BDS PPP-IAR: Apply and assess the satellite corrections from different regional networks

Abstract

BeiDou Navigation Satellite System (BDS) has contributed to, extended, and densified the concept of satellite navigation since its first generation. Although the traditional precise point positioning (PPP) technique has been gradually replaced by its successor, that is, PPP-IAR by means of integer ambiguity resolution, most of the current studies regarding BDS-only positioning are only in the scientific sense and thus lack the feasibility of implementing PPP-IAR in societal applications. This is because building up a global or a large regional network with hundreds of reference stations is less realistic for small- and medium-sized enterprises. This manuscript aims to bridge the gap between scientific research and societal applications and thereby expand the BDS commercial services to various fields of navigation, positioning and timing. Three regional networks with the approximate distances of 470km, 1100km, and 1700km in Eastern Asia are selected, and each network contains no more than 15 reference stations and 5 user stations. First, the satellite-related corrections generated from individual networks are compared to each other, and the results show that the differences of satellite clock corrections vary from 0.1 to 0.15m, whereas those of satellite phase delay corrections vary from 0.39 to 0.53m. Then, users apply the satellite corrections not only from their own network but from the other two networks to verify if these corrections are interchangeable between different networks because it would be meaningful for improving the robustness and integrity of the positioning services once these corrections can be backups for each other. The results show that the ambiguity fixed kinematic positioning can always achieve centimeter accuracy level; however, ambiguity wrong fixing problems may appear when a user applies another network’s corrections. Besides, users may expect an 8.5min time span to achieve a centimeter-accuracy level if they apply the satellite corrections from their own network. Though it is well known that not so much the number of epochs but the change of geometry that contributes to the determination of the positions, a high sampling rate does speed up ambiguity fixing by means of a large number of observations within a short period. The experiments of 1s interval indicate that the convergence time of centimeter level positioning accuracy can be reduced to 2min under some conditions.