CAREER: Data Transmission Techniques: Trellis-Decoding and Beyond

Alexander Vardy这项研究的第一个重点是对网格代码的解码。这项工作将试图建立线性码的格复杂度的新下界，研究线性码的渐近格复杂度，找到给定格的最佳分段，为所有最著名的线性码制表格复杂度的边界，并将结果外推到格和球填充。第二项活动是发展新的数据传输技术，适合于具有实际重要性的特定渠道，并扩展到经典的误差控制方法之外。在设计良好的通信系统中应考虑信道结构的一般原则的指导下，将考虑以下信道：突发码间干扰信道，例如当今的双绞线和无线数字语音传输，以及新兴的数字用户环路；在不使用熵编码的情况下，固定率量化产生的最大后验似然信道在可能的消息集合上具有非均匀先验分布；以任意指定的一组最可能的错误模式为特征的信道，例如在串联编码、逻辑网络和人为噪声环境中产生的错误模式；以及以主观失真标准为特征的信道，而不是整个系统的误码率，例如在语音和图像编码中产生的误码率。Konstantopoulos， Takis这是一份关于发展一种严格的网络管理方法和高速网络性能分析的提案，考虑到网络管理系统的本地和全局方面。局部方面包括在网络边缘的流量控制器的设计，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基于所谓反射映射的技术，开发测试技术和模拟，并将其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由综合业务高速网络运行产生的自相似流量过程，并使用这些模型建立性能分析方法。研究管理系统的全局方面涉及使用研究者目前正在开发的网络的宏观图片。这幅图去掉了网络运行的细节，同时保留了它的动态特征（它不是静态的）。研究者建议通过网络管理系统使用这样的图像来预测、预防和纠正可能导致整个网络服务退化的不良行为。

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.