Target Tracking In Wireless Sensor Networks

The problem being tackled here relates to the probl em of target tracking in wireless sensor networks. It is a specific problem in localization. Localization primarily refers to the detection of spatial coordinates of a node or an object. Target tracking deals with finding spatial coordinates of a moving object and being able to track its movements. In the track ing scheme illustrated, sensors are deployed in a triangular fashion in a hexagonal mesh such that th e hexagon is divided into a number of equilateral triangles. The technique used for detection is the trilateration technique in which intersection of three circles is used to determine the object location. While the object is being tracked by three sensors, distance to it from a fourth sensor is also being calculated simultaneo usly. The difference is that closest three sensors detect at a frequency of one second while the fourth sensor det ects the object location at twice the frequency. Us ing the distance information from the fourth sensor and a s imple mathematical technique, location of object is predicted for every half second as well. The key th ing to note is that the forth sensor node is not us ed for detection but only for estimation of the object at half second intervals and hence does not utilize mu ch power. Using this technique, tracking capability of the sy stem is increased.