公开(公告)号：US20190334627A1

公开(公告)日：2019-10-31

申请号：US15966697

申请日：2018-04-30

Applicant: Nokia Solutions and Networks OY

Inventor： Noriaki Kaneda ,  Stephan Weisser ,  Carlo Costantini

IPC: H04B10/61 ,  H04B10/63

Abstract: A coherent optical receiver in which the channel equalizer and the clock-recovery circuit are connected in a nested-loop configuration, wherein the channel estimate generated by the equalizer is used to adjust the phase of the clock signal generated by the clock-recovery circuit. The channel equalizer can be implemented using a bank of time-domain or frequency-domain FIR filters. In an example embodiment, the clock-recovery circuit is configured to track the phase rotation corresponding to the equalized signals in a frequency-dependent manner; track the phase rotation in the channel equalizer either in a frequency-dependent manner or based on the mean signal delay therein; and adjust the phase of the clock signal based on an effective difference between these two phase rotations. The clock-recovery circuit enhances the clock tone by applying a Fourier transform to the squared absolute values of the equalized signals outputted by the channel equalizer.