Multipath Mitigation in Various Environments for Blind Navigation

M. A. Shah

Abstract:	This paper reports the impact of multipath error and the improvements in the performance of the system after mitigating multipath errors in different environments. Typical positioning scenarios are selected with particular reference for blind navigation. The combined impact of mask elevation angle and multipath effect is then observed over the performance of the system. A GPS system is developed consisting of a Javad JGG20 GPS receiver, a Motorola Oncore GPS antenna, a battery and a laptop PC. The established system is capable of observing and mitigating multipath effects using signal-processing techniques. Then the performance criteria and methodology are set to measure the performance of the system. These experiments are conducted in a variety of different environments. In this aspect, ten different positioning scenarios are selected where a blind or partially sighted pedestrian may pass frequently in everyday walking. The selected positioning scenarios are semi- covered, in between buildings and trees, in a car park, under a top-covered and sides open building, in a narrow path between two tall buildings, underneath a thickly covered tree, at a pedestrians’ footpath, in a public park, in a shopping centre and in open sky environments. From the experimental results, it is observed that the performance of the system is significantly improved in a narrow path between tall buildings, top-covered sides-open and semi-urban environments. The system also mitigates multipath effects in all the other environments apart from the open sky environment, where negligible multipath effects are observed. Another set of experiments is conducted to show the combined impact of multipath effects and satellite mask elevation angle over the performance of the navigation system. The experimental results show that the accuracy of the system increases when the mask elevation angle increases, provided a minimum of four satellites are tracked. The experimental results recommend the development of a handheld unit based on a Javad JGG20 GPS receiver to guide blind and partially sighted pedestrians.
Published in:	Proceedings of the 15th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2002) September 24 - 27, 2002 Oregon Convention Center Portland, OR
Pages:	841 - 850
Cite this article:	Shah, M. A., "Multipath Mitigation in Various Environments for Blind Navigation," Proceedings of the 15th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2002), Portland, OR, September 2002, pp. 841-850.
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