说明：  LDPC(Low-density-parity-check，低密度奇偶校验)码是一类具有稀疏校验矩阵的线性分组码，不仅有逼近Shannon限的良好性能，而且译码复杂度较低，结构灵活，是近年信道编码领域的研究热点
(LDPC (Low-density-parity-check, low-density parity check) codes are a class of sparse check matrix of linear block codes, is not only good performance approaching Shannon limit, and the decoding complexity low, flexible structure , the field of channel coding in recent years the research focus)