This paper studies the design of energy-efficient artificial noise (AN) schemes in the context of physical layer security in visible light communications (VLC). Two different transmission schemes termed $\textit{selective AN-aided single-input single-output (SISO)}$ and $\textit{AN-aided multiple-input single-output (MISO)}$ are examined and compared in terms of secrecy energy efficiency (SEE). In the former, the closest LED luminaire to the legitimate user (Bob) is the information-bearing signal's transmitter. At the same time, the rest of the luminaries act as jammers transmitting AN to degrade the channels of eavesdroppers (Eves). In the latter, the information-bearing signal and AN are combined and transmitted by all luminaries. When Eves' CSI is unknown, an indirect design to improve the SEE is formulated by maximizing Bob's channel's energy efficiency. A low-complexity design based on the zero-forcing criterion is also proposed. In the case of known Eves' CSI, we study the design that maximizes the minimum SEE among those corresponding to all eavesdroppers. At their respective optimal SEEs, simulation results reveal that when Eves' CSI is unknown, the selective AN-aided SISO transmission can archive twice better SEE as the AN-aided MISO does. In contrast, when Eves' CSI is known, the AN-aided MISO outperforms by 30%.

翻译：本文研究了可见光通信（VLC）中面向物理层安全的高能效人工噪声（AN）方案设计。考察并比较了两种不同的传输方案，即“选择性AN辅助的单输入单输出（SISO）”和“AN辅助的多输入单输出（MISO）”，并以其保密能效（SEE）为指标进行对比。在前一种方案中，距离合法用户（Bob）最近的LED灯具作为信息承载信号的发射器，同时其余灯具充当干扰器，发射AN以降低窃听者（Eves）的信道质量。在后一种方案中，信息承载信号与AN合并后由所有灯具共同传输。当Eves的信道状态信息（CSI）未知时，通过最大化Bob信道的能量效率，提出了一种旨在间接提升SEE的优化设计。此外，还提出了一种基于迫零准则的低复杂度设计方案。在Eves的CSI已知的情况下，我们研究了最大化所有对应窃听者中最小SEE的设计。仿真结果表明，在各自的最优SEE下：当Eves的CSI未知时，选择性AN辅助的SISO传输能够达到AN辅助的MISO两倍的SEE；相反，当Eves的CSI已知时，AN辅助的MISO方案优于前者30%。