Robust Phase Offset Estimation for IEEE 1588 PTP in Electrical Grid Networks

This paper addresses the problem of robust clock phase offset estimation for the IEEE 1588 precision time protocol in the presence of unknown asymmetric path delays in electrical grid networks. Assuming the availability of multiple master-slave communication paths, new lower bounds on the mean square estimation error for this problem were recently derived by the authors. In this paper, we present a novel phase offset estimation scheme that uses robust M-estimators for identifying the asymmetric master-slave communication paths. After discarding observations from the paths identified as asymmetric, we employ the computationally efficient L-estimators, which are linear combinations of order statistics, to estimate the phase offset from the symmetric master-slave communication paths. Simulation results show that the proposed phase offset estimation scheme exhibits performance close to the lower bounds in different network scenarios.