# New Satellite Selection Approach for GPS/BDS/GLONASS Kinematic Precise Point Positioning
## 5 Conclusions  
PPP can be widely used in many fields to provide spatial and temporal information due to its high accuracy and reliability. However, with the development of GNSS constellations, the increasing visible satellites also bring a huge computation load to the GNSS equipment in a kinematic environment. Thus, computational complexity and excessive redundant information should be considered in real-time kinematic PPP. At this time, the satellite selection algorithm that can effectively reduce the computational complexity and guarantee centimeter-level positioning accuracy with original solution causes us to consider its application in kinematic PPP.  
Based on the characteristics of different satellite selection algorithms and GNSS constellations, we proposed a new satellite selection approach for GPS/BDS/GLONASS kinematic PPP with undifferenced  
Figure 11: Position residuals of PPP using different satellite selection solutions based on the measured data.  
Figure 10: The satellite number and GDOP of kinematic PPP using the original PPP, NSS model, and Optimal DOP algorithm based on the measured data.  
and uncombined observations. The constantly re-estimated ambiguity encountered in the application of satellite selection algorithm was also considered with the method that is the inheritance of ambiguity. This NSS model includes three different algorithms (maximum volume algorithm, fast-rotating partition satellite selection algorithm, and the elevation partition satellite selection algorithm), and these algorithms were applied in GPS, GLONASS, and BDS, respectively. The principle of this classification is mainly decided by the accuracy and spatial distribution of these three constellations. The characteristics of different satellite selection algorithms was also considered. Compared with the optimal DOP algorithm, a huge amount of computation is reduced in the NSS model due to the conciseness of satellite selection algorithms and the structure of system classification. In order to verify the positioning accuracy of the NSS model, the original PPP with all visible satellites and optimal DOP algorithm was compared based on the MGEX data and the measured data. Results show that the number of visible satellites was reduced greatly, and a centimeter-level positioning accuracy can be obtained with the NSS model in GPS/BDS/GLONASS kinematic PPP while the original PPP and optimal DOP algorithm PPP solutions were compared.  
In general, this study provided a new satellite selection approach to reduce the computational complexity and excessive redundant information in GPS/BDS/GLONASS kinematic PPP. In addition, it proposed a method to solve the situation of constantly re-estimated integer ambiguity in PPP when the satellite selection algorithm is used. In the future, for the reduction of the amount of computation and better real-time performance, the application of the satellite selection algorithm that considers satellite quality for kinematic PPP with fixed integer ambiguity may attract more attention.  
[PERSON] and [PERSON] conceived the idea. [PERSON] and [PERSON] designed the experiments. [PERSON] performed the experiments. [PERSON], [PERSON], [PERSON] and [PERSON] analyzed the data. [PERSON] organized the paper. [PERSON] and [PERSON] wrote the paper. All authors read and approved the final manuscript.  
This research was funded by National Natural Science Foundation of China (grant number: 41604006, 41874006 and 41674008) and partially sponsored by Natural Science Foundation of Jiangsu Province (grant number: BK20160247).  
The authors are also grateful for the test data provided by MGEX and the open-source software: GAMP.  
The authors declare no conflict of interest.