A New Design Method of Multi-Rate Quasi-Cyclic LDPC Codes

A new method called fractional row combination is proposed to design a group of multi-rate quasi-cyclic LDPC codes in this paper. Unlike the original row combination method, it guarantees all the codes under different rates have concentrated check-node degree distributions, hence better performance under iterative decoding. Moreover, a combinatorial method based on BIBD is applied to our design. Together with fractional row combination, a family of multi-rate quasi-cyclic LDPC codes can be constructed. A low-complexity architecture of the universal decoder for all rates is also introduced