PON Supervision via Wavelength-Adapted OTDR Signals
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Solution Overview
Problem
Existing solutions for supervising Passive Optical Networks (PONs) are costly, require expensive custom OTDR devices and wavelength-specific components, and can only detect significant fiber link faults, failing to meet requirements for non-invasive, low-power detection and efficient monitoring.
Innovation Solution
A Wavelength Adaptation Module and Remote Node system that adapts OTDR signals by phase modulating and filtering them to select a specific wavelength, allowing a splitter to forward the signal to a dedicated group of ONTs, enabling efficient fault detection and reduction of service downtime and maintenance costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing supervision solutions are implemented, then fault detection capability is provided, but capital expenditures significantly increase due to custom OTDR devices and wavelength-specific components
Solution Approach 1:
The OLT transmitter is upgraded to perform both data communication and OTDR signal transmission functions. The single OLT transmitter generates both data signals and OTDR supervision signals, eliminating the need for separate custom OTDR devices and reducing capital expenditures while maintaining fault detection capability
Solution Approach 2:
The patent combines data communication and OTDR supervision functions into a single optical infrastructure. By merging these functions and using wavelength-specific components only where necessary for signal separation, the solution reduces overall system cost while maintaining supervision capability
2Reliability
If wavelength-specific components are added to fibre links, then OTDR signal supervision is enabled, but power budget is reduced
Solution Approach 1:
The patent segments the optical network into different wavelength channels, with data communication and OTDR supervision operating on separate wavelengths. This allows wavelength-specific components to be placed only at the OLT and RN, not throughout the entire fibre link, minimizing power budget impact
Solution Approach 2:
The Remote Node (RN) acts as an intermediary that receives the OTDR signal on one wavelength and forwards it to dedicated ONTs on the same wavelength. This intermediary function enables supervision without requiring wavelength-specific components in every drop link, preserving power budget
3Reliability
If advanced OLT transmitter upgrades are implemented, then light path doubling is achieved, but device complexity increases
Solution Approach 1:
The OLT transmitter is upgraded to generate multiple wavelengths simultaneously, with data communication and OTDR supervision operating on different wavelengths. This parameter change (wavelength multiplication) enables light path doubling without requiring physically separate transmitters, managing complexity through wavelength domain separation
4Reliability
If existing monitoring solutions are used, then fault detection is provided, but only faults with loss greater than 5 dB can be detected, far above the expected threshold of 1 dB
Solution Approach 1:
The system performs periodic OTDR measurements by injecting OTDR pulses at regular intervals. This periodic action allows accumulation of measurement data over time, enabling detection of smaller faults (1 dB threshold) through temporal averaging and repeated observations that would be invisible in single measurements
Solution Approach 2:
The system implements feedback by continuously monitoring back-scattered OTDR signals and comparing them against baseline measurements. This feedback mechanism enables detection of small deviations (1 dB threshold) through cumulative analysis of multiple measurements, improving sensitivity beyond what single measurements can achieve
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 accurate and sensitive fault detection in PONs with reduced capital expenditures, using a single wavelength channel for multiple ONTs and allowing passive Remote Nodes, thus improving monitoring efficiency and cost-effectiveness.
Implementation Method 1
receiving an OTDR signal comprising at least one main carrier and phase modulating the received OTDR signal, thereby producing a plurality of spectral modes around the main carrier of the received OTDR signal
Implementation Method 2
filtering the phase modulated OTDR signal, thereby selecting one of the spectral modes of the received OTDR signal, the selected spectral mode of the received OTDR signal constituting a new OTDR signal having a selected or tuned wavelength
Implementation Method 3
The selected wavelength of the new OTDR signal enables a splitter in the RN to forward the new OTDR signal to a dedicated group of ONTs in the PON
Data Source
AI summary
A Wavelength Adaptation Module and a method therein for adapting an Optical Time Domain Reflectometry, OTDR, signal for supervision of Optical Network Terminals, ONTs, in a Passive Optical Network, PON, are provided. The wavelength of the OTDR signal is adapted to have a selected wavelength to enable a splitter in a remote node to forward the OTDR signal to a dedicated group of ONTs in the PON, thereby supervising the fiber links between the remote node and the dedicated group of ONTs. Likewise, a remote node and a method therein for receiving an OTDR signal having a pre-selected wavelength from the Wavelength Adaptation Module and for outputting the OTDR signal to a dedicated group of ONTs with regards to the pre-selected wavelength of the received OTDR signal are provided.