System and method for blind frequency recovery
AssigneeAT&T Intellectual Property I, L.P.
InventorXiang Zhou
Life of this patent
Estimating the term…
Abstract
Described herein are systems and methods for accurately estimating and removing a carrier frequency offset. One exemplary embodiment relates to a system comprising a frequency offset detection circuit detecting a carrier frequency offset in an optical signal, and a frequency testing circuit calculating an estimated frequency offset value of the carrier frequency offset, wherein the frequency testing circuit removes a carrier phase based on the estimated frequency offset value and recovers the optical signal. Another exemplary embodiment relates to a method comprising detecting a carrier frequency offset in an optical signal, calculating an estimated frequency offset value of the carrier frequency offset, removing a carrier phase based on the estimated frequency offset value, and recovering the optical signal.
Claims20
A system, comprising:
- a frequency offset detection circuit configured to detect a carrier frequency offset in an optical signal;
- and
- a frequency testing circuit configured to calculate an estimated frequency offset value of the carrier frequency offset by:
- generating a coarse phase error frequency based on rotating a plurality of samples of the optical signal by a corresponding one of a plurality of phase angles and selecting one of the plurality of phase angles having a lowest mean square error value as the coarse phase error frequency;
- generating a plurality of fine test frequencies by applying a plurality of offsets to the coarse phase error frequency, the fine test frequencies being dispersed throughout a desired range of fine test frequencies, each of the fine test frequencies being separated from an adjacent one of the fine test frequencies by an interval determined based on a predetermined quantity of the fine test frequencies, and selecting as the estimated frequency offset value, one of the fine test frequencies based on a mean square error,
- wherein the frequency testing circuit is configured to remove a carrier phase from the optical signal based on the estimated frequency offset value to recover the optical signal.
A method, comprising:
- detecting a carrier frequency offset in an optical signal;
- calculating an estimated frequency offset value of the carrier frequency offset by generating a coarse phase error frequency based on rotating a plurality of samples of the optical signal by a corresponding one of a plurality of phase angles and selecting one of the plurality of phase angles having a lowest mean square error value as the coarse phase error frequency and generating a plurality of fine test frequencies by applying a plurality of offsets to the coarse phase error frequency, the fine test frequencies being dispersed throughout a desired range of fine test frequencies, each of the fine test frequencies being separated from an adjacent one of the fine test frequencies by an interval determined based on a predetermined quantity of the fine test frequencies, and selecting, as the estimated frequency offset value, one of the fine test frequency based on a mean square error;
- removing a carrier phase from the optical signal based on the estimated frequency offset value;
- and
- recovering the optical signal.
A circuit, comprising:
- a calculation component that calculates an estimated frequency offset value of a carrier frequency offset by generating a coarse phase error frequency based on rotating a plurality of samples in an optical signal by a corresponding one of a plurality of phase angles and selecting one of the plurality of phase angles having a lowest mean square error value as the coarse phase error frequency and generating a plurality of fine test frequencies by applying a plurality of offsets to the coarse phase error frequency, the fine test frequencies being dispersed throughout a desired range of fine test frequencies, each of the fine test frequencies being separated from an adjacent one of the fine test frequencies by an interval determined based on a predetermined quantity of the fine test frequencies, and selecting, as the estimated frequency offset value, one of the fine test frequencies based on a mean square error.
Dependencies are inferred from the claim text.