Using PPP Information to Implement a Global Real-Time Virtual Network DGNSS Approach

Global Navigation Satellite Systems (GNSS) provide positioning services for connected and autonomous vehicles. Differential GNSS (DGNSS) has been demonstrated to provide reliable, high quality range correction information enabling real-time navigation with sub-meter or centimeter accuracy. However, DGNSS requires a local reference station near each user, which for a continental or global scale implementation would require a dense network of reference stations whose construction and maintenance would be prohibitively expensive. Precise Point Positioning (PPP) affords more flexibility as a public service for GNSS receivers, but its State Space Representation (SSR) format is not currently supported by most receivers. This article proposes a novel Virtual Network DGNSS (VN-DGNSS) design that capitalizes on the PPP infrastructure to provide global coverage for real-time navigation without building physical reference stations. Correction information is computed using data from public GNSS SSR data services and transmitted to users by Radio Technical Commission for Maritime Services (RTCM) Observation Space Representation (OSR) messages which are accepted by most receivers. The real-time stationary and moving platform testing performance, using u-blox M8P and ZED-F9P receivers, surpasses the Society of Automotive Engineering (SAE) specification (68% of horizontal error $\leqslant$ 1.5 m and vertical error $\leqslant$ 3 m) and shows significantly better horizontal performance than GNSS Open Service (OS). The moving tests also show better horizontal performance than the ZEDF9P receiver with Satellite Based Augmentation Systems (SBAS) enabled and achieve the lane-level accuracy which requires 95% of horizontal errors less than 1 meter.