Polarization Tracking Speed Estimation for Optical Links
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Solution Overview
Problem
Coherent optical communication systems face performance degradation due to fast polarization changes and polarization dependent loss in optical fiber links, which existing adaptive equalization techniques struggle to track effectively.
Innovation Solution
A polarization change tracking apparatus and method that estimates polarization change speed and sets a response coefficient to synchronize polarization tracking and adaptive equalization, ensuring continuous response and compensation for polarization changes in the optical link.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the AEQ update rate is increased to track fast polarization changes, then the tracking speed is improved, but the system complexity and computational burden increase
Solution Approach 1:
The patent divides polarization tracking into two segments: fast polarization tracking for rapid changes and adaptive equalization for slower variations. This segmentation allows each component to operate at optimized speeds, with the fast tracker handling Mrad-level changes while AEQ manages krad-level changes, reducing overall system complexity while maintaining tracking performance
Solution Approach 2:
The patent implements dynamic adjustment of the response coefficient based on estimated polarization change speed. When fast polarization changes are detected, the response coefficient is increased to accelerate tracking; when changes are slower, the coefficient is reduced to decrease computational burden. This dynamic adaptation resolves the contradiction between tracking speed and system complexity
2Speed
If the response coefficient of polarization tracking is increased to track fast polarization changes, then the tracking response is improved, but the stability and convergence of adaptive equalization deteriorate
Solution Approach 1:
The patent applies different response coefficients to different components based on their specific requirements. The fast polarization tracker uses a higher response coefficient optimized for rapid tracking, while the adaptive equalization uses a lower response coefficient optimized for stability. This local optimization of parameters resolves the contradiction between tracking response and AEQ stability
Solution Approach 2:
The patent introduces an intermediary mechanism that estimates polarization change speed and dynamically adjusts the response coefficient accordingly. This intermediary controls the transition between fast tracking mode and stable AEQ mode, ensuring that high response coefficients are only used when necessary, thereby maintaining both tracking performance and AEQ stability
3Ease of manufacture
If conventional AEQ algorithms are used, then the system is simple to implement, but the performance significantly reduces when fast RSOP of Mrad magnitude occurs
Solution Approach 1:
The patent merges fast polarization tracking with adaptive equalization into a unified system. The fast tracker handles rapid polarization changes that conventional AEQ cannot track, while the AEQ component maintains stability and handles slower variations. This combination preserves the simplicity of conventional AEQ implementation while adding the reliability needed for fast RSOP tracking through the integrated fast tracking component
Data Source
AI summary
A polarization change tracking apparatus, a processing apparatus for a received signal and methods thereof. The polarization change tracking method includes: estimating a polarization change speed in a link according to a received signal; setting a response coefficient of polarization tracking according to a relationship between an estimated polarization change speed and a predetermined value, to make a response of polarization tracking and a response of adaptive equalization be consecutive; and performing compensation for polarization change on the received signal according to a set response coefficient of polarization tracking.