scholarly journals Constellation Design and GPS Augmentation Effectof Quasi-Zenith Satellite System

2003 ◽  
Vol 51 (593) ◽  
pp. 307-313
Author(s):  
Isao Kawano
Keyword(s):  
Satellite System ◽  
Constellation Design

scholarly journals Optimal Walker Constellation Design of LEO-Based Global Navigation and Augmentation System

2020 ◽  
Vol 12 (11) ◽  
pp. 1845
Author(s):  
Meiqian Guan ◽  
Tianhe Xu ◽  
Fan Gao ◽  
Wenfeng Nie ◽  
Honglei Yang
Keyword(s):  
Genetic Algorithm ◽  
Elevation Angle ◽  
Satellite System ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Constellation Design ◽  
Computation Efficiency ◽  
Leo Satellites ◽  
Global Navigation ◽  
Walker Constellation

Low Earth orbit (LEO) satellites located at altitudes of 500 km~1500 km can carry much stronger signals and move faster than medium Earth orbit (MEO) satellites at about a 20,000 km altitude. Taking advantage of these features, LEO satellites promise to make contributions to navigation and positioning where global navigation satellite system (GNSS) signals are blocked as well as the rapid convergence of precise point positioning (PPP). In this paper, LEO-based optimal global navigation and augmentation constellations are designed by a non-dominated sorting genetic algorithm III (NSGA-III) and genetic algorithm (GA), respectively. Additionally, a LEO augmentation constellation with GNSS satellites included is designed using the NSGA-III. For global navigation constellations, the results demonstrate that the optimal constellations with a near-polar Walker configuration need 264, 240, 210, 210, 200, 190 and 180 satellites with altitudes of 900, 1000, 1100, 1200, 1300, 1400 and 1500 km, respectively. For global augmentation constellations at an altitude of 900 km, for instance, 72, 91, and 108 satellites are required in order to achieve a global average of four, five and six visible satellites for an elevation angle above 7 degrees with one Walker constellation. To achieve a more even coverage, a hybrid constellation with two Walker constellations is also presented. On this basis, the GDOPs (geometric dilution of precision) of the GNSS with and without an LEO constellation are compared. In addition, we prove that the computation efficiency of the constellation design can be considerably improved by using master–slave parallel computing.

scholarly journals Extended Geometry and Probability Model for GNSS+ Constellation Performance Evaluation

2020 ◽  
Vol 12 (16) ◽  
pp. 2560
Author(s):  
Lingdong Meng ◽  
Jiexian Wang ◽  
Junping Chen ◽  
Bin Wang ◽  
Yize Zhang
Keyword(s):  
Probability Model ◽  
Satellite System ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Navigation Satellite ◽  
Constellation Design ◽  
Leo Satellites ◽  
Satellite Visibility ◽  
Global Navigation Satellite ◽  
Gnss Constellation

We proposed an extended geometry and probability model (EGAPM) to analyze the performance of various kinds of (Global Navigation Satellite System) GNSS+ constellation design scenarios in terms of satellite visibility and dilution of precision (DOP) et al. on global and regional scales. Different from conventional methods, requiring real or simulated satellite ephemerides, this new model only uses some basic parameters of one satellite constellation. Verified by the reference values derived from precise satellite ephemerides, the accuracy of visible satellite visibility estimation using EGAPM gets an accuracy better than 0.11 on average. Applying the EGAPM to evaluate the geometry distribution quality of the hybrid GNSS+ constellation, where highly eccentric orbits (HEO), quasi-zenith orbit (QZO), inclined geosynchronous orbit (IGSO), geostationary earth orbit (GEO), medium earth orbit (MEO), and also low earth orbit (LEO) satellites included, we analyze the overall performance quantities of different constellation configurations. Results show that QZO satellites perform slightly better in the Northern Hemisphere than IGSO satellites. HEO satellites can significantly improve constellation geometry distribution quality in the high latitude regions. With 5 HEO satellites included in the third-generation BeiDou navigation satellite system (BDS-3), the average VDOP (vertical DOP) of the 30° N–90° N region can be decreased by 16.65%, meanwhile satellite visibility can be increased by 38.76%. What is more, the inclusion of the polar LEO constellation can significantly improve GNSS service performance. When including with 288 LEO satellites, the overall DOPs (GDOP (geometric DOP), HDOP (horizontal DOP), PDOP (position DOP), TDOP (time DOP), and VDOP) are decreased by about 40%, and the satellite visibility can be increased by 183.99% relative to the Global Positioning System (GPS) constellation.

Sign in / Sign up

Export Citation Format

Share Document