Optical Protection Switching for Single Fibre Bidirectional WDM Rings
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing protection schemes for single fibre bidirectional WDM optical rings are costly and inefficient, particularly in ring network topologies, as they require duplication of transceivers and complex switching mechanisms, and do not effectively manage fibre breaks without causing signal overlap.
Innovation Solution
An optical protection switching apparatus with a first and second port, an optical splitter, an optical switch, and processing circuitry that uses an out-of-band probe signal to detect fibre continuity or discontinuity, controlling the switch to broadcast or isolate the WDM aggregate optical signal accordingly, ensuring all nodes are reached without signal overlap during fibre breaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical switching based protection scheme is implemented, then transmission protection is provided, but cost increases due to duplication of WDM transceivers and requirement for electrical switching at both main node and remote nodes
Solution Approach 1:
The patent extracts the switching function from remote nodes and concentrates it only at the main node. The protection mechanism uses a single optical switch at the main node to redirect traffic, eliminating the need for switching mechanisms at remote nodes. This extraction of the switching function resolves the contradiction by maintaining protection capability while reducing device complexity and cost.
Solution Approach 2:
The optical switch at the main node serves multiple functions: it handles both working and protection traffic routing, and can accommodate multiple wavelength channels simultaneously. This multi-functionality allows a single device to provide protection for the entire WDM system without requiring separate transceivers and switches at each node, thereby reducing overall system complexity while maintaining reliability.
2Reliability
If per-channel switching is implemented, then channel-specific protection is provided, but device complexity increases due to requiring two switches for each wavelength channel
Solution Approach 1:
The patent merges the protection function for all wavelength channels into a single optical switch at the main node. Instead of having separate switches for each channel, the optical switch handles all channels simultaneously by routing optical signals directly without electrical conversion. This consolidation reduces the number of switches from two per channel to a single multi-channel switch, resolving the contradiction between channel-specific protection and device complexity.
3Device complexity
If per-band switching is implemented, then the number of switches is reduced to the number of bands, but signal overlap may occur during fibre breaks
Solution Approach 1:
The patent introduces an out-of-band probe signal as an intermediary to detect fibre continuity. This probe signal, transmitted at a wavelength outside the WDM bands, serves as a mediator to detect fibre breaks without interfering with working traffic. The detection of probe signal loss triggers the optical switch to redirect traffic, preventing signal overlap by ensuring that protection switching only activates when actual fibre breaks are detected, thus maintaining reliability while using fewer switches.
4Quantity of substance
If optical fiber is minimized in the fronthaul network, then resource efficiency is improved, but protection capability may be compromised
Solution Approach 1:
The patent implements preliminary protection routing configuration at the main node, where the optical switch is pre-configured with protection paths for all possible fibre break scenarios. This preliminary setup ensures that when a fibre break occurs, protection switching can immediately redirect traffic without requiring additional physical fibres or complex real-time reconfiguration, thus maintaining protection capability while minimizing the number of fibres deployed in the fronthaul network.
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
The solution provides a simple, cost-effective protection scheme that ensures all nodes in a single fibre bidirectional WDM optical ring are reachable without signal overlap, even during fibre breaks, while maintaining compatibility with existing passive filter technology and minimizing latency.
Implementation Method 1
an optical splitter configured to receive a WDM aggregate optical signal and output a first and second optical signal
Implementation Method 2
an optical switch configured to connect the second output of the optical splitter to the second port when a said out-of-band probe signal is not detected at the optical detection apparatus
Implementation Method 3
The optical detection apparatus is configured to detect a said out-of-band probe optical signal received at the second port
Implementation Method 4
The optical routing apparatus is configured to deliver an out-of-band probe optical signal to the first port
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Optical protection switching apparatus (10), for a single fibre bidirectional WDM optical ring, comprising: first (12) and second (14) ports for coupling to first and second adjacent portions of a single fibre bidirectional WDM optical ring; an optical splitter (16) comprising an input to receive a WDM aggregate optical signal, and first and second outputs coupled to the first and second ports; an optical switch (108) between the second output and the second port; and processing circuitry (24) to receive at least one of an indication of transmission continuity in the optical ring and an indication of transmission discontinuity in the optical ring, and to generate a switch control signal (20) comprising instructions to cause the optical switch to be open when there is transmission continuity in the optical ring and to cause the optical switch to be closed when there is transmission discontinuity in the optical ring.