Directionless CD ROADM Loop Interconnects for Scalable Degrees
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Solution Overview
Problem
Existing CD ROADM architectures are limited to N/2 degrees due to the need for full-mesh interconnections between degrees and add-drop modules, requiring excessive ports and hindering scalability and flexibility.
Innovation Solution
A multi-degree CD ROADM system with selective connections between degrees and add-drop modules, forming a loop of interconnections instead of a full mesh, allowing each degree to connect to a subset of add-drop modules, reducing the number of ports required and enabling scalability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a full-mesh interconnection configuration is used between degrees and add-drop modules, then traffic routing flexibility is improved, but the number of ports required increases exponentially
Solution Approach 1:
The patent segments the full-mesh interconnection into two parts: (1) a simplified connection structure where each degree connects to a subset of add-drop modules rather than all modules, and (2) a central routing fabric that provides the necessary traffic routing flexibility. This segmentation reduces the number of direct degree-to-add-drop-module connections while maintaining routing capabilities through the routing fabric.
Solution Approach 2:
The patent introduces a routing fabric as an intermediary component between degrees and add-drop modules. Instead of direct full-mesh connections, traffic routing is mediated through this fabric, which consolidates the routing function and reduces the number of required ports at degree and add-drop-module interfaces.
2Productivity
If the number of degrees is increased in a CD ROADM system, then network capacity is improved, but system complexity increases
Solution Approach 1:
The patent implements a universal routing fabric that serves multiple functions: routing traffic between any degrees, managing add-drop operations, and providing scalability. This multi-functional approach allows the system to handle increased network capacity requirements without proportionally increasing complexity, as the same routing fabric infrastructure supports multiple operational modes and scales gracefully with added degrees.
3Adaptability or versatility
If WSS ports are increased to support more degrees, then the number of supported degrees is improved, but cost increases
Solution Approach 1:
The patent applies partial action by implementing just enough connectivity to achieve the desired number of supported degrees. Rather than providing full-mesh connections for all possible degree combinations, the system implements selective connections through the routing fabric, using only the necessary ports to achieve N-degree support with fewer than N(N-1)/2 connections.
Data Source
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AI summary
A Colorless Directionless (CD) Reconfigurable Optical Add Drop Multiplexer (ROADM) system is described. Compared to known CD-ROADM architectures, the described system is directionless while using fewer interconnections between the degrees (D1-D3) and the add-drop modules (AD1-AD3). Additionally, a method of establishing such a CD ROADM system is described, and a method of re-configuring such a CD ROADM to re-route network traffic.