Adaptive Filter Coefficients for Optical Carrier Phase Recovery
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Solution Overview
Problem
Current digital phase recovery techniques in optical coherent receivers are suboptimal due to lack of adaptive optimization of filter coefficients, which does not account for the relative relationship of phase offset across symbols, leading to less than optimal performance.
Innovation Solution
A filter coefficient control apparatus that calculates autocorrelation and related statistics of the phase offset to determine optimal filter coefficients, allowing for adaptive optimization of the phase recovering apparatus without requiring a priori knowledge of channel or laser characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fixed filter parameters are used in digital phase recovery, then the system is simple to implement, but the phase recovery performance deteriorates when channel conditions vary
Solution Approach 1:
The patent implements feedback by using the detected phase offset statistics to dynamically adjust filter coefficients. The autocorrelation calculator continuously monitors phase offset characteristics, and the filter coefficient calculator uses this feedback to optimize filter parameters in real-time, creating a closed-loop adaptive system that maintains optimal performance under varying channel conditions.
Solution Approach 2:
The patent transforms the static filter parameters into dynamic adjustable parameters. Instead of using fixed filter coefficients, the system dynamically calculates optimal filter coefficients based on real-time phase offset statistics, allowing the filter to adapt its characteristics to match current channel conditions and maximize phase recovery performance.
2Measurement precision
If filter parameters are optimized for specific channel conditions, then phase recovery accuracy improves, but the system cannot adapt to varying real-world conditions
Solution Approach 1:
The system performs self-service by automatically detecting its own channel conditions through phase offset estimation and using this self-detected information to optimize its filter parameters. The autocorrelation calculator analyzes the actual phase offset statistics from the received signal, and the filter coefficient calculator automatically adjusts coefficients based on this self-measured data, eliminating the need for external channel knowledge or manual configuration.
Solution Approach 2:
The patent dynamically changes filter parameters based on detected phase offset characteristics. The filter coefficient calculator adjusts filter coefficients in real-time according to the statistical properties of phase offset measured by the autocorrelation calculator, allowing the system to adapt filter behavior to match actual channel conditions and maximize recovery accuracy under varying conditions.
3Adaptability or versatility
If real-time detection of channel characteristics is performed, then adaptive filter optimization becomes possible, but the detection complexity and computational burden increase
Solution Approach 1:
The patent extracts only the essential information needed for adaptation - the phase offset statistics and autocorrelation characteristics - from the complex received signal. By focusing computation on calculating these specific statistical parameters rather than analyzing all signal characteristics, the system achieves real-time adaptability with reduced computational complexity.
Solution Approach 2:
The system performs preliminary action by pre-establishing the relationship between phase offset statistics and optimal filter coefficients. The filter coefficient calculator uses the detected autocorrelation data to directly compute optimal coefficients without requiring complex real-time optimization algorithms, thereby reducing computational burden while maintaining real-time adaptation capability.
Data Source
AI summary
This invention relates to an apparatus and a method for controlling a filter coefficient. The filter coefficient control apparatus controls a coefficient of a filter of a phase recovering apparatus, and comprises a phase offset obtaining means, for obtaining a phase offset between a carrier and a local oscillation; an autocorrelation calculating means, for calculating an autocorrelation and related statistics of the phase offset; and a filter coefficient determining means, for determining the coefficient of the filter in accordance with the autocorrelation and related statistics.