Abstract
Increasing concerns regarding wireless systems’ security are leading researchers to exploit the physical properties of a medium while designing any secured wireless network. The secrecy performance of a mixed radio frequency-free space optical (RF-FSO) system with a variable gain relaying scheme is investigated in this paper under the attempt of wiretapping by an eavesdropper. We assume that the eavesdropper can intrude the target data from the RF link only. Both the RF links (main and eavesdropper) undergo the $\alpha -\mu $ fading statistics and the FSO link experiences the exponentiated Weibull fading statistics. Exploiting the amplify-and-forward (AF) relaying scheme while considering two detection techniques (i.e. heterodyne detection and intensity modulation/direct detection) with pointing error impairments, the mathematical formulations of the unified probability density function and cumulative distribution function are performed for the equivalent signal-to-noise ratio of the considered dual-hop RF-FSO link. Closed-form analytical expressions for average secrecy capacity, secrecy outage probability, and the probability of non-zero secrecy capacity are derived in terms of Meijer’s $G$ and Fox’s $H$ functions to quantify the system performance. Capitalizing on these expressions, the secrecy performance is further analyzed for various channel parameters of RF links, aperture sizes of the receiver, pointing errors, and atmospheric turbulence severity. The results reveal that aperture averaging can improve the secrecy performance remarkably by suppressing the effects of turbulence. Monte Carlo simulations are provided to justify the accuracy of the proposed model.
Highlights
This channel can represent the non-linearity of the physical channel. All these positive attributes of the α − μ fading channel make it a proper candidate to be utilized as radio frequency (RF) link in the high speed radio frequency-free space optical (RF-Free space optical (FSO)) network. In this presented work, a secure mixed RF-FSO single-input single-output (SISO) communication link is modeled with generalized α−μ fading channel at the RF hop and exponentiated Weibull (EW) fading at the FSO hop
In this figure we consider strong atmospheric turbulence condition i.e. δR2 = 19.2 for which we assume a Gaussian beam of λ = 780 nm propagating along a 1500 m horizontal path with a RI structure constant of
In this work, we examined the secrecy performance of a hybrid RF-FSO system over α-μ and unified EW mixed fading system with AF based variable gain relaying scheme under the attempt of an eavesdropper
Summary
All these positive attributes of the α − μ fading channel make it a proper candidate to be utilized as RF link in the high speed RF-FSO network In this presented work, a secure mixed RF-FSO single-input single-output (SISO) communication link is modeled with generalized α−μ fading channel at the RF hop and EW fading at the FSO hop. Is the non-linearity parameter of the propagation environment, μm > 0 is the number of multipath clusters, γ m stands for the average SNR of the T − R link with respect to which we have plotted multiple graphs in this work, and (μm) designates incomplete Gamma function Another most important attribute of α-μ fading distribution which drives the authors to deal with this particular model is TABLE 1. Even some large scale and composite fading models can be unified utilizing the proposed RF model [8], [39]
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