Abstract This research investigates the security of a visible light communication (VLC) system in an indoor setting. The system consists of multiple transmitters (referred to as Alice), a legitimate receiver (referred to as Bob), and a passive adversary (referred to as Eve). A scheme is proposed to enhance secrecy by using optical jamming signals alongside the confidential signal, under constraints of nonnegativity and average optical intensity. The optical jamming signals follow a truncated Gaussian distribution to adhere to predefined constraints. The analysis takes into account both noise independent of the signal and noise dependent on the signal. The study obtains lower and upper bounds on secrecy rate through the application of the variational method, the dual expression of secrecy rate, and the notion of ‘the optimal input distribution that tends towards infinity’. An asymptotic analysis reveals a minimal performance difference between the upper and lower bounds under large optical intensity. Introducing a peak optical intensity constraint enables further scrutiny of both the exact and asymptotic secrecy-rate bounds. Numerical results are provided to validate the obtained secrecy-rate bounds.
Abstract This research investigates the security of a visible light communication (VLC) system in an indoor setting. The system consists of multiple transmitters (referred to as Alice), a legitimate receiver (referred to as Bob), and a passive adversary (referred to as Eve). A scheme is proposed to enhance secrecy by using optical jamming signals alongside the confidential signal, under constraints of nonnegativity and average optical intensity. The optical jamming signals follow a truncated Gaussian distribution to adhere to predefined constraints. The analysis takes into account both noise independent of the signal and noise dependent on the signal. The study obtains lower and upper bounds on secrecy rate through the application of the variational method, the dual expression of secrecy rate, and the notion of ‘the optimal input distribution that tends towards infinity’. An asymptotic analysis reveals a minimal performance difference between the upper and lower bounds under large optical intensity. Introducing a peak optical intensity constraint enables further scrutiny of both the exact and asymptotic secrecy-rate bounds. Numerical results are provided to validate the obtained secrecy-rate bounds.
In physical-layer security, secrecy capacity is an important performance metric. This work aims to determine the secrecy capacity for an indoor visible light communication system consisting of a transmitter, a legitimate receiver and an eavesdropping receiver. In such a system, both signal-independent noise and signal-dependent noise are considered. Under nonnegativity and average optical intensity constraints, lower and upper bounds on secrecy capacity are derived by the variational method, the dual expression of the secrecy capacity, and the concept of “the optimal input distribution that escapes to infinity”. By an asymptotic analysis at large optical intensity, there is a small gap between the asymptotic upper and lower bounds. Then, by adding a peak optical intensity constraint, we further analyze the exact and asymptotic secrecy-capacity bounds. For practical considerations, the effects of imperfect channel state information, multi-photodiode eavesdropper, and artificial noise on secrecy performance are also discussed. Finally, the derived secrecy-capacity bounds are verified by numerical results.
This study examines the physical-layer security of an indoor visible light communication (VLC) system using spatial modulation (SM), which consists of several transmitters, an authorized receiver, and a passive adversary. The SM technique is applied at the transmitters so that only one transmitter is operational at any given time. A uniform selection (US) strategy is employed to choose the active transmitter. The two scenarios under examination encompass the conditions of non-negativity and average optical intensity, as well as the conditions of non-negativity, average optical intensity, and peak optical intensity. The secrecy rate is then obtained for these two scenarios while accounting for both signal-independent noise and signal-dependent noise. Additionally, the high signal-to-noise ratio (SNR) asymptotic behavior of the derived secrecy rate constraints is investigated. A channel-adaptive selection (CAS) strategy and a greedy selection (GS) scheme are utilized to select the active transmitter, aiming to enhance the secrecy performance. The current numerical findings affirm a pronounced convergence between the lower and upper bounds characterizing the secrecy rate. Notably, marginal asymptotic differentials in performance emerge at elevated SNRs. Furthermore, the GS system outperforms the CAS scheme and the US method, in that order. Additionally, the impact of friendly optical jamming on the secrecy rate is investigated. The results show that optical jamming significantly enhances the secrecy rate, particularly at higher power levels.
This paper investigates the physical-layer security for an indoor visible light communication network consisting of a transmitter, a legitimate receiver, and an eavesdropper. Both the main channel and the wiretapping channel have non-negative inputs, which are corrupted by additive white Gaussian noises. Considering the illumination requirement and the physical characteristics of lighting source, the input is also constrained in both its average and peak optical intensities. Two scenarios are investigated: one is only with an average optical intensity constraint and the other is with both average and peak optical intensity constraints. Based on the information theory, closed-form expressions of the upper and lower bounds on secrecy capacity for the two scenarios are derived. Numerical results show that the upper and lower bounds on secrecy capacity are tight, which validates the derived closed-form expressions. Moreover, the asymptotic behaviors in the high signal-to-noise ratio (SNR) regime are analyzed from the theoretical aspects. At high SNR, when only considering the average optical intensity constraint, a small performance gap exists between the asymptotic upper and lower bounds on secrecy capacity. When considering both average and peak optical intensity constraints, the asymptotic upper and lower bounds on secrecy capacity coincide with each other. These conclusions are also confirmed by numerical results.
In this paper, we investigate the physical-layer security for a spatial modulation (SM)-based indoor visible light communication (VLC) system, which includes multiple transmitters, a legitimate receiver, and a passive eavesdropper (Eve). At the transmitters, the SM scheme is employed, i.e., only one transmitter is active at each time instant. To choose the active transmitter, a uniform selection (US) scheme is utilized. Two scenarios are considered: one is with non-negativity and average optical intensity constraints and the other is with non-negativity, average optical intensity, and peak optical intensity constraints. Then, lower and upper bounds on the secrecy rate are derived for these two scenarios. Besides, the asymptotic behaviors for the derived secrecy rate bounds at high signal-to-noise ratio (SNR) are analyzed. To further improve the secrecy performance, a channel adaptive selection (CAS) scheme and a greedy selection (GS) scheme are proposed to select the active transmitter. Numerical results show that the lower and upper bounds of the secrecy rate are tight. At high SNR, small asymptotic performance gaps exist between the derived lower and the upper bounds. Moreover, the proposed GS scheme has the best performance, followed by the CAS scheme and the US scheme.
In order to enhance the secrecy performance of the generalized space shift keying (GSSK) visible light communication (VLC) system, in this paper, an optical jamming-aided secrecy enhancement scheme is proposed, in which the source transmitter (S) simultaneously sends both the confidential desired signal and optical jamming signals under the amplitude and power constraints. The optical jamming signals obey the truncated Gaussian distribution for satisfying the constraints. Given the discrete set of channel inputs, the optical jamming-aided GSSK-VLC system's secrecy performance is analyzed. Explicitly, the average mutual information (AMI), the lower bound of AMI and its closed-form approximation as well as the achievable secrecy rate are formulated analytically. Furthermore, the optimal power sharing strategy of the proposed GSSK-VLC systems relying on optical jamming is derived. Closed-form expressions are provided for the optimal power sharing in both the low- and high-SNR regions. Finally, the extensive simulation results are presented to validate our analytical results.
Recently, the physical-layer security, which exploits the channel characteristics in order to hide information from unauthorized receivers and does not reliance on the upper-layer encryption, has been proposed as a promising complement to the traditional security schemes. In this paper, the lower bounds on secrecy capacity for indoor visible light communications (VLC) are investigated. The noise is assumed to be Gaussian, which is independent of the input signal. The non-negativity and the average optical intensity constraint are taken into consideration. Based on the system model, three lower bounds on secrecy capacity for VLC are derived, respectively. Numerical results show that method 2 is better than the other two methods at high signal-to-noise ratio (SNR) regime, while method 3 is the best method at low SNR regime.