A Generic Tool for Assessing the Soft-FEC Performance in Optical Transmission Experiments

We propose a tool for assessing the performance of soft-input forward-error-correction codes with recorded optical transmission experiments. This tool, which can be used to evaluate the performance of any linear coding scheme, is especially suited for higher order modulation schemes. Without having to redo the channel measurements, recorded data can be used to perform offline evaluation of various coding schemes. This is facilitated by the linearity of the code. We demonstrate the usefulness of the tool by applying it in a 16-quadrature amplitude modulation (QAM) experiment, where recorded channel data is used to compare the performance of two different low-density parity-check coding schemes using differentially encoded 16-QAM modulation.