Abstract
In recent years, wireless sensor networks have become an interesting and important research area. The applications for such networks require collaborative execution of a distributed task among a large set of sensor nodes. Therefore, the time synchronization is a critical issue for wireless sensor networks. Because of limited energy for WSN, we utilize the concept of overhearing to decrease the control overhead while calculating the clock offset values to adjust the timers of sensor nodes. Especially, it can use in the modify topology without other extra steps. In this thesis, we propose the message-efficient time synchronization scheme (METS) which aims at providing network-wide time synchronization for a homogeneous sensor network where the transmission ranges of sensor nodes are assumed to be the same. In order to reduce synchronization error, we further propose a Heterogeneous METS to decrease hop counts by taking advanced nodes into consideration. The simulation results show that our proposed synchronization schemes provide accurate time synchronization and are energy efficient comparing to other schemes.