Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

IEEE photonics journal

Physical-Layer Security in Free-Space Optical Communications

F. Javier López‐Martínez, Gerardo Gómez, José María Garrido-Balsells

Published Feb 10, 2015• 252 citations
Publisher

Abstract

The communication between two legitimate peers in the presence of an external eavesdropper is studied from a physical-layer security perspective in the context of free-space optical (FSO) communications. We discuss viable mechanisms to eavesdrop the communication and study the effect of random optical irradiance fluctuations inherent to FSO communications on the probability of achieving a secure transmission. We observe that the joint effect of laser-beam divergence and turbulence-induced fading on the received irradiance, under certain conditions, allows an external eavesdropper close to the legitimate receiver to compromise the communication. Interestingly, we also observe that an eavesdropper placed close to the legitimate transmitter can easily compromise the communication by taking advantage of the larger attenuation suffered by the signal when propagating through the FSO link.

DOI
10.1109/jphot.2015.2402158

Related papers

Secrecy analysis of a free-space laser communication system with a coherent main channel

Manuel Prasanna Kalaimani, Harishankar Ramachandran

Physical layer security of a free-space optical (FSO) communication link is investigated for certain eavesdropping scenarios in which the eavesdropper exploits the divergence of the transmitted laser beam, which is subject to atmospheric turbulence, to compromise the security of the transmission link. A solution for physical layer security in which the legitimate receiver is positioned to receive only the coherent component of the transmitted laser beam is proposed. The irradiance fluctuations are modeled with separate distributions for the coherent and non-coherent components of the transmitted beam, corresponding to the main channel and the eavesdropper’s channel, respectively. Complete secrecy analysis of this setup is presented, and closed form expressions of the probability of strictly positive secrecy capacity, average secrecy capacity, and secrecy outage probability are derived. The analytical results are verified by Monte-Carlo simulations. Secrecy performance for worst-case scenarios corresponding to an adversary with powerful resources to capture all of the leaked information is explored. Results are analyzed for different turbulence regimes, and it was found that secure communication is possible even in the region of strong turbulence.

Optical Engineering•Jun 2, 2023•2 citations

Free-space optical channel estimation for physical layer security

Hiroyuki Endo, Mikio Fujiwara, Mitsuo Kitamura +10 more

We present experimental data on message transmission in a free-space optical (FSO) link at an eye-safe wavelength, using a testbed consisting of one sender and two receiver terminals, where the latter two are a legitimate receiver and an eavesdropper. The testbed allows us to emulate a typical scenario of physical-layer (PHY) security such as satellite-to-ground laser communications. We estimate information-theoretic metrics including secrecy rate, secrecy outage probability, and expected code lengths for given secrecy criteria based on observed channel statistics. We then discuss operation principles of secure message transmission under realistic fading conditions, and provide a guideline on a multi-layer security architecture by combining PHY security and upper-layer (algorithmic) security.

arXiv:1607.07799•Optics Express•Apr 14, 2016•48 citations

Physical Layer Security of Hybrid FSO-mmWave Communications in Presence of Correlated Wiretap Channels

Sezer Can Tokgoz, Saud Althunibat, Serhan Yarkan +1 more

Hybrid Free-Space Optical (FSO) and millimeter Wave (mmWave) systems have emerged as a promising candidate for high data rate wireless transmissions due to the unique complementary properties against the different channel and environment conditions. Consequently, in this study, we investigate the hybrid FSO-mmWave systems from a physical-layer security point of view in the presence of a hybrid type eavesdropper, where the communication between two legitimate peers takes place over both FSO and RF links simultaneously. We examine practical scenarios to eavesdrop the legitimate communication and discuss the effects of random radio power of mmWave link and optical irradiance of FSO link on the probability of achieving a secure transmission. The impact of the fundamental physical layer parameters on the secrecy performance of the hybrid system is analyzed by obtaining closed-form derivations of the probability of strictly positive secrecy capacity (SPSC) for correlated wiretap channels.

International Conference on Communications•Jun 1, 2021•10 citations

On the Secrecy Capacity of Hybrid FSO-mmWave Wiretap Channels

Sezer Can Tokgoz, Saud Althunibat, Scott L. Miller +1 more

Hybrid Free-Space Optical (FSO) and millimeter Wave (mmWave) systems have emerged as a promising candidate for high data rate wireless transmissions due to the unique complementary properties against the different channel and environment conditions. Consequently, in this study, we investigate the hybrid FSO-mmWave systems from a physical-layer security point of view in the presence of different types of eavesdroppers, where the communication between two legitimate peers takes place over both FSO and RF links simultaneously. In particular, exponential atmospheric turbulence and Weibull fading channels are considered for FSO and mmWave links, respectively. We examine practical scenarios to eavesdrop the legitimate communication, and discuss the effects of random radio power of mmWave link and optical irradiance of FSO link on the probability of achieving a secure transmission. The impact of the fundamental physical layer parameters on the secrecy performance of the hybrid system is analyzed by obtaining analytical derivations of the probability of strictly positive secrecy capacity (SPSC) for different types of eavesdroppers, namely RF-, FSO- and Hybrid-Eve. In the light of results, we show that the analytical expressions are in exact agreement with the Monte-Carlo simulations.

IEEE Transactions on Vehicular Technology•Feb 4, 2022•21 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 Access•Dec 31, 2020•37 citations

Physical Layer Security for FSO-based Data Center

Wenning Lu, Bingbing Li

Wireless data center network has recently received a lot of academic attention. Relevant studies have shown that Free Space Optical (FSO) technology can bring flexible topologies, high speed transmission and low energy consumption to data centers. However, it can also make the cloud data broadcast in the data center space. Some work has shown that outdoor FSO channel is vulnerable to eavesdropping attacks due to the combined attenuation effects of atmospheric turbulence and long distance transmission. Unfortunately, it is not clear the security of FSO channel in data centers and there are few studies discussing it. We study the physical layer security of FSO link in the data center indoor scenario. A suitable tapping channel model was given based on the viable mechanism of eavesdrop communication in data center. We also numerically simulate the FSO eavesdropping channel in short distance and study the impact of the relevant factors on probability of secrecy capacity. The results show that in data centers, only path attenuation of FSO also poses a channel eavesdropping risk. Under certain conditions, the distance of a few tens of meters combined with the use of shorter wavelengths can result in serious channel security risks. At the same time, the use of long wavelengths or special window wavelengths with small attenuation of FSO in FSO-based data centers has significantly improved channel security.

International Academic Exchange Conference on Science and Technology Innovation (IAECST)•Dec 9, 2022•1 citation
The communication between two legitimate peers in the presence of an external eavesdropper is studied from a physical-layer security perspective in the context of free-space optical (FSO) communications. We discuss viable mechanisms to eavesdrop the communication and study the effect of random optical irradiance fluctuations inherent to FSO communications on the probability of achieving a secure transmission. We observe that the joint effect of laser-beam divergence and turbulence-induced fading on the received irradiance, under certain conditions, allows an external eavesdropper close to the legitimate receiver to compromise the communication. Interestingly, we also observe that an eavesdropper placed close to the legitimate transmitter can easily compromise the communication by taking advantage of the larger attenuation suffered by the signal when propagating through the FSO link.
Physical layer security of a free-space optical (FSO) communication link is investigated for certain eavesdropping scenarios in which the eavesdropper exploits the divergence of the transmitted laser beam, which is subject to atmospheric turbulence, to compromise the security of the transmission link. A solution for physical layer security in which the legitimate receiver is positioned to receive only the coherent component of the transmitted laser beam is proposed. The irradiance fluctuations are modeled with separate distributions for the coherent and non-coherent components of the transmitted beam, corresponding to the main channel and the eavesdropper’s channel, respectively. Complete secrecy analysis of this setup is presented, and closed form expressions of the probability of strictly positive secrecy capacity, average secrecy capacity, and secrecy outage probability are derived. The analytical results are verified by Monte-Carlo simulations. Secrecy performance for worst-case scenarios corresponding to an adversary with powerful resources to capture all of the leaked information is explored. Results are analyzed for different turbulence regimes, and it was found that secure communication is possible even in the region of strong turbulence.
We present experimental data on message transmission in a free-space optical (FSO) link at an eye-safe wavelength, using a testbed consisting of one sender and two receiver terminals, where the latter two are a legitimate receiver and an eavesdropper. The testbed allows us to emulate a typical scenario of physical-layer (PHY) security such as satellite-to-ground laser communications. We estimate information-theoretic metrics including secrecy rate, secrecy outage probability, and expected code lengths for given secrecy criteria based on observed channel statistics. We then discuss operation principles of secure message transmission under realistic fading conditions, and provide a guideline on a multi-layer security architecture by combining PHY security and upper-layer (algorithmic) security.
Hybrid Free-Space Optical (FSO) and millimeter Wave (mmWave) systems have emerged as a promising candidate for high data rate wireless transmissions due to the unique complementary properties against the different channel and environment conditions. Consequently, in this study, we investigate the hybrid FSO-mmWave systems from a physical-layer security point of view in the presence of a hybrid type eavesdropper, where the communication between two legitimate peers takes place over both FSO and RF links simultaneously. We examine practical scenarios to eavesdrop the legitimate communication and discuss the effects of random radio power of mmWave link and optical irradiance of FSO link on the probability of achieving a secure transmission. The impact of the fundamental physical layer parameters on the secrecy performance of the hybrid system is analyzed by obtaining closed-form derivations of the probability of strictly positive secrecy capacity (SPSC) for correlated wiretap channels.
Hybrid Free-Space Optical (FSO) and millimeter Wave (mmWave) systems have emerged as a promising candidate for high data rate wireless transmissions due to the unique complementary properties against the different channel and environment conditions. Consequently, in this study, we investigate the hybrid FSO-mmWave systems from a physical-layer security point of view in the presence of different types of eavesdroppers, where the communication between two legitimate peers takes place over both FSO and RF links simultaneously. In particular, exponential atmospheric turbulence and Weibull fading channels are considered for FSO and mmWave links, respectively. We examine practical scenarios to eavesdrop the legitimate communication, and discuss the effects of random radio power of mmWave link and optical irradiance of FSO link on the probability of achieving a secure transmission. The impact of the fundamental physical layer parameters on the secrecy performance of the hybrid system is analyzed by obtaining analytical derivations of the probability of strictly positive secrecy capacity (SPSC) for different types of eavesdroppers, namely RF-, FSO- and Hybrid-Eve. In the light of results, we show that the analytical expressions are in exact agreement with the Monte-Carlo simulations.
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.
Wireless data center network has recently received a lot of academic attention. Relevant studies have shown that Free Space Optical (FSO) technology can bring flexible topologies, high speed transmission and low energy consumption to data centers. However, it can also make the cloud data broadcast in the data center space. Some work has shown that outdoor FSO channel is vulnerable to eavesdropping attacks due to the combined attenuation effects of atmospheric turbulence and long distance transmission. Unfortunately, it is not clear the security of FSO channel in data centers and there are few studies discussing it. We study the physical layer security of FSO link in the data center indoor scenario. A suitable tapping channel model was given based on the viable mechanism of eavesdrop communication in data center. We also numerically simulate the FSO eavesdropping channel in short distance and study the impact of the relevant factors on probability of secrecy capacity. The results show that in data centers, only path attenuation of FSO also poses a channel eavesdropping risk. Under certain conditions, the distance of a few tens of meters combined with the use of shorter wavelengths can result in serious channel security risks. At the same time, the use of long wavelengths or special window wavelengths with small attenuation of FSO in FSO-based data centers has significantly improved channel security.