Performance Analysis of BDS-2, BDS-3 and GPS in Relative Positioning through Short, Medium and Long Baselines

BDS-3 (Beidou System 3) reached global coverage in June 2020. In comparison with BDS-2(Beidou system 2), BDS-3 has greatly improved in terms of satellite orbits, atomic clocks and signal transmissions. BDS-3 is now being used widely in practice. This paper is focused on performance analysis of BDS-3 vs.BDS-2 and GPS. Six baselines of different lengths were selected to result in single-system multi-frequency relative positioning solutions from BDS-2, BDS-3 and GPS, respectively. The long baselines were resolved by using the random walk constraints on the residual atmospheric delay. The positioning performance of each system was analysed against the atmospheric delay error and the convergence property of the floated ambiguity resolution. The experiments showed that the convergence speed of BDS-3 was twice as fast as BDS-2, and the average convergence speed was also faster than GPS, which was increased by about 2.7%. In comparison with BDS-2, the accuracy of BDS-3 was improved by about 40%, but the accuracy was 7% lower than the GPS solution and the positioning stability of BDS-3 was also not as good as GPS.