Exploiting The Turbo Principle

近年来，Turbo编码已经成为一种强大的前向差错控制编码范例。Turbo编码虽然是一种新的编码技术，但它的成功已经被广泛应用于深空通信、卫星通信和数字蜂窝通信等领域。这一成功背后的关键是优雅的迭代解码器，它以合理的实现复杂性接近理论极限。最近，迭代解码器结构被抽象和推广到现在被称为Turbo原理。由于其卓越的性能，预计Turbo原理将对数字通信系统的几乎所有方面产生巨大的影响。本研究的主要目标是探索Turbo原理的基本限制，同时提供实际的implementations.First研究推力旨在开发一种分析方法来计算Turbo解码器的收敛阈值。除了预期的节省计算复杂性，分析方法的目的是为代码设计提供更有用的见解。收敛性分析将有助于构造接近加性白色高斯噪声（AWGN）信道容量极限的不规则“类Turbo”码。小块和中等块长度的代码性能将被视为一个额外的设计标准。本研究也将探讨多径衰落信道下的图形码设计。码的结构将被优化的参数衰落模型，捕捉在实际系统中的不同限制。此外，收敛性分析将被用来探讨在广义衰落信道中Turbo多用户接收机性能的基本限制。

In recent years, Turbo coding has emerged as a powerful forward error control coding paradigm. Although still new, the success of Turbo coding is witnessed by its widespread use in a variety of applications, including deep space communication, satellite communication, and digital cellular communication. The key behind this success is the elegant iterative decoder that approaches theoretical limits with reasonable implementation complexity. More recently, the iterative decoder structure was abstracted and generalized to what is now known as the Turbo Principle. Because of its remarkable performance, it is expected that the Turbo Principle will have an enormous impact on virtually all aspects of digital communication systems. The main goal of this research is to explore the fundamental limits of the Turbo Principle while offering practical implementations.The first research thrust aims at developing an analytical approach for computing the convergence thresholds of Turbo decoders. In addition to the expected savings in computational complexity, the analytical approach is sought to offer more useful insights for code design. The convergence analysis will facilitate constructing irregular ``Turbo-like" codes that approach the capacity limit of Additive White Gaussian Noise (AWGN) channels. The code performance with small and moderate block lengths will be considered as an additional design criterion. This research will also investigate graphical code design for multi-path fading channels. Code constructions will be optimized for parametric fading models that capture the different limitations in practical systems. Furthermore, The convergence analysis will be used to explore fundamental limits on the performance of Turbo multi-user receivers in generalized fading channels.