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arXiv 0911.4432cs.ITmath.IT
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反馈在双向保密通信中的作用

The Role of Feedback in Two-way Secure Communications

Xiang He, Aylin Yener

摘要:

大多数实际的通信链路是双向的。在这些模型中,由于源节点也接收信号,因此其编码器可以根据过去接收的信号计算其输出。另一方面,从实际的角度来看,还期望识别这样的编码器设计可能不提高通信速率的情况。这个问题对于传输的消息和反馈信号遭受窃听的情况特别有趣。在这项工作中,我们调查的问题有多大的影响反馈的保密能力,通过研究两个基本模型。首先,我们考虑高斯双向窃听信道,并推导出其保密容量区域的外边界。我们发现,除了我们确定的特殊情况下,不利用反馈信号时,保密率损失可以是无界的,从而得出结论,利用反馈可以是非常有益的一般。其次,我们考虑一个半双工高斯双向中继信道中的中继节点也是一个窃听者,并发现反馈的影响是不太明显相比,以前的情况。具体地说,在保密率的损失,当忽略反馈,量化为小于0.5位每信道使用时,中继功率趋于无穷大。该可实现的速率区域是通过简单的分时以及协作干扰来获得的,协作干扰由于其简单性和接近最佳的性能,是利用反馈信号的编码器的可行替代方案。

英文摘要:

Most practical communication links are bi-directional. In these models, since the source node also receives signals, its encoder has the option of computing its output based on the signals it received in the past. On the other hand, from a practical point of view, it would also be desirable to identify the cases where such an encoder design may not improve communication rates. This question is particularly interesting for the case where the transmitted messages and the feedback signals are subject to eavesdropping. In this work, we investigate the question of how much impact the feedback has on the secrecy capacity by studying two fundamental models. First, we consider the Gaussian two-way wiretap channel and derive an outer bound for its secrecy capacity region. We show that the secrecy rate loss can be unbounded when feedback signals are not utilized except for a special case we identify, and thus conclude that utilizing feedback can be highly beneficial in general. Second, we consider a half-duplex Gaussian two-way relay channel where the relay node is also an eavesdropper, and find that the impact of feedback is less pronounced compared to the previous scenario. Specifically, the loss in secrecy rate, when ignoring the feedback, is quantified to be less than 0.5 bit per channel use when the relay power goes to infinity. This achievable rate region is obtained with simple time sharing along with cooperative jamming, which, with its simplicity and near optimum performance, is a viable alternative to an encoder that utilizes feedback signals.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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