低密度奇偶校验码编码算法研究-信息与通信工程专业毕业论文.docx

二次扩展的准循环 LDPC 码的构造方法,该方法利用近似下三角形式的矩阵能实现
低复杂度编码的特点,构造的准循环 LDPC 码具有线性编码复杂度和准循环结构, 硬件实现简单,码长码率灵活可变,同时在 AWGN 信道下能取得优于 Mackay 随机码的良好性能。
第五章全面的分析了规则 LDPC 码和不规则 LDPC 码性能差异的成因,介绍了指导不规则 LDPC 码的最佳度序列分布搜索理论,密度进化理论和高斯逼近理论, 提出一种不规则 LDPC 码确定性构造方法,该方法设计的校验矩阵基于范德蒙矩阵, 具有确定的代数结构,硬件实现简单,利用掩模技术,可以构造满足一定度数分布的不规则准循环 LDPC 码,同时在 AWGN 信道下能取得良好性能。
最后对全文进行总结,并指出今后需要进一步研究的工作。
关键词:低密度奇偶校验码; 准循环码; 迭代译码; 和积算法; 斐波那契数列; 范德蒙矩阵
Abstract
Due to its near-Shannon-limit error-correcting capability and highly parallel decoding architecture, low-density parity-check(LDPC) code is very suitable for the new generation high-quality, high-data-rate multimedia transmission. However, as a new coding technique, the application of LDPC codes still appers to be challenging. Imbursed by the great item “Research of munication System Fundamental Theory and Technology ()” and the basic item “Research of the algebra structure algorithm of the high performance and plexity LDPC code” of National Natural Science Fund, the dissertation studies the encoding and decoding techniques of Low-Density Parity-Check (LDPC) Codes that were considered much in error correction codes field.
There were not good methods for constructing LDPC codes though they have good performance. Good LDPC codes, especially long codes, often are obtained by searching puter. As lacking the circlular or quasi-circular character of these LDPC codes, these search-based codes have plex encoding structure. This makes them unsuitable for application. However, Quasi-cyclic LDPC codes have linear plexities, their error correcting performance parable to random LDPC codes or even better. Therefore Quasi-cyclic LDPC codes are suitable for application. The construction of QC LDPC codes and related problems are focused on.
In Chapter Two, the definition and Tanner graph reprensentation of LDPC codes are introduced. Then random construction methods and algebraical construction methods of LDPC codes are described. Two decoding algorithms with plexiti