Primary Exploration on Approaches to Establish BeiDou Terrestrial Reference Frame

Beidou-2 satellite navigation system adopts China Geodetic Coordinate System 2000 (CGCS2000), which can't meet the requirements of Beidou-3 global service and timely update. This paper discusses two approaches to build BeiDou Terrestrial Reference Frame (BTRF), one is precise point position (PPP) and the other is net-solution with MGEXs. We only relied on BDS observations to determine precise coordinates of each BDS monitoring station under ITRF and verify the two approaches. Especially, we analyzed the improvement for the accuracy of Beidou satellites orbit determination (OD) with regional tracking network after refining and updating the coordinates of tracking stations by means of net-solution. Initial results show that repeatability of PPP for the horizontal and vertical components of a BDS monitoring receiver is better than 2.3 cm and 3.4 cm, respectively, which may be reduced to 0.8 cm and 2.2 cm for net-solution. After the refinement, the OD accuracy of IGSOs 3D overlap increase by 15.4%, while MEOs increase by 25.9%. We also evaluate BDS satellite orbit with SLR measurements, results reveal that SLR residuals of BD-2 satellites reduce from 0.39 m to 0.24 m, the accuracy increases by 38%, the residuals of BD-3 satellites reduce from 0.25 m to 0.18 m, the accuracy increases by 28%.