Inexistingsensornetworks,power-constrainedsensorsaredeployedinthetargetedareaanddataiscollecteduntilthe
sensorsrunoutofbatterypowerorthecollectiontimewindowexpires.Thereareseveraldisadvantagesinsuchtraditional
sensor networks. First, the size of the sensor network is usually small. Second, most sensors are power constrained and
hencemayrequirereplacingorrechargingoftheirbatteries;eitherofthesetasksisintrusivetothesensingprocessandcan
sometimesbetimeconsumingifthesensingenvironmentisnoteasilyaccessible