Erasure Based Soft Decision Decoding for Optical Transport Networks
Abstract
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 applications in high-speed optical communications. First, we evaluate the performance of various choices of inner and outer codes when the inner decoder uses a soft-decision decoder and the outer decoder is a hard-decision error-only decoder. Then, we evaluate the performance of the concatenated coding scheme when erasures are introduced at the output of the inner decoder and the outer decoder is an errors-and-erasures decoder. An exact expression for the number of errors and erasures that are guaranteed to be decoded by an iterative decoder is derived. Then, an approach for deriving an approximation of the error probability for the erasures decoder 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 the error and erasures iterative decoder can be better than that of errors only iterative decoder in the error floor region. It is also shown that simulation results are in close agreement with the mathematical approximations developed at error floors.
Citation
Soma, Dileep Kumar (2018). Erasure Based Soft Decision Decoding for Optical Transport Networks. Master's thesis, Texas A & M University. Available electronically from https : / /hdl .handle .net /1969 .1 /174432.