Improving BDS-2 and BDS-3 joint precise point positioning with time delay bias estimation

Abstract

The third-generation BeiDou navigation satellite system (BDS-3) began providing a global positioning, navigation and timing (PNT) service on 27 December 2018. After completion of the construction of BDS-3, BDS-2 will continue to provide PNT services for the next few years. Hence, the technology of BDS-2/BDS-3 joint precise point positioning (PPP) has become very important. BDS-2 and BDS-3 are two generations of navigation systems, so a time delay bias may exist between them. To investigate the influence of time delay bias on BDS-2/BDS-3 joint PPP performance, four kinds of time delay bias processing strategies are performed, i.e. no operation, random constant, random walk process, and white noise process, with the datasets provided by the multi-GNSS experiment and the international GNSS monitoring and assessment system. The results demonstrate that the JAVAD TRE_3, CETC-54-GMR-4016 and GNSS_GGR receivers have obvious time delay bias between BDS-2 and BDS-3, whereas the UB4B0-13478 receiver has no obvious time delay bias. The positioning performances of the receivers with time delay bias in terms of positioning accuracy and convergence time can be improved when estimating the time delay bias parameters. It is recommended that the time delay bias is estimated as a random constant as it is the most effective of the four strategies. The positioning accuracy of BDS-2/BDS-3 PPP with time delay bias estimated as a random constant is improved by 2.38%, 9.71% and 6.74%, and the convergence time is reduced by 2.39%, 10.21% and 6.28%, respectively, compared with the no operation strategy in three coordinate components.