Field Test Assessment of Assisted GPS and High Sensitivity GPS Receivers under Weak/Degraded Signal Conditions

Sanjeet Singh, M.E Cannon, R. Klukas and G. Cox

Abstract:	The Federal Communications Commissions (FCC) Enhanced 911 (E-911) phase II mandate requires the wireless operators to locate mobile users with an accuracy of 50 m 67% of the time and an accuracy of 150 m 95% of the time. Some wireless carriers are currently using positioning technologies such as Assisted GPS (AGPS) and High Sensitivity GPS (HSGPS) in order to meet the E-911 challenge. A wireless network can aid a AGPS receiver enabling it to acquire and obtain a position fix under weak signal conditions (e.g. inside a building), while the HSGPS receiver may require initialization under open sky conditions before it can be brought inside to continue tracking GPS signals. The purpose of this paper is to investigate the effects of aiding parameters such as satellite ephemeris or almanac, and varying timing or horizontal positioning uncertainties on AGPS signal acquisition. A SiRFLocTM evaluation kit is used to investigate the performance of the AGPS receiver. The other objective is to compare the tracking performance of HSGPS and AGPS receivers. Field tests were carried out in a sub-urban environment, a residential garage and a concrete basement under static receiver conditions. Acquisition tests show the importance of aiding data such as satellite ephemeris and good timing or position accuracy under significantly weak signal conditions, e.g. the concrete basement. Tracking tests show that AGPS and HSGPS receivers have similar results in terms of position solution accuracy, availability and number of satellites tracked.
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:	2930 - 2943
Cite this article:	Singh, Sanjeet, Cannon, M.E, Klukas, R., Cox, G., "Field Test Assessment of Assisted GPS and High Sensitivity GPS Receivers under Weak/Degraded Signal Conditions," 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. 2930-2943.
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