Errors and Erasures Decoding of Product Codes for Optical Transport Networks
Dileep Kumar Soma, Asit Kumar Pradhan, Krishna R. Narayanan · IEEE Communications Letters · 2021
A concatenated soft decision forward error correcting (FEC) coding scheme with an inner low density generator matrix (LDGM) code and an outer product code (PC) is considered for high-speed optical communications. We compare the performance of the concatenated coding scheme in which erasures are introduced at the output of the inner decoder to that of the scheme in which hard-decision is made at the input of inner decoder. An exact expression for the number of errors and erasures that are guaranteed to be decoded by the outer product code is derived. Then, an approach for deriving an approximation of the error probability for theerasure+errordecoder is proposed. Using this approach, optimal thresholds can be chosen for declaring erasures at the output of the inner decoder. It is shown that the codeword error rate for theerror+erasureiterative decoder is better than that oferror onlyiterative decoder in the error floor region.