A method includes applying an error-detecting code to first input data to generate first protected data and applying the error-detecting code to second input data to generate second protected data. The method also includes generating a first encoded codeword by encoding the first protected data using a first low density parity check (LDPC) code, and generating an output by performing a binary exclusive-or operation on the first protected data and the second protected data. The method further includes generating a second encoded codeword by encoding the output of the of the binary exclusive-or operation using a second LDPC code, and multiplexing data for transmission over a communications channel based on (i) the first encoded codeword and (ii) the second encoded codeword.