ROADM Loopback Bandwidth Control in Pre-Occupied Spectrum

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Solution Overview

Problem

Existing photonic loopback techniques in optical networking systems face challenges when performed in pre-occupied spectrum, as they require dedicated free spectral space which is often unavailable due to pre-provisioned Media Channels (MCs), leading to issues with filter-roll off penalties and limitations in modem compatibility.

Innovation Solution

The system automatically adjusts by either reducing the modem's baud rate or adding additional deadbands outside the loopback channel to ensure sufficient bandwidth for loopback tests, prioritizing in-service traffic integrity, without de-provisioning the entire MC setup.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If photonic loopback is performed in pre-occupied spectrum with pre-provisioned Media Channels, then spectrum utilization is improved, but filter-roll off penalties occur and modem compatibility is limited

Engineering Contradiction:

Improvespectrum utilizationVSAvoidfilter-roll off penalties

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The system dynamically adjusts the spectral allocation for loopback testing based on the presence of neighboring Media Channels. When MCs are detected, the loopback bandwidth is automatically reduced to prevent filter-roll off penalties. This dynamic adaptation allows the system to maintain reliability while utilizing pre-occupied spectrum, resolving the contradiction between spectrum utilization and filter performance.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the bandwidth parameter of the loopback signal based on spectrum occupancy conditions. By adjusting the spectral width of the loopback test signal to match available gaps between pre-provisioned Media Channels, the system eliminates filter-roll off penalties while maintaining spectrum efficiency. This parameter adaptation resolves the technical contradiction.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If dedicated free spectral space is allocated for loopback tests, then modem compatibility is improved, but spectrum availability is reduced

Engineering Contradiction:

Improvemodem compatibilityVSAvoidspectrum availability

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent enables pre-provisioned Media Channels to serve dual purposes: carrying in-service traffic and providing space for loopback testing. By utilizing the spectral gaps between MCs for loopback tests rather than requiring dedicated free spectrum, the system achieves modem compatibility while maintaining high spectrum availability. This multi-functional use of spectrum resolves the contradiction.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Measurement precision

If full Media Channel setup is de-provisioned and re-provisioned for loopback tests, then connection validation accuracy is improved, but operational disruptions increase

Engineering Contradiction:

Improveconnection validation accuracyVSAvoidoperational disruptions

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system performs preliminary detection of neighboring Media Channels and automatically configures appropriate deadbands and bandwidth parameters before conducting loopback tests. This preliminary action ensures connection validation accuracy without requiring full de-provisioning and re-provisioning of the Media Channel setup, thereby minimizing operational disruptions and resolving the contradiction.

Inventive Principle:

Principle #10Preliminary action

4Area of stationary object

If additional deadbands are added outside loopback channel, then bandwidth for loopback test is improved, but spectrum efficiency decreases

Engineering Contradiction:

Improvebandwidth for loopback testVSAvoidspectrum efficiency

Core Design Contradiction:

Area of stationary objectVSLoss of energy

Solution Approach 1:

The patent applies deadbands locally and selectively only in the specific spectral regions where pre-provisioned Media Channels create potential interference issues. Rather than adding deadbands across the entire spectrum, the system targets only the necessary gaps, thereby improving loopback bandwidth where needed while maintaining spectrum efficiency in other regions. This localized approach resolves the contradiction.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS12476704B2Bandwidth optimization for connection validation in pre-occupied spectrum

Publication Date: 2025.11.18 CIENA CORP

AI summary

A Reconfigurable Optical Add/Drop Multiplexer (ROADM) includes degree components where there are one or more Media Channels (MCs) configured thereon; multiplexer and demultiplexer components; and a controller configured to, responsive to a request for a loopback test on Network Media Channel (NMC) that is part of a configured Media Channel (MC), determine whether there are neighboring channels to the NMC, configure deadbands on optical spectrum based on the determining, cause configuration of a modem for the loopback test, and cause performance of the loopback test with the modem.