Patent ID: 8196014

Claim:
A check matrix generating device provided with a quasi-cyclic matrix generating means for arranging J cyclic permutation matrices I(p j,l ) with p rows and q columns (0≦j≦J−1, 0≦l≦L−1) in a row direction and also arranging L cyclic permutation matrices I(p j,l ) in a column direction so as to generate a regular quasi-cyclic matrix having uniform row and column weights, a mask matrix generating means for generating a mask matrix which can adapt to a plurality of coding rates, a masking means for converting a specific cyclic permutation matrix within the regular quasi-cyclic matrix generated by said quasi-cyclic matrix generating means by using the mask matrix generated by said mask matrix generating means into a zero matrix so as to generate an irregular masked quasi-cyclic matrix, and a parity check matrix generating means for placing both the masked quasi-cyclic matrix generated by said masking means, and a matrix in which said cyclic permutation matrices are arranged in a stair-step shape at predetermined positions respectively so as to generate an irregular parity check matrix for LDPC code, wherein said quasi-cyclic matrix generating means configures the regular quasi-cyclic matrix by combining cyclic permutation matrices in each of which matrix elements whose row number is r (0≦r≦p−1) and whose column number is (r+p j,l ) mod p are “1”s, and other matrix elements are “0”s, and a plurality of cyclic permutation matrices arranged at a specific row differ from one another.