Accurate and Robust Clock Parameters Estimation for Energy-Efficient Time Synchronization With Multi-Link Overhearing in Wireless Networks

Time synchronization is a significant premise for the proper functioning of wireless networks. Several energy-efficient protocols targeting time synchronization have been proposed to maximize accuracy while minimizing energy consumption. Since no packet transmission is required, receiver-only synchronization has been extensively studied in wireless networks. However, there is a performance loss in synchronization accuracy and robustness because inactive nodes are synchronized by passively receiving messages over a single link. In wireless environments, an inactive node inevitably overhears paired synchronization messages from multiple communication links due to the broadcast characteristic. Based on this consideration, an accurate and robust clock parameters estimation algorithm for energy-efficient synchronization with multi-link overhearing is developed. Specifically, a robust joint estimator of clock skew and offset based on invariant decision rules is derived with the assumption that prior information regarding the availability of overhearing links is known. In the absence of such information, as in harsh wireless channel conditions, we also propose a linear aggregation estimation mechanism with outlier diagnostic, which further enhances the robustness and resilience of time synchronization over wireless networks. Finally, numerical simulations are implemented and simulation results demonstrate that the synchronization accuracy and robustness are significantly enhanced.