Apparatus and methyod for channel encoding and decoding in communication system using low-denisty parity-check codes

A method for decoding a channel in a communication system using a Low-Density Parity-Check (LDPC) code, the method comprising the steps of:

• determining a shortening pattern and a puncturing pattern based on a received signal;
• and
• setting a value of a shortened bit to 0 according to the determined shortening pattern, setting erasures according to the determined puncturing pattern, and performing LDPC decoding, when bits exist which have been used to perform shortening or puncturing,
• wherein determining the shortening pattern and the puncturing pattern comprises setting a ratio of the number of punctured bits to the number of shortened bits to (B+1)/B, wherein B is an integer.

An apparatus for encoding a channel in a communication system using a Low-Density Parity-Check (LDPC) code, the apparatus comprising:

• a shortening pattern application unit for performing shortening using a predetermined number of shortened bits;
• an LDPC encoder for performing encoding based on an LDPC code shortened by the shortening pattern application unit;
• a control unit for applying predetermined rules to the predetermined number of shortened bits, and for determining a number of bits to be punctured;
• and
• a puncturing pattern application unit for carrying out puncturing on an LDPC codeword generated by the LDPC encoder based on the determined number of bits to be punctured.

An apparatus for decoding a channel in a communication system using a Low-Density Parity-Check (LDPC) code, the apparatus comprising:

• a demodulator for receiving and demodulating a channel;
• a shortening/puncturing pattern determination or estimation unit for determining a predetermined shortening and puncturing pattern based on a demodulated signal, and providing position information on bits to be shortened and punctured to an LDPC decoder;
• and
• the LDPC decoder for inserting as many zeros as a number of shortened bits and setting as many erasures as a number of punctured bits, according to the position information on the bits to be shortened and punctured, and decoding the LDPC code,
• wherein, in the shortening and puncturing pattern, a ratio of the number of punctured bits to the number of shortened bits is set to (B+1)/B, where B is an integer.