  The generalization of the maximum-likelihood-like estimator for clock skew by
Leng and Wu in the above paper is erroneous because the correlation of the
noise components in the model is not taken into account in the derivation of
the maximum likelihood estimator, its performance bound, and the optimal
selection of the gap between two subtracting time stamps. This comment
investigates the issue of noise correlation in the model and provides the range
of the gap for which the maximum likelihood estimator and its performance bound
are valid and corrects the optimal selection of the gap based on the provided
range.
