Implementation of High Precision Synchronization Protocols in Wireless Sensor Networks

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Microsecond-level time synchronization is needed in realtime applications of wireless sensor networks. While several synchronization protocols have been proposed, most performance evaluations have been limited to theoretical analysis and simulation, with a high level of abstraction by ignoring several practical aspects, e.g. packet handling jitters, clock drifting, packet loss, etc. Effective implementation in real motes faces several challenges due to motes' limitations and the unreliable lossy channels. These issues affect the protocol performance and precision. Authors of some pragmatic solutions followed empirical approaches for the evaluation, where the proposed solutions have been implemented on real motes and evaluated in testbed experiments. While there are several survey articles presenting the protocols from the conception perspectives, and others dealing with mathematical and signal processing issues of the estimators, a survey on aspects related to the practical implementation is missing. This article throws light on issues related to the implementation of synchronization protocols in WSN. The challenges related to WSN environment are presented, the importance of real implementation and the testbed evaluation are motivated by some experiments that we conducted. Finally, some relevant implementations of the literature that meet microsecond-level precision are discussed.
wireless sensor network, time synchronization, implementation