Dispersion Compensation in Optical Mesh Networks
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Solution Overview
Problem
Optical mesh networks face challenges in balancing chromatic dispersion and minimizing non-linearity impairments, especially when supporting traffic at multiple bit rates, as existing methods require advance knowledge of trail paths and cannot simultaneously satisfy different dispersion compensation requirements for 10 Gbps, 40 Gbps, and 100 Gbps services.
Innovation Solution
The method involves providing in-line dispersion compensation for every network span to maintain average residual dispersion below 3 km, using external pre-compensation negative Dispersion Compensation modules (DCMs) at start points and external post-compensation positive DCMs at termination points, creating a common dispersion map suitable for all bit rates without pre-planning trails or knowing specific bit rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dispersion compensation is optimized for high bit rates (40 Gbps, 100 Gbps), then non-linearity impairments are minimized for advanced services, but dispersion requirements for basic bit rates (10 Gbps) are not satisfied
Solution Approach 1:
The dispersion compensation is segmented into two distinct parts: in-line compensation modules distributed across network spans providing average residual dispersion, and external compensation modules placed at network nodes. This segmentation allows different parts of the network to serve different bit rate requirements simultaneously.
Solution Approach 2:
Different dispersion compensation characteristics are applied at different locations: in-line modules provide uniform average residual dispersion across all spans, while external modules at specific nodes provide additional compensation tailored to local requirements. This enables 10 Gbps trails to receive appropriate dispersion management at their endpoints without affecting 40/100 Gbps trail performance.
2Adaptability or versatility
If a common dispersion map is designed to support multiple bit rates, then network versatility is improved, but the precision of dispersion compensation for each specific bit rate deteriorates
Solution Approach 1:
The system dynamically adapts to different trail types and bit rates by providing a baseline in-line dispersion compensation that works for all trails, with additional external compensation modules that can be selectively activated based on the specific trail requirements. This dynamic approach maintains precision for each bit rate while supporting network versatility.
Solution Approach 2:
The in-line dispersion compensation modules serve universal functions for all trails regardless of bit rate, while external modules provide specialized compensation for specific trail types. This multi-functional approach allows a single network infrastructure to precisely support multiple bit rates simultaneously.
3Reliability
If in-line dispersion compensation is provided for every span, then average residual dispersion is controlled, but non-linearity impairments in overlapping trails increase
Solution Approach 1:
The system optimizes the parameter of residual dispersion by providing in-line compensation that maintains average residual dispersion below 3 km per span. This parameter control reduces chromatic dispersion effects while the selective use of external modules prevents excessive dispersion that would cause non-linearity impairments in overlapping trails.
4Adaptability or versatility
If external pre-compensation and post-compensation modules are added at network nodes, then dispersion requirements for all bit rates are satisfied, but device complexity increases
Solution Approach 1:
External pre-compensation modules are placed at the beginning of trails to proactively manage dispersion before signals traverse the network. This preliminary action, combined with post-compensation at trail endpoints, ensures dispersion requirements are met without requiring complex real-time adjustment mechanisms, thus managing device complexity while maintaining versatility.
Data Source
AI summary
A method is provided for carrying out dispersion compensation in an optical mesh network supporting simultaneously traffic services being provided at two or three different bit rates including a basic bit rate being 10 Gbps and at least one higher bit rate selected from among 40 Gbps and 100 Gbps. The method comprises the following steps: providing in-line dispersion compensation for every span in the network so as to reach positive average residual dispersion RDS per span extending to less than about 3 km; providing start points of possible trails in the network with respective external, pre-compensation negative Dispersion Compensation modules (DCMs), and providing termination points of possible trails in the network with respective external post-compensation positive DCMs.