On the Construction of LDPC Codes Free of Small Trapping Sets by Controlling Cycles

作者：Xiongfei Tao, Yufei Li, Yonghe Liu, Zuoqi Hu · 发表于：IEEE Communications Letters · 年份：2017 · DOI：10.1109/lcomm.2017.2679707 · 被引用次数：31 · 研究领域：Error Correcting Code Techniques、Cooperative Communication and Network Coding、Advanced Wireless Communication Techniques

Low-density parity-check (LDPC) codes exhibit excellent error correcting capability. However, small trapping sets in the Tanner graph are harmful to the iterative decoding algorithm. In this letter, we present a method of constructing (3, n) girth-eight quasi-cyclic LDPC codes with low error floor by removing the small trapping sets from the Tanner graph. To address this issue, we analyze the relationship between eight-cycles and small trapping sets of Tanner graphs based on fully connected base graphs without parallel edges. We find that if some eight-cycles are not found in the Tanner graphs, any elementary trapping set in the range of a ≤ 8 and b ≤ 3 is removed naturally. We also derive a lower bound on the permutation size for the construction of such codes. The experimental simulation shows a favorable error rate performance with lower error floor over additive white Gaussian noise channels.