Satellite Availability and Service Performance Evaluation for Next-Generation GNSS, RNSS and LEO Augmentation Constellation

Abstract

Positioning accuracy is affected by the combined effect of user range errors and the geometric distribution of satellites. Dilution of precision (DOP) is defined as the geometric strength of visible satellites. DOP is calculated based on the satellite broadcast or precise ephemerides. However, because the modernization program of next-generation navigation satellite systems is still under construction, there is a lack of real ephemerides to assess the performance of next-generation constellations. Without requiring real ephemerides, we describe a method to estimate satellite visibility and DOP. The improvement of four next-generation Global Navigation Satellite Systems (four-GNSS-NG), compared to the navigation constellations that are currently in operation (four-GNSS), is statistically analyzed. The augmentation of the full constellation the Quasi-Zenith Satellite System (7-QZSS) and the Navigation with Indian Constellation (11-NavIC) for regional users and the low Earth orbit (LEO) constellation enhancing four-GNSS performance are also analyzed based on this method. The results indicate that the average number visible satellites of the four-GNSS-NG will reach 44.86, and the average geometry DOP (GDOP) will be 1.19, which is an improvement of 17.3% and 7.8%, respectively. With the augmentation of the 120-satellite mixed-orbit LEO constellation, the multi-GNSS visible satellites will increase by 5 to 8 at all latitudes, while the GDOP will be reduced by 6.2% on average. Adding 7-QZSS and 11-NavIC to the four-GNSS-NG, 37.51 to 71.58 satellites are available on global scales. The average position DOP (PDOP), horizontal DOP (HDOP), vertical DOP (VDOP), and time DOP (TDOP) are reduced to 0.82, 0.46, 0.67 and 0.44, respectively.

Analysis on BDS-3 Autonomous Navigation Performance Based on the LEO Constellation and Regional Stations

“…The observation data of the BDS-3 ground station are simulated, the elevation angle threshold is set to 5 degrees. The pseudorange measurement is added with a random noise of 1.000 m and a systematic error of 0.030 m, while the carrier-phase measurement is added with random noise of 0.002 m and a systematic error of 0.030 m [29,39]. We simulate BDS-3 ISL observations between GEO and MEO, IGSO and MEO, MEO and MEO, and IGSO and IGSO.…”

“…Both analog ground stations and LEO satellite-monitoring stations can receive navigation signals from the BDS-3 satellites navigation constellation to obtain carrier and pseudorange observation of all visible satellites in the epoch. We added 1.000 m of random noise and 0.030 m of pseudorange systematic error [29,39], as well as 0.002 m of random noise and 0.030 m of carrier system error, to the simulated observations data, and the orbital arc is 3 days. As shown in Figure 8, the average 3D accuracies of all LEO satellite orbits in 3D are 1.7 cm, 1.6 cm, and 0.6 cm, respectively.…”

“…The first-order Taylor series expansion of the satellite on X s, * = (x s, * , y s, * , z s, * ) reference orbit. X s, * is defined as the reference orbit of the satellite [17,18,29]. According to Equations ( 1) and ( 14), the linearized equation can be obtained as:…”