Transmitting apparatus and mapping method thereof

A broadcast signal transmitting apparatus for transmitting broadcast data, the apparatus comprising:

• an encoder configured to encode input bits to generate parity bits based on a low density parity check (LDPC) code having a code rate being 2/15, wherein the input bits are based on the broadcast data;
• an interleaver configured to interleave a codeword comprising the input bits and the parity bits;
• a constellation mapper configured to map bits of the interleaved codeword onto non uniform constellation points using a 1024-quadrature amplitude modulation (QAM) scheme;
• a signal generator configured to generate a broadcast signal based on the constellation points using orthogonal frequency division multiplexing (OFDM) scheme;
• and
• a transmitter configured to transmit the broadcast signal,
• wherein each of the constellation points is represented as one of A+Bi, −A+Bi, A−Bi and −A−Bi, and
• wherein A is a real component, B is an imaginary component, and each of A and B comprises one of values listed below:
• 0.3317
• 0.3321
• 0.3322
• 0.3321
• 0.3327
• 0.3328
• 0.3322
• 0.3322
• 0.9369
• 0.9418
• 0.9514
• 0.9471
• 0.9448
• 0.9492
• 0.9394
• 0.9349.