Estimation of Synchronization Parameters Using SAGE in a GNSS-Receiver

Felix Antreich, Oriol Esbrý-Rodrýguez, Josef A. Nossek and Wolfgang Utschick

Abstract:	The potential of the SAGE (Space-Alternating Generalized Expectation Maximisation) algorithm for navigation systems in order to distinguish the line-of-sight signal (LOSS) is to be considered. The SAGE algorithm is a low-complexity generalization of the EM (Expectation- Maximisation) algorithm, which iteratively approximates the maximum likelihood estimator (MLE) and has been successfully applied for parameter estimation (relative delay, incident azimuth, incident elevation, Doppler frequency, and complex amplitude of impinging waves) in mobile radio environments. This study discusses receivers using a single antenna, and also points out the capabilities of this technique using multiple antennas (array processing), for the application in a GNSS (Global Navigation Satellite System) environment. Whereas for the single antenna case we estimate the complex amplitudes and relative delays of the impinging waves, in the latter additionally the spatial signature of the impinging waves (incident azimuth and elevation) is estimated. In order to describe the behaviour of the SAGE algorithm classical concepts like the RMSE (root mean square error) and the CRB (Cramer-Rao lower bound) are employed. The results of the performed computer simulations and discussion indicate that the SAGE algorithm has the potential to be a very powerful high- resolution method to successfully estimate parameters of impinging waves for navigation systems. SAGE has proven to be a promising method to combat multipath for navigation applications due to its good performance, fast convergence, and low complexity.
Published in:	Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005) September 13 - 16, 2005 Long Beach Convention Center Long Beach, CA
Pages:	2124 - 2131
Cite this article:	Antreich, Felix, Esbrý-Rodrýguez, Oriol, Nossek, Josef A., Utschick, Wolfgang, "Estimation of Synchronization Parameters Using SAGE in a GNSS-Receiver," Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005), Long Beach, CA, September 2005, pp. 2124-2131.
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