1 Davanc Road, Xuzhou 221116, China; [EMAIL_ADDRESS] NASG Key Laboratory of Land Environment and Disaster Monitoring, China University of Mining and Technology, NO. 1 Davanc Road, Xuzhou 221116, China; [EMAIL_ADDRESS] (Q.Z. )1 NASG Key Laboratory of Land Environment and Disaster Monitoring, China University of Mining and Technology, NO. 1 Davanc Road, Xuzhou 221116, China; [EMAIL_ADDRESS] (Q.Z. )1 NASG Key Laboratory of Land Environment and Disaster Monitoring, China University of Technology, NO. 1 Davanc Road, Xuzhou 221116, China; [EMAIL_ADDRESS] (Q.Z. )1 NASG Key Laboratory of Land Environment and Disaster Monitoring, China University of Mining and Technology, NO. 1 Davanc Road, Xuzhou 221116, China; [EMAIL_ADDRESS] (Q.Z. )1 NASG Key Laboratory of Land Environment and Disaster Monitoring, China University of Mining and Technology, NO. 1 Davanc Road, Xuzhou 221116, China; [EMAIL_ADDRESS] (Q.Z. )1 NASG Key Laboratory of Land Environment and Disaster Monitoring, China University of Mining and Technology, NO. 1 Davanc Road, Xuzhou 221116, China; [EMAIL_ADDRESS] (Q.Z. )1 NASG Key Laboratory of Land Environment and Disaster Monitoring, China University of Mining and Technology, NO. 1 Davanc Road, Xuzhou 221116, China; [EMAIL_ADDRESS] (Q.Z. )1 NASG Key Laboratory of Land Environment and Disaster Monitoring, China University of Mining and Technology, NO. 1 Davanc Road, Xuzhou 221116, China; [EMAIL_ADDRESS] NASG Key Laboratory of Land Environment and Disaster Monitoring, China University of Mining and Technology, NO. 1 Davanc Road, Xuzhou 221116, China; [EMAIL_ADDRESS] (Q.Z. )1 NASG Key Laboratory of Land Environment and Disaster Monitoring, China University of Mining and Technology, NO. 1 Davanc Road, Xuzhou 221116, China; guzhaocumt@cumt. improve availability and reliability. QZSS is not an independent satellite system and is based on GPS, so it can be seen as an enhanced GPS constellation in the range of the Japanese longitude. BDS and QZSS both enhance the coverage of the Asia-Pacific region by adding synchronous orbit satellites to the constellations. [PERSON] et al. (2012) found that BDS could provide high-accuracy location services comparable to GPS in the Asia-Pacific region [6]. Recently, the number of QZS increased to four in March 2018 and three satellites have been available to users since then. It is necessary to study the enhancement effect of QZSS to GPS and BDS in the Asia-Pacific region. Much literature has studied the performance of integrated GPS/BDS, and QZSS enhancement in GPS has been discussed since the concept of QZSS was proposed [7; 8; 9; 10; 11; 12; 13; 14; 15]. A multi-carrier fast partial ambiguity resolution strategy was proposed to sequentially resolve BDS/GPS dual- and triple-frequency ambiguities sequentially to significantly improve the computational efficiency of AR [7]. The potential of GPS/BDS to serve as the early warning system for tsunamis in the South China Sea region was investigated [8]. The positioning performance of BDS/GPS is superior to that of GPS/GLONASS or BDS/GLONASS, and can be further improved using BDS/GPS/GLONASS [9]. The performance of a short baseline ambiguity resolution with different scenarios of the present GPS and future GPS/QZSS system was analyzed when QZSS was still in the argumentation stage [10]. Meanwhile, the availability, accuracy, and reliability of GPS and GPS/QZSS in the Asia-Pacific and Australian regions were simulated in [11; 12]. The simulation results showed that QZSS not only improves the availability and accuracy of GPS positioning, but also enhances the reliability of GPS positioning in Japan and its neighboring areas. In [13], the positioning performance of GPS aided by QZSS was improved by more than 30% for high elevation mask angles and positioning availability, which is more stable than the single GPS.