Multi-hop based highly precise time synchronization Protocol for ZigBee networks

Wireless sensor networks (WSN) have emerged as an interesting and important research area in the last few years. Time synchronization is a critical middleware service of distributed system. In particular, wireless sensor networks is a distributed system which makes extensive use of synchronized time in many contexts (e.g. for data fusion, TDMA schedules, synchronized sleep periods, etc.). In addition, synchronization precision has become a critical area of research today. Time synchronization with very high precision is needed at some special application. In this paper, we proposed a high degree of accuracy time synchronization Protocol--Physical Layer Integrated Synchronization Protocol (PLISP). Different from adding timestamp in MAC layer of traditional time synchronization protocol, we advocate a novel way to add timestamp. We add timestamp in physical layer which can utmost reduce influence of nondeterminacy factor to synchronization precision. Result shows that this method is feasible and can be used to wireless sensor networks based on multi-hop.