Decoding apparatus, decoding method, and program to decode low density parity check codes

A decoding method for use with a decoding apparatus for decoding Low Density Parity Check (“LDPC”) codes, the LDPC codes being represented by a check matrix, which is composed of a plurality of sub-matrices, the sub-matrices including a (P×P) unit matrix, a quasi-unit matrix, a shift matrix, a sum matrix, and a (P×P) zero matrix, wherein the quasi-unit matrix is a unit matrix having one or more 1s being substituted with 0, the shift matrix is a unit matrix or a quasi-unit matrix which is cyclically shifted, the sum matrix is the sum of two or more of said unit matrix, said quasi-unit matrix, and said shift matrix, the decoding method comprising:

• a first computation step of simultaneously performing P check node computations for decoding said LDPC codes;
• a second computation step of simultaneously performing P variable node computations for decoding said LDPC codes;
• and
• a message storage step of simultaneously reading and writing message data corresponding to P edges, the message data being obtained as a result of said P check node computations or said P variable node computations;
• wherein the message storage step stores message data corresponding to the edges, the message data being read during the check node computation in such a manner that the sub-matrices of the check matrix are packed closer in a predetermined direction excluding the zero matrix.

A computer readable medium having a program for causing a computer to perform a decoding method for use with a decoding apparatus for decoding Low Density Parity Check (“LDPC”) codes, said method comprising:

• a first computation step of simultaneously performing P check node computations for decoding said LDPC codes;
• a second computation step of simultaneously performing P variable node computations for decoding said LDPC codes;
• and
• a message storage step for simultaneously reading and writing message data corresponding to P edges, the message data being obtained as a result of said P check node computations or said P variable node computations;
• wherein the message storage step stores message data corresponding to the edges, the message data being read during the check node computation in such a manner that the sub-matrices of the check matrix are packed closer in a predetermined direction excluding the zero matrix.