The Beidou Navigation Satellite System (BDS) has been independently constructed and operated by China with an eye to the needs of the country's national security and economic and social development. As a temporal-spatial infrastructure of national significance, the BDS provides all-time, all-weather and high-accuracy positioning, navigation and timing services to global users. Through radio determination satellite system (RDSS) and radio navigation satellite system (RNSS), BDS provides excellent positioning, navigation, timing, position report, and short message communication services for users in China and its surrounding areas. RDSS is the characteristic service and unique advantage of BDS.