Energy efficient intruder detection in a wireless sensor network

Abstract

The main function of a wireless sensor network (WSN) is to detect intruders in its service area. Once a WSN is installed, it is desired to work as long as possible. For that the scarcity of energy from the limited size of sensor batteries has to be effectively handled, motivating us to develop energy efficient intruder detecting schemes in a WSN.Popularly used for extending the lifetime of a sensor network is a policy to let only a selected subset of sensors actively operate at a time while other sensors remain idle or in a sleep mode consuming only a tiny fraction of energy. This policy is adopted throughout, rendering the focus of our study on finding an optimal sleep schedule of sensors. For the sleep scheduling, introduced as a unit of selected sensor subset is the sensor path, which can by itself detect intruders and deliver that data via a form of alarm message to the gateway hub node for further processing. A sensor area is the area within which any intruder can be detected by a sensor at its center, taking the circular form. A sensor path is defined as a connected chain of overlapped sensor areas stretching from one side to the other side of a rectangular shaped cover (or service) area. Then the detection area covered by a sensor path looks like a strip stretching horizontally the rectangular service area. Penetration (confined here the vertical type only) by an intruder cannot thus be made without crossing the sensor area. Note that activating a certain sensor path means operating actively all the sensors constituting the barrier while letting all other sensors in the area be in the sleep mode. With the notion of sensor path, we deal with the problem on how to optimally schedule in time active ones from a list of sensor paths so as to maximize the lifetime of a WSN. Included in this setting is how to configure each candidate sensor path, which also affects the network’s lifetime. Provided that an intruder located within a sensor area is surely detect...