Session E1: Advanced Technologies in High Precision GNSS Positioning

The Potential of Precise Point Positioning Using Simulated Data
Tomohiro Ozeki, Nobuaki Kubo,Tokyo University of Marine Science and Technology
Alternate Number 2

Precise Point Positioning (PPP) [1] is an advanced global navigation satellite system technology that offers high-precision positioning capabilities. This technology is anticipated to have a wide range of applications, such as weather forecasting, tsunami buoy and crustal movement monitoring [2], and future integration in advanced driver assistance systems/Autonomous driving (ADAS/AD) applications [3]. Unlike Real-time Kinematic (RTK) positioning, PPP does not require a reference station; however, PPP requires a convergence time to achieve optimal results . Factors influencing convergence time include the number of augmented satellites, the accuracy of the precise ephemeris, local corrections, such as regional slant ionosphere delay, and satellite phase bias. One key technique for improving positioning accuracy and reducing convergence time is the resolution of integer ambiguity, such as with PPP-AR and PPP-RTK techniques. Despite its potential benefits, integer ambiguity resolution in PPP is not yet a fully established technology; thus, numerous studies have proposed methods, such as the utilization of triple frequency, partial ambiguity fixing, and wide lane techniques to address this challenge. Several factors contribute to the lack of standardization in integer ambiguity resolution in PPP. First, the GNSS receivers utilized in ground stations for estimating correction data are not standardized, potentially leading to the non-separation of correction data from the receiver-specific bias. Second, a mismatch exists between the satellite attitude model utilized in PPP and that utilized to estimate correction data. Satellite attitude models are crucial in PPP as they correct phase wind-up effects. However, correction data services that describe satellite attitude models in Interface Control Document (ICD) are limited. Third, the integer ambiguity resolution technique in PPP software may not be sufficiently developed. These factors, when combined, render the identification of the root cause challenging, whether they stem from the correction data generator or user.
This study aims to investigate the true performance of PPP by simulating correction data, pseudoranges, carrier phases, and other relevant data. By generating correction data through simulation, potential issues related to correction data generation can be preemptively addressed. This allows for a thorough evaluation of the existing and proposed integer ambiguity resolution techniques. . In addition, the impact of the correction data accuracy for orbit, satellite clock, and atmospheric errors can be analyzed to determine its effect on PPP convergence and positioning accuracy. GNSS simulations generally utilize a GNSS simulator to generate RF signals; however, the RF signals generated by the simulation must be received by a GNSS receiver. Therefore, the receiver-specific bias must be considered.
Therefore, in this study, instead of generating RF signals, only pseudoranges, carrier phases, and correction data were generated to conduct PPP analysis.