Researchers in the Netherlands have developed and demonstrated a new positioning technology that is more robust and accurate than conventional GPS, capable of pinpointing a location with 10-centimeter accuracy. The system, which uses a hybrid optical-wireless network, is particularly effective in urban environments where traditional GPS signals falter, paving the way for advanced applications ranging from autonomous driving to next-generation mobile communications.
The breakthrough overcomes key limitations of current satellite-based systems by integrating a mobile network with a highly precise atomic clock. Unlike GPS, which can be easily confused by radio signals reflecting off buildings, this terrestrial network provides a stable and reliable signal. This leap in precision and reliability is critical for technologies that require unwavering positional awareness, such as self-driving cars navigating dense city streets or unmanned aerial vehicles performing complex tasks.
A Novel Hybrid Network Infrastructure
The new system was created by a collaboration between researchers at Delft University of Technology, Vrije Universiteit Amsterdam, and VSL, the Dutch National Metrology Institute. Their approach effectively creates a new form of mobile network infrastructure for positioning. At its core, the technology links the mobile network to a central atomic clock via existing fiber-optic cables. This connection allows the network to broadcast perfectly synchronized, time-stamped messages that devices can use to determine their location with extreme precision.
The prototype demonstrated that this method could achieve an accuracy of 10 centimeters. The project leverages the stability of the fiber-optic network to distribute the national time standard maintained by VSL. By doing so, any device with wireless access can tap into a signal that is accurate to within one billionth of a second, functioning like an extremely precise radio clock.
Overcoming GPS Limitations
Standard Global Positioning System (GPS) technology, while revolutionary, has well-known weaknesses. Once signals from satellites reach a receiver, their accuracy is generally within five to 10 meters. Even the ongoing, multi-year upgrade to the GPS III satellite constellation is only expected to improve guaranteed accuracy to between one and three meters. This level of precision is insufficient for applications that demand centimeter-level awareness for safety and functionality.
A primary issue, especially in cities, is the multipath effect, where radio signals bounce off buildings and other structures. These reflected signals can confuse a GPS receiver, leading to significant errors in position calculation. Furthermore, GPS signals are weak and can be lost in dense urban canyons or indoors. To address these shortcomings, various augmentation systems have been developed, such as the Wide Area Augmentation System (WAAS) used in aviation and Differential GPS (DGPS), which uses stationary reference stations for corrections.
Current Augmentation Methods
To achieve higher precision, many industries rely on techniques like Real-Time Kinematic (RTK) positioning. RTK uses a stationary base receiver and a moving “rover” receiver to correct for errors caused by the Earth’s ionosphere, often achieving accuracy better than three centimeters. A similar but newer technology is Precise Point Positioning (PPP), which requires only one receiver. Some modern systems are working to combine these two approaches into a hybrid called PPP-RTK. However, these methods still depend on often-vulnerable satellite signals. The new Dutch system is fundamentally more robust because its signals originate from a ground-based network that is less susceptible to these atmospheric and reflection-based errors.
Key Technological Innovations
The success of the new positioning system hinges on two main innovations. The first is the novel use of the telecommunications network as a conduit for national time standards. By connecting radio transmitters to the national atomic clock via fiber optics, the researchers turned the network itself into a distributed, nationwide atomic clock. This provides a timing signal for positioning that is orders of magnitude more stable and precise than the clocks within individual GPS receivers.
The second innovation involves the use of radio signals with a much wider bandwidth than is common for navigation. This wider bandwidth makes the signal far more resilient to the reflection-based errors that plague GPS in urban settings. A receiver can more easily distinguish between the direct signal and delayed, reflected signals, allowing it to lock onto the correct one and calculate a more accurate position.
Enabling Future Technologies
The development of a reliable, centimeter-level positioning system is an essential step for a host of emerging technologies. The most frequently cited application is autonomous vehicles, which require constant, precise knowledge of their position to navigate safely and effectively. For a self-driving car to maneuver in complex traffic, it must know its location relative to lane markings, other vehicles, and infrastructure with a margin of error far smaller than what conventional GPS can provide.
Beyond autonomous driving, this technology is important for the future of mobile and quantum communication. Ultra-precise timing and synchronization are foundational for managing data traffic in 5G and future 6G networks. It also opens new possibilities in logistics, machine automation, and scientific research where precise location and timing are critical. As this technology matures, it could provide a robust and powerful alternative or supplement to satellite-based navigation, making high-precision positioning universally accessible.
