Optical Channel Power Management in Branched Networks
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Solution Overview
Problem
In branched optical networks, maintaining uniform channel loading across branch channels while preventing unintended trunk channels from reaching branch terminals is challenging, leading to performance degradation due to noise accumulation and gain reshaping effects.
Innovation Solution
The system reuses loading signals from the branch add path to maintain uniform loading on the branch drop path, preventing trunk channels not intended for the branch terminal from being dropped, by loading unutilized channels with broadband noise or dummy tones, ensuring that only intended information signals are passed to the branch terminal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If channels are dropped at a branching unit, then the optical output power per channel increases, but nonlinear optical effects increase causing transmission penalty
Solution Approach 1:
The patent applies preliminary action by pre-loading dummy tones onto channels that will be dropped at the branching unit. This ensures that when these channels are dropped, the optical power per channel remains controlled and does not exceed thresholds that would cause nonlinear optical effects. The dummy tones are added in advance to the trunk signal before it reaches the branching unit, so the power distribution is already optimized when the drop occurs.
2Object-affected harmful factors
If dummy tones are added to control channel power, then nonlinear effects are reduced, but noise accumulation increases due to amplifier operation
Solution Approach 1:
The patent applies local quality by selectively adding dummy tones only to specific channels that are intended to be dropped at the branching unit, rather than adding dummy tones to all channels in the system. This localized approach ensures that noise is only introduced where necessary for power control, minimizing overall noise accumulation. The dummy tones are precisely targeted to channels E1, E3, and others marked for dropping, while channels carrying information signals to the branch terminal remain clean.
3Reliability
If express channels are blocked at the OADM branching unit, then unintended signals are prevented from reaching the branch terminal, but uniform loading is disrupted causing performance degradation
Solution Approach 1:
The patent uses dummy tones as intermediaries to maintain uniform loading in the transmission band. These dummy tones are added to channels that will be dropped at the branching unit, serving as placeholders that preserve the uniform power distribution across all channels. The dummy tones mediate between the need to block express channels (for reliability) and the need to maintain uniform loading (for performance), allowing the OADM to drop channels without creating power imbalances that would degrade performance.
Data Source
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AI summary
Channel power management may be achieved in a branched optical communication system such that uniform loading is provided across branch channels on a branch drop path without passing information signals that are not intended for the branch terminal to the branch drop path. In general, a system and method consistent with the present disclosure reuses one or more loading signals (e.g., noise bands) from the branch add path to maintain uniform loading in the branch drop path of the same branch. The system and method thus prevents trunk channels from being dropped to a branch terminal when those trunk channels are not intended for the branch terminal.