System and Method for Recovering Carrier Phase in Optical Communications

摘要

The embodiments of the invention provide methods to deal with problems of cycle slips, angular skew, and residual phase noise for high-speed optical communications employing any arbitrary high-order multi-dimensional modulation formats. The embodiments use a slip process analyzer, a skew angle estimator, and a phase noise variance estimator to provide feedforward soft-decision information of a carrier phase recovery (CPE) for more accurate likelihood calculation based on a high-order hidden Markov model (HMM). The log-likelihood calculation can be done jointly in dual polarization with joint Markov state transition. Some embodiments use a kernel filter or a particle filter for log-likelihood calculation.

主权项

1. A system for decoding received data sent from a transmitter to a receiver over an optical communications channel, comprising:
a carrier phase estimator (CPE) to estimate a carrier phase of received symbols; a slip process analyzer to provide feedforward decision information in a form of a slip state-transition matrix using a high-order hidden Markov model (HMM) based on the carrier phase; a demodulator to calculate log-likelihood ratios (LLR) according to the feedforward soft-decision information; and a forward-error-correction (FEC) decoder to produce hard decision on symbols corresponding to the data, and to correct errors.