With the development of wireless communication, free-space optical (FSO) communication is becoming a highly promising technology. In this paper, we consider the covert FSO communication between two legitimate peers in the presence of an external warden. We establish a system model under a nonnegativity constraint, a peak optical intensity constraint, an average optical intensity constraint and a covertness constraint. For the considered system, the optimal input signal is shown to follow a uniform distribution. Based on the optimal input signal and covertness constraint, we obtain an upper bound that should be satisfied by the transmitter’s peak optical intensity, which provides a basis for the transmitter to set the transmit optical intensity. We also derive the upper bound of maximum amount of information transmitted covertly, which reveals the fundamental performance limit of covert FSO communication. Finally, we verify the theoretical analysis by numerical simulations.

随着无线通信的发展，自由空间光（FSO）通信正成为一项极具发展前景的技术。在本文中，我们考虑了在外部管理员在场的情况下两个合法对等方之间的隐蔽 FSO 通信。我们在非负约束、峰值光强约束、平均光强约束和隐蔽性约束下建立了系统模型。对于所考虑的系统，最佳输入信号显示为遵循均匀分布。基于最优输入信号和隐蔽性约束，我们得到了发射端峰值光强应满足的上界，为发射端设置发射光强提供了依据。我们还推导出秘密传输的最大信息量的上限，这揭示了隐蔽 FSO 通信的基本性能限制。最后，我们通过数值模拟验证了理论分析。