Performance bounds for phase offset estimation in IEEE 1588 synchronization

There has been recent interest in the use of packet-based synchronization techniques based on the IEEE 1588 Precision Time Protocol, in order to meet challenges arising in mobile telecommunication networks. An important problem in this area is to design estimators that determine the phase offset of slave clocks, while being resilient to the degrading effects of random network traversal times. While a number of simple non-parametric estimation techniques for this problem have been described in literature, little is known about the best theoretically achievable accuracy. In this paper, we address this issue by describing two novel lower bounds on the error variance of estimators for such problems. These bounds are obtained by adapting two classical Bayesian estimation bounds, namely the Weiss-Weinstien bound and the Ziv-Zakai bound, to a non-Bayesian estimation scenario. The results provide new insights into scenarios where existing phase offset estimation techniques perform well, and where significant scope for performance improvements exists.