Collaborative Research: The Role of Feedback in Two-Way Communication Networks

协作研究：反馈在双向通信网络中的作用

• 批准号: 0729195
• 负责人: Young-Han Kim
• 金额: $ 30万
• 依托单位: University of California-San Diego
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-15 至 2010-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0729195&HistoricalAwards=false
• 关键词: Collaborative; Research; Role; Feedback; Two

Many common communication situations are over inherently two-way channels, such as telephone systems, digital subscriber lines (DSL), cellular networks, and the Internet. In fact, even `point-to-point' systems, where the end goal is to transfer information in one direction, often give rise to two-way communication scenarios due to the presence of feedback. In such systems, one can receive feedback from the other end of the channel, which can be used to improve the quality of communication. Although feedback is present in many communication systems, and is being used in certain primitive forms as in channel estimation and automatic repeat request, the theory behind its use is far from complete. This research investigates the role of feedback in two-way communication networks and provides architecture-level guidance for designing robust and efficient communication systems. While positive results lead to novel approaches to communication systems design, negative results prevent over-engineering and allow more confidence in simple and modular implementations. At the same time, feedback is a pivotal concept in biological and artificial control systems, learning machines, and communication networks. A deeper understanding of the role of feedback in one area (communication) will lead to a better understanding of the role of feedback in a broader multidisciplinary context.Concretely, this research focuses on and develops new approaches for tackling problems arising in the following areas: 1) feedback capacity of single-user channels with memory (new coding theorems based on directed information, causal conditioning, and Shannon strategy, as well as the development of concrete schemes for achieving the fundamental limits), 2) multiple-user channels with feedback (emphasis on multiple access channels and broadcast channels: characterization of fundamental limits as well as the construction of practical coding schemes), 3) capacity region of the two-way channel such as the Blackwell-Shannon binary multiplying channel (dynamic programming and infinite-dimensional convex optimization), 4) robust feedback coding techniques under channel uncertainty (universal decoding schemes), and 5) reliable communication with noisy feedback (new perspectives on cross-layer design of channel codes and network protocols). Massey's directed information takes the role of Shannon's mutual information in many feedback communication problems. Thus the role of directed information is investigated as a fundamental notion in general causal inference problems. Examples include gambling in horse-race markets with causal side information and its dual in source coding.

许多常见的通信情况本质上是通过双向通道进行的，例如电话系统、数字用户线路 (DSL)、蜂窝网络和互联网。 事实上，即使是最终目标是在一个方向上传输信息的“点对点”系统，由于反馈的存在，也常常会产生双向通信场景。在此类系统中，可以从信道的另一端接收反馈，这可用于提高通信质量。 尽管反馈存在于许多通信系统中，并且以某些原始形式使用，例如信道估计和自动重复请求，但其使用背后的理论还远未完成。 这项研究调查了反馈在双向通信网络中的作用，并为设计稳健且高效的通信系统提供了架构级指导。虽然积极的结果会带来新的通信系统设计方法，但消极的结果可以防止过度设计，并让人们对简单和模块化的实现更有信心。 同时，反馈是生物和人工控制系统、学习机和通信网络中的关键概念。更深入地了解反馈在一个领域（沟通）中的作用将有助于更好地理解反馈在更广泛的多学科背景中的作用。具体而言，本研究重点关注并开发新方法来解决以下领域中出现的问题： 1）具有记忆的单用户通道的反馈能力（基于定向信息、因果条件和香农策略的新编码定理，以及实现基本限制的具体方案的开发），2）具有反馈的多用户通道（强调多址信道和广播信道：基本限制的表征以及实际编码方案的构建），3）双向信道的容量区域，例如Blackwell-Shannon二进制乘法信道（动态规划和无限-维凸优化），4）信道不确定性下的鲁棒反馈编码技术（通用解码方案），5）带噪声反馈的可靠通信（信道编码和网络协议跨层设计的新视角）。 梅西有向信息在许多反馈沟通问题中扮演了香农互信息的角色。 因此，定向信息的作用被作为一般因果推理问题的基本概念来研究。 例子包括赛马市场上的赌博，其中包含因果辅助信息及其源代码的双重性。