Improved PPP Ambiguity Resolution with the Assistance of Multiple LEO Constellations and Signals

Abstract

The fusion of low earth orbit (LEO) constellation and Global Navigation Satellite Systems (GNSS) can increase the number of visible satellites and optimize spatial geometry, which is expected to improve the performance of precise point positioning (PPP) ambiguity resolution (AR). In addition, the multi-frequency signals of LEO satellites can bring a variety of observation combinations, which is potential to further improve the efficiency of PPP AR. In this contribution, multi-frequency PPP AR was achieved with the augmentation of different LEO constellations. Three types of LEO constellations were designed with 60, 192, and 288 satellites. Moreover, the corresponding observation data were simulated with the GNSS observations over the ground stations. The LEO constellations were designed to transmit navigation signals on three frequencies: L1, L2, and L5 at 1575.42, 1227.6, and 1176.45 MHz, respectively, which are consistent with the GPS signals. For PPP AR, the uncalibrated phase delay (UPD) products of GNSS and LEO were estimated first. Furthermore, the quality of UPD products was also analyzed. The research findings show that the performance of estimated LEO UPD is comparable to that of GNSS UPD. Based on the UPD products, LEO-augmented multi-GNSS PPP AR can be achieved. Numerous results show that the performance of single-system and multi-GNSS PPP AR can be significantly improved by introducing the LEO constellations. The augmentation performance is more remarkable in the case of increasing LEO satellites. The time to first fix (TTFF) of the GREC fixed solution can be shortened from 7.1 to 4.8, 1.1, and 0.7 min, by introducing observations of 60-, 192-, and 288-LEO constellations, respectively. The positioning accuracy of multi-GNSS fixed solutions is also improved by about 60%, 80%, and 90% with the augmentation of 60-, 192-, and 288-LEO constellations, respectively. Compared to the dual-frequency solutions, the triple-frequency LEO-augmented PPP fixed solution presents a better performance. The TTFF of GREC fixed solutions is shortened to 33 s with the augmentation of 288-LEO constellation under the triple-frequency environment. It is worth indicating that the 288-satellite LEO-only PPP AR was conducted in dual-frequency and triple-frequency modes, respectively. The averaged TTFFs of both modes are 71.8 s and 55.2 s, respectively. It indicates that LEO constellation with 288 satellites is capable of achieving high-precision positioning independently and shows an even better performance than GNSS-only solutions.

High-order pseudorange rate measurement model for multi-constellation LEO/INS integration: Case of Iridium-NEXT, Orbcomm, and Globalstar

“…These articles can be divided in GNSS-aided and non-GNSS environments. In 30 , a new fusion method is derived to support the pseudorange GNSS measurements by multiple LEO satellites. The authors claimed a remarkable enhancement of the PPP solution in GNSS/SOP situation compared to GNSS-only solution.…”

“…33 Also, c is the speed of light.where normal⊚ is the element-wise product sign and Pδtr and Ptrueδ˙tr are the process noise power spectra for the clock bias and clock drift of the receiver. As fully discussed in 30 , these two parameters are related to the power law coefficients, {hα,r}α=−22 , and are approximated in equation (10). 34 …”

Beyond Mapping Functions and Gradients

“…Hopefully, Augmented Constellations and Low-Earth-Orbits constellations (LEO) will become soon a reality [72][73][74], thanks to the ever-decreasing size and costs of satellites, as well as the availability of miniaturized atomic clocks [75]. LEO constellations are particularly interesting for GNSS meteorology, as their satellites will cross the sky in a few minutes instead of hours, with a boost by one order of magnitude, or even two, of the available line-of-sight geometries.…”

GNSS rapid precise point positioning enhanced by low Earth orbit satellites

“…Iridium and the Iridium NEXT can transmit Satellite Time and Location (STL) signals outside communication services, which can provide PNT services in canyon areas, indoors, and outdoors (Landry et al, 2019;Lawrence et al, 2017). Many scholars tested LEO's contribution to improve GNSS positioning performance in different scenarios (Gao et al, 2021;Ge et al, 2018;Ke et al, 2015;Li et al, 2019aLi et al, , 2019bLi et al, , 2022aLi et al, , 2022bTian et al, 2014;Zhao et al, 2020). Ke et al tested the enhancement performance of LEO for GNSS PPP.…”