New Directions In Convolutional Codes

长期以来，卷积码一直被认为是在各种通信信道上提供差错控制的首选方法。它们实际应用的例子可以在深空通信、数字卫星传输、军事通信、移动蜂窝电话和高速数据调制解调器中找到。尽管卷积码的实际重要性的例子很多，但与其他差错控制方法相比，对卷积码的基本性质进行的研究相对较少。这个项目是对几种新的方法进行基础研究的计划，这些方法可以找到高效的卷积编码和译码方法。在网格编码调制、迭代译码技术和非常复杂代码的译码的最新进展的推动下，开展了五个领域的研究：级联卷积码、多级卷积码、乘积卷积码、非标准速率卷积码和非平衡存储器卷积码。目标是发现与标准结构相比能够在错误性能、解码器复杂性和系统延迟之间提供更好折衷的新的编码结构。特别强调研究延迟在决定性能和复杂性之间的关系中所起的基本作用。这项研究的结果可能为现有编码方案在低地球轨道卫星网络、数字移动蜂窝通信和无线室内分组传输系统中的应用提供可行的替代方案。

Convolutional codes have long been recognized as the preferred method of providing error control over a variety of communication channels. Examples of their practical application can be found in deep space communication, digital satellite transmission, military communications, mobile cellular telephony, and high speed data modems. Despite the many examples of their practical importance, relatively little research has been conducted into the fundamental properties of convolutional codes, compared to other methods of error control. This project is a program of basic research into several new approaches to finding efficient methods of encoding and decoding convolutional codes. Spurred by recent advances in trellis coded modulation, iterative decoding techniques, and the decoding of very complex codes, five areas of research are undertaken: cascaded convolutional codes, multilevel convolutional codes, product convolutional codes, non-standard rate convolutional codes, and unbalanced memory convolutional codes. The goal is to uncover new code structures which can offer better trade-offs between error performance, decoder complexity, and system delay than the standard structure. Particular emphasis is given to studying the fundamental role that delay plays in determining the relationship between performance and complexity. The results of this research may provide viable alternatives to existing coding schemes in applications such as low earth orbiting satellite networks, digital mobile cellular communications, and wireless indoor packet transmissiol systems.