Maximum-Likelihood GPS Parameter Estimation

Ilir F. Progri, Matthew C. Bromberg, and William R. Michalson

Peer Reviewed

Abstract:	Recently we proposed an acquisition process for a maximum-likelihood GPS receiver that considers the joint processing of all GPS satellite waveforms. The resulting estimator was shown to provide an elegant solution to the near – far problem and to perform better than the suboptimal sliding-correlator estimator. However, the proposed acquisition model included only the code search, which estimates just the time of arrival (TOA) between a GPS satellite and a maximum-likelihood GPS receiver. In this paper we enhance the acquisition process by including the estimation of Doppler along with the estimation of the TOA, which results in a two-dimensional Doppler and code search. A maximum-likelihood GPS receiver would require only one front-end hardware section for processing all GPS signals in view, thus simplifying the entire architecture of a GPS receiver. An assessment based on theoretical performance and simulation results indicates that a maximum-likelihood GPS receiver can achieve an order-of-magnitude performance improvement relative to a sliding-correlator GPS receiver. Simulation data will be validated in the near future using GPS acquisition data from the Novatel ProPack AG-G2DB9-RT2, and the results of this work will be presented in a future publication.
Published in:	NAVIGATION: Journal of the Institute of Navigation, Volume 52, Number 4
Pages:	229 - 238
Cite this article:	Progri, Ilir F., Bromberg, Matthew C., Michalson, William R., "Maximum-Likelihood GPS Parameter Estimation", NAVIGATION: Journal of The Institute of Navigation, Vol. 52, No. 4, Winter 2005-2006, pp. 229-238.
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