Optical Link Latency Measurement Using Delimiter Devices
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Solution Overview
Problem
Existing methods for determining the latency of optical transmission links suffer from limited resolution and inaccuracy, particularly due to the data rate of probe signals and equipment delays, which hinder precise measurement of link latency in optical transmission networks.
Innovation Solution
The introduction of delimiter devices at each connection port of neighboring nodes in an optical transmission link allows for separate measurement of section and pass-through latencies, enabling accurate calculation of total link latency by defining demarcations within the optical link path and using high-accuracy correlation techniques to measure time delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If probe signals with finite data rate are used for latency measurement, then the measurement can be implemented with standard equipment, but the time resolution is limited by the data rate period
Solution Approach 1:
The patent replaces traditional electrical/electronic measurement methods with optical correlation techniques. By using optical signals and correlation processing, the system achieves picosecond-level time resolution without being constrained by electronic data rate limitations, fundamentally substituting the measurement paradigm from electrical to optical domain
Solution Approach 2:
The patent changes the measurement parameter from electrical signal timing to optical correlation peak position. By measuring the time shift of correlation peaks between transmitted and received optical signals, the system achieves high-resolution latency measurement independent of data rate, transforming the measurement approach from electrical timing to optical correlation analysis
2Ease of operation
If measurement equipment is placed at a distance from the link, then the setup is more flexible, but equipment delay introduces measurement inaccuracy
Solution Approach 1:
The patent extracts the measurement reference point directly to the optical link endpoints by placing delimiter devices at the exact boundaries of the optical path. This removes the intermediate equipment that introduces delay, allowing flexible positioning while maintaining accuracy by measuring latency exactly where it matters - at the link boundaries
Solution Approach 2:
The patent introduces delimiter devices as optical intermediaries that mark the exact boundaries of the optical link. These delimiters serve as reference points that define the measurement scope, allowing the measurement system to accurately capture only the link latency without including equipment delays from external measurement apparatus
3Measurement precision
If delimiter devices are added at each connection port to define demarcations, then section and pass-through latencies can be measured separately with high accuracy, but the device complexity increases
Solution Approach 1:
The patent segments the optical link into distinct sections by placing delimiter devices at connection ports and pass-through nodes. This segmentation allows separate measurement of section latency and pass-through latency, enabling precise identification of latency contributions from each component while maintaining overall system measurability
Solution Approach 2:
The delimiter devices serve multiple functions: they define measurement demarcations, reflect probe signals for timing reference, and mark pass-through nodes. This multi-functionality reduces the need for separate dedicated components for each measurement task, mitigating the complexity increase from adding delimiters
4Length of moving object
If unidirectional optical pass-through paths with optical amplifiers are used, then signal transmission is enabled over long distances, but bidirectional measurement methods cannot be applied
Solution Approach 1:
The patent inverts the measurement approach by using reflection instead of transmission through the amplifier. Since optical amplifiers in unidirectional paths prevent bidirectional signal exchange, the system reflects probe signals back through the same path and measures the round-trip time, enabling latency measurement in unidirectional configurations where traditional bidirectional methods fail
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method provides high-accuracy measurement of link latency independent of measurement equipment length, allowing for precise synchronization and monitoring of optical transmission links with improved resolution and reduced measurement errors.
Implementation Method 1
measuring, at the first node, a first time delay of a first reflection signal, which is created by the delimiter element of the delimiter device of the first node by reflecting a power portion of the section probe signal
Data Source
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Figure 3a~3b
AI summary
The invention relates to A method for determining the link latency of an optical transmission link, wherein the optical transmission link (100) comprises an end node (102, 104) at each end thereof and one or more pass-through nodes (106), wherein each pair of neighboring nodes (102, 104, 106) is connected, at a connection port (110, 112) of each node, by an optical connecting path, and wherein each pass-through node comprises an optical pass-through path between its connection ports (110, 112), the optical connecting paths (114) and optical pass-through paths (116) forming an optical link path (108, and wherein a delimiter device (118, 120) comprising a delimiter element (148) is provided at each connection port (110, 112) of each node, wherein the delimiter element (148) forms a demarcation within the optical link path. According to the method the following steps are carried out: measuring, for each pair of neighboring nodes (102, 104, 106), a section latency by transmitting a section probe signal from a first one of the pair of nodes (102, 104, 106) to the second one of the pair of nodes (102, 104, 106), by measuring, at the first node (102, 104, 106), a first time delay of a first reflection signal, which is created by the delimiter element (148) of the delimiter device (118, 120) of the first node (102, 104, 106) by reflecting a power portion of the section probe signal, and a second time delay of a second reflection signal, which is created by the delimiter element (148) of the delimiter device (118, 120) of the second node (102, 104, 106) by reflecting a power portion of the section probe signal received from the first node (102, 104, 106), and by calculating the section latency as half the difference between the second time delay and the first time delay; determining, for each pass-through node (106) either theoretically or by measurement, a pass-through latency of an internal optical pass-through path (116') between the delimiter elements (148) of the delimiter devices (118, 120) of the respective pass-through node (106); and adding all section latencies and pass-through latencies in order to obtain the link latency of the optical link path (108). The invention further relates to an optical transmission link (100) that implements this method and a pass-through node (106) for realizing such an optical transmission link (100).