The risk of information leakage increases when the relay technology is introduced to extend the communication range and improve the quality of communication services of cell-edge users in visible light communication (VLC) systems. To evaluate these security risks, physical layer security (PLS) performance for decode-and-forward (DF) relay-aided VLC system is investigated in this paper. Specifically, the theoretical expressions of the upper and lower bounds of the security outage probability (SOP) for the DF relay-aided VLC system under the amplitude constraint are obtained based on a stochastic geometry analysis method. Monte Carlo simulation validates the correctness of the derived theoretical expressions of the upper and lower bounds of the SOP. Moreover, simulation results show that the security outage performance of the DF relay-aided VLC system is deteriorated compared with the non-relay VLC system. Furthermore, the influences of the eavesdroppers' distribution density, the radiation radius of LED source, the radiation radius and deployment height of the relay on the SOP have been investigated. Last but not least, the optimal deployment height of the relay can be determined for achieving the optimum security outage performance. These parameters can effectively guide the design of the secure relay-aided VLC system.
The risk of information leakage increases when the relay technology is introduced to extend the communication range and improve the quality of communication services of cell-edge users in visible light communication (VLC) systems. To evaluate these security risks, physical layer security (PLS) performance for decode-and-forward (DF) relay-aided VLC system is investigated in this paper. Specifically, the theoretical expressions of the upper and lower bounds of the security outage probability (SOP) for the DF relay-aided VLC system under the amplitude constraint are obtained based on a stochastic geometry analysis method. Monte Carlo simulation validates the correctness of the derived theoretical expressions of the upper and lower bounds of the SOP. Moreover, simulation results show that the security outage performance of the DF relay-aided VLC system is deteriorated compared with the non-relay VLC system. Furthermore, the influences of the eavesdroppers' distribution density, the radiation radius of LED source, the radiation radius and deployment height of the relay on the SOP have been investigated. Last but not least, the optimal deployment height of the relay can be determined for achieving the optimum security outage performance. These parameters can effectively guide the design of the secure relay-aided VLC system.
Traditional physical layer security (PLS) schemes for multi-user visible light communication (MuVLC) are designed with multiple light sources, rendering them inapplicable to MuVLC with single light source. To address this limitation, we propose an innovative relay-aided PLS scheme based on cooperative jamming for MuVLC with single light source. First, we randomly select parts of relays for cooperative jamming, modeling their locations as a Poisson point process (PPP). Then, a jamming signal introduced through these selected relays significantly decreases the signal-to-interference-plus-noise-ratio of the randomly located eavesdroppers, thereby increasing the security capacity. By modeling the eavesdropper locations as another independent PPP, we analyze the security performance by deriving closed-form expressions for the cumulative distribution function of security capacity, security outage probability, its lower and upper bounds, and ergodic security capacity. These theoretical expressions are verified via Monte Carlo simulations. Numerical results show that our scheme achieves high-level communication security. Furthermore, increasing relay density, decreasing eavesdropper density, reducing target security capacity, or lowering relay plane height can effectively reduce security outage probability, offering valuable insights for designing secure MuVLC with single light source.
This letter studies the security performance of hybrid radio frequency (RF) and visible light communication (VLC) system. In this hybrid system, the source node (i.e., Alice) transmits information to the relay node via the outdoor RF link. Nakagami-m fading and path loss are considered for the RF link. The relay using the decode-and-forward (DF) relaying scheme. A legitimate receiver (Bob) arranged on the floor receives the optical signal. An eavesdropper (Eve) deployed in VLC link wiretaps the confidential information. In this paper, secrecy outage probability (SOP) is used to assess the performance of the system. We derive the closed expression of the lower bound of SOP when VLC link is wiretapped. Numerical results to validate the accuracy of our derivation.
A visible light communication (VLC) system with an improved noise model applied to physical layer security (PLS) is investigated, where secure beamforming signals with superposition coding are used. In the improved model, the output signal follows Gaussian distribution, but its variance is signal-dependent. Two different methods are proposed to obtain lower and upper bounds on the secrecy rate of the strong user for direct transmission. Under some constraints, closed-form expressions of the lower and upper bounds on secrecy rate regions for various (trusted cooperative half-duplex) relaying schemes are derived. Moreover, the scenarios of blockage/outside coverage are included, and the relevant security performances are discussed. Numerical results show that the lower and upper bounds on secrecy rate regions are tight enough, and the cooperative jamming is superior over other relaying schemes.
In this paper, we propose an innovative relay-aided physical layer security scheme leveraging cooperative transmission and jamming that operates effectively in time-division-multiple-access-based multi-user visible light communication (MuVLC) systems with obstructed communication links. First, to circumvent obstacles between the light source (LS) and legal receivers, we utilize a transmission relay (TR) to forward information signals from the LS to the receiver plane. Subsequently, to ensure communication security, we select a jamming relay to enlarge the channel capacity gap between eavesdroppers and legal receivers through cooperative jamming. Using stochastic geometry, we derive closed-form expressions for key performance metrics, including the cumulative distribution function of secrecy capacity, security outage probability, and their lower and upper bounds, both with and without relay cooperation. To further enhance system security, we introduce a disk-shaped security-protected zone around the TR. All analytical expressions are numerically verified through Monte Carlo simulations, serving as benchmarks to evaluate security performance. Numerical results confirm that our proposed scheme can ensure continuous signal reception and high-level security. Furthermore, while relay cooperation modestly enhances system security, the introduction of a security-protected zone around the TR yields substantial security improvement, which offers practical insights for designing secure time-division-multiple-access-based MuVLC where communication links are obstructed.
In this letter, the system performance of the DF full-duplex (FD) Relaying communication network is investigated with Physical Layer Security (PLS). In this system model, the source (S) and the destination (D) communicate via a helping relay (R) in the presence of the Eavesdropper (E). From the system model, we derive the closed-form expressions for Intercept Probability (IP) and secrecy outage probability (SOP). For verifying the correctness of the analytical analysis, the Monte Carlo simulation is conducted. In addition, the influence of the main system parameter on the system performance is investigated. Finally, the results show that the analytical and the simulation values agree well with each other.
In this article, the secrecy performance of a hybrid radio frequency (RF)/visible light communication (VLC) system is studied. In this hybrid system, the source node (i.e., Alice) transmits information to the relay node via the outdoor RF link. Nakagami-m fading and path loss are considered for the RF link. The relay node includes an outdoor component and an indoor component, which are connected by using a wired medium. The outdoor component receives and recovers information by using the decode-and-forward (DF) relaying scheme and then transmits it to the indoor component. The indoor component then converts the received electrical signal into an optical signal by using a light-emitting diode. A legitimate receiver (i.e., Bob) deployed on the floor receives the optical signal. An eavesdropper (i.e., Eve) deployed in the RF or VLC link wiretaps the confidential information. In this study, we use the secrecy outage probability (SOP) and the probability of strictly positive secrecy capacity (SPSC) to evaluate the system performance. We then obtain the closed-form expression for a lower bound on the SOP and an exact closed-form expression for the probability of SPSC when the RF and VLC links are wiretapped, respectively. Numerical results are presented to validate the accuracy of our derivations. We further discuss the effects of the noise standard deviation, the equivalent threshold of the signal-to-noise ratio, and the floor radius on the system secrecy performance when the VLC link is eavesdropped upon. For the case when the RF link is eavesdropped upon, the impacts of the distance between Alice and the relay, the path loss exponent, the fading factor, and the distance between Alice and Eve on secrecy performance are also provided.