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Korean Navigation Satellite System (KNSS)

The Ministry of National Defense established the '21~'25 mid-term defense plan 10 August 2020. Currently, the US satellite navigation system GPS is mainly being used. In parallel with GPS, a Korean satellite navigation system is promoted jointly with the Ministry of Science and ICT. Th epla is to start development during the mid-term target period. Scheduled to be electrified in the mid-2030's.

Many studies relating to satellite navigation have been done by a relatively small research community in Korea. Most of domestic research has been focused on the application of the satellite navigation technology, but recently the topics of the next generation satellite navigation system are emphasized for its importance. Even opinions suggesting a future Korea's own satellite navigation system are not that uncommon.

Due to the geographic, economic, and technological reasons, it is not widely discussed yet. However, a development technical roadmap regarding the Korea's own navigation satellite was established on the Korea Space Development Plan in general term. Currently four global navigation satellite systems are operating or being deployed. Several regional navigation satellite systems are in planning and development phase. Particularly in Asia, China has launched several satellites to complete their own global navigation satellite system, COMPASS until 2020. Japan is producing and launching the regional satellite navigation system QZSS (Quasi Zenith Satellite System).

It is proper time to develop Korea's own navigation satellite system to acquire the domestic space development technology and the security of navigational infrastructure. The possibility and suitability of the additional information to the current operational navigation message a target. For the first payload of the future Korea's satellite navigation satellite, a regional augmented system is more likely.

In Korea, a Korean-type satellite consisting of three geostationary orbiting satellites and four elliptical inclined Earth-driven orbital satellites for the purpose of providing independent navigation services without relying on the Global Navigation Satellite System (GNSS) in the Korean Peninsula. Basic research on the Korea Regional Navigation Satellite System (KRNSS) is being conducted. As part of the study, research is being conducted on an alternative that can provide continuous navigation services even in emergencies that may occur in KRNSS due to solar flare, jamming, etc., unlike normal situations. In order to improve the quality of navigation services that become inaccurate in emergency situations, it is essential to maintain precise orbit determination of the navigation satellites constituting the satellite navigation system. In the study of emergency situations, a study on real-time orbit determination using the Inter-Satellite Ranging (ISR) and Extended Kalman Filter (EKF) in the situation where the orbital force cannot be transmitted from the ground to the satellite is not possible.

A regional navigation satellite system is a prospective candidate for use in the Korean navigation satellite system (KNSS), which will have South Korea and the remainder of East Asia as its service area. However, orbit design is a prerequisite for any navigation satellite system. This paper implements a conceptual design process prior to orbit design for an indigenous KNSS. Orbits are examined in terms of suitability, and an orbit combination based on the dilution-of-precision (DOP) performance is presented. Through simulation, an orbit combination capable of providing a stable DOP for the Korean Peninsula is proposed. Moreover, the orbit combination proposed incorporates design constraints such as satellite unavailability or potential position errors in the north-south direction, with the Korean Peninsula as a reference position. The simulation results suggest that the KNSS requires an orbit combination involving geostationary orbit (GEO) and elliptically inclined geosynchronous orbit (EIGSO), along with backup satellites in EIGSO; thus, the proposed system consists of 11 satellites in total.