Indoor Positioning Using Frequency Translators

Heinz Mathis, Daniel Megnet, Thomas Kneubühler, Andreas Thiel and Etienne Favey

Abstract:	Whereas most GPS repeater based indoor navigation systems apply time switching between the different repeaters, the proposed system uses different frequencies among the repeaters. Rather than cycling through the different repeaters, the repeaters all transmit simultaneously in time. However, prior to retransmission, each repeater translates the signal onto a different frequency location within the ISM band at 2.4 GHz. Such a system has a couple of significant advantages: First, precision accuracies reported in and are preserved since the fundamental arrangement (e.g., geometry, signal structure etc.) remains. Second, no time synchronization between the repeaters/translators is necessary. The receiver does not need to synchronize its time to the repeaters (apart from the usual GPS range/time reception and computation). Third, there is no danger of GPS interference. Other standard GPS equipment will either work undisturbed indoors if it has weak-signal capability or will not be interfered outdoors close to buildings containing the translator system. Fourth, the RF front-end of such a repeater/translator might potentially be combined with WLAN access points, since 802.11b/g use the same band. Coexistence of WLAN and GPS translator technology is provided through the spread-spectrum approach of either of the systems. Different navigation solutions are shortly discussed and convergence regions for a couple of setups of translator geometries are given based on Matlab simulations. Complying with FCC and other regulations as far as radiation in ISM bands are considered, the current approach is believed to gain more acceptance than other systems, where interference to the L1 band is a potential hazard.
Published in:	Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005) September 13 - 16, 2005 Long Beach Convention Center Long Beach, CA
Pages:	2789 - 2799
Cite this article:	Mathis, Heinz, Megnet, Daniel, Kneubühler, Thomas, Thiel, Andreas, Favey, Etienne, "Indoor Positioning Using Frequency Translators," Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005), Long Beach, CA, September 2005, pp. 2789-2799.
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