A Robust Approach for Clock Offset Estimation in Wireless Sensor Networks

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The Maximum Likelihood Estimators (MLEs) for the clock phase offset assuming a two-way message exchange mechanism between the nodes of a wireless sensor network were recently derived assuming Gaussian and exponential network delays. However, the MLE performs poorly in the presence of non-Gaussian or non-exponential network delay distributions. Currently, there is a need to develop clock synchronization algorithms that are robust to the distribution of network delays. This paper proposes a clock offset estimator based on the Composite Particle Filter (CPF) to cope with the possible asymmetries and non-Gaussianity of the network delay distributions. Also, a variant of the CPF approach based on the Bootstrap Sampling (BS) is shown to exhibit good performance in the presence of reduced number of observations.