Evaluating a clock synchronization for dependable sensor networks

A synchronized clock is an important prerequisite for many distributed algorithms. This clock is used to give an "occured before" relationship, as well as for synchronizing distributed actions. There are many clock synchronization algorithms with varying precisions and assumptions on the underlying network topology. In this paper, a synchronization protocol is presented which achieves a high precision in the order of 20 mus to 30 mus in a one-hop wireless environment, and a multiple of this value for multi-hop wireless networks, such as sensor networks. The protocol works reliably even if message losses occur, which is very likely in wireless networks. For this, it utilizes redundancy in the sent time information. This protocol is implemented and evaluated on standard PC hardware running RT-Linux/Free, and an outline of the extension for multi-hop scenarios is given