Satellite navigation regional augmentation system performance analysis based on BDS

BeiDou Navigation Satellite System is called BeiDou System for short, with the abbreviation as BDS. In China, BDS will be used as the primary navigation system for civil aviation, especially for the approach and landing operation, and marine application, especially for the entering harbor stage. BDS Satellite-based augmentation systems (SBAS) is ongoing. Different with the SBAS of GPS and GLONASS, BDS SBAS will operate using five GEO satellites of its constellation, instead of additional GEO satellites, such as PRN 120/124/126 of EGNOS and PRN 135/138. With BDS SBAS, BDS will provide global service meeting the Category I (CAT I) precise approach performance requirements. For CAT II/III precise approach, Ground-based augmentation systems (GBAS) is expected. There are some special areas in China whose coverage radius is more than 200km, and the performance requirement is intended to meet CAT II/III. So GBAS will not meet the requirement, because its coverage is only about 50km. For example, in Zhujiang Delta, China, five airports including Zhuhai airport, Shenzhen airport, Guangzhou airport, Hongkong airport, and Macao airport are distributed inside the area whose radius is about 200km. The similar case also could be found on Yangtze Delta, China. Therefore, Satellite Navigation Region Augmentation System (RAS) is proposed by National Key Laboratory of CNS/ATM, Beihang University. For RAS, multi-GBAS is distributed on a region whose radius is about 200km, and the airborne inside the region could use the information broadcasted by multi-GBAS. Also, one of the GBAS stations could use the information from SBAS GEO satellites and one or more other GBAS stations to improve its integrity, for example to monitor the ionospheric anomaly. In the paper, we will study on integrity risk allocation and fault mode of RAS Firstly. As follows, proposes an ionosphere storm monitor method for RAS. Then, analyze the position performance of RAS based on BDS mixed orbits. Finally, estimate the availability of BDS RAS.