Short cycle-optimizing QC-LDPC (Quasi-Cyclic-Low Density Parity Check) code construction method

The invention discloses a short cycle-optimizing QC-LDPC (Quasi-Cyclic-Low Density Parity Check) code construction method, which includes the following steps: (1) the values of matrix dimensionality, a stopping threshold and maximum iterations are set; (2) according to the size of a template matrix, a 4-cycle distribution matrix and a 6-cycle distribution matrix of each iteration are obtained, and moreover, the total numbers of 4-cycles and 6-cycles of the kth iteration are calculated; (3) for the kth iteration, whether (img file=DDA0000664848400000011.TIF wi=200 he=80 /) and (img file=DDA0000664848400000012.TIF wi=211 he=72 /) hold simultaneously is judged, and if so, then iteration is stopped and step 6 is executed; otherwise whether k less than or equal to N holds is judged, if so, then step 6 is executed, or else step 4 is executed; (4) for the kth iteration, weighted values formed by position elements corresponding to the 4-cycle distribution matrix and the 6-cycle distribution matrix are calculated; (5) the maximum value is found out, the row number and the column number are recorded, the value of the element at the corresponding position in the matrix is corrected, and step 2 is executed; (6) the corrected matrix is outputted. The short cycle-optimizing QC-LDPC code construction method has the advantage that the short cycle-optimizing QC-LDPC code construction method effectively reduces the numbers of 4-cycles and 6-cycles at the same time and greatly enhances iterative decoding performance.