Abstract: Aiming at the problem of insufficient positioning accuracy of smart phone GNSS caused by multi-path effect,signal occlusion and hardware noise in complex urban scenarios.This paper proposes a positioning method based on factor graph optimization (FGO).By jointly using pseudorange and doppler observations,sliding window technology is adopted to fuse multi-epoch data,so as to optimize state parameters such as position,clock error and inter-system bias.Experiments using Huawei Mate20 (static)and P40 (dynamic)mobile phone data show that compared with the extended Kalman filter (EKF),FGO significantly improves the positioning accuracy.In the static experiment,the errors in the east,north and elevation directions are reduced by 21.2%,9.0% and 15.2%,respectively.In the dynamic experiment,the elevation error is reduced by 37.7%.When the sliding window size is 30,the balance between accuracy and real-time performance can be achieved.The fusion of multi-system data further suppresses the positioning divergence,which can provide an effective solution for high-precision mobile positioning in complex scenarios.

Key words: mobile phone positioning, factor graph optimization, GNSS, Doppler observations