Impact of Multiple Reflections on Secrecy Capacity of Indoor VLC System

K. Nagaraja, Soumya Prakash Dash, Frank Yong Li

Jin‐Yuan Wang, Sheng‐Hong Lin, Cheng Liu +3 more

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.

Grzegorz Blinowski

Fan Yang, Jingjing Wang, Yuhan Dong

In this paper, we consider the physical-layer security for single-input single-output (SISO) indoor visible light communication (VLC) wiretap systems in the presence of multipath reflections. We derive both the lower and upper bounds on the secrecy capacity in the context of both the symbol- and block-based transmission policies. To enhance the secrecy performance relying on block transmission policy, we propose a low-complexity amplitude scaling (AS) scheme by scaling the amplitudes of different symbols in each block to maximize the achievable secrecy rate. We further provide the upper bound on the optimal secrecy rate achieved by precoding for the sake of validating the effectiveness of the proposed AS scheme. Numerical results suggest that the secrecy performance is severely degraded by inter-symbol interference (ISI) imposed by multipath reflections, which yet can be alleviated by long-block based transmission. Moreover, the proposed AS scheme can enhance the secrecy performance significantly and achieve a secrecy rate very close to the optimal solution.

Bo Huang, Jianxin Dai

Jiaoli Liu, Jin‐Yuan Wang, Bingyuan Zhang +1 more

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.