Performance of Multi-GNSS in the Asia-Pacific Region: Signal Quality, Broadcast Ephemeris and Precise Point Positioning (PPP)

Abstract

Since BeiDou Navigation Satellite System (BDS) and Japan’s Quasi-Zenith Satellite System (QZSS) have more visible satellites in the Asia-Pacific region, and navigation satellites of Global Positioning System (GPS), Galileo satellite navigation system (Galileo), and GLONASS satellite navigation system (GLONASS) are uniformly distributed globally, the service level of multi-mode Global Navigation Satellite System (GNSS) in the Asia-Pacific region should represent the best service capability. Based on the observation data of 10 Multi-GNSS Experiment (MGEX) stations, broadcast ephemeris and precision ephemeris from 13 to 19 October 2021, this paper comprehensively evaluated the service capability of multi-GNSS in the Asia-Pacific region from three aspects of observation data quality, broadcast ephemeris performance, and precision positioning level. The results show that: (1) the carrier-to-noise-density ratio (C/N0) quality of the GPS and Galileo is the best, followed by BDS and GLONASS, and QZSS is the worst. GPS, BDS-2, GLONASS, and QZSS pseudorange multipath values range from 0 to 0.6 m, while Galileo system and BDS-3 pseudorange multipath values range from 0 to 0.8 m. (2) In terms of broadcast ephemeris accuracy, BDS-3 broadcast ephemeris has the best orbit, and the three-dimensional (3D) Root Mean Square (RMS) is 0.21 m; BDS-2 was the worst, with a 3D RMS of 1.99 m. The broadcast ephemeris orbits of GPS, Galileo, QZSS, and GLONASS have 3D RMS of 0.60 m, 0.62 m, 0.83 m, and 1.27 m, respectively. For broadcast ephemeris clock offset: Galileo has the best performance, 0.61 ns, GLONASS is the worst, standard deviation (STD) is 3.10 ns, GPS, QZSS, BDS-3 and BDS-2 are 0.65 ns, 0.75 ns, and 1.72 ns, respectively. For signal-in-space ranging errors (SISRE), the SISRE results of GPS and Galileo systems are the best, fluctuating in the range of 0 m–2 m, followed by QZSS, BDS-3, Galileo, and BDS-2. (3) GPS, BDS, GLONASS, Galileo, GPS/QZSS, and BDS/QZSS were used for positioning experiments. In static PPP, the convergence time and positioning accuracy of GPS show the best performance. The positioning accuracy of GPS/QZSS and BDS/QZSS is improved compared with that of GPS and BDS. In terms of kinematic PPP, the convergence time and positioning accuracy of GPS/QZSS and BDS/QZSS are improved compared with that of GPS and BDS. In addition to GLONASS and Galileo systems, the other combinations outperformed 3 cm, 3 cm, and 5 cm in the east, north, and up directions.

Real-Time Estimation of BDS-3 Satellite Clock Offset with Ambiguity Resolution Using B1C/B2a Signals

“…The distribution of WL UPD residuals for B1I/B3I signals is better due to its longer wavelength. Compared to B1I/B3I signals, the NL UPD residual distribution of the B1C/B2a signals is slightly better for both (−0.15, 0.15) and (−0.25, 0.25) cycles, which may be caused by the better observation quality of the B1C/B2a signals [12,35]. The NL UPD residual distribution shows better performance compared to that of the WL UPD.…”

“…Therefore, its performance is of great interest for this study. Although the NL wavelength of these two signal combinations is nearly identical, the NL UPD stability using B1C/B2a is superior, which could be caused by its better observation quality [12,35]. Moreover, the STDs are larger on DOY 170 than on other days for both the WL and NL UPDs, which could be caused by the convergence problems during the initial processing time.…”

“…A larger wavelength implies less sensitivity of the integer ambiguity fixing to the measurement noise and mis-modeled effects. The mean STD of the NL UPDs is 0.122 cycles for B1I/B3I, and 0.081 cycles for B1C/B2a signals, showing better stability of the NL UPDs estimated from the B1C/B2a signals.Although the NL wavelength of these two signal combinations is nearly identical, the NL UPD stability using B1C/B2a is superior, which could be caused by its better observation quality[12,35]. Moreover, the STDs are larger on DOY 170 than on other days for both the WL and NL UPDs, which could be caused by the convergence problems during the initial processing time.…”

PPP-AR reference satellite selection based on the observation quality factors

“…Because PPP is a single receiver operation when performing PPP-ambiguity resolution (PPP-AR), the receiver UPD is eliminated using the single difference between satellites, which can recover the single difference between satellite ambiguity after conducting AR [5,6]. When performing single-difference between satellites PPP-AR, since the elevation of the observation shows a positive correlation with the carrier-to-noise density ratio (C/N0) and a negative correlation with the pseudorange multipath, it is considered that the higher the elevation of the observation, the stronger the C/N0, the smaller the pseudorange multipath, and the better the quality of the observations [7,8]. Therefore, the satellite with the highest elevation is usually selected as the reference satellite to eliminate the impact of the receiver UPD on PPP-AR [9,10].…”

Hassas Nokta Konumlama (PPP) Yöntemindeki Hata Kaynaklarının Konum Belirleme Performansı Üzerindeki Etkilerinin İncelenmesi: PPPH Yazılımı Örneği

“…Li vd. [14], Asya-Pasifik bölgesindeki GPS, GPS/QZSS, BDS, BDS/QZSS, GLONASS ve GALİLEO donanımlarını statik ve kinematik PPP performanslarıyla değerlendirmişlerdir. Statik PPP için konum doğruluğunda GPS'in GLONASS'tan daha iyi olduğunu, kinematik PPP'de ise doğu ve kuzey yöndeki bileşenlerde GPS'in, yukarı bileşende de BDS'nin Galileo'dan daha iyi olduğunu elde etmişlerdir.…”