ODN Detection Using Shared Wavelength Test Windows
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Solution Overview
Problem
Current methods for detecting fiber link issues in Optical Distribution Networks (ODNs) are complex and costly, particularly when they require different wavelengths for test and data signals, disrupting downlink data transmission and necessitating additional hardware.
Innovation Solution
A method and system that utilize a test window to send a test excitation signal with the same wavelength as uplink data, allowing for time-domain or frequency-domain analysis without interrupting downlink data transmission, and without the need for additional hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a test signal with a different wavelength is used for ODN detection, then the detection can be performed, but additional hardware (filter) is required and cost increases
Solution Approach 1:
The patent changes the wavelength parameter of the test signal to match the uplink data transmission wavelength. This parameter alignment allows the test signal to share the same transmission path and receiver as uplink data, eliminating the need for additional wavelength filtering hardware while maintaining detection capability
Solution Approach 2:
The uplink wavelength is made to serve dual purposes: carrying both data transmission and test detection functions. By using the same wavelength for both uplink data and test signals, the system achieves multi-functionality without requiring separate hardware paths or additional filters
2Measurement precision
If amplitude modulation control is applied to downlink laser for test signal superposition, then test signals can be inserted, but the processing difficulty increases due to weak reflected and scattered signals
Solution Approach 1:
The patent extracts the test detection function from the downlink path and relocates it to the uplink path. By sending test signals in the uplink direction rather than superposing them on downlink data, the system avoids the complexity of amplitude modulation control and the challenge of detecting weak reflected/scattered signals from downlink signals
3Device complexity
If a test window is introduced for test signal transmission, then detection can be performed without additional hardware, but downlink data transmission may be affected
Solution Approach 1:
The patent employs periodic action by allocating specific time windows (test windows) within the TDMA framework for test signal transmission. During these periodic intervals, test signals are sent in the uplink direction while downlink transmission continues, ensuring both detection functionality and continuous data service
4Adaptability or versatility
If different wavelengths are used for uplink and downlink, then wavelength division multiplexing is achieved, but test signal detection requires additional filtering hardware
Solution Approach 1:
The patent changes the wavelength parameter of the test signal to match the uplink wavelength rather than using a separate test wavelength. This parameter alignment allows the test signal to be indistinguishable from uplink data at the receiver, eliminating the need for additional wavelength-based filtering hardware while maintaining the wavelength division multiplexing structure for uplink and downlink
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
This approach simplifies the detection process, maintains uninterrupted downlink signal sending, and reduces costs by eliminating the need for extra functional modules or hardware, while providing accurate line evaluation information.
Implementation Method 1
receiving, by the central office subsystem, an optical signal reflected and/or scattered by the ODN
Implementation Method 2
receiving, by the central office subsystem, an optical signal reflected and/or scattered by the ODN
Data Source
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AI summary
A detecting method, an apparatus, and a system in an Optical Distribution Network (ODN) are provided. The method includes: an Optical Line Termination (OLT) reserves a test window, and an Optical Network Unit (ONU) stops sending an uplink signal in the test window, the OLT emits a downlink test signal having a wavelength the same as that of the uplink signal in the test window, the OLT receives backward signals of the downlink test signal, in which the backward signals include a backward scattered signal and a backward reflected signal, processes the backward signals, and obtains state information of the ODN according to the backward signals. The method does not need to add other hardware, and the downlink signal is sent normally in the downlink. The implementation is low in the cost and easy in the technology.