Sensor node localization using uncontrolled events

Many event-driven localization methods have been proposed as low cost, energy efficient solutions for wireless senor networks. In order to eliminate the requirement of accurately controlled events in existing approaches, we present a practical design using totally uncontrolled events for stationary sensor node positioning. The novel idea of this design is to estimate both the event generation parameters and the location of each sensor node by processing node sequences easily obtained from uncontrolled event distribution. To demonstrate the generality of our design, both straight-line scan and circular wave propagation events are addressed in this paper, and we evaluated our approach through theoretical analysis, extensive simulation and a physical testbed implementation with 41 MICAz motes. The evaluation results illustrate that with only randomly generated events, our solution can effectively localize sensor nodes with excellent flexibility while adding no extra cost at the resource constrained sensor node side. In addition, localization using uncontrolled events provides a nice potential option of achieving node positioning through natural ambient events.