Patent ID: 8185797

Claim:
A method for generating an encoder/decoder based on Low Density Parity Check (LDPC) code, the encoder/decoder being determined uniquely by a parity check matrix of a LDPC code, wherein said method comprises: storing a base matrix of the parity check matrix; and based on the base matrix of the parity check matrix, performing an encoding operation by the encoder for obtaining a codeword from source data or performing a decoding operation by the decoder by correcting input codeword bits that have been interfered and then outputting the corrected input codeword bits; wherein the base matrix is unique to the LDPC code with a fixed code rate and variable code sizes; said method further comprises steps of reading the stored base matrix, modifying non-minus elements in the base matrix according to the code size of a current data flow; to make the matrix meets at least one of the following conditions: when ∀zε[z min , L, z max ], after the elements are modified according to the code size, for random elements i, j, k, l which construct in anticlockwise a short cycle with length 4, there is always mod(i−j+k−l, z)≠0; when ∀zε[z min , L, z max ], after the elements are modified according to the code size, for random elements i, j, k, l which construct in anticlockwise a short cycle with length 4, there is always mod(i−j+k−l, z)≠0; and for random elements i, j, k, l, m, n which construct in anticlockwise a short cycle with length 6, there is always mod(i−j+k−l+m−n, z)≠0; or when ∀zε[z min , L, z max ], after the elements are modified according to the code size, for random elements i, j, k, l which construct in anticlockwise a short cycle with length 4, there is always mod(i−j+k−l, z/2)≠0; for random elements i, j, k, l, m, n which construct in anticlockwise a short cycle with length 6, there is always mod(i−j+k−l+m−n, z)≠0; and for random elements i, j, k, l, m, n, s, t which construct in anticlockwise a short cycle with length 8, there is always mod(i−j+k−l+m−n+s−t, z)≠0; wherein z, in all of the above conditions, refers to any extension factor appearing in a set [z min , . . . , z max ], z min is the extension factor of the LDPC code with the shortest code size, z max is the extension factor of the LDPC code with the longest code size.