Asymmetric Delay Measurement in Communication Paths
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Solution Overview
Problem
Current methods for measuring asymmetric delays in communication paths, such as those used in 3G networks, are inefficient and costly, particularly when GPS is unavailable or when fibers are not symmetric, leading to synchronization errors that affect time synchronization precision.
Innovation Solution
A method involving synchronized nodes that exchange delay measurement messages to calculate communication path delays in both directions, allowing for the determination of asymmetric delays without the need for on-site measurements or complex equipment like OTDRs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS is used to provide high-precision synchronous clock reference source, then time synchronization precision is improved, but cost and operational complexity increase
Solution Approach 1:
The patent uses delay measurement messages that traverse the communication path to create a virtual model of the path characteristics. By analyzing the timestamps and delay values in these messages, the system derives asymmetric delay information without requiring physical measurement equipment like OTDR or GPS receivers at each site, thus reducing operational complexity while maintaining measurement precision
Solution Approach 2:
The communication path itself serves as the measurement instrument. The delay measurement messages use the same communication infrastructure (fibers, switches, routers) to measure the asymmetric delay, eliminating the need for separate measurement equipment. The system measures what it actually uses for data transmission, making the measurement process self-contained and reducing external dependencies
2Measurement precision
If OTDR is used to measure asymmetric delay, then measurement capability is improved, but operational complexity and skill requirements increase
Solution Approach 1:
The patent replaces the mechanical/optical measurement system (OTDR) with an information-based measurement approach using timestamped delay messages. Instead of sending optical pulses and analyzing reflected signals, the system uses software-based timestamp comparison of messages traversing the path, eliminating the need for specialized measurement equipment and operator skills
Solution Approach 2:
The delay measurement messages serve multiple functions: they carry timing information for asymmetric delay measurement, traverse the actual communication path to reflect real conditions, and can be processed by standard network equipment. This multi-functional approach eliminates the need for dedicated measurement devices and simplifies operations
3Measurement precision
If on-site point-by-point measurement is performed, then measurement accuracy is improved, but workload and time consumption increase
Solution Approach 1:
The patent segments the measurement process into automated message exchanges between network nodes rather than manual point-by-point measurements. Each delay measurement message automatically traverses through multiple network elements, collecting timing information along the path without requiring human intervention at each segment, thus maintaining accuracy while improving efficiency
Solution Approach 2:
The system uses periodic delay measurement messages that automatically traverse the communication path at regular intervals. This automated periodic measurement replaces manual on-site measurements, maintaining measurement accuracy through consistent sampling while dramatically improving productivity by eliminating repetitive human operations
4Device complexity
If fiber asymmetry is not considered, then device complexity is reduced, but time synchronization precision deteriorates
Solution Approach 1:
The patent implements feedback by using the measured asymmetric delay information to correct time synchronization calculations. The delay measurement messages provide feedback about the actual path characteristics, which are then used to compensate for asymmetric delays in the PTP synchronization process, maintaining precision without adding significant complexity to the synchronization protocol
Data Source
AI summary
A method for measuring the asymmetric delay of a communication path includes: sending, by a first node, a first delay measurement message to a second node whose local clock is synchronized with the first node; receiving, by the first node, a second delay measurement message sent by the second node; calculating, according to time when the first delay measurement message is sent by the first node and time when the second node receives the first measurement message, a communication path delay in a direction towards the second node; calculating, according to time when the second node sends the second delay measurement message and time when the second measurement message is received by the first node, a communication path delay in a direction leaving the second node; and obtaining a measured value of the asymmetric delay of the communication path according to the communication path delays in the two directions.