A Construction of QC LDPC Codes by a Greedy Algorithm

Recently, some classes of quasi-cyclic (QC) low-density parity-check (LDPC) codes have been constructed based on different explicit methods. In this paper, by introducing a strictly increasing sequence with size ? as the second row of the exponent matrix, girth-8 (3,L)-QC LDPC codes are obtained for any row weight ?L ≥ 4. The results show, the constructed codes are shorter than perviously codes by other explicit methods with the same girth.

Keywords:

QC-LDPC codes , explicit constructions , girth , exponent matrix.