Collaborative Research: Code Design and Analysis to Approach Capacity with Short Blocklengths Using Feedback

这项研究的特点反馈的好处，在沟通和开发技术，以实现这些好处。 当今的通信系统寻求尽可能快地将信息从发射机传送到接收机。 该研究涉及使用反馈（从接收器发送回发射器的消息），以允许通信系统使用更少的传输时间（延迟）和更低的复杂度解码来接近最高可能的通信速率（信道容量）。 这项研究的一个关键方面是开发新的错误控制码和新技术，使用这些代码来促进传输，接近容量与低得多的延迟比不使用反馈的系统。 更广泛的影响包括通过加州大学洛杉矶分校工程（HSSEAS）高中暑期研究计划培训高中生，以及通过加州大学洛杉矶分校工程本科生研究计划培训本科生。传统技术通过使用长块长度和复杂解码，在没有反馈的情况下接近容量。 然而，信息理论表明，反馈允许容量接近较短的块长度和较简单的解码。 本研究采用了速率兼容的球体包装分析，提供了一个定量分析的延迟减少可能与反馈。 这种分析提供了解码错误轨迹，指导率兼容的代码家庭的发展需要接近的反馈能力。 这些具有反馈的速率兼容码族的实际益处将在加性白色高斯噪声中操作的典型无线通信系统的上下文中表征。 这些技术被扩展到衰落信道和高阶调制。 这个研究项目的总体目标是发展和颁布一个基本的理解，代码族应如何设计，以实现与反馈的容量非常短的块长度。

This research characterizes the benefits of feedback in communication and develops techniques to achieve those benefits. Today's communication systems seek to move information as rapidly as possible from transmitter to receiver. This research involves using feedback (messages sent from the receiver back to the transmitter) to allow communication systems to approach the highest possible communication rate (the channel capacity) using less transmission time (latency) and lower-complexity decoding. A key aspect of this research is the development of new error control codes and new techniques to use those codes to facilitate transmissions that approach capacity with much lower latency than systems that do not use feedback. Broader impacts include training high school students through the UCLA Engineering (HSSEAS) High School Summer Research program and training undergraduates through the UCLA Engineering undergraduate research program.Traditional techniques approach capacity without feedback by using long block lengths and complex decoding. However, information theory indicates that feedback permits capacity to be approached with shorter block lengths and simpler decoding. This research employs a rate-compatible sphere-packing analysis to provide a quantitative analysis of the latency reduction possible with feedback. This analysis provides decoding error trajectories that guide the development of rate-compatible code families needed to approach capacity with feedback. Practical benefits of these rate-compatible code families with feedback will be characterized in the context of a typical wireless communication system operating in additive white Gaussian noise. These techniques are extended to fading channels and higher-order modulations. The overall goal of this research project is the development and promulgation of a fundamental understanding of how code families should be designed to work with feedback to achieve capacity with very short block lengths.