Construction of Quasi Cyclic LDPC Codes Based on Girth Opt-PSO Algorithm

The QC(quasi-cyclic) LDPC codes are an important subclass of LDPC codes. The key to improving the performance of QC LDPC codes is how to construct a parity-check matrix H with a girth distribution as good as possible. In this paper, method of girth detection of QC LDPC codes is described first. Furthermore, a novel algorithm, GirthOpt-PSO algorithm, is proposed to construct the QC LDPC codes, which achieves a good girth distribution based on the PSO algorithm. Simulation results show that the performance of the QC LDPC codes constructed by proposed algorithm is better than Tanner code and Array codes. Besides, the proposed algorithm is more flexible for designing the QC LDPC codes with desired block length and rate as well as good girth.