Signalling coding and modulation method and demodulation and decoding method and device

A signalling coding and modulation method, of the method comprising:

• scrambling signalling and conducting BCH coding on the scrambled signalling to obtain BCH parity bits with a length of 168 bits;
• splicing the BCH parity bits to the end of the scrambled signalling to obtain a BCH codeword;
• extending the BCH codeword according to an extension pattern table to obtain an extended BCH codeword with a length of 6480 bits;
• conducting LDPC coding on the extended BCH codeword to generate an LDPC codeword based on a LDPC code with a code rate of 6/15 and a code length of 16200 bits, the LDPC codeword comprises the extended BCH codeword and parity bits;
• conducting parity bit permutation on the parity bits in the LDPC codeword and splicing the permutated parity bits to the end of the extended BCH codeword in the LDPC codeword to obtain a permutated LDPC codeword;
• according to a length of the signalling, puncturing the permutated LDPC codeword according to a predetermined puncturing rule to obtain a punctured LDPC codeword;
• and
• conducting bit rotation on a tuple sequence obtained by conducting predetermined processing based on the punctured LDPC codeword, and then mapping the rotated tuple sequence into signalling symbols according to 256QAM mapping rule.