Wireless sensor network
A wireless sensor network (WSN) is a network made of numerous small independent sensor nodes. The sensor nodes, typically the size of a 35 mm film canister, are self-contained units consisting of a battery, RF adapter, microcontroller, and sensor board. The nodes self-organize their networks, rather than having a pre-programmed network topology. Because of the limitations due to battery life, nodes are built with power conservation in mind, and generally spend large amounts of time in a low-power "sleep" mode or processing the information.
The Center for Information Technology Research in the Interest of Society {CITRIS} at the University of California, Berkeley, currently directed by S. Shankar Sastry, is a major center of research and development into wireless sensor networks, and has used them to study microclimate variations in individual redwood trees [1]. The Center for Embedded Networked Sensing, directed by Deborah Estrin, is also a leading research center with $40 million in core funding from the National Science Foundation [2]. Essentially, UCLA and Berkeley are the leaders in the area of wireless sensor networks with a majority of the publications in the cutting-edge field at top conferences and journals.