• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Design & analysis for practical LDPC-coded systems from broadcast channel to low error-floor applications.
【24h】

Design & analysis for practical LDPC-coded systems from broadcast channel to low error-floor applications.

机译：从广播频道到低误码率应用的实际LDPC编码系统的设计和分析。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The application of low-density parity-check (LDPC) codes to classic point-to-point communication channels with independently and identically distributed noises has been well studied. Various results have demonstrated near-optimal performance with manageable complexity based on the sub-optimal but ultra-efficient belief propagation (BP) decoders. Nonetheless, the suboptimality of the BP decoder presents new challenges when applying LDPC codes to other non-traditional scenarios. This thesis considers two such problems: the code design for binary dirty paper coding (DPC) / broadcast channels, and the error-floor characterization/mitigation for low-error-rate applications.;In the first part of this thesis, we consider practical schemes for binary dirty-paper channels and broadcast channels with two receivers and varying channel quality. We first propose a new design for binary DPC. By exploiting the concept of coset binning, the complexity of the system is greatly reduced when compared to the existing works, which used symbol mappers to design the non-uniformly distributed dirty paper code. Some unique design challenges of coset binning for binary DPC are identified and addressed. The proposed system achieves comparable performance to the state-of-the-art, superposition-coding-based binary DPC system while demonstrating significant advantages in terms of complexity and flexibility of system design. For the binary broadcast channel, achieving the capacity generally requires the superposition of a primary channel code and a carefully designed secondary error control code with non-uniform distribution, the latter of which is similar to the one used in binary DPC. Motivated by our results in binary DPC, we propose a new binary broadcast scheme that generalizes the concept of DPC, which we term soft DPC. By combining soft DPC with time-sharing, we achieve a large percentage of the capacity for a wide range of channel quality. Our scheme uses only one fixed pair of codes for users 1 and 2, and a single quantization code, which possesses several practical advantages over traditional time-sharing and superposition coding solutions and provides better performance.;The second part of this thesis focuses on providing an exhaustive search algorithm for finding small error-prone substructures (EPSs) such as fully absorbing sets (FASs) of arbitrary regular LDPC codes and relaxed FASs (RFASs) and near FASs (NFASs) of arbitrary irregular LDPC codes. The proposed algorithm is based on the branch-&-bound principle for solving NP-complete problems. In particular, given any LDPC code, the problem of finding all EPSs of size less than s is formulated as an integer programming problem, for which a new branch-&-bound algorithm is devised. The proposed solution also incorporates new cut conditions that speed up the computation and reduce the memory usage. New node selection and the tree-trimming mechanisms are designed to further enhance the efficiency of the algorithm. The proposed algorithm is capable of finding all FASs (resp. NFASs) of size ≤13 with no larger than 2 induced odd-degree check nodes for regular (resp. irregular) LDPC codes of length ≤ 1000.;The resulting exhaustive list of small EPSs is then used to devise a new efficient post-processing low-error floor LDPC decoder. Numerical results show that by taking advantage of the exhaustive list of small FASs, the proposed post-processing decoder significantly lowers the error floor by a couple of orders of magnitude for codes of practical lengths and outperforms the state-of-the-art low error-floor decoders. In addition, the list of EPSs can also be used to estimate the error floor when combined with the importance sampling techniques. Moreover, with the list of EPSs we can find the dominant EPSs and eliminate them using edge swapping to lower the error floor of any given LDPC codes.;Finally, we introduce a new type of EPSs of LDPC codes called one-shot EPSs and static EPSs for the binary-input ternary-output (BITO) channel . The proposed new EPS is motivated by the observation that compared to binary erasure Channel (BEC) and binary symmetric channel (BSC), the decoder behavior of a BITO channel is a step closer to that of the additive white Gaussian noise channel (AWGNC). Therefore, the EPSs of a BITO would better characterize the EPSs of an AWGNC than the existing BEC- or BSC-based definitions. We develop a new exhaustive algorithm for these new EPSs for the BITO channel. The new exhaustive search algorithm enables us to order the harmfulness of EPSs and also distinguish the harmful bits of a given EPS. The algorithm can also be regarded as a unified search method for the existing EPSs such as codewords, stopping sets, FASs, and RFASs. The proposed algorithm is potentially generalizable to the binary-input m-ary output channel, which provides a concrete step towards understanding the notoriously complicated BP decoding behavior in the high-SNR (low FER) regime.
机译：已经对低密度奇偶校验（LDPC）码在具有独立且相同分布噪声的经典点对点通信信道中的应用进行了深入研究。基于次优但超高效的置信传播（BP）解码器，各种结果证明了具有可控制复杂性的接近最佳性能。然而，当将LDPC码应用于其他非传统场景时，BP解码器的次优性提出了新的挑战。本文考虑了两个这样的问题：二进制脏纸编码（DPC）/广播通道的代码设计，以及低错误率应用程序的错误层特征/缓解方法。具有两个接收器和变化的通道质量的二进制脏纸通道和广播通道的方案。我们首先提出一种针对二进制DPC的新设计。通过利用陪集合并的概念，与使用符号映射器设计非均匀分布的脏纸代码的现有作品相比，系统的复杂性大大降低了。识别并解决了二进制DPC的coset装箱的一些独特设计挑战。所提出的系统达到了与最新的基于叠加编码的二进制DPC系统相当的性能，同时在系统设计的复杂性和灵活性方面显示出显着的优势。对于二进制广播频道，要达到容量要求，通常需要叠加主频道代码和精心设计的具有非均匀分布的辅助错误控制代码，后者与二进制DPC中使用的类似。基于二进制DPC的研究结果，我们提出了一种新的二进制广播方案，该方案概括了DPC的概念，我们将其称为软DPC。通过将软DPC与分时相结合，我们可以在很大范围的信道质量上获得很大一部分容量。我们的方案仅为用户1和2使用一对固定的代码，以及一个单一的量化代码，与传统的分时和叠加编码解决方案相比，它具有许多实际优势，并且提供了更好的性能。一种穷举搜索算法，用于查找易于出错的较小子结构（EPS），例如任意规则LDPC码的完全吸收集（FAS）和任意不规则LDPC码的松弛FAS（RFAS）和近FAS（NFAS）。该算法基于分支定界原理，解决了NP完全问题。特别地，在给定任何LDPC码的情况下，将找到所有小于s的EPS的问题表述为整数规划问题，为此，设计了一种新的分支定界算法。提出的解决方案还结合了新的剪切条件，可加快计算速度并减少内存使用量。设计了新的节点选择和树修剪机制，以进一步提高算法的效率。对于长度≤1000的常规（随机）LDPC码，所提出的算法能够找到大小≤13的所有FAS（NFAS相对），且不大于2个诱导奇数校验节点。然后，EPS用于设计一种新型的高效后处理低错误本底LDPC解码器。数值结果表明，通过利用小型FAS的详尽清单，所提议的后处理解码器对于实用长度的代码将误码率显着降低了几个数量级，并且胜过了最新的低误码率-地板解码器。此外，当与重要性采样技术结合使用时，EPS列表也可以用于估计误差底限。此外，通过EPS列表，我们可以找到优势EPS并通过边缘交换来消除它们，以降低任何给定LDPC码的错误基底。最后，我们引入了一种新型的LDPC码EPS，称为单次EPS和静态二进制输入三进制输出（BITO）通道的EPS。与二进制擦除通道（BEC）和二进制对称通道（BSC）相比，BITO通道的解码器行为与加性高斯白噪声通道（AWGNC）的行为相距更近一步，因此提出了新的EPS。因此，与现有的基于BEC或BSC的定义相比，BITO的EPS可以更好地表征AWGNC的EPS。我们针对BITO通道的这些新EPS开发了一种新的穷举算法。新的穷举搜索算法使我们能够确定EPS的危害性，并区分给定EPS的有害位。该算法也可以被视为现有EPS的统一搜索方法，例如代码字，停止集，FAS和RFAS。所提出的算法可能可以推广到二进制输入的m-ary输出通道，这为理解高SNR（低FER）状态中众所周知的复杂BP解码行为提供了具体步骤。

著录项

  • 作者

    Kyung, Gyu Bum.;

  • 作者单位

    Purdue University.;

  • 授予单位 Purdue University.;
  • 学科 Engineering Electronics and Electrical.
  • 学位 Ph.D.
  • 年度 2011
  • 页码 152 p.
  • 总页数 152
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号