WSS Frequency Offset Detection Using Preset Channel Calibration
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Solution Overview
Problem
In high-speed optical transmission systems, frequency offsets in wavelength selective switches (WSS) cause signal quality deterioration and service impairment due to asymmetric filtering, especially in multi-level WSS cascading, and current methods fail to precisely detect these offsets, leading to significant reductions in channel filtering bandwidth.
Innovation Solution
A frequency offset processing method and apparatus that determines the frequency offset of a WSS by using a preset channel to establish a correspondence between frequency offset and wavelength or pixel position, allowing for accurate detection and calibration of the traffic channel's frequency offset, thereby improving signal transmission quality and preventing service interruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequency offset is not detected and calibrated, then the system operates without additional detection mechanisms, but signal quality deteriorates and service impairment occurs due to asymmetric filtering
Solution Approach 1:
The patent makes the WSS device itself perform frequency offset detection by utilizing its existing filtering function. The WSS filters a broadband light signal at different wavelengths and the detector measures optical power across wavelengths, allowing the same device to both switch traffic and detect frequency offsets, thereby improving reliability without adding separate detection equipment.
Solution Approach 2:
The system performs self-diagnosis by using the WSS to detect its own frequency offset. The controller directs the WSS to filter signals at specific wavelengths corresponding to preset channels, and the detector measures the optical power to determine the frequency offset of the traffic channel, enabling the system to monitor and calibrate itself without external intervention.
2Productivity
If multi-level WSS cascading is used to improve transmission efficiency, then bandwidth utilization increases, but the impact of frequency offset becomes more severe resulting in significant reduction in overall filtering bandwidth
Solution Approach 1:
The patent implements a feedback mechanism where the detector continuously measures optical power at different wavelengths and reports to the controller. The controller calculates the frequency offset based on these measurements and adjusts the WSS tuning wavelength accordingly, creating a closed-loop system that compensates for frequency drift and maintains filtering bandwidth in multi-level cascaded configurations.
Solution Approach 2:
The system performs preliminary frequency offset detection and calibration before actual traffic transmission. The controller configures the WSS to detect preset channels first, determines the frequency offset, and calibrates the traffic channel wavelength in advance, ensuring optimal filtering performance before production use.
3Ease of operation
If frequency offset detection is not performed, then the system operates simpler without detection procedures, but center wavelength shifts due to temperature, pressure, vibration, and aging cause service impairment
Solution Approach 1:
The patent replaces complex mechanical wavelength measurement systems with an optical measurement approach. Instead of using separate wavelength meters or mechanical scanning systems, the WSS itself performs optical filtering and the detector measures optical power across wavelengths, using the relationship between wavelength and frequency offset to determine the traffic channel's frequency offset, thereby maintaining measurement precision while simplifying operation.
Data Source
AI summary
A frequency offset processing method, apparatus, and a storage medium, where the method includes: determining a frequency offset of a preset channel in a wavelength selective switch (WSS); determining a correspondence between a frequency offset and a wavelength or a correspondence between a frequency offset and a pixel position based on the frequency offset of the preset channel; and determining a frequency offset of a traffic channel according to the determined correspondence.