ETH Zurich : Computer Science : Pervasive Computing : Distributed Systems : Education : Student Projects : Abstract

Time Synchronization in a BTnode-Network (S)

Status: Abgeschlossen

A basic primitive of time synchronization is to learn about the clock offset of two clocks. There are various methods to do this and their accuracy determines the overall time accuracy. So far, the existing approach on the BTnodes basically measures the round-trip time of a packet sent by A to B, and from B back to A. Node A measures the time between sending and receiving the packet, Node B measures the time it takes to process the packet and send it back. Due to various reasons, there is a high variability in these measurements -- a packet might take up to 100 ms, which leads to very bad time synchronization ( 30-100 ms error).

Recently, we found a new (simpler) way for node A to learn about B's local clock with an error of only 1.25 ms. Based on this, a new basic time synchronization scheme should be developed. Additionally, this can further be used for clock drift synchronization.

In this project, we would like to see the current time sync mechanism used on the BTnode replaced by a new and simpler one which achieves better accuracy.