Lokalisieren von Mobilstationen in MIMO-Mobilfunksystemen mit Mehrwegeausbreitung
Zusammenfassung der Projektergebnisse
Localization and tracking using satellite navigation systems, where the signal propagates in a LOS fashion from the transmitter to the receiver, has been well developed and deployed. However, localization in NLOS environments remains challenging and it is still a hot research topic. In this project a physically inspired parametric model, the SBS model, has been investigated for localizing and tracking a MS in NLOS environments. The SBS model relies on MIMO systems which enable the TOA, the AOA, and the AOD estimation. Using the SBS model and the TOA, the AOA, and the AOD estimates different localization scenarios have been investigated and different algorithms have been proposed to localize and track the MS In NLOS environments. The essential contribution of this project work Is to exploit the geometry of the SBS model so that a nonlinear estimation problem of localization in NLOS environments is transformed into a linear estimation problem in the position of the MSs and the BSs. Thus simple linear estimators have been proposed to estimate the position of the MSs. It has been shown that unlike classical localization algorithms which require at least three BSs for MS localization, only a single BS is sufficient for localization using the SBS model to provide a satisfactory estimate of the position of the MS. It has also been shown that consideration of more scatterers results in a significant performance improvement when estimating the MS position. This is an important result as the scatterers have been used to aid in the localization process. This is counter-intuitive to other NLOS localization approaches where the impact of the scatterers on the localization process is considered as something that needs to be identified and mitigated. In addition, the proposed NLOS localization approach has been extended to localization in networks where several BSs and MSs participate in the localization process. It has been shown that as in classical cooperative localization algorithms, cooperation in NLOS network localization is possible. The MSs cooperate with each other to enable localization in cases where localization of the MSs is otherwise impossible. Another important contribution of this work is the extension of the localization approach to the case of incomplete observations, i.e, the TOA, the AOA, or the AOD are not available. The practicability and feasibility of the proposed localization algorithms has been investigated by conducting an experiment in an office environment at the University of Rostock. It has been shown that it is possible to estimate the position of the MS with satisfactory accuracy in a multipath environment using the proposed algorithms. In addition, the efficiency of the proposed algorithms has been assessed by developing the lower bounds for the MS estimates precision in NLOS environments. Due to the increased capacity and reliability offered by MIMO systems, future wireless radio systems will be certainly based on MIMO systems. The localization algorithms proposed in this project can be used to deliver a satisfactory MS localization in NLOS environments exploiting the capability of MIMO systems to estimate the propagation path length and the direction of arrival of the signals.
Projektbezogene Publikationen (Auswahl)
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AOD/AOA/TOA-based 3-D positioning in NLOS multipath environments. In Proc. IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC'11), pp. 1294-1298, Toronto, September 2011
X. Wei, N. Palleit, T. Weber
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Discrete position processing techniques for indoor NLOS localization, In Proc. International Symposium on Wireless Communication Systems 2012 (ISWCS'12), pp. 631 - 635, Paris, France, August 2012
B. Y. Shikur, T. Weber
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TOA/AOA/AOD-based 3-D mobile terminal tracking in NLOS multipath environments. In Proc. Workshop on Positioning. Navigation and Communication 2012 (WPNC'12), pp. 201-205, Dresden, Germany, March 2012
B. Y Shikur, M. Farmani, T. Weber
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Posterior CRLB for tracking a mobile station in NLOS multipath environments, In Proc. IEEE International Conference on Acoustics, Speech and Signal Processing 2013 (ICASSP'13), pp. 5175-5179, Vancouver, Canada, May 2013
B. Y. Shikur, T. Weber
