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 modulation method using a non-uniform 16-symbol signal constellation, comprising:
receiving a codeword having a code rate of 4/15;
mapping the codeword to 16 symbols of the non-uniform 16-symbol signal constellation on a 4-bit basis; and
determining at least one of amplitude and phase of a carrier in accordance with the mapping for generating a modulated signal,
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,
and
wherein the modulated signal corresponds to a transmission signal, the transmission signal being transmitted to a reception device.
2. The modulation method of claim 1 , wherein the codeword corresponds to a low-density parity check (LDPC) codeword.
3. The modulation method of claim 2 , wherein the LDPC codeword is interleaved on a bit group basis before mapping the codeword to the 16 symbols.