Optical Switch Line Side Loopback for Fiber Continuity Detection
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Solution Overview
Problem
Fiber optic communication systems face challenges in distinguishing between remote site failures and loss of continuity in fiber optic lines, as both issues can result in a Loss of Signal (LOS) at the receiver, making it difficult to determine the root cause of traffic loss, especially in C-RAN systems where remote transceivers are accessed only through limited supervisory channels.
Innovation Solution
An apparatus and method utilizing an optical switch with two configurations to provide a line side loopback of optical signals, allowing systems to determine if the fiber optic line has continuity by transitioning to a configuration that passes signals from the input to the output in case of a failure state, such as power failure, thereby distinguishing between line continuity and remote site failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external sources at the remote site are used to check fiber continuity, then fiber continuity can be detected, but additional monitoring wavelengths require additional filters and components, increasing device complexity and cost
Solution Approach 1:
The system uses the remote transceiver's own transmitted signals to detect fiber continuity. The local transceiver sends test signals through the fiber optic line, and the remote transceiver's automatic response (either through successful signal reception or failure states) provides the continuity information without requiring external testing equipment or additional components at the remote site.
Solution Approach 2:
The patent uses the existing optical switch and failure state detection mechanism as intermediaries to enable continuity testing. The optical switch redirects signals based on the remote transceiver's operational state, and the local system detects continuity through the fiber optic line by observing signal transmission and reception patterns, eliminating the need for external continuity testing devices.
2Measurement precision
If Optical Time Domain Reflectometry (OTDR) is used to detect a break in the fiber optic line, then fiber continuity can be detected, but expensive fiber test systems and specific calibration are required
Solution Approach 1:
The system leverages the remote transceiver's own signal transmission and the local transceiver's signal reception capabilities to perform continuity testing. By sending test signals through the fiber optic line and detecting whether they return (directly or through loopback configurations), the system determines fiber continuity without requiring expensive OTDR equipment or prior calibration of specialized test systems.
3Ease of operation
If OOB and OA&M methods are used to access remote transceivers, then remote transceiver control is possible, but these methods cannot be relied upon to isolate faults when loss of signal occurs
Solution Approach 1:
The patent introduces an optical switch as an intermediary mechanism that operates independently of the supervisory channels. The optical switch can redirect signals based on the operational state of the remote transceiver, providing a reliable fault isolation method that does not depend on the reliability of OOB or OA&M communication channels themselves.
Solution Approach 2:
The system segments the fault detection function from the data communication function. By using separate optical paths and the optical switch mechanism, the patent creates an independent fault isolation capability that operates parallel to the supervisory channels, allowing reliable fault detection even when OOB and OA&M methods fail.
Data Source
AI summary
There is provided an apparatus for fiber optic line continuity detection. The apparatus comprises an optical input connectable to a first optical fiber of a fiber optic line, an optical output connectable to a second optical fiber of the fiber optic line an optical interface unit configured to transmit and receive optical signals; and an optical switch having a first configuration and a second configuration. In the first configuration the optical switch is configured to pass optical signals received at the optical input to the optical interface unit and to pass optical signals received from the optical interface unit to the optical output. Whereas, in the second configuration the optical switch is configured to pass optical signals received at the optical input to the optical output.