Frequency Standards: Key Enabler to Optimizing Indoor GPS Performance

L. Vittorini, B. Robinson

Abstract:	GPS is poised to make a life-changing impact on our lives over the next decade, as it will be embedded into a plethora of wireless applications. There is a frenzied effort by companies all over the world to find the wireless "killer app" and a number of these require precise geo-location. GPS was never intended for indoor environments and, indeed, the relatively weak signals transmitted by the orbiting constellation do not readily lend themselves to use in the highly attenuated and multipath-filled environments these applications present. The FCC's E911 mandate has spurred significant effort in the GPS community to apply our combined expertise to solve this dilemma; much in the same way the US government's Selective Availability policy spurred the collective brainpower of engineers worldwide, ultimately leading to solutions rendering it ineffective and no doubt hastening its early abandonment in May 2000. While progress has been made in pushing the limits of physics via sophisticated hardware and signal processing to solve the challenges presented by this new operational environment, there are always trade-offs to be made when deciding how best to optimally apply available resources to detect, acquire and then track the attenuated and multipath-corrupted signals resulting from transmission around and through concrete and steel building structures which may be attenuated from 10-30 dB. Last, while wireless networks can potentially provide significant aiding assistance to GPS, it's not as simple as it may appear to the casual observer. There are some fundamental business, technical and performance issues driving GPS manufacturers' desire to minimize their dependence on network aiding driving the need for robust autonomous navigation.
Published in:	Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003) September 9 - 12, 2003 Oregon Convention Center Portland, OR
Pages:	660 - 678
Cite this article:	Vittorini, L., Robinson, B., "Frequency Standards: Key Enabler to Optimizing Indoor GPS Performance," Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003), Portland, OR, September 2003, pp. 660-678.
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