Research On Time Synchronization Algorithm For Wireless Sensor Network

Time synchronization technology has been a hot topic of wireless sensor networks for a very long time. With the help of theoretical analysis and numerical simulation, the Timing-Sync Protocol for Sensor Networks and Flooding Time Synchronization Protocol which are based on sender-receiver synchronization mechanism has been studied. At the same time a comparison and analysis on performance property between Reference-broadcast Synchronization which is based on receiver-receiver synchronization mechanism has been studied. The outcome of analysis indicates that FTSP has a better performance property than RBS and TPSN. After a deeper inside study, FTSP also has obvious shortcomings. An optimization method has been proposed. The results have theoretical significance and practical value.Firstly, the security property of linear regression arithmetic for calculating time offset in FTSP is low. The arithmetic is easy to be attracted by anomaly data. The compensation of the wrong time offset will lead a larger synchronization error. This paper improves the linear regression, increase the precision of time offset and restrain the effect of anomaly data.Secondly, in the long distance multi-hop networks, the synchronization error caused by transmission delay can never be ignored ever. A synchronization arithmetic based on Maximum Likelihood Estimation has been proposed. The simulation result indicates that the error accumulation caused by transmission delay is decreased.Thirdly, although FTSP uses time offset compensation to decrease the synchronization error, the study shows that the order of nodes clock skew on the synchronization path will lead lack compensation or over compensation of time offset which can have a different degree effect on synchronization error accumulation. Theoretical analysis and numerical simulation shows that descending order will cause a larger synchronization accumulation error, while ascending order or random order has smaller accumulation error.Lastly, deeper analysis possible malicious attracts of FTSP, wrong sending time will lead an obvious deviation of time offset. Add an anomaly clock skew detection and a malicious node ID filter. The secure property and robust of arithmetic have been improved.