Integrating GPS and LEO to accelerate convergence time of precise point positioning

Ke, Mingxing; Lv, Jing; Chang, Jiang; Dai, Weiheng; Tong, Kaixiang; Zhu, Ming-Qiang

doi:10.1109/wcsp.2015.7341230

Cited by 35 publications

(18 citation statements)

References 9 publications

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“…The long initialization time is still a serious problem of PPP, which limits the wider application of PPP in some time-critical applications. The fast motion of LEO satellites contributes to geometry diversity, allowing for the rapid convergence of PPP [21][22][23]. Since the previous studies focused on the contribution of LEO constellation to dual-frequency GNSS float solutions, in this contribution, we investigated the PPP rapid ambiguity resolution with the augmentation of LEO constellations and the triple-frequency observation data was fully exploited to further improve the performance of ambiguity resolution.…”

Section: Discussionmentioning

confidence: 99%

“…To demonstrate the contribution of LEO to GNSS, many researchers conducted numerous experiments about LEO-augmented high-precision positioning based on the simulated LEO observations. Ke et al [22] found that with the inclusion of the LEO satellites, the convergence time of the GPS-only PPP decreased by 51.31%. The results of Ge et al [23] show that LEO-augmented GNSS (GPS+BDS+Galileo) can decrease the PPP convergence time to 5 min.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2019

Remote Sensing

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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.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2019

Remote Sensing

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“…Hence, a quite long time (normally up to more than 30 min) is needed for the ambiguities to be reliably converged to the correct integer values [2]. By using the satellites at Lower Earth Orbiter (LEO) as the navigation satellites, these disadvantages can be improved [4,5,6].…”

Section: Introductionmentioning

confidence: 99%

BeiDou Augmented Navigation from Low Earth Orbit Satellites

Zhao

et al. 2019

Sensors

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Currently, the Global Navigation Satellite System (GNSS) mainly uses the satellites in Medium Earth Orbit (MEO) to provide position, navigation, and timing (PNT) service. The weak navigation signals limit its usage in deep attenuation environments, and make it easy to interference and counterfeit by jammers or spoofers. Moreover, being far away to the Earth results in relatively slow motion of the satellites in the sky and geometric change, making long time needed for achieved centimeter positioning accuracy. By using the satellites in Lower Earth Orbit (LEO) as the navigation satellites, these disadvantages can be addressed. In this contribution, the advantages of navigation from LEO constellation has been investigated and analyzed theoretically. The space segment of global Chinese BeiDou Navigation Satellite System consisting of three GEO, three IGSO, and 24 MEO satellites has been simulated with a LEO constellation with 120 satellites in 10 orbit planes with inclination of 55 degrees in a nearly circular orbit (eccentricity about 0.000001) at an approximate altitude of 975 km. With simulated data, the performance of LEO constellation to augment the global Chinese BeiDou Navigation Satellite System (BeiDou-3) has been assessed, as one of the example to show the promising of using LEO as navigation system. The results demonstrate that the satellite visibility and position dilution of precision have been significantly improved, particularly in mid-latitude region of Asia-Pacific region, once the LEO data were combined with BeiDou-3 for navigation. Most importantly, the convergence time for Precise Point Positioning (PPP) can be shorted from about 30 min to 1 min, which is essential and promising for real-time PPP application. Considering there are a plenty of commercial LEO communication constellation with hundreds or thousands of satellites, navigation from LEO will be an economic and promising way to change the heavily relay on GNSS systems.

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“…The constellation, with a large number of LEO satellites, is expected to enhance the positioning service of GNSS, notably reducing the long convergence time of the precise point positioning technique [7]. Many studies on the availability, design, and performance of LEO-augmented GNSS positioning have been conducted by many researchers [8][9][10][11][12][13]. The aforementioned LEO constellations (such as Hongyan), which aim to provide augmented navigation services, usually carry a state-of-the-art GNSS receiver to obtain the precise knowledge of LEO orbits.…”

Section: Introductionmentioning

confidence: 99%

Integrated Precise Orbit Determination of Multi-GNSS and Large LEO Constellations

Zhang

et al. 2019

Remote Sensing

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Global navigation satellite system (GNSS) orbits are traditionally determined by observation data of ground stations, which usually need even global distribution to ensure adequate observation geometry strength. However, good tracking geometry cannot be achieved for all GNSS satellites due to many factors, such as limited ground stations and special stationary characteristics for the geostationary Earth orbit (GEO) satellites in the BeiDou constellation. Fortunately, the onboard observations from low earth orbiters (LEO) can be an important supplement to overcome the weakness in tracking geometry. In this contribution, we perform large LEO constellation-augmented multi-GNSS precise orbit determination (POD) based on simulated GNSS observations. Six LEO constellations with different satellites numbers, orbit types, and altitudes, as well as global and regional ground networks, are designed to assess the influence of different tracking configurations on the integrated POD. Then, onboard and ground-based GNSS observations are simulated, without regard to the observations between LEO satellites and ground stations. The results show that compared with ground-based POD, a remarkable accuracy improvement of over 70% can be observed for all GNSS satellites when the entire LEO constellation is introduced. Particularly, BDS GEO satellites can obtain centimeter-level orbits, with the largest accuracy improvement being 98%. Compared with the 60-LEO and 66-LEO schemes, the 96-LEO scheme yields an improvement in orbit accuracy of about 1 cm for GEO satellites and 1 mm for other satellites because of the increase of LEO satellites, but leading to a steep rise in the computational time. In terms of the orbital types, the sun-synchronous-orbiting constellation can yield a better tracking geometry for GNSS satellites and a stronger augmentation than the polar-orbiting constellation. As for the LEO altitude, there are almost no large-orbit accuracy differences among the 600, 1000, and 1400 km schemes except for BDS GEO satellites. Furthermore, the GNSS orbit is found to have less dependence on ground stations when incorporating a large number of LEO. The orbit accuracy of the integrated POD with 8 global stations is almost comparable to the result of integrated POD with a denser global network of 65 stations. In addition, we also present an analysis concerning the integrated POD with a partial LEO constellation. The result demonstrates that introducing part of a LEO constellation can be an effective way to balance the conflict between the orbit accuracy and computational efficiency.

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Integrating GPS and LEO to accelerate convergence time of precise point positioning

Cited by 35 publications

References 9 publications

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

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

BeiDou Augmented Navigation from Low Earth Orbit Satellites

Integrated Precise Orbit Determination of Multi-GNSS and Large LEO Constellations

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