Block-Repetitive Iterated Processing for Software GPS Receiver: Dichotomized Search of Correlation Peak

C. Yang, M. Miller, T. Nguyen

Abstract:	The software GPS receiver offers a block-repetitive iterated processing capability that is difficult, if not impossible, to realize with a hardware correlator-based GPS receiver. Applications of such block-repetitive iterated processing include iterative estimation of GPS signal parameters under high dynamics and nonlinearities, cross-correlation cancellation of near-far problem and multi-access interference, and multipath mitigation. In this paper, we first analyze the block-repetitive iterated processing capability offered by a software GPS receiver in both the acquisition and tracking modes as compared to conventional hardware correlator-based GPS receivers. Then we present a dichotomized search of the true correlation peak for delay estimation as an illustrating example of block iterative processing. This is in contrast to a conventional delay-locked loop (DLL) that moves several correlators of fixed spacing so as to drive the delay error discriminator to zero (an early-minus-late type). An advantage of this dichotomized search is its reduced sensitivity to multipath. This can be understood as if it implements a sequential software narrow correlator vs. parallel hardware narrow correlators. Since it adapts to data with a variable spacing, it is computationally more efficient than a software implementation that uses a fixed number of correlators with the same coverage. Simulation results are presented to show the multipathdesensitized delay estimation as compared to the theoretical multipath error envelope and to the thermal noise errors under various SNR conditions for different multipath parameters.
Published in:	Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006) September 26 - 29, 2006 Fort Worth Convention Center Fort Worth, TX
Pages:	2856 - 2864
Cite this article:	Yang, C., Miller, M., Nguyen, T., "Block-Repetitive Iterated Processing for Software GPS Receiver: Dichotomized Search of Correlation Peak," Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006), Fort Worth, TX, September 2006, pp. 2856-2864.
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