Handbook of Sensor Networks

Recent technological advances have enabled the development of low-cost, lowpower, and multifunctional sensor devices. These nodes are autonomous devices with integrated sensing, processing, and communication capabilities. A sensor is an electronic device that is capable of detecting environmental conditions such as temperature, sound, chemicals, or the presence of certain objects. Sensors are generally equipped with data processing and communication capabilities. The sensing circuitry measures parameters from the environment surrounding the sensor and transforms them into electric signals. Processing such signals reveals some properties of objects located and/or events happening in the vicinity of the sensor. The sensor sends such sensed data, usually via a radio transmitter, to a command center, either directly or through a data-collection station (a base station or a sink). To conserve the power, reports to the sink are normally sent via other sensors in a multihop fashion. Retransmitting sensors and the base station can perform fusion of the sensed data in order to filter out erroneous data and anomalies, and to draw conclusions from the reported data over a period of time. For example, in a reconnaissance-oriented network, sensor data indicates detection of a target, while fusion of multiple sensor reports can be used for tracking and identifying the detected target.