Practical Approaches to Real-Time Position Accuracy Improvement of Android Smartphone Dual-Frequency GNSS

Jeonghyeon Yun, Cheolsoon Lim, Yongjun Lee, Suyeol Kim, Yongrae Jo, Byungwoon Park

Abstract:	Since Google’s announcement of providing GNSS raw measurements on smartphones with Android 7 Nougat or higher operating system (OS), a number of researchers have devoted to increase the location accuracy of smartphones using GNSS raw measurements. Despite various attempts and efforts, the performance gaps from commercial geodetic receivers have been shown too large to be overcome due to due to structural differences from low-cost GNSS chips installed in smartphones. With an early version of the smartphone GNSS chipset that provided low quality L1-only single frequency measurements, high-precision positioning technologies such as Real-Time Kinematics (RTK) and Precision Point Positioning (PPP) were not feasible to deliver the generally expected performance. Multi-constellations (GPS, GLONASS, Galileo, Beidou and QZSS) and dual-frequency enabled chips, Broadcom BCM 47755 released in 2017, was also expected as a new game changer that could lead effective ionospheric error mitigation and reliable determination of carrier phase ambiguity. Many researchers were overly optimistic about the application of high-precision positioning technology to the dual frequency measurements of smartphones as they are. However, low-quality LP antenna and chip-based processing modules were still bottle-necks toward the precise positioning due to frequent cycle slips. Just turning-off duty cycle function did not guarantee continuous carrier tracking nor slip-free raw phase measurement. In addition, unless the issues on unmodelled measurement noise, undetected multipath errors, and the instability of the clock are not cleared, the precision positioning algorithm will not be as effective to a smartphone as commercial receivers. In this research, we presented a practical approach considering the inherent limitations of smartphones and suggested how to take advantage of dual-frequency benefit for the real-time quality monitoring process.
Published in:	Proceedings of the 35th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2022) September 19 - 23, 2022 Hyatt Regency Denver Denver, Colorado
Pages:	2226 - 2234
Cite this article:	Yun, Jeonghyeon, Lim, Cheolsoon, Lee, Yongjun, Kim, Suyeol, Jo, Yongrae, Park, Byungwoon, "Practical Approaches to Real-Time Position Accuracy Improvement of Android Smartphone Dual-Frequency GNSS," Proceedings of the 35th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2022), Denver, Colorado, September 2022, pp. 2226-2234. https://doi.org/10.33012/2022.18373
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