1. Overview
The BeiDou Navigation Satellite System (BDS) has been independently constructed and operated by China with an eye on 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.
Since provision of services, BDS has been widely used in transportation, agriculture, forestry, fisheries, hydrological monitoring, meteorological forecasting, communication, power dispatching, disaster relief, public security and other fields, and has been serving national significant infrastructures, thereby resulting in remarkable economic and social benefits. The BDS-based navigation services have been widely adopted by e-commerce enterprises, manufacturers of intelligent mobile terminals and location-based services providers, which have extensively entered into the fields of mass consumption, share economies, and those related to people's livelihood. New modes, business forms and economy of the BDS applications are emerging, profoundly changing people's production and life. China will continue to promote the BDS applications and industrial development, so as to serve the country's modernization construction and daily life of the people, and to make contributions to the global scientific, technological, economic and social development.
China applies the principle that “BDS is developed by China, dedicated to the world, and aiming to be top-class”, and is keen to share the outcome of the BDS construction and development with all other countries, to promote global satellite navigation development and make Global Navigation Satellite Systems (GNSS) serve the world and benefit mankind. BDS provides spatial and temporal information security for economic and social development, and is one of the important achievements in the past 40 years of China’s reform and opening-up, and serves as a global public product contributed by China to the world. China will continue to actively promote international exchanges and cooperation, so as to achieve compatibility and interoperability with other satellite navigation systems in the world and provide global users with higher performance, more reliable and multiple services.
2. The Development Strategy
In the late 20th century, China started to explore a path to develop a navigation satellite system suitable for its national conditions, and gradually formulated a three-step development strategy: By 2000, the construction of BDS-1 was completed to provide services to China; by 2012, the construction of BDS-2 was completed to provide services to the Asia-Pacific region; the construction of BDS-3 will be completed to provide services worldwide in 2020.
3. The Development Goals
The BDS development aims to build a world-class navigation satellite system to meet the needs of the country’s national security as well as economic and social development; to provide continuous, stable and reliable services for global users; to develop the BDS-related industries to support China’s economic and social development, as well as improvement of people’s living standards; and to enhance international cooperation to share the development fruits in the field of satellite navigation, increasing the comprehensive application benefits of global navigation satellite systems.
4. The Development Principles
China upholds the principles of “independence, openness, compatibility and gradualness” in the BDS construction and development.
Independence refers to uphold independent construction, development and operation of BDS, and to acquire the capability to independently provide satellite navigation services to global users.
Openness refers to provide open satellite navigation services free of charge, and to encourage all-scale, multi-level and high-quality international cooperation and exchange.
Compatibility refers to enhance the compatibility and interoperability with other navigation satellite systems, and to encourage international collaborations and exchanges, so as to provide better services to users.
Gradualness refers to carry out the BDS development in a phased approach, to enhance BDS service performance, and to boost the development of satellite navigation industries in a comprehensive, coordinated and sustainable manner.
5. The Future Target
A more ubiquitous, integrated and intelligent, comprehensive national positioning, navigation and timing (PNT) system is scheduled to be established by 2035.
6. The Main Architecture
BDS is mainly comprised of three segments: a space segment, a ground segment and a user segment.
The BDS space segment consists of a number of satellites located in the Geostationary Earth Orbit (GEO), Inclined Geo-Synchronous Orbit (IGSO) and Medium Earth Orbit (MEO).
The BDS ground segment consists of various ground stations, including master control stations, time synchronization/uplink stations, monitoring stations, as well as operation and management facilities of the inter-satellite link.
The BDS user segment consists of various kinds of BDS basic products, systems, and services as well as those compatible with other navigation systems, including basic products such as chips, modules and antennae, terminals, application systems and application services.
7.The BDS Characteristics
The BDS development follows a model of developing regional service capacities, then gradually extending the services globally. This practice has blazed a path for building a satellite navigation system with Chinese characteristics, and enriched the development models for navigation satellite systems worldwide.
BDS possesses the following characteristics: First, its space segment is a hybrid constellation consisting of satellites in three kinds of orbits. In comparison with other navigation satellite systems, BDS operates more satellites in high orbits to offer better anti-shielding capabilities, which is particularly observable in terms of performance in the low-latitude areas. Second, BDS provides navigation signals of multiple frequencies, and is able to improve service accuracy by using combined multi-frequency signals. Third, BDS integrates navigation and communication function, and possesses multiple service capabilities, namely, positioning, navigation and timing, short message communication, international search and rescue, satellite-based augmentation, ground augmentation and precise point positioning, etc.
