Protected Optical Single-Fiber WDM System Design
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Solution Overview
Problem
Current protected optical single-fiber WDM systems require high costs to achieve protection against fiber cuts and external impacts, often necessitating the use of multiple fibers or ring structures that increase expenses and bandwidth limitations.
Innovation Solution
An open ring structure with two head-end terminals and add/drop filter devices connected via a single optical fiber, using dedicated wavelength bands for bidirectional communication to establish both working and protection paths, ensuring minimal fiber usage and equipment protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a closed ring structure or bus structure is used to provide protection against fiber cuts, then system reliability is improved, but device complexity and cost increase
Solution Approach 1:
The invention segments the protection function by introducing add/drop filter devices at intermediate network nodes, allowing each node to independently drop and add signals. This segmentation transforms the complex closed ring structure into a simpler linear structure with distributed protection capabilities, reducing overall system complexity while maintaining reliability.
Solution Approach 2:
The add/drop filter devices act as intermediaries between the optical fiber transmission path and the network nodes. These intermediaries enable protection functionality without requiring the entire system to adopt a complex ring structure, thus improving reliability while controlling device complexity.
2Reliability
If multiple fibers are used to achieve protection, then system reliability is improved, but cost increases
Solution Approach 1:
The invention makes the add/drop filter devices multi-functional by enabling them to handle both working and protection signals through the same optical fiber. This universality allows a single fiber to serve multiple purposes, providing protection capability without increasing the number of fibers required.
Solution Approach 2:
The invention changes the operational parameters of the system by using different wavelength channels for working and protection signals within the same fiber. This parameter change (using wavelength division multiplexing) enables protection functionality while maintaining single-fiber operation, thus avoiding the need for additional fibers.
3Device complexity
If bandwidth is shared among all tail-end terminals, then device complexity is reduced, but productivity decreases
Solution Approach 1:
The invention segments the bandwidth allocation by assigning dedicated wavelength channels to specific tail-end terminals rather than sharing a single channel among all terminals. This segmentation provides each terminal with guaranteed bandwidth while keeping the system relatively simple through the use of add/drop filter devices for channel management.
Data Source
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AI summary
The invention relates to a protected optical single-fiber WDM system. A first (3) and a second (5) head-end terminal and at least one optical add/drop filter device (11) are connected to form a chain-like transmission path, each of the first and second head-end terminals (3, 5) being connected, at a WDM port (3a, 5a), through a single optical fiber (13) to a western (11a) or an eastern WDM port (11d) of an adjacent one of the optical add/drop filter devices (11), respectively, and each of the optical add/drop filter devices (11) being connected, at an eastern or western WDM port (11d, 11a), to a western or eastern WDM port (11a, 11d) of an adjacent one of the optical add/drop filter devices (11), respectively. At least one tail-end terminal (9) is connected to each optical add/drop filter device (11), wherein a first (9a) and a second (9b) channel port of the respective add/drop tail-end terminal (9) is connected to a dedicated first (11 b) and second (11 c) channel port of the optical add/drop filter device (11) through a respective optical fiber (15,17). The head-end terminals (3, 5), the optical add/drop filter devices (11) and the tail-end terminals (9) are adapted to selectively or simultaneously establish a bidirectional communication between each tail-end terminal (9) and the first and second head-end terminal (3, 5), wherein each tail-end terminal (9) bidirectionally communicates through its first channel port (9a) with the first head-end terminal (3) and bidirectionally communicates through its second channel port (9b) with the second head-end terminal (5), one of these communication paths serving as a working communication path and the other of these communication paths serving as a protection path, wherein for the communication between each of the tail-end terminals (9) and the first and second head-end terminal (3, 5), respectively, dedicated optical channel signals lying in a first wavelength band and a second wavelength band are used for each transmission direction, the first and second wavelength band revealing no overlap and the optical channel signals in each wavelength band forming, in each transmission direction in the chain-like transmission path, respective optical WDM signals.