Low density parity check coded modulation for optical communications

A system for data transport in optical communications systems, comprising:

• a transmitter, including a processor, the processor being configured for:
• generating concatenated code with a particular target code rate by encoding a received information sequence by constructing an outer and inner quasi cyclic-low-density parity check (QC-LDPC) code, the encoding comprising:
• dividing the received information sequence into a plurality of messages of equal length;
• encoding each of the messages into a codeword to generate a plurality of outer codewords;
• cascading the plurality of outer codewords to generate a bit sequence;
• and
• executing inner encoding to encode each of the plurality of outer codewords into codewords in QC-LDPC inner code, the dividing the received information sequence, encoding each of the messages into the codeword, cascading the plurality of outer codewords, and the executing the inner encoding being iteratively executed to continually improve the code rate until the target code rate is achieved;
• and
• transmitting a data stream in accordance with the QC-LDPC inner code over a transmission medium.

A system for data transport in optical communications systems, comprising:

• a receiver, including a processor, the processor being configured to:
• decode a received data stream based on a QC-LDPC inner code using two-phase decoding, the received data stream including generated concatenated code with a particular target code rate, the decoding comprising iteratively performing at least one of inner/outer and outer/inner decoding until a threshold condition is reached, the inner/outer decoding further comprising:
• setting a maximum number of inner decoding iterations, and checking a syndrome of a decoded word based on a parity check matric of the inner code at the end of each inner decoding iteration;
• setting a maximum number of outer decoding iterations, and decoding all failed words outputted by an inner decoder;
• and
• iteratively performing the inner/outer decoding until the entire decoding is successful or a preset maximum number of overall inner/outer decoding iterations is reached.