Network Time Distribution Error Estimation for Asymmetric Delay
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Solution Overview
Problem
Existing clock synchronization methods, such as NTP and PTP, assume symmetric Ethernet latency, leading to inaccuracies in time synchronization due to asymmetric network delays, which are difficult to measure without additional hardware setups at remote sites.
Innovation Solution
A method and system for estimating time distribution error by using alternative transmission pathways to calculate the difference in time offsets between direct and indirect paths, allowing for accurate time synchronization without additional hardware at the receiver end.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard protocols (NTP/PTP) are used for time distribution, then time synchronization can be achieved across the network, but measurement precision deteriorates due to asymmetric Ethernet latency
Solution Approach 1:
The patent introduces an intermediary measurement mechanism that uses a round-trip time measurement approach. Instead of directly measuring one-way time offset which is affected by asymmetric latency, the system measures round-trip time by sending a request message from the client to the server and receiving a response message back. The round-trip time measurement serves as an intermediary that eliminates the impact of asymmetric Ethernet latency on time accuracy measurements.
2Measurement precision
If additional hardware setups are deployed at remote sites to measure asymmetric delay, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent implements a self-service approach where the time distribution system itself performs the measurement function without requiring additional external hardware at remote sites. The client device uses its existing clock and communication capabilities to send request messages and process response messages, thereby measuring round-trip time and calculating time offsets using only the standard time distribution protocol infrastructure already present in the system.
3Measurement precision
If round-trip time measurement is used to compensate for transmission delay, then time distribution accuracy improves, but device complexity increases due to bidirectional communication requirements
Solution Approach 1:
The patent makes the time distribution protocol multi-functional by enabling it to perform both time synchronization and time offset measurement functions using the same bidirectional message exchange mechanism. The request and response messages serve dual purposes: they establish the time reference relationship for synchronization while simultaneously providing the timing data needed for round-trip time measurement and offset calculation, eliminating the need for separate measurement protocols.
Data Source
AI summary
The present disclosure provides systems and methods for testing time distribution in a network. The method comprises: receiving, at a time receiver, a first time signal transmitted along a first transmission pathway between the time receiver and a time server, the first time signal is provided by a first clock of the time serve; receiving a second time signal transmitted along a second transmission pathway, the second transmission pathway is different from the first transmission pathway; deriving a first time offset between the first time signal and a corresponding arrival time generated by a second clock of the time receiver, and a second time offset between the second time signal and a corresponding arrival time generated by the second clock; and determining an estimated error of distributing time along the first transmission path based on a difference between the first time offset and the second time offset.