Assessment of Real-time Multipath Detection with Android Raw GNSS Measurements by Using a Xiaomi Mi 8 Smartphone

In the last years, the domain of Global Navigation Satellite System has been revolutionized by several technological and non-technological milestones. The first dual-frequency GNSS smartphone, Xiaomi Mi 8, was released in May 2018, while the number of mass-market dual-frequency chipsets has been constantly increasing since then. The availability of raw GNSS measurements in Android devices enabled several applications and it brought a set of remarkable tools to the GNSS research community. In this work the multipath effects on a smartphone-based positioning have been deeply examined. A long 22h static test has been performed over a geodetic pillar, thus exploiting the Xiaomi Mi 8 dual-frequency capabilities for evaluating different multipath observables. Both the Code-Minus-Phase (CMP) and the Multipath Linear Combination (MLC) observables have been constructed and investigated, while the Multipath Indicator flag available from the API also considered. The validation of these results is performed in the positioning domain, based on a Single Point Positioning (SPP) algorithm. The signals' robustness to the multipath effects for both GPS and Galileo systems has also been discussed, when considering both L1 and L5 signal-bands.