One-Way Packet Delay Measurement Without Clock Synchronization
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Solution Overview
Problem
Accurate measurement of one-way data packet transmission delay in communications networks is challenging due to lack of synchronization between node clocks, leading to inaccuracy in delay measurements.
Innovation Solution
A method called Nonsynchronized Delay Measurement (NDM) that involves transmitting delay measurement packets between nodes without requiring clock synchronization, using a virtual clock to adjust timestamps and calculate one-way delays, allowing for accurate measurement without independent synchronization protocols like NTP or PTP.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If clock synchronization protocols (NTP or PTP) are used to measure one-way delay, then measurement accuracy is improved, but device complexity and network maintenance requirements increase
Solution Approach 1:
The patent extracts the clock synchronization requirement from the one-way delay measurement process. Instead of synchronizing clocks between nodes, the invention uses only local clock measurements at each node and combines them through mathematical processing to calculate one-way delay, eliminating the need for NTP or PTP protocols
Solution Approach 2:
The patent introduces a mediator node that receives packets from both source and destination nodes and performs the delay calculation. This mediator node acts as an intermediary that processes timestamp data from both ends without requiring the source and destination clocks to be synchronized, resolving the contradiction between measurement accuracy and synchronization complexity
2Stability of the object's composition
If bidirectional traffic is co-routed to achieve identical floor delays, then path consistency is improved, but queuing delays still differ due to asymmetric traffic volumes
Solution Approach 1:
The patent acknowledges that perfect path symmetry cannot be achieved due to asymmetric traffic patterns, but uses statistical processing of multiple measurements to compensate. By taking multiple samples and applying statistical analysis, the invention achieves accurate average delay measurements even when individual paths have different queuing delays
Solution Approach 2:
The patent changes the approach from measuring single-direction delays to measuring round-trip delays and deriving one-way delays through parameter transformation. By measuring the sum of forward and reverse delays and using statistical methods, the invention overcomes the problem of asymmetric queuing delays in co-routed bidirectional traffic
Data Source
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AI summary
A method for measuring one-way delays in a communications network, the method comprising: maintaining a virtual clock state comprising information for converting times measured with respect to remote clocks into times as would be measured with respect to a local reference clock; registering, for each packet of the plurality of packets in a communications session between the first and second nodes, a timeset comprising transmission and reception times at the first and second nodes; converting, responsive to the virtual clock, times in the timeset measured with respect to the first node clock or the second node clock, into times as would be measured with respect to the reference clock; calculating, for each packet of the series of packets, a forward one-way delay (FOWD) from the first node to the second node and a reverse one-way delay (ROWD) from the second node to the first node, responsive to the converted timeset.