Cost-effective single-lane 112 Gb/s solution for mobile fronthaul and access applications.

We experimentally demonstrate the possibility of transmitting 112  Gb/s PAM-4 signals over 30-km standard single-mode fibers with commercial 20-GHz components. The impact on system performance of three different equalization schemes-feed-forward equalizer (FFE), Volterra filter (VF), and maximum likelihood sequence estimator (MLSE)-is investigated and compared. We prove that the |x| and x|x| components of the VF can efficiently reduce the chirp-induced signal skew distortion, and that an MLSE with only four states can be used to remove the error floor. In contrast, the performance of FFE is worse than that of VF with a 4-state MLSE, even when a 64-state MLSE is used.