Digital Coherent Optical Signal Processing Tap Reduction
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Solution Overview
Problem
Existing adaptive equalization circuits in digital coherent optical transmission systems face increased computational complexity due to the exponential growth of tap coefficients, leading to inefficient processing.
Innovation Solution
A signal processing method that converts real and imaginary components of polarization multiplexed signals into frequency domain signals, performs complex conjugation and frequency inversion, and applies first and second equalization processing using complex transfer functions, followed by phase rotation and data bias correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If adaptive equalization is performed using conventional circuits with separate compensation for waveform distortion and device imperfections, then compensation accuracy is improved, but the total number of taps increases and calculation amount increases exponentially
Solution Approach 1:
The patent merges waveform distortion compensation and device imperfection compensation into a single adaptive equalization process. By combining these previously separate compensation functions, the system achieves accurate compensation for both types of distortions simultaneously without requiring separate tap coefficients for each function, thereby reducing the total number of taps while maintaining compensation accuracy.
Solution Approach 2:
The adaptive equalization circuit is designed to perform multiple functions simultaneously - it compensates for both waveform distortion in the transmission path and device imperfections in the transceiver through a unified processing approach. This multi-functional design allows a single set of tap coefficients to handle multiple compensation tasks, reducing overall system complexity.
2Productivity
If the number of taps is reduced to decrease calculation amount, then processing efficiency is improved, but compensation accuracy may deteriorate
Solution Approach 1:
By merging waveform distortion compensation and device imperfection compensation into one unified adaptive equalization process, the system achieves better compensation accuracy with fewer taps. The combined approach allows the same tap coefficients to serve dual purposes, improving processing efficiency while maintaining or enhancing compensation accuracy compared to separate compensation processes.
3Reliability
If separate compensation processes are used for waveform distortion and device imperfections, then each compensation function is optimized, but the overall processing time increases
Solution Approach 1:
The patent combines waveform distortion compensation and device imperfection compensation into a single parallel processing stage. By performing both compensation functions simultaneously in one process rather than sequentially, the system reduces overall processing time while maintaining the optimization benefits of dedicated compensation functions through proper signal processing architecture.
Data Source
AI summary
A signal processing method includes performing first equalization processing for converting a real component and an imaginary component of each polarization of a polarization multiplexed reception signal into a frequency domain signal, receiving, as input signals, a frequency domain signal of the real component and a frequency domain signal of the imaginary component of each polarization, and a signal obtained by performing frequency inversion on the frequency domain signal of the real component and the frequency domain signal of the imaginary component of each polarization and performing complex conjugate, performing, for each polarization, multiplying the real component and the imaginary component of each polarization by a complex transfer function, adding results, and performing inverse transform from the frequency domain signal to a time domain signal, performing second equalization processing for performing frequency inversion of the real component of each polarization included in the input signal, performing frequency inversion of a real component signal and an imaginary component subjected to complex conjugate, multiplying the imaginary component signals subjected to complex conjugation by a complex transfer function, adding results of the multiplications, and performing inverse transform from a frequency domain signal to a time domain signal, and adding or subtracting a transmission data bias correction signal to or from a signal obtained by adding a first addition signal to a second addition signal.