Identification Mitigation of NLOS Information for UWB based Indoor Localization
Technology advancements such as GPS, automation and robotics have completely changed the world and produced new industries, once thought to be unimaginable a century ago. As with all technology, these systems come with limitations and can be further improved. At this time, all of these systems share one common problem; they cannot work together in an indoor environment. The advent of indoor positioning systems aims to create a union between these technologies such as allowing robots to be location aware. Indoor positioning is currently a new technology with no defined standard. Ultra wideband based indoor positioning systems have become popular because of their resistance to multipath and high resolution due to a large bandwidth. The Ultra wideband based system in this thesis utilizes the time of arrival technique to calculate distances and thus a user's position. Time of arrival is only reliable when there is a line of sight between two transceivers. If there is no line of sight, the distances calculated are inaccurate thus impacting the accuracy of a user's position. This thesis proposes a practical, non hardware intensive solution to identify if there is a no line of sight condition and mitigates the measured range between a tag and the anchor nodes. Line of sight identification was implemented using the channel impulse response data. Ranging and positioning mitigation was achieved using a geometric based mitigation scheme. An accuracy of 90% was achieved for the identification of no line of sight and an improvement factor of 2.81 was achieved for the calculated mitigated position of a tag.