“…The relay system techniques represent efficient way to speed up data-rate, extend coverage and save energy but also to efficiently merge different wireless technologies (Zedini et al, 2014;Anees & Bhatnagar, 2015;Petkovic et al, 2017;Stefanovic et al, 2019a). Moreover, amplify-andforward relay (AFR) scheme plays an important role in all-RF, RF-FSO and all-FSO relay systems (Stefanovic, 2017;Karimi & Masoumeh, 2011;Petkovic & Trpovski, 2018) and in some cases * Corresponding author: stefan.panic@pr.ac.rs the signal envelope, signal-to-interference ratio (SIR) and signalto-noise ratio (SNR) can be modeled as the product of two or more random processes (RPs) (Zlatanov et al, 2008;Stefanovic et al, 2018;Milosevic et al, 2018;Stefanovic et al, 2019b;Talha & Pätzold, 2007;Issaid & Alouini, 2019).…”