Transmitting apparatus and interleaving method thereof
A transmitting apparatus is provided. The transmitting apparatus includes: an encoder configured to generate a low density parity check (LDPC) codeword by LDPC encoding based on a parity check matrix; an interleaver configured to interleave the LDPC codeword; and a modulator configured to map the interleaved LDPC codeword onto a modulation symbol, wherein the modulator is further configured to map a bit included in a predetermined bit group from among a plurality of bit groups constituting the LDPC codeword onto a predetermined bit of the modulation symbol.
1. A transmitting apparatus comprising:
an encoder configured to encode input bits to generate parity bits based on a low density parity check (LDPC) code according to a code rate of 13/15 and a code length of 16200;
an interleaver configured to interleave the parity bits, split a codeword comprising the input bits and the interleaved parity bits into a plurality of bit groups, and interleave the plurality of bit groups to provide an interleaved codeword; and
a mapper configured to map bits of the interleaved codeword onto constellation points for quadrature phase shift keying (QPSK),
wherein the plurality of bit groups are interleaved based on a following equation:
Y j = X π(j) for (0 ≦j<N group ),
where X j is a j th bit group among the plurality of bit groups, Y j is a j th bit group among the interleaved plurality of bit groups, N group 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:
Order of interleaving of the plurality of bit groups
π(j) (0 ≦ j < 45)
Code
j
0
1
2
3
4
5
6
7
8
9
10
11
12
Rate
23
24
25
26
27
28
29
30
31
32
33
34
35
13/15
π(j)
26
10
12
38
28
15
0
44
34
24
14
8
40
7
5
37
27
4
16
43
33
23
2
18
39
29
Code
j
13
14
15
16
17
18
19
20
21
22
Rate
36
37
38
39
40
41
42
43
44
13/15
π(j)
30
20
13
42
32
22
11
9
36
25
19
6
41
31
21
3
17
35
1.
2. The transmitting apparatus of claim 1 , wherein each of the plurality of bit groups comprises 360 bits.
3. The transmitting apparatus of claim 1 , wherein the π(j) is determined based on at least one of the code length, a modulation method of the mapping and the code rate.