ABSTRACT
In the near future, small intelligent devices will be deployed in homes, plantations, oceans, rivers, streets, and highways to monitor the environment [1]. Events, such as target tracking, speed estimating, and ocean current monitoring, require the knowledge of time between sensor nodes that detect the events. In addition, sensor nodes may have to time-stamp data packets for security reasons. With a common view of time, voice and video data from different sensor nodes can be fused and displayed in a meaningful way at the sink. Also, medium access scheme such as Time Division Multiple Access (TDMA) requires the nodes to be synchronized, so the nodes can be turned off to save energy.
