Modular Protection Switching System for Telecommunication Line Cards
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Solution Overview
Problem
Existing protection switching systems in telecommunication systems face limitations, including inability to protect multiple faulty line cards, incompatibility with certain line card types like 2 Mb/s E1, and requirement for different standby line card designs, due to the use of a fixed protection bus.
Innovation Solution
A modular protection switching system with detachable electrical connection elements and a local bridge connector, allowing flexible configuration of protection units between line cards, enabling 1+1 and N+1 configurations with various line card types, and eliminating the need for distinct standby line card designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed protection bus is used in the backplane, then protection switching can be implemented, but it is not possible to protect a second faulty line card if protection switching already has been performed for a first faulty line card
Solution Approach 1:
The invention divides the protection switching system into multiple independent protection units, each with its own protection bus. This segmentation allows each protection unit to independently handle protection switching for specific line cards, enabling the system to protect multiple faulty line cards simultaneously without interference between protection operations.
Solution Approach 2:
The invention transitions from a single shared protection bus (one-dimensional) to multiple protection units with separate protection buses (multi-dimensional). This dimensional change allows parallel protection operations across different protection units, resolving the limitation of sequential protection switching.
2Reliability
If a common protection bus is used, then protection switching can be implemented, but line cards such as 2 Mb/s E1 line cards can not be protected at all due to severe bridge taps
Solution Approach 1:
By segmenting the single common protection bus into multiple dedicated protection buses (one per protection unit), the invention eliminates bridge tap interference for sensitive line cards like 2 Mb/s E1. Each protection unit's dedicated bus avoids the severe bridge taps that occur when multiple line cards share a common bus.
3Reliability
If a fixed protection bus is used, then protection switching can be implemented, but the standby line card often needs to be of a different design than the other line cards
Solution Approach 1:
The invention makes all protection units identical and universal, where any protection unit can serve as a standby unit for any working line card. This universality eliminates the need for specially designed standby line cards with different architectures, as the modular protection units can be dynamically assigned to protect any line card type.
4Reliability
If a fixed protection bus is used, then protection switching can be implemented, but it introduces severe bridge taps which HDB3 line coding in E1 line signals does not tolerate
Solution Approach 1:
The invention segments the shared protection bus into dedicated protection buses for each protection unit. This segmentation ensures that E1 line signals with HDB3 coding are transmitted on dedicated buses without bridge tap interference from other line cards, making the system compatible with bridge tap-sensitive signaling schemes.
Data Source
AI summary
A unit and a system for protection switching of line cards in a telecommunication system are described. A protection unit is connectable between communication lines and a line interface unit. The protection unit can be interconnected with other protection units to form a protection switching system. One protection unit in the protection switching system is connectable to a stand-by line card. The protection switching system is configured so that when protection switching is needed, the line signal is re-directed between the communication line for a failed line card and the stand-by line card via electrical connection elements.