Innovative Techniques for GPS Indoor Positioning Using a Snapshot Receiver

D. Jiménez-Baños, N. Blanco-Delgado, G. López-Risueño, G. Seco-Granados, A. Garcia-Rodríguez

Abstract:	Indoor and dense urban positioning has received much attention in the last years, since they constitute the bottleneck in the extension of location services in mobile networks. Global Navigation Satellite System (GNSS) positioning has turned out to be a very suitable candidate to enable this kind of services. This has motivated in recent years an increasing research activity on signal processing techniques for indoor GNSS receivers. The main limitations faced by indoor GNSS receivers are due to the complex propagation of the GNSS signals in indoor sites. These limitations have given rise to the socalled High Sensitivity GNSS Receiver architecture. This kind of receivers process long periods of signal. By means of long non-coherent integration, they can achieve low sensitivity, and avoid the effects of bit transitions and clock drifts. The purpose of this paper is the presentation and evaluation of an indoor GPS positioning receiver by using real-life data. The live data used in the paper will come from the digitalization of the GPS signal collected at several indoor sites. The receiver is an Assisted-GPS one that has been implemented in software and works in snapshot mode. It includes both the signal processing able to estimate the pseudoranges and the proper positioning computation. Special emphasis is put on the newly developed way of extending the coherent correlation interval up to 20 ms without being affected by the bit transitions in the navigation message. This coherent correlation is followed by non-coherent integration in order to achieve the low sensitivity required indoors. The implementation of the coherent correlation is done in a very efficient way by intensive use of the Fast Fourier Transform (FFT) and its properties. The advantages of the new acquisition algorithm with regard to previous ones not doing data wipe-off will be stated in the paper. Furthermore, the paper addresses the advantages of the 20-ms coherent correlation in order to solve the pseudorange ambiguity, typical in Assisted-GPS, and the impact on the computation of the position.
Published in:	Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006) September 26 - 29, 2006 Fort Worth Convention Center Fort Worth, TX
Pages:	2944 - 2955
Cite this article:	Jiménez-Baños, D., Blanco-Delgado, N., López-Risueño, G., Seco-Granados, G., Garcia-Rodríguez, A., "Innovative Techniques for GPS Indoor Positioning Using a Snapshot Receiver," Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006), Fort Worth, TX, September 2006, pp. 2944-2955.
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