On Cluster-Based Time Synchronization Of Wireless Sensor Networks

Wireless sensor network, which is made by the convergence of sensor, embedded computing, distributed information processing and wireless communication technologies, is a new information acquisition, processing and transmission technologies. Time synchronization is an important issue in wireless sensor networks. Many applications of sensor networks need local clocks of sensor nodes to be synchronized requiring various degrees of precision. Some intrinsic properties of sensor networks make traditional synchronization methods unsuitable for these networks. Hence, there has been an increasing research focus on designing synchronization algorithms specifically for wireless sensor networks.Firstly, time synchronization development and its necessity are studied. Time synchronization techniques are described respectively corresponding to time synchronization categories. Then an new cluster-based time synchronization protocol-Improved Tiny-Sync Reference Broadcasting Time Synchronization (IRTS) is proposed. The paper introduces the entire process of IRTS and explains the key technology of IRTS. At last, this paper analyzes power consumption and synchronization errors of IRTS protocols by simulation, compare different energy consumption of nodes in different node floor and different synchronization errors in different hops. The result shows the superiority of IRTS on cluster-based topology.In the time synchronization algorithm: (1) To the question that Tiny-Sync algorithm doesn't think over the affects of noise data, this paper inducts curve fitting and presents an improved Tiny-Sync algorithm. Emulational experiments prove that our algorithm can availably overcome the effects of noise data on nearly the same precision of Tiny-Sync algorithm. (2)To the question that the node, which broadcasts reference information, can't synchronize with other nodes in RBS arithmetic, the paper inducts signal nodes broadcasting reference information. we synchronize the reference nodes with ordinary nodes.(3) In the static cluster-based IRTS protocol, Cluster headers consume too much power, and nodes' power load is not balanced. To solve this problem, this paper proposes dynamic cluster-based IRTS protocol. A new cluster header election algorithm is proposed. Computer simulation result shows that dynamic cluster-based IRTS protocol meeting network requirement of synchronization precision, dynamic cluster-based IRTS protocol can also save energy of the whole network and balance nodes load.As these works completed, the paper has accomplished the whole process that put forward question, analyzes question, answers question and proves conclusion. At last the paper states the research direction in the future.