Satellite-Based Commercial Services Are Formally Put into Use in Support of BDS-3 Full-System Signals

It was announced at the 12th China Satellite Navigation Conference on May 27 that satellite-based services, fully capable of commercial functions, will provide users in the Asia-Pacific region, namely users in Japan, South Korea, East Asia and Southeast Asia, and other regions with faster, more accurate, more reliable and seamlessly real-time centimeter-level high-precision services that support BDS-3 full-system signals.

The integration of satellite-based and ground-based augmentation technologies is an inevitable trend in the development of space-time services. Centimeter-level space-time services, featured by the satellite-ground integration, integrate satellite-based augmentation systems, ground-based augmentation station networks that cover the whole world, and the technologies, of independent intellectual property rights, to realize satellite-ground integration, which can provide dynamic centimeter-level positioning services for 24 hours in consecutive 7 days across the entire domain without the support of communications network. At present, the availability of satellite-ground integration services has reached 99.99%, with a continuity rate of 99.99% and an integrity index of 10-7 (-7 as the superscript)/hour.

Satellite-based augmentation service forwards differential signals through geostationary Earth orbit (GEO), thus shaking off its dependence on the Internet network while transmitting data. It can provide dynamic centimeter-level positioning services in areas without network service or areas with intermittent network service, such as desert, ocean and high-altitude regions, to meet the users’ needs in areas where there is no access to ordinary positioning services.

In the application process of traditional satellite-based services, the initial positioning time, which would last as long as 15 to 20 minutes, is the most outstanding problem for users.

Liu Jingnan, academician of the Chinese Academy of Engineering and professor at Wuhan University, believes that the integrated application of satellite-based and ground-based augmentation technologies and that ofcommunication and navigation functions, is the future direction that the sector of the satellite navigation system in the intelligent era should head for.

“With the help of ground-based augmentation technology, existing satellite navigation systems are already able to provide real-time high-precision space-time positioning services synchronized at centimeter level and nanosecond level. Through satellite-based augmentation technology, we can enjoy sub-meter-level or even centimeter-level positioning services and time synchronization with corresponding accuracy in numerous vast areas where no mobile communications services are accessible. Applied alone, neither of the two technologies is able to meet the requirement of seamless and continuous availability in the intelligent era,” said Liu Jingnan.

It is reported that distinct differences exist between the satellite-ground integration service and the traditional individual satellite-based service or ground-based augmentation service.

The significant advantages of the centimeter-level space-time satellite-ground integration service include: consistently guaranteed accuracy, single-machine global high-precision positioning, unified coordinate frame, and seamless switching.