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Liu et al. Satell Navig (2021) 2:6 Page 2 of 17

satellites was completed and began to provide services frequency with Global Positioning System (GPS) L1/L5
to global users with at least fve visible satellites (Yang as well as Galileo Navigation Satellite System (Galileo)
et al. 2020). By the end of 2019, the core BDS-3 constel- E1/E5a/E5b signals (Lu et al. 2019; Yang et al. 2019b).
lation comprising 24 MEO satellites was completed, After the BDS-3 demonstration system with fve
which comprehensively promoted the system service experimental satellites was established, the observa-
worldwide (China Satellite Navigation Ofce 2019). tional quality of its new navigation signals was intensively
On June 23, 2020, the last BDS-3 Geostationary Orbit investigated in aspects of the carrier-to-noise power den-
(GEO) satellite was successfully launched, signifying the sity ratio, code multipath efect, triple-frequency carrier
accomplishment of the BDS-3 constellation deployment, phase combination, as well as carrier phase and code
including 24 MEO, three IGSO, and three GEO satel- observation precision, etc. (Xie et al. 2017; Zhang et al.
lites. As of July 2020, the constellation status of BDS-3 is 2017, 2019a; Zhou et al. 2018). It was proved that the
listed in Table 1 (CSNO-TARC 2020). Te BDS-3 opera- data quality of B1C/B2a/B2b observations of BDS-3 dem-
tional satellites transmit multiple open service navigation onstration system was comparable to those of GPS and
signals on fve diferent frequency bands, i.e., the legacy Galileo. Meanwhile, its contribution to the precise posi-
B1I (1561.098 MHz) and B3I (1268.52 MHz) signals, tioning was evaluated by several researchers. Te results
the new B1C (1575.42 MHz), B2a (1176.45 MHz), and revealed that the additional observations from BDS-3
B2b (1207.14 MHz) signals that having the same center demonstration system improved the precise positioning

Table 1 Constellation status of BDS-3 as of July 2020

PRN code Common name Date of launch Orbit Status Fundamental PNT
service signal
C19 BDS-3 MEO-1 5.11.2017 MEO Operational B1I/B1C/B2a/B2b/B3I
C20 BDS-3 MEO-2 5.11.2017 MEO Operational
C27 BDS-3 MEO-7 11.01.2018 MEO Operational
C28 BDS-3 MEO-8 11.01.2018 MEO Operational
C22 BDS-3 MEO-4 12.02.2018 MEO Operational
C21 BDS-3 MEO-3 12.02.2018 MEO Operational
C29 BDS-3 MEO-9 29.03.2018 MEO Operational
C30 BDS-3 MEO-10 29.03,2018 MEO Operational
C23 BDS-3 MEO-5 29.07.2018 MEO Operational
C24 BDS-3 MEO-6 29.07.2018 MEO Operational
C26 BDS-3 MEO-11 24.08.2018 MEO Operational
C25 BDS-3 MEO-12 24.08.2018 MEO Operational
C32 BDS-3 MEO-13 19.09.2018 MEO Operational
C33 BDS-3 MEO-14 19.09.2018 MEO Operational
C35 BDS-3 MEO-16 15.10.2018 MEO Operational
C34 BDS-3 MEO-15 15.10.2018 MEO Operational
C36 BDS-3 MEO-17 18.11.2018 MEO Operational
C37 BDS-3 MEO-18 18.11.2018 MEO Operational
C38 BDS-3 IGSO-1 20.04.2019 IGSO Operational
C39 BDS-3 IGSO-2 25.06.2019 IGSO Operational
C46 BDS-3 MEO-24 23.09.2019 MEO Operational
C45 BDS-3 MEO-23 23.09.2019 MEO Operational
C40 BDS-3 IGSO-3 5.11.2019 IGSO Operational
C44 BDS-3 MEO-22 23.11.2019 MEO Operational
C43 BDS-3 MEO-21 23.11.2019 MEO Operational
C41 BDS-3 MEO-19 16.12.2019 MEO Operational
C42 BDS-3 MEO-20 16.12.2019 MEO Operational
C59 BDS-3 GEO-1 1.11.2018 GEO Operational B1I/B3I
C60 BDS-3 GEO-2 9.03.2020 GEO Operational
C61 BDS-3 GEO-3 23.06.2020 GEO Experiment