Design of Irregular Quasi-Cyclic LDPC Codes

Abstract-In this paper, a novel methodology for design irregular quasi-cyclic LDPC codes is presented. The quasi-cyclic structure facilitates encoder and decoder implementation through shift-register-based circuits. The irregularity characteristic improves the code performance in waterfall region. The structure imposed on the bipartite graphs together with shifting matrix, Lead to a class of this code suitable for fast iterative decoding. The construction method results in a class of quasi-cyclic LDPC codes with girth of at least 6.The simulation results show, using the Sum Productive Decoder, this kinds of codes having excellent performance on the additive white Gaussian noise channels.