Researchers at Delft University of Technology, Vrije Universiteit Amsterdam and VSL have developed an alternative positioning system that is more robust and accurate than GPS, especially in urban settings.
The aim of the project — SuperGPS — was to develop an alternative positioning system that makes use of the mobile telecommunication network instead of satellites and that has better accuracy than GPS.
The working prototype that demonstrated this new mobile network infrastructure achieved an accuracy of 10 centimeters.
The new technology is important for the implementation of a range of location-based applications, including automated vehicles, quantum communication and next-generation mobile communication systems.
Much of our vital infrastructure relies on GNSS. Yet systems that rely on satellites have limitations and vulnerabilities. For instance, their radio signals are weak when received on Earth, making accurate positioning no longer possible if the radio signals are reflected or blocked by buildings.
“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,” said Jeroen Koelemeij of Vrije Universiteit Amsterdam. “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.”
Illustration: TU Delft / Stephan Timmers
One innovation is to connect the mobile network to a very accurate atomic clock so that it can broadcast perfectly timed messages for positioning, just like GPS satellites do with the help of the atomic clocks they carry on board. These connections are made through the existing fiber-optic network.
“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,” said Erik Dierikx, VSL. “With the hybrid optical-wireless system that we have demonstrated now, in principle anyone can have wireless access to the national time produced at VSL. It basically forms an extremely accurate radio clock that is good to one billionth of a second.”
The system also employs radio signals with a bandwidth much larger than commonly used. “Buildings reflect radio signals, which can confuse navigation devices. The large bandwidth of our system helps sorting out these confusing signal reflections, and enables higher positioning accuracy,” explained Gerard Janssen of Delft University of Technology. “At the same time, bandwidth within the radio spectrum is scarce and therefore expensive. We circumvent this by using a number of related small bandwidth radio signals spread over a large virtual bandwidth. This has the advantage that only a small fraction of the virtual bandwidth is actually used and the signals can be very similar to those of mobile phones.”
The results of the peer-reviewed research have been published in Nature.
Photo: TU Delft / Frank Auperlé
