Scientists from VSL, TU Delft and VU Amsterdam have developed an alternative navigation system with an accuracy of 10 centimetres. This system offers a glimpse of a future where telecommunication networks not only provide connectivity but also time and location-dependent applications with an accuracy that is much higher and faster than that of satellite navigation systems such as GPS.
The system is implemented in a specially developed mobile network. The results are the first demonstration of a system that can provide connectivity such as cellular and Wi-Fi networks as well as accurate position and time information such as GPS. This technology is expected to be important for applications such as automated driving, quantum communication, renewable energy generation and the next generation of mobile networks.
The results stem from the SuperGPS project, a collaboration between VU Amsterdam, TU Delft and VSL – the National Metrology Institute of the Netherlands. “The goal of the project was to develop an alternative positioning system based on the mobile network instead of satellites, which is also more robust and accurate than GPS,” says Jeroen Koelemeij, assistant professor at VU University Amsterdam.
Growing need for alternative navigation system
Much vital infrastructure depends on satellite navigation systems such as the American GPS and the European Galileo. However, these systems have limitations and vulnerabilities: the radio signals received are weak, and positioning becomes inaccurate when the radio signals are reflected or blocked by buildings. In addition, it is a point of increasing concern for the national authorities that more and more radio waves are being disturbed by (illegal) jamming equipment.
“A lot of vital infrastructure, but also citizens and authorities, depend on GPS and comparable satellite navigation systems. But there is no backup system,” says Christian Tiberius of Delft University of Technology and coordinator of the project. “We realized that with a few smart innovations we could transform the telecommunications network into a highly accurate alternative to GPS.”
A hybrid fiber optic wireless system with GPS accuracy
One of the innovations consists of connecting a very accurate atomic clock to the mobile network. This allows the system to send perfectly timed messages for positioning, just as GPS does using atomic clocks in the satellites. This connection uses the existing fiber optic network. “With this technique we can turn the network into a nationwide distributed atomic clock, with countless new applications such as accurate positioning. And with the hybrid fibre-optic wireless system that we have now developed, everyone can in principle gain access to our atomic age. It provides an extremely accurate radio clock that is accurate to a billionth of a second,” said Erik Dierikx, scientist at VSL.
In addition, the system uses radio signals with a much larger bandwidth than usual. This helps to identify confusing reflections in the navigation equipment, which can increase location accuracy. “At the same time, bandwidth in the radio spectrum is scarce and therefore expensive. We circumvent this by means of signals in a number of narrower bandwidths, spread over a large ‘virtual’ bandwidth. So the signals actually only use a small part of the radio spectrum, and they are also more similar to what is now used in mobile networks,” says Gerard Janssen of TU Delft.