Study On Time Synchronization Algorithm In Wireless Sensor Networks

With the development of micro-sensors,integrated circuits and wireless communications technology,wireless sensor network has made widespread use in many areas.Due to the crystal frequency difference and the influence of environmental factors,there are differences in the local time of nodes in wireless sensor network.For the need of multi-node joint task,the time between nodes must be synchronized.Therefore,the time synchronization problem in wireless sensor networks has become a hot research topic.Considering the characteristics of limited energy and topology changes,current research mainly focuses on improving energy performance,robustness and other service performance of time synchronization algorithm.In view of shortcomings of the existing time synchronization algorithm,this paper studies the following three aspects,the improved TPSN algorithm based on interframe information difference,the time synchronization algorithm design based on clustering technique and the time synchronization algorithm based on event triggering.(1)Aiming at the redundancy between time synchronization messages,an improved TPSN algorithm based on interframe information difference is proposed.The algorithm analyzes internal structure of the TPSN synchronization message frame,takes into account correlation of the content such as time information,replaces the complete synchronization message frame with the information difference between two preceding synchronization message frames,and finally reduces the amount of message data of single synchronization and the communication consumption caused by synchronization message.The simulation results show that the algorithm reduces the synchronization energy by using the information redundancy of the message frame.(2)The increase of network scale causes slow convergence and large amount of traffic consumption in distributed time synchronization algorithm,in order to reduce that influence,a time synchronization algorithm based on clustering technique is proposed.The new algorithm divides the network topology into several clustering structures by using clustering technique.The distributed time synchronization algorithm is adopted for the network with cluster head nodes and overlapping nodes.The centralized time synchronization algorithm is adopted for the common member nodes in cluster.The combination of the two can effectively improve the performance of time synchronization algorithm.Simulation results show that the mechanism of taking different time synchronization algorithm in inter-cluster and inside the cluster not only realizes synchronization of the whole network,but also improves convergence speed,communication consumption and synchronization error.(3)For the problem of large communication energy consumption caused by periodic synchronization parameters broadcast in distributed time synchronization algorithm,a time synchronization algorithm based on event triggering is proposed.Event triggering mechanism is introduced into the new algorithm,the broadcast of synchronization parameter will be no longer carried out periodically,but will be depend on triggering of the specific event.By designing a reasonable event triggering function,the absolute time synchronization is realized by using the proposed new algorithm among nodes,the times of broadcast is reduced,and the communication energy consumption is saved at the same time.The simulation results show that the new algorithm maintains convergence speed of distributed time synchronization algorithm and is optimized in energy consumption of time synchronization algorithm.