Collaborative Research: CIF: Medium: A Theoretical Foundation For Practical Communication with Feedback

许多电子通信系统是双向的：它们可以双向传输信息。然而，在任何给定时间，系统可能只在一个方向上主动传输信息。在这种情况下，否则将空闲的反向链路可用于促进前向方向上的传输。虽然这一事实早就被认识到了，但如何最好地利用反馈来最大化前向链路的速率和最小化复杂性还没有被很好地理解。该项目将开发实用的方案，通过使用反馈链路并从数学上描述使用反馈链路的最佳方法来改善通信系统的性能。对如何使用反馈的理解的提高，应该会改进蜂窝系统和物联网的无线通信技术。该项目将通过向电气工程专业的女本科生提供研究机会，扩大对计算机的参与，目标是增加参加该领域研究生课程的女性人数。它还将开发一项公众可访问的服务，为数字通信课程和研究项目提供“云中”频道。从历史上看，信息和编码理论的研究重点是具有完美反馈或根本没有反馈的理想化通信场景。然而，许多实际系统都有反馈链接，这些反馈链接是可用的，但并不完美。本项目将研究如何最好地利用反馈数量有限的通信渠道，以实现信息的快速和可靠传输。该项目将提供明确的理论指导，说明有多少反馈信息是有用的，以及发射机应该如何最有效地利用反馈来调整其编码策略。该项目将提供有限数量的反馈传输可实现的通信速率和延迟的界限和近似值。利用反馈编码作为联合信源-信道编码的一种形式的新观点，该项目将解决关于二阶编码率和反馈的“中等偏差”性能的公开问题。最后，该项目将探索如何在信息来源(如传感器)不断产生信息的情况下，通过将新信息与旧信息相结合立即进行编码，而不是等待缓冲长数据块以使用传统分组代码进行编码，来改进延迟与可靠性之间的权衡。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Many electronic communication systems are bidirectional: they can transmit information in both directions. At any given time, however, the system may only be actively transmitting information in one direction. In this case, the reverse link, which would otherwise be idle, can be used to facilitate transmission in the forward direction. While this fact has long been recognized, it is not well understood how to best employ feedback to maximize the rate and minimize complexity for the forward link. This project will develop practical schemes that improve communication system performance by using feedback links and mathematically characterizing optimal methods for using feedback links. The improved understanding of how to use feedback should improve wireless communication technologies for cellular systems and the internet of things. The project will broaden participation in computing by offering research opportunities to women undergraduates in electrical engineering, with the goal of increasing the number of women who attend graduate programs in the field. It will also develop a publicly-accessible service that provides channels "in the cloud" for digital communication courses and research projects.Historically, research in information and coding theory has focused on idealized communication scenarios with either perfect feedback or none at all. Many practical systems, however, have feedback links that are available but imperfect. This project will examine how to best use communication channels with a limited amount of feedback to achieve fast and reliable transmission of information. The project will provide clear theoretical guidance about how much feedback information is useful and how the transmitter should use feedback most effectively to adapt its encoding strategy. The project will provide bounds and approximations on the communication rates and delays achievable with a limited number of feedback transmissions. Leveraging a novel view of feedback coding as a form of joint source-channel coding, the project will address open questions concerning the second-order coding rate and "moderate deviations" performance with feedback. Finally, the project will explore how to improve delay-reliability tradeoffs achievable with feedback in the scenario where an information source, such as a sensor, produces information continuously, by combining the new information with the old information to encode immediately instead of waiting to buffer long blocks of data to encode with traditional block codes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.