Modulator and modulation method using non-uniform 16-symbol signal constellation for low-density parity check codeword having 4/15 code rate

A BICM (Bit-Interleaved Coded Modulation) method, comprising:

• generating an LDPC codeword having a length of 16200 bits and a code rate of 4/15;
• generating an interleaved codeword by performing bit group basis interleaving corresponding to the LDPC codeword;
• and
• performing 16-symbol mapping using a non-uniform 16-symbol signal constellation after generating the interleaved codeword,
• wherein the interleaved codeword is generated using the following equation using permutation order:
• Yj=Xx(j) 0≤j<Ngroup
• where Xj is the j-th bit group, Yj is an interleaved j-th bit group, Ngroup is a number of bit groups and π(j) is a permutation order for bit group-based interleaving,
• wherein the 16-symbol signal constellation corresponds to 16 symbols 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.