Satellite Based Augmentation System (SBAS) enhances Global Navigation Satellite System (GNSS) by providing differential corrections and integrity bounds on the corrections. Although SBAS is not yet developed for the Korean region, if it becomes operational, it will benefit a broad community of users who need GNSS based service. However, a major concern is the ionosphere. Since the ionospheric disturbance can significantly vary from one region to another, it is essential to build location specific ionospheric threat models where SBAS will be operational. Thus this paper derives ionospheric irregularity threat model for future Korean SBAS, and demonstrates the performance of a new threat model. Although 99.9% availability for AVP-I can only be attained in a limited region of the mainland based on existing WAAS threat model, availability performance for APV-I can be achieved in a region enclosing the Korean inland area when the new ionospheric threat model is applied.

Keywords: satellite based augmentation system, ionospheric irregularity threat model