Security at the Physical Layer Over GG Fading and mEGG Turbulence Induced RF-UOWC Mixed System

Abstract

With the rapid evolution of communication technologies, high-speed optical wireless applications under the water surface as a replacement or complementary to the conventional radio frequency (RF) and acoustic technologies are attracting significant attention from the researchers. Since underwater turbulence (UWT) is an inevitable impediment for a long distance underwater optical wireless communication (UOWC) link, mixed RF-UOWC is being considered as a more feasible solution by the research community. This article deals with the secrecy performance of a variable gain relay-based mixed dual-hop RF-UOWC framework under the intercepting attempt of a potential eavesdropper. The RF link undergoes Generalized Gamma (GG) fading distribution, whereas the UOWC link is subjected to mixture Exponential Generalized Gamma (mEGG) distribution. The eavesdropper is capable of wiretapping via a RF link that also experiences the GG fading. The secrecy analysis incorporates the derivations of closed-form expressions for strictly positive secrecy capacity, average secrecy capacity, and exact as well as lower bound of secrecy outage probability in terms of univariate and bivariate Meijer's G and Fox's H functions. Based on these expressions, impacts of heterodyne and intensity modulation/direct detection techniques along with weak, moderate, and severe UWT conditions due to air bubbles, temperature, and salinity gradients are quantified. To the best of authors' knowledge, the proposed model is the first of its kind that addresses the secrecy analysis of a temperature gradient RF-UOWC system along with air bubbles, as opposed to the existing models that considered thermally uniform scenarios only. Finally, the derived expressions are verified via Monte-Carlo simulations.INDEX TERMS Eavesdropper, optical wireless communication, physical layer security, under water turbulence.

Enhancing Security of TAS/MRC-Based Mixed RF-UOWC System With Induced Underwater Turbulence Effect

“…But mEGG distribution is the most versatile model that also incorporates mEG scenario. As a result, assuming mEGG model for UOWC link, [36] investigated the PLS and proposed the consideration of air bubble sizes and temperature gradients in the underwater environments being crucially important due to the enhancement of secrecy performance. It should be noted that [32] is the only work that investigated PLS of RF-FSO based mixed system with transmit antenna selection (TAS) scheme over the RF link.…”

“…Since eavesdropping is passive-type, the eavesdropper is unaware of the TAS scheme. To the best of the authors' knowledge, conventional works only considered fading around RF link for performance evaluation [33]- [36], [42] while how TAS / MRC scheme around RF link of a dual-hop RF-UOWC mixed network can enhance secrecy performance, has not been focused yet.…”

“…By substituting ( 17) and ( 13) into (36), the expression of SOP in closed-form is developed as (34), where the derivation of three distinct integral terms S 1 , S 2 , and S 3 are calculated as follows.…”

“…It is noteworthy that for the case with c = 1, PDF of mEGG model takes the form of EG model[36]. In addition, mEGG model is also equivalent to generalized Gamma (GG) and exponential distributions[21].…”

Opportunistic Relay Selection Over Generalized Fading and Inverse Gamma Composite Fading Mixed Multicast Channels: A Secrecy Tradeoff

“…As evident in their works, one can more precisely analyze the performances of many wireless systems and networks of interest; in terms of channel capacity (CC), outage probability (OP), coverage probability (CP), and bit error rate (BER). For example, the compound fading approaches with or without shadowing have been applied to analyze advanced wireless paradigms, including D2D, amplify and forward, decode and forward, 5G radio access, and optical communication systems [18]- [20]. As known, PLS can secure information by exploiting the randomness of the wireless channel [21].…”