A navigation system with an accuracy of 10 centimeters — ScienceDaily
Researchers from 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 working prototype that demonstrated this new mobile network infrastructure achieved an accuracy of 10 centimeters. This new technology is important for implementing a range of location-based applications, including automated vehicles, quantum communication and next-generation mobile communication systems. The results were published in Nature today.
Much of our vital infrastructure relies on global navigation satellite systems such as US GPS and EU Galileo. Yet these satellite-based systems have their limitations and vulnerabilities. Their radio signals are weak when received on Earth, and precise positioning is no longer possible if the radio signals are reflected or blocked by buildings. “This can make GPS unreliable in urban settings, for example,” says Christiaan Tiberius of Delft University of Technology and project coordinator, “which is a problem if we ever want to use automated vehicles. citizens and our authorities actually depend on GPS for many location-based applications and navigation devices. Also, until now, we didn’t have a backup system.”
The aim of the project called SuperGPS was to develop an alternative positioning system that uses the mobile telecommunications network instead of satellites and which could be more robust and accurate than GPS. “We realized that with a few cutting-edge innovations, the telecommunications network could be transformed into a highly accurate, GPS-independent alternative positioning system,” says Jeroen Koelemeij of the Vrije Universiteit Amsterdam. “We have succeeded and have successfully developed a system that can provide connectivity just like existing mobile and Wi-Fi networks, as well as precise positioning and time distribution like GPS.”
An atomic clock
One of these innovations is to connect the mobile network to a very precise atomic clock, so that it can broadcast perfectly synchronized messages for positioning, just as GPS satellites do using the atomic clocks they embark. These connections are made via the existing fiber optic network. “We had already studied techniques to distribute the national time produced by our atomic clocks to users elsewhere via the telecommunications network,” explains Erik Dierikx of VSL. “With these techniques, we can transform the network into a nationally distributed atomic clock – with many new applications such as very precise positioning via mobile networks. With the optical-wireless hybrid system we have now demonstrated , in principle, anyone can have wireless access to national time produced at VSL. It essentially forms an extremely accurate radio clock that is good to a billionth of a second.”
In addition, the system uses radio signals with a much larger bandwidth than commonly used. “Buildings reflect radio signals, which can confuse navigation devices. The wide bandwidth of our system helps sort out these confusing signal reflections and allows for greater positioning accuracy,” says Gerard Janssen of the University of Delft technology. “At the same time, bandwidth in the radio spectrum is scarce and therefore expensive. We circumvent this by using a number of associated low-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 cellphones.”
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Material provided by Delft University of Technology. Note: Content may be edited for style and length.