IEEE photonics journal

On Secrecy Performance of Mixed RF-FSO Systems With a Wireless-Powered Friendly Jammer

Yi Wang, Tong Yang, Zhiwu Zhan

Published Jan 25, 2022• 18 citations

Abstract

This paper presents a study of the physical layer security performance of a mixed radio frequency-free space optical (RF-FSO) system with a wireless-powered friendly jammer. The RF links undergo the Nakagami-m fading, and the FSO link experiences the Exponentiated Weibull (EW) distribution. A two-hop decode-and-forward (DF) relay is present in the system. A single-antenna eavesdropper located on the RF link attempts to eavesdrop on the channel transmission information. There is a nearby multi-antenna jammer that can be charged wirelessly, and a save-then-transmit (ST) protocol is introduced in the jammer. The closed expressions for the secrecy outage probability (SOP) and the average secrecy capacity (ASC) of the mixed RF-FSO system are derived, and the correctness of the expressions is verified using the Monte-Carlo method. The influence of various key factors on the secrecy performance of the system is analyzed by simulations. The results show that increasing the average interference noise ratio, the number of interferer antennas, the time block allocation factor, and the size of the receiving aperture has a significant effect on the secrecy performance. This study provides a new system structure and a good theoretical basis for evaluating the physical layer security performance of mixed RF-FSO systems.

DOI: 10.1109/jphot.2022.3146019

Related papers

Physical Layer Security Performance of Multi-User Mixed Radio-Frequency/Free-Space-Optics System Based on Optimal User Interference

Zihe Shen, Yi Wang, Jiamin Wu

This paper presents research on the physical layer security performance of a multi-user mixed RF/FSO system based on optimal user interference. In this system model, the RF link experiences Rayleigh fading, and the FSO link follows the Fischer-Snedecor F distribution. The system adopts a double-hop-decode-and-forward (DF) relay scheme. We also consider the effect of directivity errors in the FSO link and assume the presence of an illegal eavesdropper with a single antenna near the RF link. The source node controls the energy collection and information forwarding using a multi-user structure based on simultaneous wireless information and power transfer (SWIPT). We select the optimal user to jam the eavesdropper's communication. We derive closed-form expressions for the mixed RF/FSO communication system's secrecy outage probability (SOP) and average secrecy capacity (ASC). Monte Carlo simulations are performed to verify the accuracy of these expressions. By formulating and simulating the simulation system, the impact of various important factors on the mixed system's physical layer security (PLS) is analyzed. The analysis indicates that increasing the number of antennas and interference signal-to-noise ratio (SNR) of the optimal user, the time allocation factor and energy conversion efficiency, and the improvement in the quality of atmospheric channels with improved weather will significantly enhance this system's PLS.

SensorsJul 19, 20236 citations

Secrecy Performance Analysis of Mixed α − μ and Exponentiated Weibull RF-FSO Cooperative Relaying System

Nazmul Hassan Juel, A. S. M. Badrudduza, S. M. Riazul Islam +5 more

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.

IEEE AccessJan 1, 202135 citations

On secrecy analysis of wireless-powered relaying FSO-RF systems

Jiliang Zhang, Wanxin He, Gaofeng Pan +1 more

We investigate the physical-layer security performance for a wireless-powered relaying mixed free-space optical-radio frequency (FSO-RF) system. In this system, a source transmits optical information to a relay (R), which decodes the received signal with a decode-and-forward protocol, converts it into an RF signal, and forwards it to a destination in the presence of an eavesdropper. Furthermore, we also assume that R has no extra power supply, and it only relies on harvesting energy from a power beacon to forward the information. Assuming that the FSO and all of the RF channels experience gamma-gamma and Rayleigh fading, the closed-form analytical expressions for secrecy outage probability and the probability of strictly positive secrecy capacity are derived. In addition, the effects of atmospheric turbulence, pointing errors, and detection techniques on the system performance are analyzed. Finally, we perform Monte Carlo simulations to verify the accuracy of the derived expressions.

Optical EngineeringJun 3, 20214 citations

Physical Layer Security Performance Analysis of Hybrid FSO/RF Communication System

Wafaa Mohammed Ridha Shakir

In this paper, the secrecy performance of the physical layer security (PLS) of the hybrid free-space optical/radio frequency (FSO/RF) communication system is analyzed. The transmission protocol of the considered system is performed under the eavesdropper's attempt to overhear the RF link between the transmitter and legitimate receiver of the hybrid system. The FSO link is characterized by Málaga-M distribution while the RF links are modeled by Nakagami-m distribution. The two practical eavesdropping modes considered in this paper include: colluding and non-colluding. Exact closed-form expressions for the system's secrecy outage probability (SOP), the asymptotic of the SOP (SOP∞), the probability of strictly positive secrecy capacity (SPSC), the average secrecy capacity (ASC), and the asymptotic of the ASC (ASC∞), are specifically derived under the influence of both eavesdropper modes. Our derived analytical expressions present an efficient tool to investigate the impact of some channel parameters on the secrecy performance, namely the fading severity of the RF links, atmospheric turbulence severity, pointing error of the FSO link, number of eavesdroppers, and the power of the eavesdropper links. The results show that the increase of the eavesdroppers' number under both modes profoundly degrades the considered system secrecy performance. The accuracy of the numerical results obtained is validated by Monte-Carlo simulations.

IEEE AccessDec 31, 202037 citations

On the Physical Layer Security of a Decode and Forward Based Mixed FSO/RF Co-operative System

Dipti R. Pattanayak, Vivek K. Dwivedi, Vikram Karwal +3 more

In this letter, the secrecy performance of a decode-and-forward (DF) principle based mixed free space optics (FSO) and radio frequency (RF) system is analyzed. The analysis is done from physical layer (PHY) security perspective. Herein, two different eavesdroppers are considered while signal is transmitting from source (S) to destination (D) through a relay (R) point. The FSO based and RF based eavesdroppers are trying to intercept the confidential signal from S-R link and R-D links respectively. The faded FSO links are modeled by Málaga (M) distribution and RF links are characterized by Nakagami-m distribution. Exact closed form expression for secrecy performance metric such as secrecy outage probability is derived and analyzed for the aforementioned system in terms of Meijer's G-function and bivariate Fox's H-function. Furthermore, the asymptotic expressions for these performance metrics are derived by employing high signal to noise ratio (SNR) approximation. Afterwards the results are verified by Monte-Carlo simulations. Finally, the secrecy threshold for the system is derived to get insight of the system reliability and secrecy.

arXiv:1907.03117IEEE Wireless Communications LettersJan 1, 202038 citations

Enhancing Physical Layer Security of Multiuser SIMO Mixed RF/FSO Relay Networks with Multi-Eavesdroppers

Ahmed Hassan Abd El-Malek, Anas M. Salhab, Salam A. Zummo +1 more

In this paper, we investigate the secrecy performance of multiuser (MU) single-input multiple-output (SIMO) mixed radio frequency (RF)/free space optical (FSO) relay network with opportunistic user scheduling and multiple eavesdropping attacks. The considered system includes multiple users, one amplify-and-froward (AF) relay, one destination and multiple eavesdroppers. The users are connected with a multi-antenna relay through RF links and the relay is connected with the destination through an FSO link. Maximal ratio combining (MRC) scheme is used at the relay node to combine the received signals at its different antennas. The RF/FSO channels are assumed to follow Nakagami-m/Gamma-Gamma fading models with considering the effect of pointing errors. In particular, we derive closed- form expressions for the exact and asymptotic outage probabilities. The asymptotic outage results are then used to obtain the optimal RF transmission power based on the dominant link between the RF and FSO links. Then, the considered system secrecy performance is investigated in the presence of multi- eavesdroppers where exact closed-form expression for the intercept probability is derived. Finally, a cooperative jamming model is proposed along with power allocation to enhance the system secrecy performance. Monte-Carlo simulations are provided to validate the achieved exact and asymptotic results.

IEEE Globecom Workshops (GC Wkshps)Dec 1, 201619 citations