Research On Time Synchronization In Sensor Networks

Wireless sensor networks are self-organised network systems, consisting of many inexpensive sensor nodes which are deployed in a certain area and capable of wireless communications. Because of their unique advantages, sensor networks have broad application prospects in the fields of national defense, industrial control, environmental monitoring, e-health, Smart-Home and other fields.Time synchronization is a basic function essential for many applications in wireless sensor networks. Because sensor network nodes have limited resources, traditional methods of time synchronization are no longer suitable for sensor networks. So far, researchers have developed a number of time synchronization protocols sensor networks.As the existing node platform can not meet the design requirements, so this paper first designed a sensor network node platform and the corresponding software programs. The node platform consists of digital signal processor, programmable logic device, wireless transceiver module, and power management modules. A high-precision clock is established and maintained in the programmable logic device which monitors and records the arrival time of wireless packet; digital signal processor is in charge of computing; wireless module enables wireless communication between nodes; power management module is responsible to provide power to various parts of the node. Then dynamic adjusting time synchronization protocol for sensor networks is presented, which use a combination of high-precision timestamp technology, Reference-Broadcasting based on broadcasting and offset and drift compensation based on dynamic adjustment. The theoretical analysis and experimental validation of the protocol is discussed in detail. Dynamic adjusting time synchronization needs only a small memory overhead, computational overhead and communication overhead, and can continue to approach the optimal clock compensation. Experimental results show that synchronization accuracy of dynamic adjusting time synchronization is 0.9655±0.9810μs, which is higher than most of the time synchronization protocols for wireless sensor networks. Meanwhile, dynamic adjusting time synchronization protocol is robust when the external environment changes, and the synchronization accuracy will not get worse significantly when the synchronization cycle increased.