Feed-forward carrier phase recovery for optical communications
AssigneeAT&T Intellectual Property I, L.P.
InventorXiang Zhou
Life of this patent
Estimating the term…
Abstract
The carrier phase of a carrier wave modulated with information symbols is recovered with a multi-stage, feed-forward carrier phase recovery method. 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.
Claims18
A method for carrier phase recovery of a carrier wave modulated with a plurality of information symbols, the method comprising:
- generating a first estimate of an optimal phase angle corresponding to a digital signal by performing a coarse blind phase search;
- 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;
- and
- generating a third estimate of the optimal phase angle corresponding to the digital signal by inputting the digital signal and the second estimate of the optimal phase angle into a second maximum likelihood phase recovery and decoding block,
- wherein the carrier wave is modulated with M-ary quadrature amplitude modulation and the performing the coarse blind phase search comprises testing fewer than M test phase angles.
An apparatus for carrier phase recovery of a carrier wave modulated with a plurality of information symbols, the apparatus comprising:
- a processor;
- and
- a memory to store computer program instructions, the computer program instructions, when executed on the processor, cause the processor to perform operations comprising:
- generating a first estimate of an optimal phase angle corresponding to a digital signal by performing a coarse blind phase search;
- 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;
- and
- generating a third estimate of the optimal phase angle corresponding to the digital signal by inputting the digital signal and the second estimate of the optimal phase angle into a second maximum likelihood phase recovery and decoding block,
- wherein the carrier wave is modulated with M-ary quadrature amplitude modulation and the performing the coarse blind phase search comprises testing fewer than M test phase angles.
A non-transitory computer readable medium storing computer program instructions for carrier phase recovery of a carrier wave modulated with a plurality of information symbols, which, when executed on a processor, cause the processor to perform operations comprising:
- generating a first estimate of an optimal phase angle corresponding to a digital signal by performing a coarse blind phase search;
- 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;
- and
- digital signal by inputting the digital signal and the second estimate of the optimal phase angle into a second maximum likelihood phase recovery and decoding block,
- wherein the carrier wave is modulated with M-ary quadrature amplitude modulation and the performing the coarse blind phase search comprises testing fewer than M test phase angles.
Dependencies are inferred from the claim text.