The analysis of cycle structure for a class of quasi-cyclic LDPC codes

In this paper, we analyse the cycle structure of a class of quasi-cyclic LDPC codes, and divide the cycles of this kind of LDPC codes into three classes. It offers some help for improving the existing construction algorithms of this kind of LDPC codes. The cycles in base matrix could be extended as long as possible when p the row¿s(or column¿s) number of block-elements was prime.