CAREER: Near-Optimum Low-Complexity Soft Decision Decoding of Linear Codes

差错控制编码已经成为几乎所有数字通信系统中不可或缺的一部分。这项建议的目的是调查编码中的几个重要问题，并制定教学计划，为快速变化的数字通信领域培养称职的工程师和科学家。提出的研究包括三个相互关联的领域：(1)线性码的软判决译码；(2)Turbo译码；(3)用于不等差错保护(UEP)的编码调制。第一个研究领域由两部分组成。在第一部分中，我们要研究一种新的统一的分析方法，它使我们能够紧密地约束许多基于可靠性的算法在实际信噪比下的差错性能。虽然30多年来已经提出了许多这样的算法，但还没有这样的界限。在(1)的第二部分中，提出了在降低译码复杂度的情况下，设计有效的长强大分组码的软判决译码方案。没有一种现有的算法可以在没有巨大计算工作量的情况下解码这样的代码。在区域(2)中，建议减少与Turbo译码相关的延迟。这种长的译码延迟阻止了Turbo码在实时通信系统中的使用，尽管它们在非常低的SNR值时具有惊人的差错性能。最后，提出了基于传统信号星座的具有UEP应用的编码调制方案。尽管对能够适应不同信道条件的编码方案(例如用于HDTV的卫星广播)的需求不断增加，但是很少有人提出这样的方案。这项建议的第二部分涉及PI的教学计划。基于学生是大多数大学电气工程专业存在的主要原因的原则，PI的教学主要目标是将学生培养成能够为数据通信系统的发展做出重大贡献的工程师和科学家。此外，夏威夷大学与其他美国-大陆大学相比的特殊地理和文化情况也被考虑在内。

Error control coding has become an integral part of almost every digital communication system . The objective of this proposal is to investigate several important problems in coding and to establish teaching plans to develop competent engineers and scientists for the fast changing area of digital communications. The proposed research includes three inter-related areas: (1) soft-decision decoding of linear codes; (2) turbo decoding; and (3) coded modulation for unequal error protection (UEP) applications. The first research area is composed of two parts. In the first part, a new unified analytical approach which lets us tightly bound the error performance of many reliability-based algorithms at practical SNR is to be investigated. Although numerous such algorithms have been proposed for more than 30 years, no such bound exists yet. In the second part of (1),it is proposed to devise efficient soft decision decoding schemes for long powerful block codes with reduced decoding complexity. No existing algorithm can decode such codes without a tremendous computational effort. In area (2), it is proposed to reduce the delay associated with turbo decoding. This long decoding delay prevents the use of turbo-codes in real time communication systems despite their astonishing error performance at very low SNR values. Finally, it is proposed to devise coded modulation schemes with UEP applications based on conventional signal constellations. Very few such schemes have been proposed despite the increasing demand of coding schemes able to adapt to different channel conditions, such as satellite broadcasting for HDTV. The second part of this proposal concerns the teaching plans of the PI. Based on the principle that students are the primary reason most electrical engineering programs exist in universities, the PI's teaching main goal is to develop students into engineers and scientists who will be able to make significant contributions to the development of data communicatio n systems. Also, the particular geographical and cultural situations of the University of Hawaii with respect to other US-mainland universities are considered.