WSS Passband Loading with Downstream ROADM State Feedback
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Solution Overview
Problem
Optical networks face significant delays in link turn-up/turn-down times due to multiple loading cycles required to manage optical power changes caused by Stimulated Raman Scattering (SRS) effects, especially in C+L optical line systems, where loading decisions are conservative and lack visibility of downstream ROADM signal status.
Innovation Solution
The system accounts for the band signal status of the immediate downstream ROADM to make more aggressive loading decisions on the local ROADM, reducing the number of loading cycles by activating or deactivating passbands based on downstream signal activation, using a processor, ASE source, WSS, and orchestrator application to manage optical service loading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conservative loading decisions are made without visibility of downstream ROADM signal status, then optical power changes due to SRS effects are managed, but link turn-up/turn-down times are significantly delayed
Solution Approach 1:
The system implements feedback by monitoring the downstream band signal status and using this information to dynamically adjust loading decisions. The loading manager receives feedback about whether downstream ROADMs are in signal present or absent states, and adjusts the loading cycle aggressiveness accordingly, resolving the contradiction between maintaining optical power stability and reducing turn-up/turn-down time.
Solution Approach 2:
The system dynamically adapts the loading strategy based on real-time downstream signal status. When downstream ROADMs report signal absent states, the system transitions to more aggressive loading decisions, reducing the number of loading cycles. This dynamic adjustment resolves the contradiction by making the system flexible rather than statically conservative.
2Productivity
If aggressive loading decisions are made without downstream visibility, then loading cycles are reduced, but optical power transients and traffic drops on pre-existing services occur due to SRS effects
Solution Approach 1:
The system uses feedback from downstream band signal status monitoring to control the aggressiveness of loading decisions. By receiving real-time information about downstream signal presence, the system can safely implement aggressive loading when appropriate while avoiding optical power transients that would harm pre-existing services, thus resolving the contradiction between productivity and harmful effects.
Solution Approach 2:
The system performs preliminary assessment of downstream signal status before making loading decisions. By checking the band signal status of downstream ROADMs in advance, the system can determine whether aggressive loading is safe, preventing optical power transients before they occur while still enabling fast loading when conditions permit.
3Reliability
If multiple loading cycles are used to manage SRS effects, then optical power stability is maintained, but network recovery times are accelerated only when downstream status is considered
Solution Approach 1:
The system uses feedback about downstream band signal status to intelligently control the number and duration of loading cycles. When downstream ROADMs are in signal absent states, the system reduces the number of loading cycles needed, thereby reducing network recovery time while maintaining optical power stability through the feedback-driven adaptation.
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 reduces the number of loading cycles, thereby accelerating network recovery times and improving user experience by optimizing loading management in optical networks.
Implementation Method 1
amplified spontaneous emission (ASE) noise is filled in the spectral gaps where the signal is absent to keep power levels maintained at a constant level in the transmission line
Implementation Method 2
a wavelength selective switch (WSS) in optical communication with the line port and the one or more tributary ports, the WSS being configured to selectively route optical content between the one or more tributary ports and the line port
Implementation Method 3
C+L optical line systems may be susceptible to experiencing significant optical power transients during loading operations due to the Stimulated Raman Scattering (SRS) effect across different frequency bands
Data Source
AI summary
Methods and systems include a method, comprising: providing, by an orchestrator of a network element, an optical service loading request identifying requested passbands to be loaded on a wavelength selective switch (WSS) for transmission of optical content; determining, by a loading manager of the network element, a subset of the requested passbands to be loaded on the WSS based on a downstream band signal status; and loading, by control blocks of the network element, the subset of the requested passbands on the WSS. The optical content includes client data and amplified spontaneous emission (ASE) noise. The network element comprises an ASE source, a light source, a light sink, a line port coupled to an optical fiber link, tributary ports, and the WSS. At least one of the tributary ports is coupled to the ASE source. The light source and the light sink transmit and receive the client data, respectively.