Nonlinear Lookup Unit for Coherent Optical Phase Error Compensation
Solution Overview
Problem
Existing carrier phase recovery systems in coherent optical communications face challenges such as hardware complexity, high heat dissipation, and inability to compensate for nonlinear phase errors, leading to phase ambiguity and cycle slips, which limit their applicability and efficiency.
Innovation Solution
A system and method using a feedforward phase correction (FFCR) with a nonlinear lookup unit (NL-LUU) and decision circuit to remove nonlinear phase errors and carrier phase noise, employing a linear filter and NL-LUT based phase correction for pattern-dependent compensation, which simplifies hardware implementation and compensates for phase distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional carrier phase recovery systems are used, then phase recovery function is provided, but hardware complexity increases and heat dissipation increases
Solution Approach 1:
The patent replaces complex hardware-based carrier phase recovery systems with a software-implemented solution running on a general-purpose processor. The phase recovery functionality is achieved through digital signal processing algorithms rather than dedicated hardware circuits, thereby reducing hardware complexity and heat dissipation while maintaining the required phase recovery reliability
Solution Approach 2:
The patent employs a general-purpose processor that can perform multiple functions including carrier phase recovery, signal processing, and data handling. This multi-functional approach eliminates the need for dedicated hardware components for each function, reducing overall system complexity and hardware requirements
2Reliability
If conventional carrier phase recovery systems are used, then phase recovery function is provided, but inability to compensate for nonlinear phase errors occurs
Solution Approach 1:
The patent implements advanced digital signal processing algorithms that dynamically adjust processing parameters to compensate for nonlinear phase errors. By changing the processing approach from fixed hardware characteristics to adaptive software-controlled parameters, the system achieves both high phase recovery accuracy and the ability to handle nonlinear phase distortions
Solution Approach 2:
The patent incorporates feedback mechanisms where the processed signal information is used to continuously refine and adjust the phase recovery process. This feedback loop enables the system to detect and compensate for nonlinear phase errors by comparing expected versus actual signal characteristics and adjusting processing accordingly
3Productivity
If conventional carrier phase recovery systems are used, then basic phase recovery is achieved, but phase ambiguity and cycle slips occur
Solution Approach 1:
The patent implements preliminary processing steps that prepare the signal before main phase recovery operations. By pre-processing the signal to reduce noise and preliminary estimate phase characteristics, the system achieves faster convergence and more reliable phase recovery, avoiding phase ambiguity and cycle slips that plague conventional systems
Data Source
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AI summary
An apparatus comprising a nonlinear lookup unit (NL-LUU) configured to add a phase shift to a signal sample to compensate for pattern dependent phase distortion, and one or more first phase adjustment units coupled to NL-LUU and configured to remove from the signal sample a nonlinear phase error from the NL-LUU, wherein the signal sample corresponds to a received signal polarization component of a polarization multiplexed (PM) coherent signal in a PM coherent optical system.