Optical Network Fault Detection via Integrated OTDR
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Solution Overview
Problem
Passive optical network communication systems lack effective methods for monitoring the performance and optical properties of optical links, particularly in large networks, where optical faults can degrade performance and require costly and disruptive testing.
Innovation Solution
An optical network communication system that sends a downstream data message and a continuous OTDR broadcast pattern at different wavelengths, using a broadband photo detector to receive an OTDR reflected response pattern during unused time slots to detect and calculate error distances along the optical fiber, allowing for real-time fault detection without disrupting the network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external OTDR testing is used to detect optical faults, then fault detection capability is provided, but network disruption occurs and testing costs increase
Solution Approach 1:
The patent combines OTDR testing functionality with the downstream data transmission function by integrating an OTDR transmitter into the optical line terminal. This allows the same infrastructure to perform both data communication and optical fault detection, eliminating the need for separate external testing equipment and enabling continuous monitoring without network disruption.
Solution Approach 2:
The system performs preliminary optical fault detection by continuously transmitting OTDR test signals along with data signals. This proactive approach allows faults to be detected before they cause network failures, enabling preventive maintenance and reducing the need for disruptive reactive testing.
2Reliability
If OTDR testing is performed continuously, then real-time fault detection is achieved, but interference with upstream data messages occurs
Solution Approach 1:
The system uses periodic action by utilizing unused upstream time slots for OTDR signal detection. The TDMA protocol creates periodic opportunities for fault detection without continuous interference, as testing occurs only during designated idle periods in the upstream transmission schedule.
Solution Approach 2:
The patent introduces wavelength division multiplexing as an intermediary mechanism, using different wavelengths for downstream data, upstream data, and OTDR testing. This allows multiple signals to coexist on the same optical fiber without interference, with the broadband photo detector selectively receiving OTDR reflections at the specific test wavelength during unused time slots.
3Reliability
If monitoring is added to the optical terminal, then optical link performance is monitored, but device complexity increases
Solution Approach 1:
The optical terminal is designed with multi-functionality by integrating OTDR testing capabilities into the existing downstream transmitter. The same optical path and photo detector used for data reception are utilized for OTDR signal detection, eliminating the need for separate dedicated testing hardware and reducing overall system complexity.
Solution Approach 2:
The system provides self-service monitoring where the optical terminal autonomously performs OTDR testing and fault detection without requiring external testing equipment or manual intervention. The integrated OTDR functionality enables the network to self-diagnose optical link conditions, reducing operational complexity.
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
Enables real-time optical fault detection and location within the optical network, reducing the need for external testing and improving network performance and reliability by integrating OTDR functionality into the optical subassembly.
Implementation Method 1
receiving an OTDR reflected response pattern on a broadband photo detector during an open time slot
Data Source
AI summary
A system and method of operation of an optical network communication system includes: an optical fiber; an optical link attached to the optical fiber; a data transmitter for sending a downstream data message at a downstream data wavelength in the optical link; an optical time domain reflectometry (OTDR) transmitter for sending a OTDR broadcast pattern continuously at an OTDR wavelength different from the downstream data wavelength in the optical link; a broadband photo detector coupled to the optical fiber; and an OTDR receiver for receiving an OTDR reflected response pattern on the broadband photo detector during an open time slot not used for receiving an upstream data message for indicating an optical fault and for calculating an error distance along the optical fiber based on the optical fault.