One-Way Delay Measurement Using Symmetric Reference Network
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Solution Overview
Problem
Existing methods for measuring one-way connection delay in VoIP networks often provide inaccurate results due to assuming equal delays in both directions of transmission, and require synchronized test equipment at both call termination points, which is impractical and costly when endpoints are not collocated.
Innovation Solution
A method that measures round trip delays in both a VoIP and a symmetric network from a single location, using synchronized recordings of test signals to calculate one-way transmission delays in each direction, eliminating the need for equipment and personnel at the far-end termination points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If synchronized test equipment is deployed at both call termination points to measure one-way delay, then measurement precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent introduces a symmetric network connection as an intermediary reference channel. By comparing the asymmetric VoIP connection against this symmetric reference, the system can calculate one-way delays using only single-ended measurement equipment, eliminating the need for synchronized test equipment at both endpoints while maintaining measurement accuracy
Solution Approach 2:
The patent creates a copy of the test signal that travels through both the asymmetric VoIP network and the symmetric reference network simultaneously. By recording and comparing these identical signals at a single location, the system can derive one-way delay measurements without requiring physical test equipment at distant endpoints
2Measurement precision
If test personnel are deployed to both call termination points for delay measurement, then measurement precision is improved, but productivity decreases due to increased field workforce requirements
Solution Approach 1:
The patent enables the measurement system to perform self-service by automatically calculating one-way delays from round-trip measurements taken at a single location. The symmetric reference network serves itself as the comparison baseline, eliminating the need for field personnel to travel to distant endpoints and significantly improving testing productivity
3Ease of operation
If round trip delay is divided by two to estimate one-way delay, then ease of operation is improved, but measurement precision deteriorates due to asymmetric network delays
Solution Approach 1:
The patent explicitly accounts for network asymmetry by introducing a symmetric reference connection as a counterbalance. By measuring against this symmetric baseline, the system can separately determine forward and reverse one-way delays through mathematical calculation, transforming the asymmetric measurement problem into a solvable system of equations while maintaining operational simplicity
Data Source
AI summary
A method and apparatus enabling the measurement of one way delay in each of the two directions of transmission from a single location are disclosed. The method measures a first roundtrip delay at a first location between a first endpoint and a second endpoint over a first communication network, and measures a second roundtrip delay between a third endpoint and a fourth endpoint over a second communication network with symmetric delay characteristics. The method performs synchronous recordings of a test signal that is sent simultaneously from the second endpoint to the first endpoint and from the fourth endpoint to the third endpoint, to measure an arrival time (t1) of the test signal over the first communication network, and, an arrival time (t2) of the test signal over the second communication network t2, where the arrival times (t1) and (t2) are used to calculate an one way transmission delay in the first communication network.