Irregular low-density parity-check codes: construction and performance on perpendicular magnetic recording channels

In this paper, we propose an algorithm to design an irregular low-density parity-check code (LDPC), with a given degree distribution pair, from a random regular LDPC code. The proposed algorithm splits columns and rows of the regular code in order to achieve the desired degree distribution pair. Kou, Lin, and Fossorier have used column splitting to increase code rate. However, we use the splitting technique to achieve a given degree distribution pair in the bipartite graph of the resultant irregular code. The bit-error rate (BER) performance of high-rate irregular LDPC codes, constructed using this algorithm, were simulated on equalized perpendicular magnetic recording channels. In addition, this paper compares the performance of these irregular codes with that of random regular LDPC codes.