Channel interleaving/deinterleaving apparatus in a communication system using low density parity check code and control method thereof

A channel interleaving method in a communication system using a low density parity check (LDPC) code, the method comprising:

• encoding information data bits into an LDPC codeword using a predetermined coding scheme upon receipt of the information bits;
• interleaving the LDPC codeword according to a predetermined channel interleaving rule;
• and
• modulating the channel-interleaved LDPC codeword into a modulation symbol using a predetermined modulation scheme,
• wherein the channel interleaving rule is defined such that if a degree of a check node is greater than or equal to a threshold set in the system, codeword bits mapped to high-degree variable nodes are allocated to higher-reliability bits among the bits in the modulation symbol.

A channel interleaving method in a communication system using a low density parity check (LDPC) code, the method comprising:

• encoding information data bits into an LDPC codeword using a predetermined coding scheme upon receipt of the information bits;
• interleaving the LDPC codeword according to a predetermined channel interleaving rule;
• and
• modulating the channel-interleaved LDPC codeword into a modulation symbol using a predetermined modulation scheme,
• wherein the channel interleaving rule is defined such that if a corresponding LDPC code is a chain-structured LDPC code in which low-degree variable nodes are chain-connected, a distance between parity bits mapped to high-reliability bits remains constant.

A channel deinterleaving method in a communication system using a low density parity check (LDPC) code, the method comprising:

• demodulating a received signal using a demodulation scheme corresponding to a modulation scheme used for channel interleaving;
• deinterleaving the demodulated signal using a channel deinterleaving scheme corresponding to a channel interleaving rule used for the channel interleaving;
• and
• decoding the channel-deinterleaved signal into information data bits using a decoding scheme corresponding to an LDPC codeword coding scheme used for the channel interleaving,
• wherein the channel interleaving rule is defined such that if a degree of a check node is lower than a threshold set in the system, codeword bits mapped to low-degree variable nodes are allocated to high-reliability bits among the bits in a modulation symbol, wherein the modulation symbol is generated by encoding the information data bits using the coding scheme and then modulating the encoded information data bits using the modulation scheme.

A channel interleaving method in a communication system using a low density parity check (LDPC) code, the method comprising the steps of:

• determining a degree of a check node from a parity check matrix of an LDPC code;
• if the degree of the check node is lower than a threshold set in the system, channel-interleaving the LDPC code according to a first channel interleaving rule;
• if the degree of the check node is greater than or equal to the threshold set in the system, channel-interleaving the LDPC code according to a second channel interleaving rule;
• and
• if the LDPC code is a chain-structured LDPC code in which parity bits are chain-connected, channel-interleaving the LDPC code according to a third channel interleaving rule,
• wherein the third channel interleaving rule is defined such that for the chain-structured LDPC code in which low-degree variable nodes are chain-connected, a distance between parity bits mapped to high-reliability bits remains constant.

A channel interleaving apparatus in a communication system using a low density parity check (LDPC) code, the apparatus comprising:

• an encoder for encoding information data bits into an LDPC codeword using a predetermined coding scheme upon receipt of the information data bits;
• a channel interleaver for interleaving the LDPC codeword according to a predetermined channel interleaving rule;
• and
• a modulator for modulating the channel-interleaved LDPC codeword into a modulation symbol using a predetermined modulation scheme,
• wherein the channel interleaving rule is defined such that if a degree of a check node is lower than a threshold set in the system, codeword bits mapped to low-degree variable nodes are allocated to high-reliability bits among the bits in the modulation symbol.

A channel deinterleaving apparatus in a communication system using a low density parity check (LDPC) code, the apparatus comprising:

• a demodulator for demodulating a received signal using a demodulation scheme corresponding to a modulation scheme used in a channel interleaver;
• a channel deinterleaver for deinterleaving the demodulated signal using a channel deinterleaving scheme corresponding to a channel interleaving rule used in a channel interleaver;
• and
• a decoder for decoding the channel-deinterleaved signal into information data bits using a decoding scheme corresponding to an LDPC codeword coding scheme used in the channel interleaver,
• wherein the channel interleaving rule is defined such that if a degree of a check node is lower than a threshold set in the system, codeword bits mapped to low-degree variable nodes are allocated to high-reliability bits among the bits in a modulation symbol, wherein the modulation symbol is generated by encoding the information data bits using the coding scheme and then modulating the encoded information data bits using the modulation scheme.