Precision time synchronization over standardized networking protocols

Abstract

A system, method and computer product for performing a time synchronization between first and second nodes includes the first node performing: generating a synchronization message, transmitting the synchronization message to the second node at a first time, taking a first timestamp in response to the synchronization message being transmitted and transmitting a timestamp message including the first timestamp to the second node at a second time; and the second node performing: receiving the synchronization message and the timestamp message from the first node, taking a second timestamp in response to the synchronization message being received, receiving the timestamp message from the first node, obtaining the first timestamp based on the received timestamp message, obtaining a timing offset between the first timestamp and the second timestamp and performing a time synchronization to the first node based on the timing offset.

Description

TECHNICAL FIELD[0001]The present invention relates to a time synchronization technique between network nodes, and more particularly to a method for performing a time synchronization between network nodes over a multi-hop network and a network system using the method.BACKGROUND[0002]In many applications including real-time systems that requires events to occur simultaneously across network nodes with millisecond or sub-millisecond precision, a time synchronization has become more important.[0003]When such systems are required to operate over a wireless network, the problem of establishing a common time base can be a difficult one to solve due to non-deterministic medium access control in the networking stack.[0004]Modern computing systems traditionally adopt one or more standardized networking interfaces for communicating with a variety of remotely located devices. Wi-Fi®. Bluetooth®, ZigBee®. Thread, and Ethernet are some examples of standardized networking protocols and interfaces ...

AI Technical Summary

Benefits of technology

This approach provides reliable and accurate time synchronization across network nodes using existing standardized protocols, avoiding compatibility issues and hardware limitations, enabling efficient multi-hop network synchronization.

Problems solved by technology

When such systems are required to operate over a wireless network, the problem of establishing a common time base can be a difficult one to solve due to non-deterministic medium access control in the networking stack.

While each standardized networking protocol has advantages and disadvantages in terms of throughput, power consumption, range, and cost, they all lack the capability to synchronize time across the network and therefore have inherently limited use in real-time systems.

Various time synchronization methods have been developed as follows, but they all exhibit many technical problems in accuracy and compatibility with devices using existing standardized protocols.

However, Maroti requires hardware timestamping, which is not widely available in hardware such as microcontrollers and microprocessors.

It also requires custom MAC frames to be exchanged across the network to synchronize nodes, thus resulting in many problems when working with an existing protocol or a third-party networking stack that does not have any provisions for sending custom MAC frames.

Moreover, Maroti requires that a timestamp of a transmitter triggering the time synchronization be embedded within a synchronization message itself, which is impossible for protocols using a MAC or application layer encryption.

This assumes that a collision could not occur after the CCA, which would be particularly problematic if that message were to be retransmitted without replacing the timestamp data.

Furthermore, it is not necessarily likely that all radio hardware will have access to this interrupt.

In addition, while U.S. Patent Publication No. 2015 / 0071309 to Aweya has proposed a method for synchronizing a master and a slave over a multi-hop network, it does not give a solution for synchronizing more than two devices, or synchronizing devices in a decentralized network (no master).

However, Aweya also requires hardware timestamping, which is not widely available in microcontrollers and microprocessors.

Thus, it is unclear how this time synchronization method might be applied to a protocol utilizing a MAC or application layer encryption without breaking it.

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