Research On Time Synchronization Algorithm Based On Wireless Sensor Network

The rapid development of technology makes wireless sensor network(WSN)widely used in many fields,such as military intelligence detection,medical patient testing,urban construction and home intelligent control.In a designated detection area,there are countless man-made micro-sensor nodes dispersedly distributed.These nodes form a multi-hop ad hoc network integrating data acquisition,transmission and processing.The multi-hop ad hoc network is a wireless sensor network.In many large applications,the number of nodes in a wireless sensor network reaches the order of tens of thousands.Many functional applications such as network controls in wireless sensor networks require accurate node time synchronization.Once the sensor node time lost synchronization,the information collected by the nodes would lose the timeliness,the user also lost value.However,there are many shortcomings such as limited energy and limited storage capacity of wireless sensor networks,So there are still many obstacles in the research of time synchronization.The traditional wireless sensor network node time synchronization protocols include RBS,TPSN,FTSP and PBS.Different nodes send the messages and exchange timestamps between each other to adjust the local clock.There are also time-synchronized wireless sensor network network topology constructions,including clustering,grid,tree topology,so as to achieve the spread of the whole network time synchronization.In recent years,the study on the estimation accuracy of clock parameters has become a new research hotspot from the perspective of statistical signal processing.In view of the existing protocols are mostly based on sending special time-synchronization data packets between nodes of wireless sensor networks,in order to reduce a large amount of node energy consumed by this part,this paper inserts the time-stamp message into the basis of node MAC layer data frames and ACK acknowledgment frames.The frame format is further improved.When a specific pair of nodes performs data packet communicate,other nodes in the public communication range of this two nodes use eavesdropping mode to obtain the timestamp information of the data packets sent and received by the pair of nodes to complete the adjustment of the local clock.However,the communication packages between non-special nodes do not need to embed timestamp information,so as to reduce the node energy.Based on the single-hop mechanism,an improved IFDSS time synchronization protocol is proposed.Then,from the perspective of statistical signal processing,we establish the random time delay in the communication process as a Gaussian model and estimate the synchronization parameters by using the least square method to improve the synchronization accuracy.After the experimental simulation,the improved protocol proposed in this paper has better performance in node energy saving and clock synchronization.Finally,this paper combines the proposed MAC layer protocol and network topology and node time synchronization protocol to realize the prototype of wireless sensor network system.It is proved that it has good practical usability and has the value of further research.