CAREER: Data Transmission Techniques: Trellis-Decoding and Beyond

NCR-9501345亚历山大瓦迪 本研究的第一个焦点是格状码的译码。 这项工作将试图建立新的下界的线性码的网格复杂性，调查的渐近网格复杂性的线性码，找到一个给定的网格的最佳sectionalization，列表上的所有最知名的线性码的网格复杂性的界限，并外推的结果格和球包装。第二项活动是开发适用于具有实际重要性的特定信道的新型数据传输技术，并扩展到传统的差错控制方法之外。 在设计良好的通信系统时应考虑信道结构这一一般原则的指导下，将考虑下列信道：脉冲串码间干扰信道，例如当今的数字话音传输，双绞线和无线传输，以及新兴的数字用户环路;最大后验似然信道，其特征在于在可能消息的集合上的非均匀先验分布，在没有熵编码的固定速率量化中产生;以任意指定的一组最可能的错误模式为特征的信道，例如在级联编码、逻辑网络和人为噪声环境中出现的错误模式;以及以主观失真标准而不是整个系统BER为特征的信道，例如在语音和图像编码中出现的错误模式。 NCR-9502582 Konstantopoulos，Takis 这是一个关于开发一个严格的方法来进行网络管理和性能分析的高速网络，考虑到网络管理系统的局部和全局方面的建议。 本地方面包括在网络边缘处的流量控制器的设计，该流量控制器考虑到服务质量的提供和网络交换机中用户之间的交互。 研究人员将扩展最近开发的艾德技术，这些技术是基于所谓的反射映射，开发测试技术和模拟，并将其与现有方案进行比较。 研究人员还将研究交通建模。 他将开发严格的方法来验证从综合服务高速网络的操作中产生的自相似流量过程，并使用这些模型来建立性能分析方法。 研究一个管理系统的全球方面涉及到使用一个宏观的网络图片目前正在开发的调查。 这幅图去掉了网络运行的细枝末节，同时保留了它的动态特征（它不是静态的）。 研究人员建议网络管理系统使用这样的图片，以预测、预防和纠正可能导致网络服务降级的不良行为。

NCR-9501345 Alexander Vardy The first focus of this research is on decoding of trellis codes. The work will attempt to establish new lower bounds on the trellis complexity of linear codes, to investigate the asymptotic trellis complexity of linear codes, to find the optimal sectionalization of a given trellis, to tabulate bounds on the trellis complexity for all of the best-known linear codes, and to extrapolate the results to lattices and sphere packings. The second activity is the development of novel data transmission techniques suited to specific channels of practical importance and extending beyond the classical error control approach. Guided by the general principle that the channel structure should be taken into account in a well-designed communication system, the following channels will be considered: bursty intersymbol interference channels, such as present day digital voice transmission, both twisted pair and wireless, and emerging digital subscriber loops; maximum a posteriori likelihood channels characterized by a nonuniform a priori distribution on the set of possible messages, arising in fixed rate quantization without entropy coding; channels characterized by an arbitrary specified set of most likely error patterns, such as those arising in concatenated coding, logic networks, and man-made noise environments; and channels characterized by subjective distortion criteria, rather than the overall system BER, such as those arising in speech and image coding. NCR-9502582 Konstantopoulos, Takis This is a proposal about the development of a rigorous approach toward network management and performance analysis for high-speed networks considering local and global aspects of a network management system. Local aspects include the design of flow controllers at the edges of the network that take into account the provision of quality of service and the interaction between users in a network switch. The investigator will extend recently develop ed techniques that are based on the so-called reflection mapping, develop testing techniques and simulations, and compare these to existing schemes. The investigator will also study traffic modeling. He will develop rigorous methods for validating self-similar traffic processes arising from the operation of an integrated services high-speed networks and use such models in establishing performance analysis methods. Studying the global aspects of a management system involves using a macroscopic picture of the network currently being developed by the investigator. The picture strips out the minutiae of the operation of the network, while retaining its dynamic character (it is not static). The investigator proposes the use of such a picture by a network management system in order to predict, prevent, and correct undesirable behavior that might lead to degradation of services across the network.