Coupled Phase Recovery for Adjacent-Channel Optical Interference
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Solution Overview
Problem
Existing optical communication systems face challenges in phase recovery due to interference from adjacent channels, leading to false phase estimations and reduced processing efficiency, particularly in high-speed and high-order modulation formats like 100 Gbit/s CP-QPSK, where symbol rate reduction increases robustness against distortions but also complicates processing.
Innovation Solution
A method for phase recovery that involves pre-correction of each channel's phase independently before applying a coupling factor to superimpose phases from adjacent channels, allowing for efficient consideration of adjacent channel interference and adaptive adjustment of coupling factors based on fiber length and input power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If phase estimation is performed independently for each channel, then processing complexity is reduced, but phase estimation accuracy deteriorates due to adjacent channel interference
Solution Approach 1:
The patent merges the phase estimation process across multiple channels by introducing a coupling factor that combines phase information from different channels. Instead of estimating phases independently, the method superimposes phase estimates from different channels using coupling factors, thereby capturing adjacent channel interference effects and improving overall phase estimation accuracy while maintaining manageable processing complexity through structured combination rather than complete independent processing
2Productivity
If higher order modulation formats are used, then bandwidth efficiency is improved, but robustness against distortions deteriorates
Solution Approach 1:
The patent applies preliminary action by performing pre-correction of phase estimates before final phase recovery. The method estimates phases independently as a preliminary step, then uses coupling factors to combine these preliminary estimates while accounting for adjacent channel effects. This preliminary independent estimation followed by corrective combination allows the system to handle high-order modulation formats with improved robustness against distortions like chromatic dispersion and polarization mode dispersion
3Reliability
If symbol rate is reduced, then robustness against optical distortions is improved, but processing speed requirements increase
Solution Approach 1:
The patent changes the parameter of phase estimation approach from completely independent per-channel estimation to coupled estimation using superposition with coupling factors. This parameter change in the estimation methodology allows the system to maintain lower processing speeds (higher robustness) while still achieving accurate phase recovery by leveraging the structured relationship between channels through the coupling factor mechanism
Data Source
AI summary
A method and a device are provided for phase recovery of at least two channels comprising the steps of (i) a phase is estimated for each channel; (ii) the phase estimated of each channel is superimposed by a coupling factor with at least one other phase estimated. Further, a communication system is suggested comprising such a device.