A partial TPSN time offset synchronization scheme in Wireless Sensor Network applied for Bridge Health Diagnosis System

This article is aimed to introduce a new hybrid time offset synchronization (sync) scheme for Wireless Sensor Network (WSN) for Bridge Health Diagnosis System (BHDS), which is wildly used as a main monitoring method in japan for collection of vibration information to diagnose the health condition of the bridge affected by the frequent nature disasters around whole country. It is publicly known that the collection and communication of such a large-scale distributed WSN requires a strict time sync scheme with little average sync error as well as max error, while taking energy-awareness and sync latency into consideration. In some cases, the traditional sync scheme such like TPSN or RBS fail to fulfill the needs. Therefore a hybrid scheme between the TPSN and direct-adjustment ensuring the sync accuracy without consuming more power has been studied in this paper. Generally speaking, the partial TPSN time offset scheme studied in this paper is a scheme to choose No. k of the children nodes to sync according to TPSN protocol and calculate the time offset for rest of nodes by using the data from both kind of nodes (the No. k´s and the rest´s). The mathematical model has been introduced and the simulator also has been developed to calculate the optimized k. By choosing different k, different average error and power consumption will occur hence to fulfill the different needs for BHDS. At last, the idea has been evaluated and experimented to make sure that it can, especially in BHDS, meet the needs for WSN.