Simulation-Based Performance Analysis of SBAS in Korea: Accuracy & Availability

C. Kee, Y. Yun, D. Kim, H. Park, K. Huh

Abstract:	SBAS provides vector corrections of ephemeris and clock offset errors for each GPS satellite, and ionospheric time delay parameters to GPS users so that they can have more accurate and reliable position solutions. The correction information provided by SBAS can be useful and reliable in a very wide area. So it can be used as the primary navigation sensor, and actually many countries are planning or implementing the system like WAAS (U.S.A), EGNOS (Europe), MSAS (Japan). Recently, Korean Government decided to develop Korean WADGPS. Seoul National University GPS Laboratory has conducted the research for deriving a desirable WADGPS implementation scheme in Korea. In this paper, we focus on SBAS. The performance of a navigation system can be represented by accuracy and availability. So we simulated SBAS in Korea to predict accuracy and availability of the system. The program simulates the following subsystems - GPS and GEO satellites constellation, WRSs(Wide-area Reference Stations), WMS(Wide-area Master Station), and SBAS user. WRSs collect and process signals from GPS and GEO satellites. WMS processes the raw data from WRSs to determine error corrections that are composed of satellite position error, satellite clock error and vertical ionospheric time delay at predefined grid points. Then, GEO satellite provides ranging signals and broadcasts correction and integrity information to users. Finally, SBAS users can estimate their own positions with the correction messages. We analyzed the results as follows. Accuracy is calculated from user positions estimated and true positions. For the availability analysis, we computed confidences of UDRE (User Differential Range Error), GIVE (Grid Ionosphere Vertical Error), troposphere error, and airborne system error.
Published in:	Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003) September 9 - 12, 2003 Oregon Convention Center Portland, OR
Pages:	1297 - 1306
Cite this article:	Kee, C., Yun, Y., Kim, D., Park, H., Huh, K., "Simulation-Based Performance Analysis of SBAS in Korea: Accuracy & Availability," Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003), Portland, OR, September 2003, pp. 1297-1306.
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