Forward error correction for 100 G transport networks

TLDR

Forward error correction is essential for fiber‑optic backbone networks at 40–100 Gb/s, where increased amplifier use degrades signal‑to‑noise and drives the adoption of diverse FEC schemes from block to concatenated codes and hard‑ to soft‑decision options. The article evaluates the advantages of hard‑decision versus soft‑decision FEC schemes in specific transmission environments. The authors compare hard‑decision and soft‑decision codes across varying optical‑signal‑to‑noise conditions to guide their selection.

Abstract

The role of forward error correction has become of critical importance in fiber optic communications, as backbone networks increase in speed to 40 and 100 Gb/s, particularly as poor optical-signal-to-noise environments are encountered. Such environments become more commonplace in higher-speed environments, as more optical amplifiers are deployed in networks. Many generations of FEC have been implemented, including block codes and concatenated codes. Developers now have options to consider hard-decision and soft-decision codes. This article describes the advantages of each type in particular transmission environments.