Impression of experiments carried out with a road vehicle, using the prototype system deployed at The Green Village on TU Delft campus. (Image:

This new technology — developed by engineers at Delft University of Technology, Vrije Universiteit Amsterdam, and VSL, and which can achieve an accuracy of 10 centimeters — is important for the implementation of a range of location-based applications, such as automated vehicles, quantum communication, and next-generation mobile communication systems.

Current navigation satellite systems boast weak radio signals when received on Earth, and tall buildings can hinder their accuracy too.

“This can make GPS unreliable in urban settings, for instance,” said Christiaan Tiberius of Delft University of Technology and Coordinator of the project, “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 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 could be more robust and accurate than GPS.

“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, 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.”

One innovation was to connect the mobile network to a very accurate atomic clock to broadcast perfectly timed positioning messages, just like GPS satellites do. These connections are made through the existing fiber-optic network.

“We had already been investigating techniques to distribute the national time produced by our atomic clocks to users elsewhere through the telecommunication network,” said Erik Dierikx, VSL. “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. 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.”

“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,” said Gerard Janssen, 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.”

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