Based on the concept of constructive interference (CI), multiuser interference (MUI) has recently been shown to be beneficial for communication secrecy. A few CI-based secure precoding algorithms have been proposed that use both the channel state information (CSI) and knowledge of the instantaneous transmit symbols. In this article, we examine the CI-based secure precoding problem with a focus on smart eavesdroppers that exploit statistical information gleaned from the precoded data for symbol detection. Moreover, the impact of correlation between the main and eavesdropper channels is taken into account. We first modify an existing CI-based precoding scheme to better utilize the destructive impact of the interference. Then, we point out the drawback of both the existing and the new modified CI-based precoders when faced with a smart eavesdropper. To address this deficiency, we provide a general principle for precoder design and then give two specific design examples. Finally, the scenario where the eavesdropper's CSI is unavailable is studied. Numerical results show that although our modified CI-based precoder can achieve a better energy-secrecy trade-off than the existing approach, both have a limited secrecy benefit. On the contrary, the precoders developed using the new CI-design principle can achieve a much improved tradeoff and significantly degrade the eavesdropper's performance.

中文翻译：

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重新思考通过干扰利用的安全预编码：智能窃听者的视角


基于相长干扰（CI）的概念，多用户干扰（MUI）最近被证明有利于通信保密。已经提出了一些基于 CI 的安全预编码算法，这些算法使用信道状态信息 (CSI) 和瞬时传输符号的知识。在本文中，我们研究基于 CI 的安全预编码问题，重点关注利用从预编码数据收集的统计信息进行符号检测的智能窃听者。此外，还考虑了主信道和窃听信道之间相关性的影响。我们首先修改现有的基于 CI 的预编码方案，以更好地利用干扰的破坏性影响。然后，我们指出了现有的和新改进的基于 CI 的预编码器在面对智能窃听者时的缺点。为了解决这个缺陷，我们提供了预编码器设计的一般原则，然后给出了两个具体的设计示例。最后，研究了窃听者CSI不可用的场景。数值结果表明，虽然我们改进的基于 CI 的预编码器可以比现有方法实现更好的能量保密权衡，但两者的保密效益都很有限。相反，使用新的 CI 设计原理开发的预编码器可以实现大大改进的权衡，并显着降低窃听者的性能。