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 interleaver configured to split a codeword comprising information bits and parity bits into a plurality of bit groups, wherein the parity bits are generated based on a low density parity check (LDPC) code having a code rate being 5/15 and a code length being 16200 bits;
interleave the plurality of bit groups based on a permutation order, to provide an interleaved codeword, wherein the permutation order is obtained based on the code rate being 5/15 and the code length being 16200 bits;
a demultiplexer configured to demultiplex bits of the interleaved codeword to generate data cells;
a mapper configured to map the data cells onto constellation points for quadrature phase shift keying (QPSK) modulation; and
a transmitter configured to transmit a signal which is generated based on the constellation points,
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 an interleaved plurality of bit groups, N group is a total number of the plurality of bit groups, and π(j) denotes the permutation order for the interleaving, and
wherein the π(j) is defined as follows:
Order of interleaving
π(j) (0 ≤ j < 45)
Code
j
0
1
2
3
4
5
6
7
8
9
10
11
Rate
23
24
25
26
27
28
29
30
31
32
33
34
5/15
π(j)
35
7
29
11
14
32
38
28
20
17
25
39
5
13
34
37
23
15
36
18
42
16
33
31
Code
j
12
13
14
15
16
17
18
19
20
21
22
Rate
35
36
37
38
39
40
41
42
43
44
5/15
π(j)
19
4
1
12
10
30
0
44
43
2
21
27
22
3
6
40
24
41
9
26
8.
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 interleaver is configured to interleave the interleaved plurality of bit groups using a plurality of columns, each of the plurality of columns comprising a first part and a second part,
wherein a number of rows in the first part and the second part is determined based on a number of the plurality of columns and a number of bits of each of the plurality of bit groups.
4. The transmitting apparatus of claim 1 , wherein π(j) is determined based on at least one of the code length, a modulation method for the mapping and the code rate.