无线传感器网络的分布扩散时钟自同步协议研究

Clock Self-Synchronization Protocol Based on Distributed Diffusion for Wireless Sensor Networks

针对大规模无线传感器网络同步协议的精度较低、可扩展性差的问题,提出一种分布式扩散时钟自同步协议(DDCSS);DDCSS是一个局部、并行执行的协议,基于分布式扩散的思想,以节点能量、分布和平均传输时延为依据,每轮动态地选取执行局部扩散的一组主节点和扩散节点,把主节点域内的节点平均时钟扩散有限的跳数,周围节点以接收的所有主节点域平均时钟取平均更新本地时钟,采用互扩散的方法使节点时钟近似同步到网络节点的平均时钟上,从而实现全网的时间同步;与RBS、TPSN协议相比较,该协议收敛速度较快,另外消除了误差累积,同步误差较低,扩展性较好。

In view of the low precision and scalability of synchronization protocol for the large--scale wireless sensor networks （WSNs）, clock self--synchronization protocol based on distributed diffusion （DDCSS） is proposed in this paper. The distributed diffusion--based protocol is full localized. Its implementations process is fully localized and parallel. According to the energy, distribution and the average transmission delay of nodes, DDCSS dynamic chooses a set of master node and diffusion nodes which are used to perform local diffusion in each round. And then the average clock in master node field is spread to surrounding nodes of hops. After that the surrounding nodes update the local clock by receiving the average clock. Eventually through several rounds of elections master nodes and diffusion nodes, networks implement mutual diffusion and the node clock is approximate synchronization the average clock of network nodes. By comparing DDCSS with RBS and TPSN, we show that, with the increasing of scale of sensor networks, DDSCC can synchronize the network quickly with good precision convergence speed and scalability, which appropriates for large--scale WSNs.