A Modified PEG Algorithm for Construction of LDPC Codes with Strictly Concentrated Check-Node Degree Distributions

Progressive edge-growth (PEG) algorithm is a good approach to construct low-density parity-check (LDPC) codes with large girth at finite block lengths. However, the check-node degrees of PEG codes are usually loosely concentrated for both regular (more than one degree) and irregular codes (more than two degrees). In this paper, the authors propose a modified PEG algorithm for construction of LDPC codes with strictly concentrated check-node degrees, which yields both completely regular codes and strictly right-concentrated irregular codes with two consecutive check-node degrees. Moreover, our algorithm further improves the girth histogram of the codes for better performance. Simulation results show that even under strictly concentrated check-node degrees, our proposed algorithm slightly improves the performance of both regular and irregular PEG codes, especially for irregular codes at high SNR values.