Secrecy Performance Analysis of Mixed Hyper-Gamma and Gamma-Gamma Cooperative Relaying System
Noor Ahmad Sarker, A. S. M. Badrudduza, S. M. Riazul Islam, Sheikh Habibul Islam, Imran Shafique Ansari, Milton Kumar Kundu, Mst. Fateha Samad, Md. Biplob Hossain, Heejung Yu
In this paper, we investigate a secure dual-hop radio frequency-free space optical (RF-FSO) mixed variable gain relaying framework in the presence of a single eavesdropper. The RF and FSO links are modeled with hyper Gamma (HG) and Gamma-Gamma (ΓΓ) fading channels, respectively. We assume that the eavesdropper utilizes another HG fading channel to wiretap the transmitted confidential data from the RF link. Our key concern is to defend this information against passive eavesdropping. We carry out the secrecy measurements by deriving closed-form mathematical expressions of average secrecy capacity (ASC), secure outage probability (SOP), and strictly positive secrecy capacity (SPSC), all in terms of Meijer's G function. Capitalizing on the derived expressions, we analyze the impacts of atmospheric turbulence and pointing errors on the secrecy capacity and outage performance of the proposed scenario. For gaining more insights, we also analyze the asymptotic outage behaviour for high signal-to-noise ratio. Two detection techniques i.e. heterodyne (HD) and the intensity modulation with direct detection (IM/DD) are taken into consideration and our results demonstrate that HD technique notably outperforms the IM/DD scheme. The supremacy and novelty of the model is demonstrated via utilizing generic properties of the HG fading channel. Finally, we provide a justification of the derived expressions via Monte-Carlo simulations.
In this paper, we investigate a secure dual-hop radio frequency-free space optical (RF-FSO) mixed variable gain relaying framework in the presence of a single eavesdropper. The RF and FSO links are modeled with hyper Gamma (HG) and Gamma-Gamma (ΓΓ) fading channels, respectively. We assume that the eavesdropper utilizes another HG fading channel to wiretap the transmitted confidential data from the RF link. Our key concern is to defend this information against passive eavesdropping. We carry out the secrecy measurements by deriving closed-form mathematical expressions of average secrecy capacity (ASC), secure outage probability (SOP), and strictly positive secrecy capacity (SPSC), all in terms of Meijer's G function. Capitalizing on the derived expressions, we analyze the impacts of atmospheric turbulence and pointing errors on the secrecy capacity and outage performance of the proposed scenario. For gaining more insights, we also analyze the asymptotic outage behaviour for high signal-to-noise ratio. Two detection techniques i.e. heterodyne (HD) and the intensity modulation with direct detection (IM/DD) are taken into consideration and our results demonstrate that HD technique notably outperforms the IM/DD scheme. The supremacy and novelty of the model is demonstrated via utilizing generic properties of the HG fading channel. Finally, we provide a justification of the derived expressions via Monte-Carlo simulations.
The emergence of an array of new wireless networks has led researchers to evaluate the prospect of utilizing the physical properties of the wireless medium in order to design secure systems. In this paper, the physical layer secrecy performance of a mixed radio frequency-free space optical (RF-FSO) system with variable gain relaying scheme is investigated in the presence of an eavesdropper. We assume that the eavesdropper can wiretap the transmitted confidential data from the RF link only. It is further assumed that the main and eavesdropper RF links are modeled as generalized Gamma (GG) fading channel, and the free space optical (FSO) link experiences Málaga turbulence with pointing error impairment. Our primary concern is to protect this confidential information from being wiretapped. Besides pointing error, the atmospheric turbulence and two types of detection techniques (i.e. heterodyne detection and intensity modulation with direct detection) are also taken into consideration. Utilizing amplify-and-forward (AF) scheme, the novel mathematical closed-form expressions for average secrecy capacity, lower bound of secrecy outage probability, and strictly positive secrecy capacity are derived. As both the links (RF and FSO) undergo generalized fading channels, the derived expressions are also general. We present a unification of some existing works utilizing the proposed model to better clarify the novelty of this work. Finally, all the derived expressions are justified via Monte-Carlo simulations.
On the Intercept Probability and Secure Outage Analysis of Mixed (α-κ-μ)-shadowed and Málaga Turbulent Model
This work deals with the secrecy performance analysis of a dual-hop RF-FSO DF relaying network composed of a source, a relay, a destination, and an eavesdropper. We assume the eavesdropper is located close to the destination and overhears the relay's transmitted optical signal. The RF and FSO links undergo (α-κ-μ)-shadowed fading and unified Málaga turbulence with pointing error. The secrecy performance of the mixed system is studied by deriving closed-form analytical expressions of secure outage probability (SOP), strictly positive secrecy capacity (SPSC), and intercept probability (IP). Besides, we also derive the asymptotic SOP, SPSC, and IP upon utilizing the unfolding of Meijer's G function where the electrical SNR of the FSO link tends to infinity. Finally, the Monte-Carlo simulation is performed to corroborate the analytical expressions. Our results illustrate that fading, shadowing, detection techniques (i.e., heterodyne detection (HD) and intensity modulation and direct detection (IM/DD)), atmospheric turbulence, and pointing error significantly affect the secrecy performance. In addition, better performance is obtained exploiting the HD technique at the destination relative to IM/DD technique.
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 α-μ 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.
Free-space optical (FSO) channel offers line-of-sight wireless communication with high data rates and high secrecy utilizing unlicensed optical spectrum and also paves the way to the solution of the last-mile access problem. Since atmospheric turbulence is a hindrance to an enhanced secrecy performance, the mixed radio frequency (RF)-FSO system is gaining enormous research interest in recent days. But conventional FSO models except for the double generalized Gamma (DGG) model can not demonstrate secrecy performance for all ranges of turbulence severity. This reason has led us to propose a dual-hop eta-mu and unified DGG mixed RF-FSO network while considering eavesdropping at both RF and FSO hops. The security of these proposed scenarios is investigated in terms of two metrics, i.e., strictly positive secrecy capacity and secure outage probability. Exploiting these expressions, we further investigate how the secrecy performance is affected by various system parameters, i.e., fading, turbulence, and pointing errors. A demonstration is made between heterodyne detection (HD) and intensity modulation and direct detection (IM/DD) techniques while exhibiting superior secrecy performance for HD technique over IM/DD technique. Finally, all analytical results are corroborated via Monte-Carlo simulations.
This work deals with the secrecy performance analysis of a dual-hop RF-FSO DF relaying network composed of a source, a relay, a destination, and an eavesdropper. We assume the eavesdropper is located close to the destination and overhears the relay’s transmitted optical signal. The RF and FSO links undergo (α-κ-μ)-shadowed fading and unified Málaga turbulence with pointing error. The secrecy performance of the mixed system is studied by deriving closed-form analytical expressions of secure outage probability (SOP), strictly positive secrecy capacity (SPSC), and intercept probability (IP). Besides, we also derive the asymptotic SOP, SPSC, and IP upon utilizing the unfolding of Meijer’s G function where the electrical SNR of the FSO link tends to infinity. Finally, the Monte-Carlo simulation is performed to corroborate the analytical expressions. Our results illustrate that fading, shadowing, detection techniques (i.e. heterodyne detection (HD) and intensity modulation and direct detection (IM/DD)), atmospheric turbulence, and pointing error significantly affect the secrecy performance. In addition, better performance is obtained exploiting the HD technique at the destination relative to IM/DD technique.
With the completion of standardization of fifth-generation (5G) networks, the researchers have begun visioning sixth-generation (6G) networks that are predicted to be human-centric. Hence, similar to 5G networks, besides high data rate, providing secrecy and privacy will be the center of attention by the wireless research community. To support the visions beyond 5G (B5G) and 6G, in this paper we propose a secure radio frequency (RF)-free-space optical (FSO) mixed framework under the attempt of wiretapping by an eavesdropper at the RF hop. We assume the RF links undergo alpha-eta-mu fading whereas the FSO link exhibits a unified Malaga turbulence model with pointing error. The secrecy performance is evaluated by deducing expressions for three secrecy metrics i.e. average secrecy capacity, secure outage probability, and probability of non-zero secrecy capacity in terms of univariate and bivariate Meijer's G and Fox's H functions. We further capitalize on these expressions to demonstrate the impacts of fading, atmospheric turbulence, and pointing errors and show a comparison between two detection techniques (i.e. heterodyne detection (HD) and intensity modulation with direct detection (IM/DD)) that clearly reveals better secrecy can be achieved with HD technique relative to the IM/DD method. The inclusion of generalized fading models at the RF and FSO hops offers unification of several classical scenarios as special cases thereby exhibiting a more generic nature relative to the existing literature. Finally, all the analytical results are corroborated via Monte-Carlo simulations.