The Possibility of Precise Automobile Navigation using GPS/QZS L5 and Galileo E5 Pseudo-ranges

Hiroko Tokura, Taro Suzuki, Tomoji Takasu, Nobuaki Kubo

Abstract:	The addition of new navigation signals is a major focus of Global Navigation Satellite System (GNSS) modernization. New L5 signals are broadcasted from three Global Positioning System (GPS) satellites and one Quasi-Zenith Satellite System (QZSS) satellite. An L5 signal has higher power, greater bandwidth, and higher chipping rate. On the other hand, the most advanced correlator for an L1 signal has been improved for a long time since the advent of GPS. Although the correlator for L5 signals has not been improved to the same degree, it is expected that its performance can exceed that of an L1 signal. When we think about future automobile high-accuracy navigation using GNSS, Real-time kinematic GPS (RTK-GPS) is one candidate that can produce precise positioning within several centimeters. However, RTK is very sensitive to multipath errors, and as a result, it is far from a perfect solution at present. It is known that the pseudo-range from an L5 signal is as robust against multipath errors as an L1 signal using the most advanced correlator. By investigating the multipath errors from the L5 pseudo-range, it is possible to predict the total positioning performance using an L5 signal. Thus far, the L5 pseudo-range has not been investigated comprehensively because satellites broadcasting L5 signals are few. Therefore, we investigated the performance of the L5 pseudo-range and the tolerance to multipath error. To estimate the multipath error for GNSS-based pseudo-ranges, we typically use the code minus carrier difference technique. However, it is impossible to use this technique for kinematic data because there are many cycle slips in urban areas. To overcome this problem, we propose a new multipath estimation method for vehicles in urban areas. We tested 4 experiments using both kinematic and static raw data and confirmed that our proposed method was useful to estimate pseudo-range multipath errors in urban areas. From these results, it was found that an L5 signal with a standard correlator has comparable performance against multipath errors to an L1 signal with the most advanced correlator used to mitigate the multipath error. Furthermore, an L5 signal is always more powerful than an L1 signal.
Published in:	Proceedings of the 2013 International Technical Meeting of The Institute of Navigation January 29 - 27, 2013 Catamaran Resort Hotel San Diego, California
Pages:	194 - 202
Cite this article:	Tokura, Hiroko, Suzuki, Taro, Takasu, Tomoji, Kubo, Nobuaki, "The Possibility of Precise Automobile Navigation using GPS/QZS L5 and Galileo E5 Pseudo-ranges," Proceedings of the 2013 International Technical Meeting of The Institute of Navigation, San Diego, California, January 2013, pp. 194-202.
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