Transmitting apparatus and modulation method thereof
A transmitting apparatus is disclosed. The transmitting apparatus includes an encoder to perform channel encoding with respect to bits and generate a codeword, an interleaver to interleave the codeword, and a modulator to map the interleaved codeword onto a non-uniform constellation according to a modulation scheme, and the constellation may include constellation points defined based on various tables according to the modulation scheme.
1. A transmitting method comprising:
encoding input bits to generate parity bits based on a low density parity check (LDPC) code;
interleaving a codeword comprising the input bits and the parity bits;
mapping bits of the interleaved codeword onto constellation points for 64-quadrature amplitude modulation (QAM); and
transmitting a signal comprising information regarding the constellation points onto which the bits of the interleaved codeword are mapped,
wherein the constellation points comprise constellation points as defined in a table below:
0.5472 + 1.1591i
0.5473 + 1.1573i
0.5467 + 1.1599i
0.5479 + 1.1585i
1.1578 + 0.5478i
1.1576 + 0.5475i
1.1591 + 0.5475i
1.1591 + 0.5475i
0.3163 + 0.5072i
0.3163 + 0.5072i
0.3163 + 0.5072i
0.3163 + 0.5072i
0.5087 + 0.3163i
0.5087 + 0.3163i
0.5087 + 0.3163i
0.5087 + 0.3163i.
2. The method as claimed in claim 1 , wherein the encoding comprising encoding the input bits according to a coding rate of 3/15.
3. The method as claimed in claim 1 , wherein the table indicates constellation points in one quadrant of a constellation, and
wherein constellation points in remaining quadrants of the constellation are obtained by indicating each constellation point a which is defined by the table as a*, −a* and −a respectively, where * indicates complex conjugation.
4. The method as claimed in claim 1 , wherein the mapping comprises demultiplexing the interleaved codeword into a plurality of cells, and mapping the plurality of cells onto the constellation points.