Investigating Performance of BDS-2+3 Dual-Frequency Absolute Positioning With Broadcast Ephemerides, RTS and Final MGEX Products

Abstract

BDS-3 was formally put into service on July 31, 2020, and now along with BDS-2 provides the positioning, navigation and timing services. In this contribution, different techniques of dual-frequency absolute positioning using the fully serviceable BDS-2+3 constellation are evaluated and compared to the positioning performance of GPS constellation. The accuracy of BDS-3 broadcast ephemerides is significantly higher than that of BDS-2 and is comparable to that of GPS, while BDS-3 International GNSS Service (IGS) Real-Time Service (RTS) products are not as good as GPS at this stage. The static Single Point Positioning (SPP) using BDS-2+3 pseudoranges based on broadcast ephemerides attains the positioning accuracy of 0.743/0.601/1.021 m (95%) and 0.453/0.365/0.566 m (68%) in east/north/up components, while its positioning accuracy is 1.210/1.097/2.447 m (95%) and 0.660/0.586/1.264 m (68%) in kinematic mode. BDS-2+3 Precise Point Positioning (PPP) using pseudoranges with carrier-phase observations based on broadcast ephemerides is able to achieve a positioning accuracy of 0.239/0.174/0.529 m (95%) and 0.115/0.096/0.296 m (68%) in static mode, and 0.636/0.486/1.108 m (95%) and 0.304/0.242/0.556 m (68%) in kinematic mode. BDS-2+3 PPP based on final Multi-GNSS Experiment (MGEX) product can obtain the positioning accuracy of centimeter to millimeter in static mode and the centimeter-level positioning accuracy in kinematic mode. The experiment results show that the positioning performances of BDS-2+3 using broadcast ephemerides and final MGEX products are both comparable to those of GPS. However, due to the poor quality and incomeless of BDS IGS RTS product, BDS-2+3 SPP and PPP based on IGS RTS product obtain the poor positioning accuracies in both static and kinematic modes, which are obviously worse than the counterparts of GPS. Another remarkable result can be obtained that BDS-2+3 achieves a better positioning performance in Asia-Pacific region at higher cut-off elevations as compared to GPS positioning.