Techniques for Reducing the Near-Far Problem in Indoor Geolocation Systems

Jonathan M. Hill, Ilir F. Progri and William R. Michalson

Abstract:	When using pseudolites to provide navigation in an indoor or underground environment there is a concern that nearby pseudolites will negatively impact the ability of a receiver to track all of the available pseudolites. This problem, known as the near-far problem is a consequence of limited dynamic range. Some techniques for solving this problem, such as modifying the pseudolite duty cycle or synchronizing pseudolite transmissions have been previously proposed. In contrast, this paper explores the dynamic range issue directly by investigating the behavior of a receivers tracking loops. By subjecting the tracking loop to various high dynamic range scenarios, the effect of signal and loop characteristics on dynamic range is directly visible. Based on this approach, proposals for increasing receiver dynamic range will be presented and validated using both analytically and simulated results.
Published in:	Proceedings of the 2001 National Technical Meeting of The Institute of Navigation January 22 - 24, 2001 Westin Long Beach Hotel Long Beach, CA
Pages:	860 - 865
Cite this article:	Hill, Jonathan M., Progri, Ilir F., Michalson, William R., "Techniques for Reducing the Near-Far Problem in Indoor Geolocation Systems," Proceedings of the 2001 National Technical Meeting of The Institute of Navigation, Long Beach, CA, January 2001, pp. 860-865.
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