Abstract: A method of encoding data using a parity check matrix, a method of decoding encoded data, and a data retransmission method using the same are disclosed. A method of encoding data by LDPC code using a parity check matrix includes variably selecting a specific sub-matrix from a parity check matrix in accordance with a coding rate to be used for encoding, the parity check matrix including at least two sub-matrixes, and encoding an input data stream by using the selected sub-matrix.

Abstract: An apparatus and method for decoding a channel code is disclosed. The method for decoding a channel code includes the steps of receiving a low density parity check (LDPC) encoded signal from a transmitting party, generating a parity check matrix by adjusting the order of rows or columns of the parity check matrix, the parity check matrix including a plurality of groups consisting of a plurality of columns, at least one of the groups including at least one row of which every element is zero (0), and iteratively decoding the received signal for each group by using the generated parity check matrix.

Abstract: A low density parity check (LDPC) coding method, and more particularly, a method of executing LDPC coding using a parity check matrix is disclosed. The present invention comprises providing an information bit stream for channel encoding, and encoding the information bit stream by using a first parity check matrix including at least one row generated by combining at least two rows of a second parity check matrix.