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Xia et al. Satell Navig (2021) 2:8 Page 2 of 19

of multi-system and multi-frequency smartphone GNSS that of BDS-2, GPS, and Galileo satellites (Zhang et al.
chipsets makes it possible for mobile users to obtain pre- 2019b). Besides, Beidou-3 shows superiority in system
cise positioning results. At present, the horizontal accu- coverage, spatial signal accuracy, availability, and conti-
racy of smartphone GNSS positioning is generally in the nuity (Guo et al. 2019; Yang et al. 2019, 2020). Te rapid
range of meter to sub-meter, including in urban environ- development of BDS enables global users to obtain accu-
ments (Liu et al. 2019; Fortunato et al. 2019; Chen et al. rate real-time location information with geodetic receivers
2019). Some researchers claimed to achieve decimeter- or low-cost GNSS devices.
level accuracy of PPP or RTK positioning (Gill et al. 2017; Nowadays, many domestic mainstream Android smart-
Zhang et al. 2019a). Banville et al. (2019) verifed that phones in China support BDS. Several overseas products
static PPP positioning accuracy at centimeter level was such as Samsung and Google Pixel series can also receive
achievable in a good observation condition and by vir- BDS satellite signals. However, much attention has been
tue of the precise ionospheric corrections derived from a paid to GPS-led mobile positioning, but little to BDS. Liu
regional network of stations. Wanninger and Heßelbarth et al. (2019) and Chen et al. (2019) incorporated smart-
(2020) calibrated the antenna phase center for a Hua- phone BDS observations in multi-system SPP and real-
wei P30 mobile phone and obtained short baseline RTK time PPP experiments, respectively. Wang et al. (2016),
accuracy at centimeter level after fxing ambiguities using and Odolinski and Teunissen (2019) studied smartphone
GPS L1 carrier phase measurements. Although the low RTK positioning performance under diferent scenarios
gain and poor multipath mitigation of the GNSS anten- using multi-system observations including BDS. But very
nas in smartphones limit the positioning accuracy, con- few research are on BDS-only positioning for LBS applica-
tinuous hardware and software advancements make the tions, especially outside the Asia–Pacifc region. In addi-
positioning performance with smartphones getting closer tion, constrained by the previous system construction and
to that of professional receivers. the observation conditions for BDS-3, the results of some
Another crucial factor that impacts the rapid develop- researches are inconclusive and even contradictory. BDS-3
ment of smartphone high-precision positioning is the global service needs to be investigated thoroughly from the
modernization of GNSS, especially the emergence of new perspective of positioning (Shi et al. 2020). From the above
systems and new signals. Te most notable system is Chi- and with the completion of BDS, it is necessary to evalu-
nese BeiDou navigation satellite System (BDS). On June 23, ate its capability in the smartphone positioning, including
2020, the last satellite of the third generation BeiDou navi- BDS alone and its integration with other GNSS constella-
gation satellite System (BDS-3) was successfully launched, tions, so as to provide a reference for the further improve-
marking the complete deployment of BDS global constella- ments in BDS global PNT services. Additionally, the 5G
tion. Te completion of the BDS constellation extends the communication and positioning technology is booming,
Positioning, Navigation, and Timing (PNT) services from and smartphones are the ideal platforms of mobile net-
the Asia–Pacifc region to the rest of the world. BDS-3 is works. Te research on BDS mobile location services also
currently composed of 30 satellites, including 3 GEosta- has a certain signifcance for promoting the integration of
tionary Orbit (GEO) satellites, 24 Medium Earth Orbit 5G and BDS on smartphones (Liu et al. 2020).
(MEO) satellites and 3 Inclined Geosynchronous Orbit Tis article is the frst to conduct a systematic evalu-
(IGSO) satellites. Te new system retains the B1I and B3I ation of the smartphone BDS positioning performance
signals of BeiDou navigation satellite (regional) System outside the Asia–Pacifc region, in Nottingham of the
(BDS-2) and replaces B2I with B2b on the same frequency. UK, since it’s fully operational. Much attention is paid to
Meanwhile, BDS-3 introduces two new signals, B1C/B2a, how BDS performs in harsh environments. Te structure
which are compatible with GPS L1/L5 and Galileo E1/E5a of the article is as follows. Firstly, the satellite visibility
(Lu et al. 2019). Since the frst two BDS-3 satellites were and Geometric Dilution of Precision (GDOP) distribu-
launched on November 5, 2017, researchers have con- tion of BDS constellation are analyzed, especially in the
ducted a lot of research on the new generation of naviga- UK area. Secondly, we introduce the experimental design
tion satellite system, including satellite visibility (Wang and data collection process. Tirdly, the quality of the
et al. 2019b), orbit determination (Wang et al. 2019a; Xie smartphone BDS observations is assessed, including the
et al. 2019), error correction (Gu et al. 2020; Wang et al. carrier-to-noise density ratio and pseudorange measure-
2020; Zhang et al. 2020), observation quality and position- ment noise. Fourthly, we analyze the performances of
ing performance (Xie et al. 2018; Zhang et al. 2019b; Lv smartphone BDS single point positioning in a static and
et al. 2020; Shi et al. 2020). Compared with BDS-2, BDS-3 open environment and a kinematic complex environ-
has some signifcant improvements in clock stability, orbit ment. Te above experimental results are compared with
accuracy, signal strength and pseudorange observation those of other GNSS. Finally, we summarize our research
quality. Te phase noise level of BDS-3 is comparable to fndings.