SuperGPS Offers Sub-4" Positioning in Urban Environments — Using Only Terrestrial Radios

Researchers at the Delft University of Technology, Vrije Universiteit Amsterdam, and VSL have come up with an alternative approach to navigation that, they say, is both more robust and accurate than the Global Positioning System (GPS): SuperGPS.

"GPS [can be] unreliable in urban settings," explains project coordinator Christiaan Tiberius of the issue the team set out to solve, "which is a problem if we ever want to use automated vehicles. Also, citizens and our authorities actually depend on GPS for many location-based applications and navigation devices. Furthermore, so far we had no back-up system."

The SuperGPS project was founded to provide both an alternative positioning system, which could work in the face of a GPS outage and to address the issue of poor accuracy in urban canyons due to weak satellite signals bouncing between buildings — and rather than satellites, the navigation system relies entirely on terrestrial radio systems.

"We realized that, with a few cutting-edge innovations, the telecommunication network could be transformed into a very accurate alternative positioning system that is independent of GPS," explains first author Jeroen Koelemeij. "We have succeeded and have successfully developed a system that can provide connectivity just like existing mobile and Wi-Fi networks do, as well as accurate positioning and time distribution like GPS."

The SuperGPS system works by hooking high-accuracy atomic clocks to the fiber optic networks already used as backhaul for cellular mobile networks. "We had already been investigating techniques to distribute the national time produced by our atomic clocks to users elsewhere through the telecommunication network," explains VSL's Erik Dierikx. "With these techniques we can turn the network into a nationwide distributed atomic clock – with many new applications such as very accurate positioning through mobile networks."

Using this system, the team was able to provide high-accuracy location services with sub-nanosecond timing — down to 10cm, or 3.94", a major improvement on unaugmented GPS or other Global Navigation Satellite System (GNSS) implementations, particularly in the target urban environments. "This work provides a glimpse of a future in which telecommunication networks provide not only connectivity," the team concludes, "but also GNSS-independent timing and positioning services with unprecedented accuracy and reliability."

The team's work has been published in the journal Nature under closed-access terms. Additional information is available on the project website.

Main article image courtesy Frank Auperlé/TU Delft.