Noise Tolerant Pilot Signal Processing in Fiber Optic Receivers
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Solution Overview
Problem
Existing pilot assisted techniques in fiber optic communication systems suffer from noise-related signal quality penalties due to amplified spontaneous emission (ASE) noise, which complicates polarization de-multiplexing and laser phase noise cancellation, requiring narrowband filtering that contradicts the broader spectral content needed for laser frequency and nonlinear phase noise compensation.
Innovation Solution
The method involves separating and averaging/filtering static and dynamic pilot components, allowing for noise reduction while maintaining broadband phase noise cancellation capabilities, effectively converting the common dynamic pilot noise into a constant amplitude phasor, thus improving signal quality and simplifying coherent receiver algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If narrowband filtering is applied to reduce ASE noise in pilots, then signal quality penalty is reduced, but broadband phase noise cancellation capability is compromised
Solution Approach 1:
The patent segments the pilot signal into static components (requiring narrowband filtering for noise reduction) and dynamic components (requiring broadband processing for phase noise cancellation). This segmentation allows each component to be processed with appropriate filtering bandwidth, resolving the contradiction between noise reduction and phase noise cancellation capability.
2Device complexity
If pilot assisted techniques are used for polarization de-multiplexing and phase noise cancellation, then DSP complexity is reduced, but ASE noise from optical amplifiers degrades signal quality
Solution Approach 1:
The patent extracts and removes ASE noise from the pilot signal through selective filtering of static components, thereby taking out the harmful noise element while preserving the useful pilot information needed for polarization de-multiplexing and phase noise cancellation, thus improving signal quality without increasing DSP complexity.
3Measurement precision
If broadband pilot processing is used for laser frequency offset and nonlinear phase noise compensation, then compensation accuracy is improved, but ASE noise impact increases
Solution Approach 1:
The patent applies local quality by using different filtering characteristics for different parts of the pilot signal spectrum. Static components are filtered with narrowband characteristics to reduce ASE noise, while dynamic components are processed with broadband characteristics to maintain compensation accuracy for laser frequency offset and nonlinear phase noise.
Data Source
AI summary
The present disclosure provides systems and methods for noise tolerant signal processing in a pilot assisted data receiver, including: given received pilots with common pilot components and individual pilot components, computing coefficients associated with the individual pilot components of the received pilots; and applying the computed coefficients to the received pilots to obtain conditioned pilots. The individual pilot components result from relatively slow changes of the received pilots relative to the common pilot components. The common pilot components result from relatively fast changes of the received pilots relative to the individual pilot components.