Abstract
Clock synchronization in the Mac layer plays a vital role in wireless sensor network communication that maintains time-based channel sharing and offers a uniform timeframe among different network nodes. Most wireless sensor networks are distributed where no common clock exists among them. Therefore, joint actions are realized by exchanging messages, with time stamps using local sensor clocks. These clocks can easily drift seconds and cause functional problems to the applications that depend on time synchronization. Time synchronization is a major and challenging factor in wireless sensor networks that needs to be studied and explored. In this paper, we propose integrated time synchronization protocols that serve wireless sensor network applications under normal, secured, and unreliable environments. The proposed protocols are discussed and evaluated based on their accuracy, cost, hierarchy, reliability, and security. Simulation results show that the proposed time synchronization protocols outperform the state-of-the-art techniques in achieving a minimum synchronization time.