Author/Authors :
LI, Li Tsinghua University - Department of Electronic Engineering, Tsinghua National Laboratory for Information Science and Technology, China , LIU, Yongpan Tsinghua University - Department of Electronic Engineering, Tsinghua National Laboratory for Information Science and Technology, China , YANG, Huazhong Tsinghua University - Department of Electronic Engineering, Tsinghua National Laboratory for Information Science and Technology, China , WANG, Hui Tsinghua University - Department of Electronic Engineering, Tsinghua National Laboratory for Information Science and Technology, China
Abstract :
The cluster global time can change in wireless sensor networks due to leader re-elections and node disabilities between two successive synchronizations, which will affect temporal relationships. This paper analyzes cluster global time continuity, using global time change models for the node dynamics. The results prove that defining the global time using the cluster average time (AGT) is more stable than defining it using a single node’s local time (SGT). With normally distributed clock-parameter assumptions, the AGT change bounds are at most 70.7% of those for the SGT’s. The impacts of the initial phase and frequency skew distributions on the global time continuity are also investigated to show that the initial phase variations may strongly influence the continuity. Simulations show that the AGT is more stable with less disabled nodes or larger clusters. The appropriate cluster size is 20-40 when there are less than 15 disabled nodes.
