Bit interleaver for low-density parity check codeword having length of 64800 and code rate of 2/15 and 64-symbol mapping, and bit interleaving method using same
A bit interleaver, a bit-interleaved coded modulation (BICM) device and a bit interleaving method are disclosed herein. The bit interleaver includes a first memory, a processor, and a second memory. The first memory stores a low-density parity check (LDPC) codeword having a length of 64800 and a code rate of 2/15. The processor generates an interleaved codeword by interleaving the LDPC codeword on a bit group basis. The size of the bit group corresponds to a parallel factor of the LDPC codeword. The second memory provides the interleaved codeword to a modulator for 64-symbol mapping.
1. A bit group-unit interleaver, comprising:
a first memory configured to store a low-density parity check (LDPC) codeword having a length of 64800 and a code rate of 2/15;
a processor configured to generate an interleaved codeword by interleaving the LDPC codeword on a bit group basis, the size of the bit group corresponding to a parallel factor of the LDPC codeword; and
a second memory configured to store the interleaved codeword corresponding to a modulator for 64-symbol mapping, wherein the 64-symbol mapping is a Non-Uniform Constellation (NUC) symbol mapping which corresponds to 64 constellations,
wherein the interleaving is performed using the following equation using permutation order:
Y j =X π(j) 0 ≦j<N group
where X j is the j-th bit group, Y j is an interleaved j-th bit group, and π(j) is a permutation order for bit group-based interleaving, and
wherein the permutation order corresponds to an interleaving sequence represented by the following equation:
interleaving
sequence
=
{
57
149
83
142
29
20
30
52
50100
156
22
130
167
121
126
137
158
132
82
138
128
89
88
162
32
107
3
97
166
125
129
1
6
68
148
40
87
0
80
49
24
78
101
43
112
75
172
23
154
12
146
19
135
48
170
123
147
95
91
13
35
127
61
60
139
44
59
55
109
157
177
153
165
66
152
77
98
131
11
81
62
175
141
171
51
155
76
150
174
58
143
37
63
31
41
140
118
94
27
10
70
56
93
176
124
151
104
46
163
179
4
18
144
178
161
145
71
114
7
105
133
84
86
17
21
28
54
74
65
110
122
169
64
111
119
42
85
73
8
116
79
120
69
53
115
67
104
16
173
92
15
159
134
99
96
117
38
9
26
164
47
103
113
136
168
102
14
45
72
25
50
34
36
90
160
2
33
39
108
}
.
2. The bit group-unit interleaver of claim 1 , wherein the parallel factor is 360, and the bit group includes 360 bits.
3. The bit group-unit interleaver of claim 2 , wherein the LDPC codeword is represented by (u 0 ,u 1 , . . . , u N ldpc −1 ) (where N ldpc , is 64800), and is divided into 180 bit groups each including 360 bits, as in the following equation:
X j ={u k |360 ×j≦k< 360×( j+ 1), 0 ≦k<N ldpc } for 0 ≦j<N group
where X j is an j-th bit group, N ldpc is 64800, and N group is 180.