ABSTRACT
In the most abstract sense, a sensor network is a collection of nodes at which data are being produced (through sensing of the physical phenomena). For the network to be of practical use, at least some of these data or a processed version of it must be provided to at least one end user. Ÿe implementation of this information ºow depends upon the application requirements as well as the resources available. In the simplest kinds of sensor networks, all the data generated may be sent continuously to a central data sink. Ÿis would naturally be resource intensive in terms of bandwidth as well as energy and may not be necessary if the end application requires only processed noti¢cation of events. Ÿerefore, more sophisticated systems opt to route only selective information based on the in-network processing of one or more nodes’ data, upon the issuance of a request (query) for this information.
