Ldpc ( low density parity check ) code is a kind of linear block code that defined by very sparse parity matrix or tanner graph , and it is also called gallager code since gallager initially presented it Ldpc ( lowdensityparitycheck )码是一类用非常稀疏的校验矩阵或二分图定义的线性分组纠错码,最初由gallager发现,故亦称gallager码。
Since their rediscovery , design , construction , decoding , analysis and applications of ldpc coded have become focal points of research . among them , the decoding algorithm and its implementation design are the focus of this thesis Ldpc码是一种具有稀疏校验矩阵的线性分组码,研究结果表明,采用迭代的概率译码算法, ldpc码可以达到接近香农极限的性能。
This class of codes decoded with soft - in soft - out ( siso ) iterative decoding performs amazingly well . since their rediscovery , design , construction , decoding , analysis and applications of ldpc coded have become focal points of research Ldpc码是一种具有稀疏校验矩阵的线性分组码,研究结果表明,采用迭代的概率译码算法, ldpc码可以达到接近香农极限的性能。
The linear block code is called a binary low - density parity - check code if it is based on a sparse parity - check matrix . this sort of code was originally proposed by dr . gallager in 1962 , which cannot attract a large amount of interest at that time 低密度奇偶校验( ldpc )码是基于稀疏校验矩阵的线性分组码,它最初由gallager于1962年提出,当时并未受到人们的重视。
Since ldpc codes have a wonderful future , an adaptive coding scheme was developed based on quasi - regular ldpc codes and it encodes the source bits with different code rate by dividing the original parity check matrix properly 由于ldpc码在未来的广阔应用前景,本文提出一种针对结构化ldpc码的自适应编码方案,对原始校验矩阵适当变化,即可对信源信息进行不同码率的自适应编码。
Then discusses conventional encoding and efficient encoding using special sparse parity check matrix in encoding algorithm , and expatiates the principle of message passing and spa which has the best performance in decoding algorithm 在编码算法里详细讨论了传统的编码算法以及使用特殊形式奇偶校验矩阵的快速编码算法。在译码算法里介绍了mp算法集的基本原理和译码性能最好的和乘积译码算法。
It gives some solutions for designing the encoder . various log - likelihood - ratio - based belief - propagation decoding algorithms and their reduced - complexity derivatives for ldpc codes used in dvb - s2 are presented , in order to avoid the “ tanh ” function in the check - node updates 接着,本文介绍了dvb - s2标准中ldpc码的特点及编码方法,给出了通过仿真得到的非规则校验矩阵,针对编码器设计中遇到的一些问题提出了改进方法。
Some properties of separation vector of linear block codes are shown , the relationship of a variety of codewords subspace and separation vector is derived , also a serie of theorems of parity check matrix and code symbol separation are proved . the singlton bound of separation is then proved 然后简单分析了线性码的码元分离度的性质，并在此基础上分析了一致校验矩阵的列相关性，从而得到了线性码的消息分离度和码元分离度的singlton限。
On the other hand , in the approach based on vector - matrix , through several special operations on vector - matrix , we have constructed a sparse ‘ 0 ’ , ‘ 1 ’ parity - check matrix with dual diagonal matrix whose structure can easily construct the code . the simulation results have demonstrated the performance of this approach is similar to that of - rotation while the complexity is also higher . this problem is to be solved in the future research 在基于矢量矩阵的结构化方法中,通过对矢量矩阵进行一系列特殊处理可以构造出稀疏的‘ 0 ’ 、 ‘ 1 ’校验矩阵,而校验矩阵中的双对角结构易于构造出相应的ldpc码字,仿真表明,采用矢量矩阵的结构化方法具有和-旋转构造法相当的性能,但是实现的复杂度大于-旋转构造法,同时码率和码长受到一定的限制,这也是未来需要研究的方向。
Low density parity check ( ldpc ) codes are good error - correcting codes , which can approach shannon ' s capacity limit . due to the sparsity of its check matrix , ldpc codes can be decoded only with linear time complexity using iterative decoding algorithm . therefore , ldpc codes have become one of the most attractive fields in the channel coding community 低密度校验码是一种逼近香农限的好码，由于其校验矩阵的稀疏特性，采用迭代译码算法，它的译码仅具有线性时间复杂度，所以目前ldpc码己成为信道编码理论界的研究热点之一。
