Reconfigurable Optical Add-Drop Multiplexer With Dual-Path Contention Resolution
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Solution Overview
Problem
Current reconfigurable optical add-drop multiplexers (ROADMs) face limitations in scaling add/drop port counts due to the need for Colorless, Directionless, and Contention-less (CDC) features, which increase complexity and hinder port scaling, while solutions focusing on Colorless and Directionless (CD) features lead to contention issues and connection blocking.
Innovation Solution
Implementing a ROADM system with a primary path using Colorless, Directionless (CD) architecture and a secondary path for contention resolution, allowing for both scaling and improved performance by directing wavelength channels without contentions to the primary path and those with contentions to the secondary path, using a controller to manage wavelength channel selection and path direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CDC (Colorless, Directionless, Contention-less) architecture is implemented to eliminate contention, then connection reliability is improved, but device complexity increases due to requiring many switches and WSS
Solution Approach 1:
The add/drop card is divided into two separate paths: a primary path handling non-contenting wavelengths and a secondary path handling contending wavelengths. This segmentation allows each path to be optimized independently, reducing the overall complexity while maintaining contention-less operation for the majority of wavelengths.
Solution Approach 2:
Instead of implementing full CDC architecture across all wavelengths, the patent applies contention resolution only partially - the primary path handles the majority of wavelengths without contention resolution, while the secondary path provides contention resolution only when needed. This partial application reduces complexity while still improving reliability where it matters most.
2Productivity
If add/drop port count is scaled to higher counts to improve add/drop rate, then productivity is improved, but device complexity increases due to CDC requirements
Solution Approach 1:
By segmenting the add/drop card into primary and secondary paths, the patent enables independent scaling of each path. The primary path can be scaled to higher port counts without the complexity overhead of full CDC architecture, while the secondary path provides targeted contention resolution only where necessary.
Solution Approach 2:
The patent applies different architectural qualities to different parts of the system: the primary path uses a simpler architecture optimized for high port counts and throughput, while the secondary path uses a more complex CDC-optimized architecture only where contention occurs. This local differentiation allows high add/drop rates without universal complexity.
3Device complexity
If CD (Colorless, Directionless) architecture is used to simplify hardware and scale ports, then device complexity is reduced, but contention issues arise causing connection blocking
Solution Approach 1:
The patent segments the wavelength handling into two paths: the primary path uses simple CD architecture for non-contenting wavelengths, while the secondary path provides CDC-like contention resolution only when needed. This segmentation maintains simplicity where possible while adding complexity only where necessary to prevent blocking.
Solution Approach 2:
The secondary path acts as an intermediary mechanism that intervenes only when contention is detected in the primary path. This mediator approach allows the system to maintain simple CD architecture for the majority of operations while providing CDC-like reliability when contention occurs, without the overhead of universal CDC architecture.
Data Source
AI summary
The systems and methods directed towards a reconfigurable optical add-drop multiplexer (ROADM). The ROADM comprising: i) a plurality of line cards, wherein each one of the plurality of line cards is configured to receive a plurality of wavelength channels from an optical link in an optical network; ii) a plurality of add/drop cards, wherein each one of the plurality of add/drop cards includes a primary path and a secondary path; and iii) a controller configured to: a) select a set of wavelength channels from the plurality of wavelength channels, b) determine if there is any contention between the set of wavelength channels, c) direct a first subset of wavelength channels from the set of wavelength channels that do not have contentions to the primary path, and d) direct a second subset of wavelength channels from the set of wavelength channels that have contentions to the secondary path.