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.
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 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.
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 the indoor scenario, visible light communications (VLC) is regarded as one of the most promising candidates for future wireless communications. Recently, the physical layer security for indoor VLC has drawn considerable attention. In this paper, the secrecy capacity of indoor VLC is analyzed. Initially, an VLC system with a transmitter, a legitimate receiver, and an eavesdropper is established. In the system, the nonnegativity, the peak optical intensity constraint and the dimmable average optical intensity constraint are considered. Based on the principle of information theory, the closed-form expressions of the upper and the lower bounds on the secrecy capacity are derived, respectively. Numerical results show that the upper and the lower bounds on secrecy capacity are very tight, which verify the accuracy of the derived closed-form expressions.
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.
This letter investigates the physical-layer security (PLS) of an indoor visible light communication system having a transmitter, a jammer, an intelligent reflecting mirror array (IRMA), a legitimate user, and an eavesdropper. Two scenarios are investigated for the non-negative input: one is having an average optical intensity constraint only, and the other is with both average and peak optical intensity constraints. By the entropy-power inequality and variational method, we derive closed-form expressions of secrecy-capacity lower bounds for the two scenarios, respectively. Based on the derived lower bound, we formulate a constrained secrecy-capacity maximization problem to further improve the PLS performance, and then transform it into a tractable problem by objective function approximation. After that, an optimization algorithm is proposed to solve the problem. Numerical results show the necessity of considering both IRMA and jammer, and also verify the effectiveness of the proposed algorithm.
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.