Fisher-Snedecor F distribution are successfully derived. The general property of a Laplace approximation approach for evaluation of N-folded complex integral-form (I-F) LCR expressions has been applied. The obtained statistical results are directly related to the performance evaluation of N-hop FSO communication links over weak, moderate and strong atmospheric turbulence conditions.