Assessment of the Contribution of QZSS Combined GPS/BeiDou Positioning in Asia-Pacific Areas

Abstract

Three QZSS satellites are launched in 2017, which implies that a four satellites regional system is to be established in 2018. There is no doubt that QZSS will play a more important role in the future global GNSS constellations. So it is quite necessary to investigate the importance of current QZSS constellation in positioning. In this paper, the number of visible satellite and PDOP (Position Dilution of Precision) value improvement by combining QZSS with the existing GPS and BeiDou system is analyzed among Asia-Pacific areas. 9 IGS stations are selected to evaluate the performance of SPP (Single Point Positioning) and PPP (Precise Point Positioning) using GPS, BeiDou and GPS + QZSS, BeiDou + QZSS system. Analysis results show that QZSS improves SPP performance for both GPS and BeiDou at different level. Especially when the satellite number is reduced, such as in urban areas or when the elevation cutoff is high, the positioning error will reduce after adding QZSS satellite and the availability of other GNSS systems will also improves. For kinematic PPP users, QZSS could also reduce the convergence period. Meanwhile, the dual frequency and single frequency RTK (Real Time Kinematic) positioning performance is compared after adding QZSS satellite into GPS and BeiDou. Kinematic car test in urban environment shows that when combining QZSS satellite with GPS and BeiDou, the rate of instantaneous ambiguity resolution will increase for both single and dual-frequency users.