Determination of Minimum Data Required to Achieve Desired Location Performance

Sameet M. Deshpande, Mangesh Chansarkar, Mahesh Chowdhary

Abstract:	As location technology becomes more mainstream it gets embedded into applications that are very energy sensitive, for example cell phones, hand held battery operated consumer devices. It is always desired to achieve accurate location computation with minimum amount of processing and computation and this is particularly true in cases of battery operated hand held devices where battery life is a prime consideration. In general location performance is characterized by location accuracy, velocity and heading accuracy. Most power sensitive applications require that only one (or a few) locations are computed for use. In such cases the location accuracy is governed by the accuracy of the underlying measurements (code phase for location and Doppler for velocity and heading) and the associated problem geometry. Under such conditions it is useful to determine the minimum amount of data that needs to be processed to achieve the desired code phase and Doppler accuracy leading to the desired location accuracy. Theoretical lower bounds on errors in estimating code-based and carrier-based pseudorange have been developed and discussed in literature. An operational theory to determine the minimum bound on amount of data required to be processed to achieve desired code phase accuracy is presented. A Cramer Rao bound formulation is used to determine the absolute bound on the amount of data required to be processed to achieve the desired accuracy using unbiased estimators. Practical considerations in design and implementation that impact this theoretical minimum are discussed. The impact of these practical aspects is analyzed to determine a practical bound on the data requirement. Tradeoff between these practical aspects is also discussed that would allow designers to make a judicious choice between performance parameters like sensitivity, size of data, processing load for various system architectures
Published in:	Proceedings of the 21st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2008) September 16 - 19, 2008 Savannah International Convention Center Savannah, GA
Pages:	1848 - 1854
Cite this article:	Deshpande, Sameet M., Chansarkar, Mangesh, Chowdhary, Mahesh, "Determination of Minimum Data Required to Achieve Desired Location Performance," Proceedings of the 21st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2008), Savannah, GA, September 2008, pp. 1848-1854.
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