Abstract
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.
Highlights
In the past ten years, the research on conventional radio frequency (RF) wireless communication has intensified [1]
The probability of strictly positive secrecy capacity (SPSC) of the hybrid RF/visible light communication (VLC) system when an eavesdropper eavesdrops on the RF link can be written as follows: PSPSC Pr min Ch′op, 1, Ch′op, 2 > 0 Pr Ch′op,1 > 0 Pr Ch′op, 2 > 0
It can be observed that the value of secrecy outage probability (SOP) becomes larger with the increase in cth, which means that the system secrecy performance is degraded, which coincides with Remark 2
Summary
In the past ten years, the research on conventional radio frequency (RF) wireless communication has intensified [1]. In reference [14], the performance of hybrid free-space optical (FSO) communication and RF dual-hop systems based on amplify-and-forward relaying and CSI-assisted relaying were analyzed, and the closed-form expressions for the outage probability and the average bit error rate were derived in the high signal-to-noise ratio (SNR) regime. The closed-form expressions for the lower bound of the SOP and the exact average secrecy capacity of mixed RF/ FSO systems were derived in reference [19], where an eavesdropper node eavesdrops on the FSO hop. For the case when the RF link is eavesdropped upon, the PDFs and cumulative distribution functions (CDFs) of the instantaneous SNR at the relay node and the Eve node have been derived Based on these statistic distributions, we derive the closed-form expressions for the lower bound of the SOP and the probability of SPSC.
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