Performance Metrics for Systems with Soft-Decision FEC and Probabilistic Shaping
Journal article, 2017

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 log-likelihood 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 1 0 times compared with the normalized AIR.

optical communication-systems

error-correction

Author

Tsuyoshi Yoshida

Chalmers, Microtechnology and Nanoscience (MC2), Photonics

Magnus Karlsson

Chalmers, Microtechnology and Nanoscience (MC2), Photonics

Erik Agrell

Chalmers, Signals and Systems, Kommunikationssystem, informationsteori och antenner, Communication Systems

IEEE Photonics Technology Letters

1041-1135 (ISSN)

Vol. 29 2111-2114

Subject Categories

Other Electrical Engineering, Electronic Engineering, Information Engineering

DOI

10.1109/LPT.2017.2765180