Global DGNSS service for mobile positioning through public corrections

Differential Global Navigation Satellite System (DGNSS) is a technique that uses a reference station to provide accurate corrections for nearby user receivers. Tens of thousands of reference stations have been deployed to provide the DGNSS service for vehicles and pedestrians all over the world. However, wide applications of DGNSS technique are limited by two challenges: (1) the cost of deploying and maintaining so many reference stations over a large region is very high; and (2) most of low-cost GNSS receivers only provide the single point positioning results via NMEA (National Marine Electronics Association) messages, without outputting raw measurements and without supporting DGNSS operations. This study aims to develop a global DGNSS platform not only for normal DGNSS receivers, but also for the receivers that only output standalone positions via NMEA messages. This platform generates the DGNSS corrections from Precise Point Positioning (PPP) corrections, without requiring additional physical reference stations. A position-domain DGNSS algorithm based on the PPP corrections is proposed for normal standalone receivers that only provide NMEA messages. Extensive static and dynamic tests on professional receivers and normal smartphones show that the accuracy is improved by more than 40% using the proposed global DGNSS service.