Method of decoding ldpc code for producing several different decoders using parity-check matrix of ldpc code and ldpc code system including the same

A method of decoding a low-density parity-check (LDPC) code, comprising:

• (a) outputting an LDPC codeword from an LDPC encoder through a channel;
• (b) decoding the LDPC codeword output through the channel by a first LDPC decoder according to a parity check matrix derived from a parity check matrix of the LDPC codeword;
• (c) when the decoding has failed in the first LDPC decoder, receiving soft information on each bit from the first LDPC decoder and decoding the LDPC codeword according to a new parity-check matrix produced from a parity-check matrix of the LDPC codeword, by a second LDPC decoder;
• (d) when the decoding has failed in the second LDPC decoder, receiving soft information newly generated after the decoding is ended from the second LDPC decoder and decoding the LDPC codeword according to said new parity-check matrix used, by the first LDPC decoder;
• and
• (e) iteratively performing (c) and (d) until the LDPC code is decoded or until a maximum iteration count.