Coherent Optical Receiver Carrier Phase Estimation
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Solution Overview
Problem
Coherent optical receivers face challenges in maintaining optimum performance due to changing spectral conditions and nonlinear effects from adjacent data signals in multi-channel optical fiber communications, where small deviations from ideal behavior significantly impact receiver performance at high data rates.
Innovation Solution
A coherent optical receiver measures the spectrum of a multi-channel optical signal, determines structure and bandwidth information, and adjusts filter parameters of a carrier phase estimator based on this information to optimize performance, including adjusting the number of taps and tap weights of digital filters to mitigate cross-phase modulation effects from adjacent channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the receiver uses fixed filter parameters for carrier phase estimation, then the device complexity is reduced, but the receiver performance deteriorates under changing spectral conditions and adjacent channel interference
Solution Approach 1:
The patent implements dynamic adjustment of filter parameters (number of taps and tap weights) in the carrier phase estimator based on measured spectral conditions and adjacent channel power levels. This transforms the static receiver into an adaptive system that optimizes performance under varying operational conditions without requiring complex manual reconfiguration
Solution Approach 2:
The system measures the spectral characteristics and adjacent channel power levels, then uses this feedback information to automatically adjust the filter parameters of the carrier phase estimator. This closed-loop approach maintains optimal receiver performance while keeping the control logic relatively simple
2Adaptability or versatility
If the receiver adjusts filter parameters dynamically based on spectral measurements, then the adaptability to changing conditions is improved, but the device complexity increases due to additional measurement and control mechanisms
Solution Approach 1:
The patent uses the existing spectral measurement capabilities of the coherent receiver for dual purposes: both for signal detection and for determining optimal filter parameters. This multi-functional approach enables adaptability without adding dedicated measurement hardware
Solution Approach 2:
The receiver automatically measures spectral conditions, determines adjacent channel power levels, and adjusts its own filter parameters without external intervention. This self-configuring capability provides adaptability while minimizing the need for external control systems
3Measurement precision
If the number of filter taps is increased to improve carrier phase estimation accuracy, then the measurement precision is improved, but the loss of time increases due to longer processing requirements
Solution Approach 1:
The patent dynamically changes the filter parameters (number of taps and tap weights) based on measured spectral conditions and adjacent channel power levels. This allows the system to optimize the trade-off between estimation accuracy and processing time for different operational scenarios, rather than being constrained to fixed parameter values
Data Source
AI summary
A coherent optical receiver measures a portion of a spectra of a multi-channel optical signal that includes at least one signal adjacent to a selected signal. The coherent optical receiver determines structure and bandwidth information for the measured portion of spectra, and determines one or more filter parameters for the selected signal based on the structure and bandwidth information of the at least one signal adjacent to the selected signal. The coherent optical receiver adjusts one or more active filter parameters of a carrier phase estimator in the optical coherent receiver to have values corresponding to the determined one or more filter parameters.