Analysis of multipath effects and mitigation techniques for enhanced smartphone GNSS positioning

Multipath significantly degrades GNSS positioning quality, especially in smartphones due to their inferior GNSS antennas. To mitigate this, the Laboratory of Space Geodesy and Hydrography (LAGEH) developed the Multipath Effect Attenuator (AEM), which was used for the first time in smartphone applications. A new prototype, AEM Smart, was also created for use in smartphones. The smartphone used in this research was the Xiaomi Mi 8, with a dual frequency GNSS sensor and allows access to raw GNSS data. The multipath effect was evaluated based on the MP1 and MP5 indices, referring to the L1 and L5 carrier phases, respectively. The positioning quality was assessed using Precise Point Positioning (PPP) GNSS data processing. This contribution shows that L5 is significantly superior to L1 measurements, with more than 73% improvement in multipath effect suppression. Furthermore, this study indicates that attenuators can reduce the multipath effect in L1 by more than 24%. Also, a strong correlation of about 94% was found between the multipath effect on L1 and the 2D and 3D positional accuracies. Finally, through the PPP technique in combination with the Xiaomi Mi 8 and AEM 3, it was possible to obtain a 2D and 3D accuracy of approximately 0.24 and 0.60 m, respectively.