In Network Processing and Data Aggregation in

environmental noise inducing this way uncertainty in readings. A damaged sensor mightalso generate inaccurate data.In Figure 1 a typical example of a sensor node (Berkeley MICA Mote) is illustrated sothat the reader is able to realize its tiny size. Table 1 provides us with the hardwarecharacteristics of the MICA Mote.ProcessorStorageRadio BandComm. RangeData RateTx PowerReceive Power4Mhz, 8bit MCU(ATMEL)512KB916Mhz33 m40 Kbits/sec12 mA1.8 mAFigure 1. The Berkeley MICA MoteTable 1. Mica Mote’s characteristicsWireless sensor networks can be used in awide range of application domains:• Environmental monitoring (coordinated sensing or information gathering in adisaster area).• Supervising items in a factory warehouse.• Intelligent building management• Organization of vehicle traffic in a large city (traffic routing).• Military (target recognition and tracking).• Medical and health care.Each one of the above applications has its own network, hardware and nodedeployment requirements. WSNs lack of standardized solutions because they areapplication specific networks, i.e., design requirements of a sensor network change dependingon the application. However, no matter the kind of the application, the communicationscenario is always identical (Figure 2). A user sends several tasks in the form of queriesto the network. The user can either be directly attached to a gateway node or he can alsobe connected remotely through an intermediate network (e.g. internet or via satellite).After the query reaches the WSN (sink), it is automatically translated into an internal