Scalable CDC ROADM Channel Pre-Combining for Lower Expansion Complexity
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Solution Overview
Problem
Conventional CDC ROADM architectures face limitations in scalability and cost-effectiveness, particularly with CWSS modules, which are high in first-in cost and do not efficiently scale beyond a certain number of degrees without complex and costly expansions.
Innovation Solution
Implement channel pre-combining with Contentionless Wavelength Selective Switch (CWSS)-based devices, utilizing splitters and combiners to interface signals to multiple CWSS modules, allowing for scalable and upgradeable CDC architectures that reduce costs per port and improve channel count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CWSS modules are used in CDC ROADM architectures, then higher port count and lower insertion loss are achieved, but first-in cost becomes extremely high and scalability beyond eight degrees becomes complex and costly
Solution Approach 1:
The ROADM node is divided into multiple degrees, where each degree handles a specific subset of channels. This segmentation allows the system to scale by adding more degrees rather than expanding existing complex modules, reducing the complexity of expansion while maintaining high port count and low insertion loss through the CWSS-based architecture.
2Quantity of substance
If a second layer of 1×32 WSSs is added to every degree to scale beyond the current limit, then channel capacity increases, but device complexity and cost increase significantly
Solution Approach 1:
Instead of adding another layer of WSSs (vertical expansion), the system scales by adding more degrees (horizontal expansion). This dimensional change allows channel capacity to increase linearly with the number of degrees rather than requiring complex multi-layer expansions, reducing device complexity while maintaining scalability.
3Ease of manufacture
If modular twin design with two 2×8×24 CWSS modules is used, then first-in cost is reduced, but additional switches internal to modules add cost, complexity, and impact performance
Solution Approach 1:
The CWSS modules are designed to be universal and configurable, where each module can support multiple degrees and channel combinations through software configuration rather than requiring additional physical switches. This multi-functionality reduces internal switch complexity while maintaining cost-effectiveness and performance.
Data Source
AI summary
A method for a scalable Reconfigurable Optical-Add Drop Multiplexer (ROADM) includes determining a plurality of channels at a ROADM node in an optical network will ingress and egress at another ROADM node in the optical network, such that the plurality of channels are able to share a same physical routing in the optical network; interfacing the plurality of channels at a degree in the ROADM node, such that the plurality of channels are connected to the another ROADM node in the optical network; adding and dropping the plurality of channels at the ROADM node with corresponding modems; and pre-combining the plurality of channels onto a common port between the degree and the corresponding modems, such that the plurality of channels connect to the degree together in a single connection. An add/channel count of the ROADM node is higher with the pre-combining.