Channel Input Design for Secure Transmission over Fast Fading Channels with Statistical-CSIT

在这个项目中，安全通信系统的整体系统设计的基本问题将研究使用快衰落信道与统计CSI在发送端。特别关注的是通道输入。首先，将设计新的标准来识别和表征窃听信道的退化，以避免复杂的信道前缀。其次，优化的信号处理将开发有关的信道输入分布和信道前缀，以实现更高的保密率在非降级的cases.In这个项目中，广泛的，但在许多情况下，不切实际的假设完美的信道知识被丢弃。相反，将假设统计信道知识，这可以先验地获得。当Alice向她的合法通信伙伴发送消息时，她可以将最近但未知的用户视为窃听者，并使用统计信道知识来生成她的窃听码本。除少数特殊情况外，一般情况下，在不完全信道知识的情况下，信道输入分布是未知的。这些将在项目实施过程中加以审查。在不完全了解窃听者信道的情况下，将人工噪声添加到信号中以降低窃听者处的信噪比。然而，关于人工噪音有几个神话。其中，存在这样的错误信念，即如果发射机在快衰落信道的情况下不具有窃听信道的完美信道知识，则必须使用人工噪声，并且信号和人工噪声必须是高斯的。对于这些说法，没有分析证明。相反，在某些情况下，它们可能是不正确的。我们研究这些神话，并得出使用人工噪声的必要和充分条件，相对于窃听通道的退化。只要窃听信道退化，就不需要人工噪声形式的信号处理;因此，系统设计可以大大简化。在非降级窃听信道的情况下，应检查其他信号处理能力，而不是信号和人工噪声的高斯分布。在这种情况下，将考虑输入分布和通道前缀。因此，该项目将开发一个基于理论的，系统的信号处理一般窃听信道的统计信道知识在发射机，这将允许有效的系统设计和有效的资源分配使用物理层安全算法。

In this project fundamental problems of the holistic system design of secure communication systems will be studied using fast fading channels with statistic CSI at the transmitter. Particular focus is placed on the channel input. At first, new criteria will be designed to identify and characterize the degradedness of wiretap channels to avoid complicated channel prefixing. Secondly, optimized signal processing will be developed regarding the channel input distribution and channel prefixing to achieve higher secrecy rates in the non degraded case.In this project, the widespread, but in many cases unrealistic assumption of perfect channel knowledge is dropped. Instead, statistical channel knowledge will be assumed, which can be obtained a priori. When Alice transmits messages to her legitimate communication partner, she can treat the closest but unknown user as an eavesdropper and use the statistical channel knowledge to generate her wiretap codebook. Apart from a few special cases, generally the channel input distribution is unknown in the case of imperfect channel knowledge. These will be examined in the course of the project. In case of imperfect knowledge of the eavesdropper's channel, artificial noise is added to the signal to reduce the signal to noise ratio at the eavesdropper. However, there are several myths about artificial noise. Among others there are the mistaken belief that if the transmitter has not perfect channel knowledge of the eavesdropping channel in case of fast fading channels, artificial noise has to be used, and that the signal and the artificial noise must be Gaussian. For these statements, there are no analytical proofs. On the contrary, they may be incorrect under certain conditions. We examine these myths and derive necessary and sufficient conditions for the use of artificial noise, with respect to the degradedness of the wiretap channel. As long as the wiretap channel is degraded, a signal processing in the form of artificial noise is not necessary; therefore, the system design can be considerably simplified. In the case of non-degraded wiretap channels other signal processing capabilities should be examined instead of the Gaussian distribution of the signal and the artificial noise. In this case, both the input distribution, and the channel prefixing will be considered. The project will therefore develop a theoretically based, systematic signal processing for general wiretap channels with statistical channel knowledge at the transmitter, which will allow efficient system design and efficient resource allocation using physical layer security algorithms.