一类低密度奇偶校验码的设计

Design of a Class of LDPC Encoder and Decoder

低密度奇偶校验码(LDPC)是哥拉格于1962年提出的一种性能非常接近香农限的好码,并被MacKay和Neal两度重新发现,且证明了它在与基于BP(Belief Propagation)的迭代译码算法相结合的条件下具有逼近Shannon限的性能。LDPC码的优异的性能及其在信息可靠传输中的良好应用前景,成为当今信道编码领域最瞩目的研究热点。笔者选用国际电信联盟推出的一种方案,设计了一类低密度奇偶校验LDPC(LowDensityParityCheck)码。设计是针对分组块长为276比特,码率为0.7572,采用了6位量化方案。根据可编程逻辑器件(CPLD)的结构特点,提出了LDPC码的译码器结构和相应的编码器结构及其具体实现方案,并对编码方案进行了严密推导。该LDPC码适合用于ADSL传输。

Low-Density Parity-Check(LDPC) codes are first introduced by Gallagerin 1960's,and independently rediscovered by both MacKay and Neal. In past few years, LDPC codes have received a lot of attention and many new developments have been brought in this area. This paper has designed a class of Low Density Parity Check(LDPC)codes based on ITU. Our design is for 6-bit quantizaton with a code rate of 0.7572 and a block size of 276 bits. This paper brings forward the architecture of the partly parallel decoder and the corresponding parallel encoder based on CPLD technology. Also we have derived the encoder scheme. And this LDPC code is used for ADSL transmission.