Carrier Phase Indoor Positioning Using Pseudolites and INS

W.W. Kao, C-L. Tsai

Abstract:	Pseudolites provide augment GPS signals and can be used in situations with limited GPS coverage. They have been found popular in precision landing as well as indoor positioning applications. In many pseudolite-only indoor positioning systems, double difference carrier phase signals between a fixed reference receiver and a moving receiver (rover) with respect to pseudolites are often used to precisely determine the rover position. One difficulty involve in such scenario is the carrier phase ambiguities need to be resolved. As indoor pseudolites have very different geometric properties compared with outdoor GPS satellites, conventional double difference ambiguity resolution techniques need to be modified. In some algorithms, initial rover position is required in order to resolve the ambiguities and to provide further positioning capability after moving. In some other methods, ambiguity resolution is achieved iteratively and times are required to yield correct solutions. There are also applications using pseudolites together with inertia navigation systems (INS). However, INS roles in many past researches are merely to improve system performance under limited coverage environments for pseudolites or GPS. In this paper we propose an efficient ambiguity resolution method for indoor pseudolite positioning by using the relative movement information provided by INS onboard of rover. This method can immediately resolve ambiguity and provide absolute and accurate carrier phase based position after obtaining suitable INS movement. There is no requirement for a priori knowledge of the initial rover position. Simulation results based on realistic indoor positioning environments has shown the validity of the algorithm, and convergence properties of the algorithm are also studied.
Published in:	Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003) September 9 - 12, 2003 Oregon Convention Center Portland, OR
Pages:	2593 - 2598
Cite this article:	Kao, W.W., Tsai, C-L., "Carrier Phase Indoor Positioning Using Pseudolites and INS," Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003), Portland, OR, September 2003, pp. 2593-2598.
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