Ultra wideBand indoor position localizaiton

• Main Author: Xu, Jun
• Other Authors: Ma Maode
• Format: Theses and Dissertations
• Language: English
• Published: 2014
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Wireless communication systems
• Online Access: http://hdl.handle.net/10356/55437
• Institution: Nanyang Technological University

Position localization is becoming increasingly important in wireless communication networks. Ultra Wideband (UWB) is a good candidate for positioning thanks to its ability to resolve multipath and penetrate through walls. However, despite the promising performance of UWB systems, indoor localization is a tough task because the radio propagation channels would degrade the ranging precision. The range estimation may be affected in clustered environment. It is specifically the case when line-of-sight (LOS) is absent due to severe blockage. Non-line-of-sight (NLOS) is one of the major drawbacks for accurate ranging and localization. Therefore performance of UWB localization capabilities in indoor environments needs to be further investigated. In this thesis, a time-difference-of-arrival (TDOA) positioning scheme which is based on maximum likelihood estimation is proposed, and its theoretical and practical performance have been evaluated for both LOS and NLOS propagation channels. We then model the TDOA/TOA range errors and present the range measurement in different indoor multipath environments. The range errors are modeled for distance-independent (DI) and distance-dependent (DD) for line-of-sight (LOS) and non-line-of-sight (NLOS) cases. A comprehensive theoretical analysis using Cramer-Rao lower bound (CRLB) is presented. Communication between unknown-location nodes can be used to improve the positioning accuracy in harsh environment. Thus we develop an angle-of-arrival (AOA) cooperative positioning algorithm which takes advantage of high connectivity of wireless networks as well as the fine temporal resolution of UWB technique. Both TDOA and AOA ranging schemes have their own advantages and drawbacks, and thus we propose hybrid methods. Hybrid localization methods combine time measurement and angle measurement to reduce the number of reference nodes and improve the coverage. We develop a cooperative hybrid positioning algorithm which takes advantage of high connectivity of wireless networks, which improves the performance of indoor positioning substantially.