GPS For The E911 Location Requirement The Practical IP Approach

Peter Anderson and Jacqueline Bickerstaff

Abstract:	The paper discusses a practical approach to providing GPS as Intellectual Property (IP). It details an implementation of GPS in a handset for indoor use. This includes the advantages of providing an IP solution compared to the methods normally used in implementing a stand-alone GPS. GPS is the leading contender for incorporation into handsets to satisfy the E911 location requirement. GPS is also a mature technology, with proven location ability. It would appear, therefore, that the problem is simply to miniaturise GPS even further, and, at the same time, also reduce its power consumption. But the problem is more complex than this. This paper takes a deeper look into the problem. GPS is usually designed for outdoor use. How will it fare indoors, where the signal (previously well below the noise) is attenuated another 20 dBs or more, and how does one achieve the time-to-fix of just a few seconds. More sensitivity, and faster time-to-fix can be addressed with large, parallel processing, architectures - more hardware (and more power). But handset and PDA manufacturers want less hardware, less chips, and more IP (intellectual property) solutions. However, existing GPS designs do not transfer well into IP, having been designed for single instantiations in custom chips. This presents the IP designer with many challenges. They must build an expanded architecture in a small die space, and achieve lots of parallel processing with the use of little power. Simultaneously they must turn a complex, customised, design, into portable, technology independent, IP. In addition, the interaction with other system functions, is a key design issue. These considerations are often contradictory, and not easy to resolve. The paper addresses the design interactions between the various issues, illustrated with the design of a practical, and commercially available product, the Parthus NavStream 3000 IP, designed specifically for portable appliance and cellular phone applications. The practical problems of interference from co-located systems (such as the phone transmitter) are also covered, and solutions proposed. In conclusion the paper reviews the issues which separate a good, portable, E911 capable, IP solution from a conventional 'GPS chipset'.
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:	218 - 226
Cite this article:	Anderson, Peter, Bickerstaff, Jacqueline, "GPS For The E911 Location Requirement The Practical IP Approach," 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. 218-226.
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