Signal Processing Circuit for Polarization Multiplexing Optical Communication
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Solution Overview
Problem
Optical phase modulation methods, such as those using 16 QAM, face challenges in accurately compensating phase deviations due to noise, leading to degraded signal waveforms and errors in phase compensation, which can result in inaccurate data regeneration in high-speed optical communication systems.
Innovation Solution
A signal processing circuit that includes optical frequency deviation and phase deviation estimating and compensating means to accurately calculate and compensate for frequency and phase deviations between optical carrier waves and local light, using algorithms like the M-th Power Algorithm and CMA, to restore the original constellation and improve data regeneration accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If optical phase modulation methods (such as 16 QAM) are used to increase transmission capacity, then the transmission rate is improved, but noise influence increases leading to degraded signal waveforms and errors in phase compensation
Solution Approach 1:
The patent segments the phase compensation process into multiple stages: initial phase compensation based on pilot signals, followed by refined phase compensation using decision-directed methods. This segmentation allows the system to handle high-order modulation formats like 16 QAM by breaking down the complex compensation task into manageable steps, thereby maintaining signal quality at high transmission rates
Solution Approach 2:
The patent implements feedback mechanisms where the compensated signal is re-evaluated and the compensation parameters are continuously adjusted. The system uses the output of the phase compensation to refine subsequent compensation operations, creating a closed-loop system that adapts to noise conditions and maintains reliability in high-rate transmissions
2Measurement precision
If phase compensation algorithms are applied to correct optical phase deviation, then data regeneration accuracy is improved, but calculation errors due to noise increase
Solution Approach 1:
The patent applies preliminary phase compensation using pilot signals or training sequences before the main data processing. This preliminary action establishes a reference frame and reduces the impact of phase deviations on subsequent data regeneration, thereby improving accuracy while minimizing error propagation in noisy environments
Solution Approach 2:
The patent dynamically adjusts compensation parameters such as phase rotation angles and filtering coefficients based on signal quality metrics. By changing these parameters adaptively, the system optimizes the balance between compensation accuracy and noise suppression, preventing calculation errors from degrading the regenerated data
3Stability of the object's composition
If frequency deviation compensation is performed to align optical carrier wave frequency with local light frequency, then phase synchronization is improved, but system complexity increases
Solution Approach 1:
The patent combines frequency deviation compensation and phase deviation compensation into a unified signal processing framework. By merging these functions, the system achieves phase synchronization without requiring separate complex circuits for each function, thereby reducing overall system complexity while maintaining synchronization stability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed solution effectively reduces noise influence and improves the accuracy of phase compensation, enabling reliable data regeneration and enhancing the transmission characteristics of high-speed optical communication systems.
Implementation Method 1
a light receiving element which receives an output of the 90 degrees hybrid outputs a beat signal between the signal light and the local light
Data Source
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AI summary
In order to reduce influence of noise due to a phase deviation, and to estimate an amount of phase compensation with superior accuracy in a polarization multiplexing/demultiplexing optical communication system, a signal processing circuit includes: optical frequency deviation estimating unit for estimating a frequency deviation which is a difference between a frequency of local light and a frequency of the optical carrier wave which is included in a signal data which corresponds to the polarizations and are generated by mixing a plurality of the optical carrier waves with the local light, which optical carrier wave is phase-modulated and have polarizations able to be demultiplexed and for outputting the estimated frequency deviation as an estimated value; for outputting the estimated frequency deviation as an estimated value; optical frequency deviation compensation amount analyzing unit for calculating an amount of frequency compensation which is an amount of compensation to make a phase of the signal data rotated so as to reduce the frequency deviation, on the basis of a plurality of the estimated values estimated per the signal data; optical frequency deviation compensating unit for making the phase of the signal data rotated correspondingly to the amount of the frequency compensation; optical phase deviation estimating unit for estimating a phase deviation included in each of input signal data and is a difference between a phase of the optical carrier wave and a phase of the local light; and optical phase deviation compensating unit for making the phase of the signal data rotated correspondingly to the phase deviation.