CAREER: Data Transmission Techniques: Trellis-Decoding and Beyond

NCR-9501345 Alexander Vardy本研究的第一个重点是格子码的译码。这项工作将试图建立线性码网格复杂度的新下界，研究线性码的渐近网格复杂度，找到给定网格的最优分段，列出所有最好的线性码的网格复杂度的下界，并将结果外推到格子和球面填充上。第二项活动是开发新的数据传输技术，适用于具有实际重要性的特定通道，并超越传统的差错控制方法。在设计良好的通信系统中应考虑信道结构这一一般原则的指导下，将考虑下列信道：突发符号间干扰信道，诸如当今数字语音传输、双绞线和无线以及新出现的数字用户环路；最大后验似然信道，其特征在于在没有熵编码的固定速率量化中出现的可能消息集合上的非均匀先验分布；特征在于最可能错误模式的任意指定集合的信道，诸如在级联编码、逻辑网络和人造噪声环境中出现的错误模式；以及以主观失真标准为特征的信道，而不是诸如在语音和图像编码中出现的那些整体系统BER。NCR-9502582 Konstantopoulos，Takis这是一项关于开发一种严格的网络管理方法和高速网络性能分析的建议，该方法考虑了网络管理系统的局部和全局方面。局部方面包括在网络边缘设计流量控制器，该流量控制器考虑了网络交换机中服务质量的提供和用户之间的交互。研究人员将扩展最近开发的基于所谓反射映射的ed技术，开发测试技术和模拟，并将这些技术与现有方案进行比较。调查员还将研究交通建模。他将开发严格的方法来验证综合业务高速网络运行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。研究管理系统的全球方面涉及使用调查员目前正在开发的网络的宏观图景。这幅图剥离了网络运行的细节，同时保留了它的动态特征(它不是静态的)。调查者建议网络管理系统使用这样的画面来预测、防止和纠正可能导致整个网络上的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.