Direction of Encounter (DoE): A Mobility-Based Location Method for Wireless Networks

Traditional location methods require specialized network infrastructure or add-on location hardware in order to estimate node positions. As an opposite approach, direction of encounter(DoE) uses standard wireless networking equipment and takes advantage of node mobility to establish static node locations. In DoE, as a mobile node enters and leaves a static node´s coverage area, it is able to discover the static node´s location with respect to its own trajectory. Mobile nodes are able to determine the position of a set of static nodes by collaborating in this discovery process. In this work, this set is called a constellation. This collaboration consists of exchanging constellation data in order to establish and improve the accuracy of the position estimates. Not only does DoE establish static node positions, but it also allows mobile users to be aware of the direction where static nodes can be found. DoE needs minimal user intervention, although fully automatic operation can be achieved if inertial sensors are available. This method can be used to develop both location-based applications and guiding procedures. By means of simulations and experiments, we carried out a performance evaluation of DoE under diverse conditions. The results show that the DoE algorithm indeed is able to estimate the static node positions without requiring additional functionality from static nodes. We believe this is an important requirement for a successful deployment of a location method.