BDS의 현황 및 분석

Abstract

Global Navigation Satellite Systems (GNSS) provide worldwide positioning services, while Regional Navigation Satellite Systems (RNSS) offer services for specific areas. Korea has been developing its own RNSS called the Korean Positioning System (KPS), which includes a Wide Area Differential-RNSS (WAD-RNSS) concept that transmits both navigation and correction signals simultaneously. In satellite navigation, Signal-In-Space (SIS) User Range Error (URE) represents errors in navigation signals, while User Range Accuracy (URA) provides a conservative estimate of the standard deviation of the SIS URE. The navigation signals are transmitted in either Legacy Navigation (LNAV) or Civil Navigation (CNAV) formats, with CNAV offering advantages including improved flexibility, shorter update intervals, and separate error component representation. Therefore, CNAV achieves smaller UREs and provides a more sophisticated URA in a format different from LNAV. This paper proposes a CNAV URA calculation model for the Korean WAD-RNSS including mathematical expressions for both Elevation-Dependent (ED) and Non-Elevation-Dependent (NED) URA parameters specifically designed for WAD-RNSS satellite orbital characteristics. Simulation results show that the proposed CNAV URA conservatively bounds the Worst User Location (WUL) URE within the service area. Furthermore, our analysis shows that the proposed CNAV URA can be reduced compared to the LNAV URA without compromising conservatism. The proposed method can contribute to the development of modernized navigation messages for WAD-RNSS.