Feed-forward carrier phase recovery for optical communications

摘要

The carrier phase of a carrier wave modulated with information symbols is recovered with a multi-stage, feed-forward carrier phase recovery method. A series of digital signals corresponding to the information signals is received. For each digital signal, a coarse phase recovery is performed to determine a first phase angle which provides a first best estimate of the information symbol corresponding to the digital signal. Using the first best estimate as input, a second stage of estimation is then performed to determine a second phase angle which provides an improved (second) best estimate of the information symbol. Additional stages of estimation can be performed. The multi-stage, feed-forward carrier phase recovery method retains the same linewidth tolerance as a single-stage full blind phase search method; however, the required computational power is substantially reduced. The multi-stage, feed-forward carrier phase recovery method is highly efficient for M-QAM optical signals.

主权项

1. A method for carrier phase recovery of a carrier wave modulated with a plurality of information symbols, the method comprising:
receiving a digital signal corresponding to an information symbol; generating a first estimate of an optimal phase angle corresponding to the digital signal by performing a coarse blind phase search; and generating a second estimate of the optimal phase angle corresponding to the digital signal by inputting the digital signal and the first estimate of the optimal phase angle into a first maximum likelihood phase recovery and decoding block.