###### Abstract
With the rapid development of BDS, Galileo and QZSS, more researchers devoted to the four-system and five-system integrated PPP. Following [PERSON] et al. [19], the convergence time of single-frequency static PPP with a threshold of 0.3, 0.3 and 0.5 m in the north, east and up directions could be shortened by 30.8%, 39.2% and 7.4% for BDS-only, GLONASS-only and GPS/GLONASS/Galileo/BDS-2 cases by further adding QZSS observations at a cut-off elevation angle of 20, respectively. The positioning accuracy of GPS/GLONASS/Galileo/BDS-2 kinematic PPP at an elevation mask of 10 was improved by 16.4%, 19.7% and 24.6% in comparison with GPS-only case in the three directions, respectively, and a further accuracy improvement of 2.2%, 2.0% and 17.4% in the three directions could be achieved after a further integration with QZSS, respectively [20]. As for the GPS/GLONASS/Galileo/BDS-2 real-time kinematic PPP with CLK93 stream, the convergence time under the elevation cut-off angle of 30 could be reduced by 30.4% when converging to 0.1 m in horizontal direction compared with GPS-only PPP [21]. [PERSON] and [PERSON] [22] also conducted the real-time GPS/GLONASS/Galileo/BDS-2 PPP processing with CLK93 streams, and the real-time static position solutions could provide a converged accuracy better than 5 and 10 cm after a processing time of tens of minutes in horizontal and vertical directions, respectively. As multi-system integration has become a trend in precise positioning, there is an increase in the number of analysis centers that can support multiple satellite systems. Many researchers focused on the orbit and clock consistency among different analysis centers, and their impact on multi-system PPP solutions. [PERSON] et al. [23] found that the agreements of satellite orbit products among different analysis centers were 3-5 cm for Galileo satellites, 8-9 cm for BDS-2 inclined geosynchronous orbit (IGSO) satellites, 12-18 cm for BDS-2 medium earth orbit (MEO) satellites, 24 cm for BDS-3 MEO satellites and 11-16 cm for QZSS IGSO satellites, respectively, while the clock products had a consistency of 0.1-0.3 ns for Galileo satellites, 0.2-0.5 ns for BDS IGSO/MEO satellites and 0.2-0.4 ns for QZSS satellites, respectively. However, only partial BDS-3 satellites were covered as they used the precise products from 1 January 2018 to 1 November 2019. [PERSON] et al. [24] also evaluated the clock consistency among different analysis centers, which was about 2, 5, 5 and 10 cm for GPS, GLONASS, Galileo and BDS-2 IGSO/MEO satellites, respectively. [PERSON] and [PERSON] [25] investigated the impact of precise products from Multi-GNSS Experiment (MGEX) analysis centers on multi-GNSS PPP performance, and the results showed that the GeoForschungsZentrum Potsdam (GFZ) and Wuhan University (WHU)precise products had relatively better positioning performance. However, besides the GPS and GLONASS satellites, only 15 Galileo satellites and 14 BDS-2 satellites were included in their study. Following [PERSON] et al. [26], the influence of ISB handling schemes on multi-GNSS PPP performance could be distinct when using the precise products from different analysis centers, and the random walk process and white noise process were recommended in multi-GNSS PPP processing. Although great achievements have been made in terms of multi-system integrated PPP, few studies related to the data fusion covering all available BDS-3 satellites under a fully deployed constellation, as most of the existing studies employed the datasets before 2020 [19; 20; 21; 22]. After a further integration with BDS-3 based on GPS, GLONASS, Galileo, BDS-2 and QZSS, the number of operational satellites has been up to approximately 136 at present. As a satellite-based positioning accuracy, the joint use of as many satellites as possible will definitely benefit the data processing of PPP. Currently, the precise products from several analysis centers, such as European Space Agency (ESA), GFZ and WHU, can support all the five satellite systems.