变换域重叠隐蔽通信系统的隐蔽性度量方法

A covert metric method for overlay transform domain covert communication systems

提出了一种基于频域加权的均方误差(MSE)感知失真度量方法以评价变换域重叠隐蔽通信系统的隐蔽性能。该方法针对Q因子度量方法应用于变换域重叠隐蔽通信的局限,根据变换域通信系统的基本原理,将信号的感知失真从时域转到频域进行度量,根据不同宿主信号频谱幅值对于叠加的隐蔽信号的感知失真程度不同,以宿主信号频谱幅值的倒数为加权因子,分别对宿主信号各频点的感知失真做加权求和,从而得到系统的感知失真度量结果。仿真结果表明,该方法不仅可以提高系统感知失真能力,与重叠隐蔽通信的基本机理保持一致,符合实际感知效果,而且还统一了系统感知能力与抗干扰能力,可以为隐蔽系统的设计提供有效参考。

A perceptual distortion measurement method based on the frequency weighted mean square error （MSE） is proposed to evaluate overlay transform domain covert communication systems＇ covert performance. For avoiding the limitations of the Q factor metric method used in overlay transform domain covert communication systems, the MSE- based method converts the perceptual distortion of a signal from the time-domain to the frequency-domain to measure it according to the basic principle of transform domain communication systems （TDCS）. The perceptual distortion of the system is obtained by summig the perceptual distortions of the host signal at each frequency, with the host signal spectrum reciprocals as the weighting factors. This is based on the fact that the perceptual distortion strength which is impacted by the overlapped covert signal is related to the host signal spectrum. The simulation resuits show that the proposed method can improve the system perceptual distortion ability. The assessment results of this method are consistent with the basic mechanism of the overlay covert communication and agree with actual perception. The method unifies the system perceptual ability and anti-jamming ability, which may offer some useful information for the design of covert systems.