Collaborative Research - New Directions in Turbo Coding

本研究涉及数字通信和存储系统的差错控制编码的一般领域。特别是，它描述了与一种被称为Turbo编码的强大的新的差错控制编码方法相关的一些基本研究主题。该研究有两个主要目标：(1)提出与当前技术水平相比具有性能和/或复杂性优势的新的Turbo编码方案，以及(2)推进关于这种令人兴奋的新的差错控制编码方法的基本知识状态。尽管仍然非常新，但是Turbo编码已经开始应用于许多需要差错控制技术的领域，包括深空通信、卫星通信和数字蜂窝电话，仅举几例。由于Turbo编码能够以合理的实现复杂度实现接近理论极限的性能，预计Turbo编码和相关技术将在未来10年左右对几乎所有差错控制编码的应用产生巨大影响。Turbo编码可以在非常接近信道容量的信噪比下获得中等的误码率(在10-4到10-6的范围内)。然而，在Turbo编码性能方面仍有改进的空间，特别是在要求误比特率低于10-6的应用中。此外，对于获得更完整的基本了解导致如此优异的性能的Turbo码的关键特性，有相当大的理论兴趣。研究人员研究了Turbo编码中的几个新的基础研究问题。要研究的主题包括：(1)能够获得比现有方案更好的性能的几种新的Turbo码设计；(2)引入与标准Turbo编码方法相比具有产生更好的码和/或降低译码复杂度的潜力的更一般类别的Turbo码；以及(3)开发可以与更多码一起使用的新的次优软输入、软输出译码方法，从而在非常低的误码率(例如低于10-10)下提供接近容量性能的承诺。

ABSTRACTThis research involves the general area of error control coding for digital communication and storage systems. In particular, it describes a number of fundamental research topics related to a powerful new method of error control coding called turbo coding. The research has two major goals: (1) to propose new turbo coding schemes with performance and/or complexity advantages compared to the current state-of-the-art, and (2) to advance the fundamental state of knowledge regarding this exciting new approach to error control coding. Although still very new, turbo coding is beginning to be applied in numerous areas that require error control techniques, including deep space communication, satellite communication, and digital cellular telephony, to name just a few. Because of its ability to perform close to theoretical limits with reasonable implementation complexity, it is anticipated that turbo coding and related techniques will have an enormous impact on virtually all applications of error control coding over the next 10 years or so.Turbo coding can achieve moderate bit error rates (in the range of 10-4 to 10-6) at signal-to-noise ratios very close to channel capacity. However, there is still room for improvement in turbo coding performance, particularly in applications that require bit error rates below 10-6. Further, there is considerable theoretical interest in achieving a more complete fundamental understanding of the key properties of turbo codes that result in such excellent performance. The investigators study several new basic research problems in turbo coding. Among the topics to be investigated are (1) several new turbo code designs capable of achieving even better performance than existing schemes, (2) the introduction of a more general class of turbo codes that has the potential to yield better codes and/or reduced decoding complexity compared to standard turbo coding methods, and (3) the development of a new sub-optimum soft-in, soft-out decoding approach that can be used with more codes, thus offering the promise of near capacity performance at very low bit error rates, say below 10-10.