Performance Metrics for Systems with Soft-Decision FEC and Probabilistic Shaping

Abstract

High-throughput optical communication systems utilize binary soft-decision forward error correction (SD-FEC) with bit interleaving over the bit channels. The generalized mutual information (GMI) is an achievable information rate (AIR) in such systems and is known to be a good predictor of the bit error rate after SD-FEC decoding (post-FEC BER) for uniform signaling. However, for probabilistically shaped (nonuniform) signaling, we find that the normalized AIR, defined as the AIR divided by the signal entropy, is less correlated with the post-FEC BER. We show that the information quantity based on the distribution of the single bit signal, and its asymmetric loglikelihood ratio, are better predictors of the post-FEC BER. In simulations over the Gaussian channel, we find that the prediction accuracy, quantified as the peak-to-peak deviation of the post-FEC BER within a set of different modulation formats and distributions, can be improved more than 10 times compared with the normalized AIR.

4 pages, 3 figures

References in corpus (2)

• Sensitivity Gains by Mismatched Probabilistic Shaping for Optical Communication Systems
• Performance Prediction of Nonbinary Forward Error Correction in Optical Transmission Experiments

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• Hierarchical Distribution Matching for Probabilistically Shaped Coded Modulation
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• Performance Prediction Recipes for Optical Links
• Compressed Shaping: Concept and FPGA Demonstration
• On the Performance under Hard and Soft Bitwise Mismatched-Decoding