Fault-Tolerant Clock Synchronization Over Unreliable Channels in Wireless Sensor Networks

In this paper, we study a distributed approach based on consensus algorithms for clock synchronization in wireless sensor networks. The sensor nodes face two types of uncertainties. One is that some of the nodes in the network can be faulty and transmit arbitrary signals by not following the given protocol; similar effects may be caused by false data injection by an external malicious attacker. The other is that the communication is unreliable and the packets exchanged may become lost. To deal with these uncertainties, we propose a resilient consensus-type algorithm based on the so-called mean subsequence reduced (MSR) technique, where each normal node ignores the outliers in the clock data collected from its neighbors and makes updates using data from the past if new data have not arrived yet. We establish network connectivity conditions in terms of graph robustness for the MSR algorithm to attain resilient properties.