Clock Skew and Offset Estimation Based on Correlation Detection under Unknown Asymmetric Time Delay Conditions in Wireless Sensor Networks

Accurate clock synchronization is essential to the application of wireless sensor networks, where time delays are unavoidable, and unknown asymmetric time delays will affect the synchronization accuracy. Currently, most researches assume that the uplink and downlink delays are equal or known for the convenience of estimating clock synchronization parameters. However, in practice, uplink and downlink delays are often unknown and asymmetric, significantly reducing estimation accuracy and affecting clock synchronization. To address this challenge, we propose a joint estimation of clock skew and offset method based on correlation detection to achieve clock synchronization under unknown asymmetric time delays. Specifically, we first change the size of transmitted packets to reduce the influence of unknown asymmetric time delays on clock synchronization accuracy. Meanwhile, the whole process is completed at the physical layer, avoiding the impact of random time delays caused by timestamps. Simulation results show that the proposed method has higher estimation accuracy in clock skew and offset than the traditional clock synchronization methods under unknown asymmetric time delays.