This paper investigates a multiple-input multipleoutput (MIMO) visible light communication (VLC) wiretap channel consisting of a transmitter, a legitimate receiver, and an eavesdropper. The optical input is subject to both peakand average-intensity constraints. By applying the generalized entropy-power inequality to truncated exponential inputs, we derive a novel closed-form expression for the achievable secrecy rate for general MIMO VLC configurations. To enhance transmission confidentiality, a fully-connected beamforming scheme is proposed, along with a low-complexity sub-connected alternative. Although the resulting beamforming design problems are nonconvex, they are efficiently addressed by transforming them into a sequence of convex subproblems solvable via the successive convex approximation framework. Numerical results demonstrate that the proposed schemes achieve significant secrecy performance improvements compared with the benchmark scheme.

翻译：本文研究了一个由发射机、合法接收机与窃听者构成的多输入多输出可见光通信窃听信道。光输入同时受到峰值强度与平均强度约束。通过将广义熵功率不等式应用于截断指数输入，我们针对一般多输入多输出可见光通信配置推导出一种新颖的、闭式的可达保密率表达式。为增强传输保密性，本文提出了一种全连接波束成形方案，以及一种低复杂度的子连接替代方案。尽管由此产生的波束成形设计问题是非凸的，但通过将其转化为一系列可通过逐次凸逼近框架求解的凸子问题，可以高效地解决这些问题。数值结果表明，与基准方案相比，所提方案实现了显著的保密性能提升。