Indoor visible light communication (VLC) is considered secure against attackers outside the confined area where the light propagates, but it is still susceptible to interception from eavesdroppers inside the coverage area. A new technology, intelligent reflecting surfaces (IRS), has been recently introduced, offering a way to control and steer light propagation in VLC systems. This letter proposes an innovative approach for enhancing the physical layer security (PLS) in IRS-assisted VLC by utilising the effect of the time delay induced by the IRS reflections. More specifically, we consider how to allocate the IRS elements in a way that produces destructive intersymbol interference at the eavesdropper’s location while enhancing the signal reception at the legitimate user. Our results show that, at a fixed light-emitting diode power of 3W, the secrecy capacity can be enhanced by up to 253% at random positions for the legitimate user when the eavesdropper is located within a 1-meter radius of the LED. We show that careful IRS allocation can lead to enhanced PLS even when the eavesdropper has a more favorable position than the legitimate user.

中文翻译：

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利用 IRS 诱导的时间延迟来增强 VLC 系统中的物理层安全性


室内可见光通信 （VLC） 被认为对光传播的狭窄区域之外的攻击者是安全的，但它仍然容易受到覆盖区域内窃听者的拦截。最近推出了一项新技术，即智能反射表面 （IRS），提供了一种控制和控制 VLC 系统中光传播的方法。这封信提出了一种创新方法，通过利用 IRS 反射引起的时间延迟效应来增强 IRS 辅助 VLC 中的物理层安全性 （PLS）。更具体地说，我们考虑了如何分配 IRS 元素，以便在窃听者的位置产生破坏性的符号间干扰，同时增强合法用户的信号接收。我们的结果表明，在 3W 的固定发光二极管功率下，当窃听者位于 LED 半径 1 米范围内时，合法用户可以在随机位置将保密能力提高高达 253%。我们表明，即使窃听者比合法用户处于更有利的地位，谨慎的 IRS 分配也可以导致增强的 PLS。