KOREA Augmentation Satellite System (KASS): First System Performance with Deployed System

Carolle Houllier, Thierry Authié, Guillaume Comelli, ByungSeok Lee, Eunsung Lee, Youngsun Yun, Cheon Sig SIN

Abstract:	The Korea Augmentation Satellite System (KASS) is the future SBAS of the Republic of Korea. It is currently developed by the Korea Aerospace Research Institute (KARI) for the government of the Republic of Korea, Thales Alenia Space is the industry prime contractor of this development. The function of the KASS is to provide SBAS service compliant with ICAO SARPS Annex 10 [1] over the South Korea area with service level up to APVI. KASS system will comprise the following segments obtained from different manufacturers or service providers: - a ground segment including network of KRSs (KASS Reference Stations), the redundant KPSs (KASS Processing Stations), the KCSs (KASS Control Stations), the KUSs (KASS Uplink Stations) and an external data interface; - a network segment ensuring the communication network between all subsystems distributed across Korea (WAN) and the WAN Network Monitoring (WNM); - a space segment including the GEOs and the navigation payloads on-board the GEOs. Two main subsystems are contributing to navigation signal performance. First subsystem is the KASS Processing Station (KPS) in charge of computing the GNSS orbits, clocks and ionosphere corrections and alert information. The KPS is composed of two independent elements: the Processing Set (PS) and the Check Set (CS). The first element is responsible for computing the complete navigation context for the GNSS constellation (orbits and clocks) and the ionosphere model. Then it prepares and sends the SBAS messages to be broadcast to the users. The second element acts as a SBAS user by applying the SBAS navigation messages to the GPS messages. It checks that this is consistent with the independent set of measurements received from KRS, to control and ensure the integrity of SBAS messages. The KPS elements hosts the navigation algorithms and as such is a key driver for the KASS performance achievement. Second main subsystem is the network of KASS Reference Stations (KRS), all located on the Rep. of Korea land masses. Each KRS includes two independent channels based on NOVATEL WAAS GIII receivers providing GPS signal tracking and measurements. 7 KRS sites are deployed on the Rep. of South Korea land masses, this leads to a very concentrated reference station network. This particularity makes necessary to adapt KPS algorithms. Thales Alenia Space has designed, developed and qualified a new complete real time navigation algorithm chain that provides SARPS-compliant navigation messages. Main adaptations are related to orbit determination and to ionosphere corrections computation due to the very low number of Ionosphere Grid Points (IGP) that need to be modeled and monitored. The KASS system deployment started end of 2020 with the installation on site of the system reference stations network. In parallel the wide area network has been extensively tested and verified to allow continuous data transmission. Since this first deployment step, data have been collected and Thales Alenia Space has realized first performance analysis on real data. This paper presents the overall KASS system architecture as well as the first performance results with deployed system under real conditions. These results are obtained through KRS real data collection and a replay on KASS test bench hosting fully representative KPS algorithms.
Published in:	Proceedings of the 35th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2022) September 19 - 23, 2022 Hyatt Regency Denver Denver, Colorado
Pages:	103 - 116
Cite this article:	Houllier, Carolle, Authié, Thierry, Comelli, Guillaume, Lee, ByungSeok, Lee, Eunsung, Yun, Youngsun, SIN, Cheon Sig, "KOREA Augmentation Satellite System (KASS): First System Performance with Deployed System," Proceedings of the 35th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2022), Denver, Colorado, September 2022, pp. 103-116. https://doi.org/10.33012/2022.18309
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