Noisy Window Method for Uncalibrated ONU Activation
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Solution Overview
Problem
In multi-wavelength passive optical networks, activating uncalibrated ONUs with weak transmitter pre-calibration properties disrupts communication bandwidth for other ONUs, as the conventional quiet window method requires suppressing all upstream transmission bursts across all channels, leading to bandwidth wastage and service impact.
Innovation Solution
The Noisy Window method introduces a time interval where unmodulated or low-frequency signals are transmitted to allow uncalibrated ONUs to calibrate their channels without interfering with active ONUs, using a Serial_Number_Mask message for set splitting and power grants to isolate and calibrate the activation channel, minimizing bandwidth impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conventional quiet window method is used to activate uncalibrated ONUs, then the ONUs can be activated and calibrated, but the communication bandwidth for other ONUs is disrupted and bandwidth is wasted
Solution Approach 1:
The patent divides the upstream wavelength channels into multiple groups and activates uncalibrated ONUs on specific channels within designated time intervals rather than suppressing all channels. This segmentation allows calibration to proceed while other channels continue normal operations, resolving the contradiction between reliable ONU activation and bandwidth efficiency.
2Reliability
If the conventional quiet window method is used to activate uncalibrated ONUs, then the ONUs can be activated and calibrated, but service quality for other ONUs deteriorates
Solution Approach 1:
The patent segments the network operations into calibration periods and normal operation periods across different wavelength channels. During calibration, only specific channels are affected while others continue serving active ONUs, thereby maintaining service quality while enabling reliable activation.
Solution Approach 2:
The patent applies calibration activities locally to specific wavelength channels and time intervals rather than globally across all channels. This localized approach ensures that calibration operations do not degrade service quality for active ONUs on other channels.
3Device complexity
If uncalibrated ONUs are activated without pre-calibration, then device complexity is reduced, but the activation process disrupts communication bandwidth
Solution Approach 1:
The patent enables uncalibrated ONUs to perform self-calibration by transmitting unmodulated signals on designated channels during specific time intervals. The OLT identifies these signals and provides feedback, allowing calibration without complex pre-calibration equipment while minimizing bandwidth impact through channel segmentation.
Solution Approach 2:
The patent implements self-service calibration where uncalibrated ONUs autonomously transmit calibration signals and receive feedback from the OLT to adjust their transmitters. This eliminates the need for complex external pre-calibration equipment while enabling activation with minimal bandwidth disruption through the noisy window mechanism.
Data Source
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AI summary
A method of Noisy Window and associated management messages to support set splitting if activating ONUs with uncalibrated transmitter, offering a power grant for unmodulated upstream transmission, measuring the average received optical power in all upstream wavelength channels and providing downstream indication of the upstream wavelength channel with abnormally high average received power.