Modulator and modulation method using non-uniform 16-symbol signal constellation for low-density parity check codeword having 4/15 code rate
A modulator and a modulation method using a non-uniform 16-symbol signal constellation are disclosed. The modulator includes a memory and a processor. The memory receives a codeword corresponding to a low-density parity check (LDPC) code having a code rate of 4/15. The processor maps the codeword to 16 symbols of the non-uniform 16-symbol signal constellation on a 4-bit basis.
1. A reception device, comprising:
a demodulator configured to perform demodulation corresponding to 16-symbol mapping using 16 symbols of a non-uniform 16-symbol signal constellation;
a deinterleaver configured to perform group-unit deinterleaving on interleaved values after the demodulation; and
a decoder configured to restore information bits by LDPC-decoding deinterleaved values generated based on the group-unit deinterleaving, the deinterleaved values corresponding to a LDPC codeword having a code rate of 4/15,
wherein the group-unit deinterleaving is performed on a group basis, the size of the group corresponding to a parallel factor of the LDPC codeword, and
wherein the 16 symbols are defined as shown in the following Table:
TABLE
W
Constellation
0
0.3412 + 0.5241i
1
0.5241 + 0.3412i
2
0.5797 + 1.1282i
3
1.1282 + 0.5797i
4
−0.3412 + 0.5241i
5
−0.5241 + 0.3412i
6
−0.5797 + 1.1282i
7
−1.1282 + 0.5797i
8
0.3412 − 0.5241i
9
0.5241 − 0.3412i
10
0.5797 − 1.1282i
11
1.1282 − 0.5797i
12
−0.3412 − 0.5241i
13
−0.5241 − 0.3412i
14
−0.5797 − 1.1282i
15
−1.1282 − 0.5797i.
2. The reception device of claim 1 , wherein the LDPC codeword is generated by performing accumulation with respect to memory using a sequence corresponding to a parity check matrix (PCM).
3. The reception device of claim 2 , wherein the LDPC codeword includes a systematic part having a length of 4320, a first parity part having a length of 1080, and a second parity part having a length of 10800.