Design of structured irregular LDPC codes from structured regular LDPC codes

Irregular Low-Density Parity-Check (LDPC) codes exhibit a performance extremely close to the Shannon capacity formula. In this paper, we presented a method of developing structured irregular LDPC codes from structured regular LDPC codes. The design is based on the expansion of the column-weight two LDPC codes. We used our proposed technique of developing a column-weight two structured regular LDPC codes based on Gray code representations and adapted the expansion method proposed in literature to convert regular codes into irregular ones, and it is noticed that there is an improvement in obtained code rates using the proposed technique. It is also found that encoding process is simpler and requires less memory.