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Three lower bounds on secrecy capacity for indoor visible light communications

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.