Transmitting apparatus and interleaving method thereof

A transmitting apparatus comprising:

• an encoder configured to encode information bits to generate parity bits based on a low density parity check (LDPC) code according to a code rate of 9/15 and a code length of 16200;
• an interleaver configured to interleave the parity bits, split a codeword into a plurality of bit groups, and interleave the plurality of bit groups to provide an interleaved codeword;
• a mapper configured to map bits of the interleaved codeword onto constellation points for 256-quadrature amplitude modulation (QAM);
• and
• a transmitter configured to transmit a signal carrying the constellation points,
• wherein the codeword comprises the information bits and the interleaved parity bits
• wherein the plurality of bit groups are interleaved based on a following equation:
• Yj=Xπ(j) for (0≦j<Ngroup),
• where Xj is a jth bit group among the plurality of bit groups, Yj is a jth bit group among the interleaved plurality of bit groups, Ngroup is a total number of the plurality of bit groups, and π(j) denotes a permutation order for the interleaving of the plurality of bit groups, and wherein the π(j) is defined as follows:
• Code
• Order of the interleaving of the plurality of bit groups
• Rate
• π(j) (0 ≦ j < 45)
• j
• 0
• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10
• 11
• 12
• 13
• 14
• 15
• 16
• 17
• 18
• 19
• 20
• 21
• 22
• 23
• 24
• 25
• 26
• 27
• 28
• 29
• 30
• 31
• 32
• 33
• 34
• 35
• 36
• 37
• 38
• 39
• 40
• 41
• 42
• 43
• 44
• 9/15
• π(j)
• 5
• 7
• 9
• 22
• 10
• 12
• 3
• 43
• 6
• 4
• 24
• 13
• 14
• 11
• 15
• 18
• 19
• 17
• 16
• 41
• 25
• 26
• 20
• 23
• 21
• 33
• 31
• 28
• 39
• 36
• 30
• 37
• 27
• 32
• 34
• 35
• 29
• 2
• 42
• 0
• 1
• 8
• 40
• 38
• 44