说明：  提出了一种码率码长灵活变化的准循环低密度奇偶校验(Quasi - Cyclic Low Density Parity Check, QC - LDPC)码,利用构造出的H 矩阵可以达到较大的圈长( girth)值,并能在 girth值不变的前提下实现码率码长的灵活变化
(Puts forward a bit rate code length of flexible change must circulation Low Density parity (Quasi-Cyclic Low Density Parity Check, QC-LDPC code), using the matrix can be constructed to larger H circle long (girth) value, and could be there The premise of girth values achieve bit rate yards long flexible changes)