OLT ONU Traffic Module In-Band OTDR Measurement
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Solution Overview
Problem
Conventional passive optical network (PON) architectures require dedicated ONUs for OTDR measurements, which complicate fault detection and maintenance due to the need for external devices and optical links, and often disrupt normal network operations.
Innovation Solution
An optical line terminal (OLT) integrated with an ONU traffic processing module that emulates a standard ONU, allowing for in-band OTDR measurements without disrupting network operations by using existing communication wavelengths and eliminating the need for dedicated optical links.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dedicated ONUs are used for OTDR measurements, then fault detection capability is improved, but device complexity and network disruption increase
Solution Approach 1:
The patent combines the OLT and ONU functionalities into a single integrated device. The OLT includes an integrated ONU module that can operate as both a line terminal and a network unit, eliminating the need for separate dedicated ONUs for OTDR measurements. This merging reduces device complexity while maintaining fault detection capabilities through the unified structure.
Solution Approach 2:
The integrated ONU module within the OLT provides multi-functionality by serving both as a line terminal for managing multiple ONUs and as a network unit for performing OTDR measurements. This universal design allows the same device to execute multiple functions without requiring additional dedicated hardware, thereby reducing overall network complexity.
2Reliability
If dedicated optical links are used for OTDR measurements, then measurement reliability is improved, but device complexity and cost increase
Solution Approach 1:
The existing communication wavelengths and optical infrastructure are utilized for dual purposes: normal data transmission and OTDR measurements. The integrated ONU module can perform measurements using the same optical links that carry traffic, eliminating the need for dedicated measurement wavelengths or separate optical paths. This approach maintains measurement reliability while reducing optical link complexity.
Solution Approach 2:
The system uses its own existing optical infrastructure and communication protocols to perform self-diagnosis through OTDR measurements. Rather than requiring external dedicated measurement equipment and links, the OLT with integrated ONU functionality leverages its own operational resources to conduct fault detection, thereby simplifying the optical link architecture.
3Measurement precision
If external OTDR devices are used, then measurement precision is improved, but ease of operation and network uptime deteriorate
Solution Approach 1:
The OTDR measurement functionality is merged directly into the OLT through the integrated ONU module. This integration eliminates the need for external OTDR devices and manual connections, allowing measurements to be initiated and executed directly from the network management system. The unified architecture simplifies operations while maintaining measurement precision through the same optical path analysis capabilities.
Solution Approach 2:
The system performs self-diagnosis by executing OTDR measurements internally through the integrated ONU module. The OLT can autonomously initiate measurements, process the reflected signals, and analyze fault conditions without requiring external equipment or manual intervention. This self-service capability improves ease of operation while maintaining continuous network uptime through automated monitoring.
4Duration of action of stationary object
If in-band measurements are performed, then network uptime is improved, but signal interference may increase
Solution Approach 1:
The integrated ONU module performs OTDR measurements in periodic time slots rather than continuously. During measurement intervals, the system temporarily suspends normal data transmission on the shared wavelength, conducts the OTDR measurement, then resumes normal operations. This periodic approach allows in-band measurements to be performed without causing continuous interference, maintaining network uptime by limiting interference to brief measurement windows.
Data Source
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AI summary
An OLT operable in a PON and structured to perform OTDR measurements. The OLT comprises an electrical module for generating continuous downstream signals and processing received upstream burst signals according to a communication protocol of the PON; an optical module for transmitting continuous optical signals over a first wavelength, receiving optical upstream burst signals over a second wavelength, and transmitting optical upstream burst signals over a third wavelength, wherein the optical module further includes an ONU traffic processing module being electrically coupled to the optical module and the electrical module, wherein the ONU traffic processing module is configured to emulate one of a plurality of ONUs of the PON, to generate an analysis pattern to be transmitted as an optical upstream burst signal over a third wavelength, and analyze an analysis pattern received in an optical upstream burst signal for the purpose of performing the OTDR measurements.