Real-time Precise Point Positioning with a Xiaomi MI 8 Android Smartphone

Abstract

The Global Navigation Satellite System (GNSS) positioning technology using smartphones can be applied to many aspects of mass life, and the world’s first dual-frequency GNSS smartphone Xiaomi MI 8 represents a new trend in the development of GNSS positioning technology with mobile phones. The main purpose of this work is to explore the best real-time positioning performance that can be achieved on a smartphone without reference stations. By analyzing the GNSS raw measurements, it is found that all the three mobile phones tested have the phenomenon that the differences between pseudorange observations and carrier phase observations are not fixed, thus a PPP (precise point positioning) method is modified accordingly. Using a Xiaomi MI 8 smartphone, the modified real-time PPP positioning strategy which estimates two clock biases of smartphone was applied. The results show that using multi-GNSS systems data can effectively improve positioning performance; the average horizontal and vertical RMS positioning error are 0.81 and 1.65 m respectively (using GPS, BDS, and Galileo data); and the time required for each time period positioning errors in N and E directions to be under 1 m is less than 30s.

Detecting Pattern Changes in Individual Travel Behavior from Vehicle GPS/GNSS Data

“…Traditional travel diaries or travel survey data were mostly derived from household interviews or regional censuses [20]. Over the past decade, with the development of data collection from transit smart cards, GPS/GNSS [21][22][23], and mobile phones, direct travel trajectory data have been complementing or replacing conventional travel data at a rapidly increasing rate. These data help us to understand human travel behavior better by zooming into individuals' behaviors more closely than ever.…”

Méter alatti pontosság mobiltelefonokba épített GNSS-vevőkkel

“…Már az első kísérletek bizonyították, hogy az okostelefonokba épített GNSS-vevőkkel lehetséges a méter alatti pontosság elérése, illetve, hogy elsősorban az olcsó antennák miatt, 1 A 2019. évi Mérnökgeodézia Konferencián elhangzott előadás írásos változata a pontosság elmarad a professzionális geodéziai vevőkkel elérhető pontosságtól (Banville-Diggelen 2016). A Google bejelentése óta számos tanulmány készült, amelyekkel az elérhető pontosságot vizsgálták, és a kutatók többször is bizonyították, hogy elérhető a szubméteres pontosság (Chen et al 2019, Darugna et al 2019, Dabove-di Pietra 2019, Warnant et al 2018, Geng et al 2018…”

Characteristics Analysis of Raw Multi-GNSS Measurement from Xiaomi Mi 8 and Positioning Performance Improvement with L5/E5 Frequency in an Urban Environment

“…Surprisingly, the single-frequency PPP provided a better solution than the dual-frequency one [16,21]. After analyzing the characteristic of raw pseudorange and carrier phase observations, a modified PPP strategy was proposed by estimating separate clock biases for pseudorange and carrier phase observations [23]. The static PPP experiments with raw GPS, BeiDou, and Galileo data from Xiaomi Mi 8 under an open environment showed that the positioning errors in the north and east directions would converge to within 1 m in 30 s [23].…”

“…After analyzing the characteristic of raw pseudorange and carrier phase observations, a modified PPP strategy was proposed by estimating separate clock biases for pseudorange and carrier phase observations [23]. The static PPP experiments with raw GPS, BeiDou, and Galileo data from Xiaomi Mi 8 under an open environment showed that the positioning errors in the north and east directions would converge to within 1 m in 30 s [23]. When conducting RTK with raw GPS, Galileo, and GLObal NAvigation Satellite System (GLONASS) observations from Xiaomi Mi 8 under complex dynamic environments, the horizontal accuracy of 1.17 m was obtained but the solution tracks were still severely fluctuated [16].…”