A Comparison of Three Multipath Mitigation Approaches for GPS Receivers

Armando Montalvo and Alison Brown

Abstract:	The presence of multipath components in the received signal of a GPS receiver can adversely affect the ability of the receiver to compute accurate navigational solutions even when differential GPS corrections are available. Thus, for applications that require high accuracy it is important to develop approaches to mitigate the effects of multipath in the received signal. In this conference paper we present the results of a study of three different approaches for multipath mitigation. The first approach uses extended maximum likelihood methods, such as those found in antenna array problems, to estimate the multipath signal parameters during carrier and code acquisition. The second approach uses several narrow band correlators to provide the time-space observations required for maximum likelihood estimation of the mulitpath signal parameters in order to cancel their effect before code synchronization and tracking is performed in the receiver. The third approach utilizes receiver autonomous integrity monitoring (RAIM) algorithms to detect errors in the navigation solution and, when permitted, correct for such errors. These three approaches are compared with computer simulations. A key figure for comparisons was the multipath cancellation return which is a measure of the amount of multipath cancellation obtained by the approach used. It was found that under both slow and fast fading conditions the first approach obtained slightly higher multipath cancellation than the second approach but at a substantial penalty in computational complexity. The third approach yield the best results if enough satellites are in view that do not suffer from multipath errors.
Published in:	Proceedings of the 8th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1995) September 12 - 15, 1995 Palm Springs, CA
Pages:	1511 - 1520
Cite this article:	Montalvo, Armando, Brown, Alison, "A Comparison of Three Multipath Mitigation Approaches for GPS Receivers," Proceedings of the 8th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1995), Palm Springs, CA, September 1995, pp. 1511-1520.
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