Optical Network Supervision via Wavelength Routing
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Solution Overview
Problem
Existing solutions for supervising optical fibers in Passive Optical Networks (PONs) are costly, require significant bandwidth, and are not sensitive enough to detect faults below 5 dB loss, often necessitating additional equipment and complex upgrades, which increases capital expenditures and disrupts regular data communication.
Innovation Solution
The method involves creating test signals of different monitoring wavelengths associated with predefined groups of Optical Network Terminals (ONTs) and routing them through a Remote Node, allowing identification of faulty fibers based on back-scattered and back-reflected signals, using components like Optical Time-Domain Reflectometry (OTDR) and External Wavelength Adaption Modules (EWAM), without requiring additional monitoring functionality on the ONT side and using a dedicated monitoring fiber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional OTDR supervision methods are used, then fault detection capability is achieved, but the system requires significant bandwidth and additional equipment, increasing capital expenditures
Solution Approach 1:
The patent makes the Remote Node serve dual functions: it acts as both a signal distributor for data communication and a wavelength router for supervision signals. By integrating the supervision functionality into existing network infrastructure rather than adding separate monitoring equipment, the system achieves fault detection capability without proportionally increasing device complexity or capital expenditures
Solution Approach 2:
The patent introduces wavelength division multiplexing as an intermediary mechanism to separate supervision traffic from data traffic. By assigning specific wavelengths exclusively for supervision signals, the system enables reliable fault detection while avoiding interference with data communication and eliminating the need for additional physical monitoring equipment
2Measurement precision
If dedicated monitoring wavelengths are assigned to each ONT, then accurate fault identification is achieved, but the bandwidth consumption increases significantly
Solution Approach 1:
The patent segments the network into groups of ONTs, with each group assigned a specific monitoring wavelength. This segmentation allows multiple ONTs to share the same wavelength resource, reducing total bandwidth consumption while maintaining sufficient fault identification capability through the hierarchical grouping structure
Solution Approach 2:
The patent merges multiple ONTs into groups that share common monitoring resources. By combining the supervision needs of multiple ONTs under a single wavelength assignment, the system achieves accurate fault identification at the group level without requiring dedicated wavelengths for each individual ONT, thereby reducing overall bandwidth consumption
3Reliability
If supervision signals are sent continuously, then real-time monitoring is achieved, but regular data communication is disrupted
Solution Approach 1:
The patent implements periodic supervision signal transmission instead of continuous transmission. By sending test signals at predetermined intervals rather than continuously, the system achieves real-time monitoring capability while minimizing disruption to regular data communication, as the periodic nature allows data traffic to flow uninterrupted between supervision cycles
Solution Approach 2:
The patent uses preliminary wavelength assignment where specific wavelengths are pre-designated for supervision purposes before data transmission begins. This preliminary configuration allows supervision signals to be injected at predetermined wavelengths that do not conflict with data communication wavelengths, enabling real-time monitoring without disrupting data traffic
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 enables efficient and accurate supervision of optical fibers with minimal impact on regular data communication, reduces initial investment, and detects faults with lower power fluctuations, using a smaller number of monitoring wavelengths to cover a larger number of ONTs, thus optimizing network performance.
Implementation Method 1
a back-scattered and back-reflected OTDR signal may be used for estimating the fibre's length and overall attenuation... a 'back-scattered' signal basically originates from any reflections along a fibre caused by a phenomena called Rayleigh Backscattering
Data Source
AI summary
Methods and apparatuses for enabling supervision of fibers in an optical communication network, where a Central Office provides data signals to a Remote Node for distribution to Optical Network Terminals (ONTs). The Central Office generates and sends test signals of different monitoring wavelengths associated to predefined groups of said ONTs, to the Remote Node. The Remote Node routes each test signal to a corresponding associated group of ONTs according to the wavelength of the test signal. When receiving a back-scattered and back-reflected test signal caused by a faulty optical fiber, the Central Office is able to identify the faulty optical fiber based on the wavelength of the back-scattered and back-reflected signal.