“…BDS-3 comprises satellites in three distinct orbits, namely the medium The BDS-3 multi-frequency signals, coupled with the three kinds of satellites in MEO, IGSO and GEO orbits, are increasing the research dimension in the GNSS community. In both BDS-only and multi-GNSS constellations, a considerable volume of research has followed in different fields such as multipath [2,3], signal-to-noise ratio (SNR) [4], GNSS interferometric reflectometry [5,6], quality of BDS products [7,8], precise time transfer [9,10], and ambiguity resolution (AR) [11]. While multi-frequency and multi-constellation GNSS may be applied in such broad areas, the increase in signals itself complicates the treatment of biases in the formulated observables.…”