LEO-based interpolation methods comparison for regional augmented PPP

Abstract

In this study, a low-Earth orbit (LEO) constellation of 160 LEO satellites was simulated, and simulated LEO observations from American regional stations were used to investigate regional augmented precise point positioning (PPP). For reference networks with scales of 75 km and 165 km, the low-order surface model (LSM), the distance-based linear interpolation method (DIM), and the modified linear combination model (MLCM) were respectively used to interpolate atmospheric delays. For both scales of the reference networks, the root mean square errors (RMSEs) of the inter-satellite single-difference (SD) ionospheric slant delay residuals and the tropospheric zenith wet delays (ZWDs) residuals interpolated by the three methods were respectively less than 2.00 cm and 0.25 cm, and the accuracy of the atmospheric delays interpolated by the three methods was comparable. Within the 75‑km and 165‑km reference networks, using the interpolated atmospheric delays to constrain undifferenced and uncombined (UDUC) PPP improved the positioning performance of both the float and fixed solutions, and also augmented the ambiguity resolution (AR) performance of the fixed solutions. The enhancement effects of the three methods were comparable, and the enhancement effect decreased slightly as the scale of the reference network increased. Among the three methods, LSM performed slightly better than DIM and MLCM in the up direction, since the LSM used in this study is an interpolation model that accounts for the elevation factor.