这是一篇关于信道编码的文章，同传统的FEC不同，这篇文章考虑的不仅仅是替代错误，同时考虑可能出现的同步错误-This is an article about the channel coding, different from a traditional FEC, this article consider not only the substitution errors might occur, taking synchronization error

LDPC encoder and the decoder of sum-product algorithm. (input H matrix form is Mackay s website form)