Low Density Parity Check Codes and Turbo Codes for Wireless Communication

随着21世纪的到来，新的无线服务正在被部署，并且设想了更多的无线服务。 为了提供这些服务，未来的无线系统应该能够处理比今天的系统高得多的数据速率。 可用于这些服务的有限频谱意味着未来系统的频谱效率必须显著提高。除了频谱效率，下一代无线系统还必须具有功率效率。 较低的发射功率意味着对其他用户的干扰更小，频谱的重用更好，因此整个网络的效率更高。 无线信道对传输的信号提供若干损害，从而使通信链路的质量恶化。 在这种不可靠的链路存在的情况下，增加功率和频谱效率是一项具有挑战性的任务，可以通过使用有效的编码和信号处理技术来大大促进。本研究主要针对无线系统中的功率与频谱利用率问题，探讨Turbo码与低密度奇偶校验码等编码技术的设计，并针对无线系统中具有低译码复杂度的Turbo码与低密度奇偶校验码（LDPC）进行详细的设计与性能分析。详细介绍的具体领域是用于多径信道和Turbo均衡的编码方案的设计，用于频谱高效调制的LDPC码的设计，以及使用LDPC码用于非平稳环境的增量冗余方案的设计。这项工作不同于现有的工作，因为它研究了几种新的编码技术，并集中在设计的代码匹配的迭代解码算法正在使用，而不是基于hyperticalmaximum-likelihood解码的代码的设计。

As the twenty-first century unfolds, new wireless services are being deployed and several more are envisioned. In order to provide these services, future wireless systems should be capable of handling much higher data rates than today's systems. The limited spectrum available for these services implies that the spectral efficiency of future systems will have to be significantly higher. In addition to being spectrally efficient, next-generation wireless systems will have to be power efficient. Lower transmit powers means lesser interference to other users, better reuse of the spectrum and, hence, higher efficiency for the overall network. Wireless channels offer several impairments to the transmitted signals, deteriorating the quality of the communication link. Increasing the power and spectral efficiency in the presence of such an unreliablelink is a challenging task which can be greatly facilitated by the use of efficient coding and signal processing techniques. This research investigates the design of powerful coding techniques such as turbo codes and low density parity check codes for increasing the power and spectral efficiency of wireless systems.This research involves a detailed study of the design and performance analysis of turbo-like codes with low decoding complexity, and low density parity check codes (LDPC) for use in a wireless environment. Specific areas covered in detail are the design of coding schemes for use with multipath channels and turbo equalization, the design of LDPC codes for spectrally efficient modulation, and the design of incremental redundancy schemes using LDPC codes for use in a non-stationary environment. This work differs from the existing work in that it studies several novel coding techniques and concentrates on the design of codes matched to the iterative decoding algorithm being used, rather than the design of codes based on hypotheticalmaximum-likelihood decoding.