Simple clock synchronization for distributed real-time systems

In distributed real-time systems, most of the end-to-end delay fluctuations, especially the delay fluctuations in the network, are bounded provided that the global network traffic loads are manually controlled to be light-weighted. This paper introduces a simple clock synchronization method in distributed real-time systems by using the traffic smoothing technique which is implemented at each end node and blocks selected types of messages during the clock synchronization duration. Only three messages are needed to synchronize all end nodes in a single-hop switched Ethernet during one clock synchronization round. At the same time, this approach can be applied to multihop distributed real-time systems. Performance measuring results show that this approach can provide clock synchronization precision less than 10 microseconds and is appropriate for most distributed real-time systems.