Experiences with an inbuilding location tracking system: Uhuru

The increasing functionality that handheld devices have come to incorporate at lower prices make them powerful candidates for various kinds of location-aware systems and services. In this work, we describe the innards of Uhuru, an RF based in-building location tracking system that we have developed and deployed on a mobile device. Our work seeks to build upon and extend previous work in this field, providing proof of concept for location information on multiple floors in a building. We outline a history monitoring algorithm that we have devised to improve the accuracy of the system and introduce a new metric of 'Survivability', which measures the ability of history-based location tracking schemes to be able to display location information consistently. We also discuss details of a heuristic that can be used for the placement of wireless base stations to improve the delivered accuracy.