An Optimized Least-Squares Technique for Improving Ambiguity Resolution and Computational Efficiency

vDonghyun Kim and Richard B. Langley

Abstract:	In GPS carrier phase integer ambiguity search methods, the number of ambiguity candidates to be searched and verified can be an important factor for the performance of ambiguity resolution and computational efficiency. The key question in assessing such methods is by how much and with what efficiency can the number of candidates be reduced before or at the search-verification step. The most effective procedure can be found in such techniques as search space (or domain) transformation and an ambiguity candidate filtering (or conditioning) in multi-search levels. An Optimal Method for Estimating GPS Ambiguities (OMEGA) that enables very high performance and computational efficiency has been developed and demonstrated. This method employs two search space reduction processes – a scaling and a screening process that are related to the search space transformation and the ambiguity candidate filtering in multi-search levels. To obtain the highest efficiency, an optimization procedure, which decides the parameters to minimize the candidates under given conditions, is implemented in closed-form before the search-verification step. The method is essentially based on the least-squares-approach originally proposed by Hatch but uses a modified and more efficient process. The simple test results reported in this paper have shown that computational efficiency is improved by about 90% when compared with that of the basic least-squares-approach.
Published in:	Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999) September 14 - 17, 1999 Nashville, TN
Pages:	1579 - 1588
Cite this article:	Kim, vDonghyun, Langley, Richard B., "An Optimized Least-Squares Technique for Improving Ambiguity Resolution and Computational Efficiency," Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999), Nashville, TN, September 1999, pp. 1579-1588.
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