Personal Positioning Using Wireless Assisted GPS with Low-Cost INS

Helena Leppakoski, Jari Syrjarinne and Jukka Saarinen

Abstract:	The United States Federal Communication Commission FCC-E911 docket sets explicitly defined requirements for the positioning accuracy of emergency calls made from mobile phones. The GPS is the only globally applicable technology that meets the FCC-E911 requirements, but suffers from serious availability and accuracy problems in urban environments. To some extent, these problems can be solved using the wireless assisted GPS (AGPS). Despite the improvement, there are environments where thick obstructions attenuate positioning signals below tracking thresholds. In addition, although the network assistance can make the positioning possible in weak signal conditions, it cannot remove the positioning errors caused by the decreased signal-to-noise ratio and multipath propagation that are typical for indoor environments. In this research, the possible benefits of the integration of low-cost INS to the wireless assisted GPS were studied. The studies were carried out by simulations using dynamic system models and covariance analysis methods. The simulations addressed questions of how much better availability of the position solution can be achieved by the INS/AGPS integration and whether it is feasible to get power savings to the positioning application by the means of low-cost INS aided AGPS. The simulation results indicated that in order to significantly improve the availability of positioning during AGPS outages, additional aiding methods are needed to reduce the position error growth in the integrated low-cost INS/AGPS-system. The simulations also showed that if the power consumption of the INS is lower than that of the GPS, this ratio could be utilized to adjust the system performance towards the desired direction. The integration of even quite low performance INS to AGPS can be used either to save power while maintaining the positioning accuracy of the non-aided AGPS or to increase the positioning accuracy while keeping the power consumption of the non-aided AGPS.
Published in:	Proceedings of the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2001) September 11 - 14, 2001 Salt Palace Convention Center Salt Lake City, UT
Pages:	1361 - 1368
Cite this article:	Leppakoski, Helena, Syrjarinne, Jari, Saarinen, Jukka, "Personal Positioning Using Wireless Assisted GPS with Low-Cost INS," Proceedings of the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2001), Salt Lake City, UT, September 2001, pp. 1361-1368.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In