WDM Optical Power Control via Dynamic Cycle Adjustment
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Solution Overview
Problem
In large-scale optical communication networks, the optical power control of WDM signals across multiple ROADM nodes interferes with each other, leading to unexpected large optical power fluctuations due to simultaneous adjustments in optical power levels.
Innovation Solution
An optical transmission system that includes an optical channel monitor, a processor for controlling optical power, and a convergence decision unit to adjust the control cycle based on detected optical power convergence, switching between high-speed and low-speed modes to prevent interference and stabilize optical power levels across nodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical power control is performed in each ROADM node independently, then each node can maintain its signal quality, but optical power fluctuations occur due to simultaneous adjustments across multiple nodes
Solution Approach 1:
The system implements feedback control where each ROADM node monitors the optical power of wavelength channels and adjusts its control actions based on the current state of the network. The processor receives monitoring information from other nodes and modifies its optical power control accordingly, creating a coordinated feedback mechanism that prevents simultaneous adjustments and stabilizes overall optical power levels.
Solution Approach 2:
The patent merges the optical power control operations of multiple independent ROADM nodes into a coordinated system. By having nodes share monitoring information and synchronize their control cycles, the system combines previously independent control actions into a unified control strategy that prevents conflicting adjustments while maintaining individual node signal quality.
2Speed
If optical power control cycle is short, then response speed to power changes is fast, but control interference between nodes increases
Solution Approach 1:
The system dynamically adjusts the control cycle length based on network conditions. When optical power levels are stable, the control cycle is extended to reduce the frequency of control actions and minimize interference between nodes. When power fluctuations are detected, the cycle shortens to provide faster response. This dynamic adjustment optimizes both response speed and interference reduction.
Solution Approach 2:
The patent implements periodic control actions with variable periods. Instead of continuous or fixed-interval control, the system performs optical power adjustments at periodic intervals that are adapted based on convergence status. This periodic approach with adjustable timing allows fast response when needed while reducing overall control frequency to minimize inter-node interference.
3Loss of time
If optical power control is performed frequently, then optical power convergence is achieved quickly, but network stability decreases due to simultaneous adjustments
Solution Approach 1:
The system uses feedback from monitoring information to determine when control actions are necessary. By continuously monitoring optical power levels and comparing them against target values, the system can identify when convergence is near and reduce control frequency accordingly. This feedback mechanism allows quick initial convergence while preventing excessive control actions that would destabilize the network.
Solution Approach 2:
The patent applies partial control actions rather than full adjustments in all cases. When optical power is close to the target level, the system makes smaller adjustments or skips control cycles entirely, rather than continuously applying full control actions. This approach achieves convergence efficiently while avoiding the instability caused by excessive control interventions.
Data Source
AI summary
Optical transmission system transmits WDM signal from first node to second node via optical fiber. The optical transmission system includes: OCM that detects optical power of each wavelength channel in second node; processor that controls optical power of each wavelength channel based on detection by OCM in first node; optical circuit that adjusts optical power of each wavelength channel based on control signal from the processor in first node; and second processor that decides whether the optical powers of wavelength channels have converged to target level based on detection by OCM. When the optical powers of wavelength channels have not converged to the target level, the processor controls the optical circuit using the control signal in first cycle. When the optical powers of wavelength channels have converged to the target level, the processor controls the optical circuit using the control signal in second cycle longer than first cycle.