Time-based Radio Location

Time-based Radio Location

At a glance

Time-based Radio Location for Industry 4.0 Applications
© Fraunhofer IIS/Kurt Fuchs

Time-based Radio Location for Industry 4.0 Applications

The position of objects or people equipped with small tags can be determined using the propagation time measurement method. Signals are transmitted between transmitters and receivers. The time it takes for a transmitted signal to travel is used to determine the object’s distance. The procedure is based on the fact that electromagnetic waves travel at the speed of light. The speed of light (c) is multiplied with the measured propagation time to determine the exact distance. The propagation time can be determined using various measuring principles, e. g. extremely short UWB pulses (ultra-wide band) and also correlation algorithms, which make use of the familiarity of signal sequences.

Technical Description

There are three benchmark architectures for wireless positioning based on time measurements.

ToA (Time of Arrival) is a one-way radio transmission comprising transmitters, receivers and absolute time measurements. The latter measures the absolute time of when the signal is being sent and when the signal reaches the receiver. Stringent timing and synchronization requirements must be met among all transmitters and receivers. It requires three spatially distributed transmitters to calculate the position of a portable receiver, for example GPS relies on satellites as transmitters.


Systems based on TDoA (Time Difference of Arrival) measure the time differences between two receivers. To determine a location, the method requires three receivers for 2D positioning or four for 3D positioning. This method is also used in the RedFIR® technology.





The RTT (Round Trip Time) describes the time required for a signal to travel from one participant to another and back again.  This way all transceivers know the distance to the other participants. A computer uses the data of the entire radio network to calculate individual positions.



Together with choosing the method appropriate for the individual case, propagation time measurement factors in environmental impacts. For example, real effects like multipath propagation caused by reflections off larger metal surfaces, like car bodies. They have to be addressed adequately. To ensure this the system is designed appropriately to distinguish distortion from the direct signal (LOS Line Of Sight).

Fraunhofer IIS finds the best balance between precision, range, degree of miniaturization and system cost suited to the individual application.



RedFIR® calculates real time precise data for game and players

RedFIR® calculates real time precise data for game and players

The project RedFIR® locates people and objects (soccer) in real time and with high precision. Besides its application in soccer, RedFIR can be used in any other team sports.

Locating systems are used in many other areas, like the positioning, protection and monitoring of resources and goods as well as the control and tracking of vehicles. Seamless tracking makes logistics and production processes more transparent and efficient.

In the area of safety, locating systems are used to locate and monitor the task forces of police, fire fighters and security services. In General, it is possible to combine wireless positioning based on propagation time determination with other measurement principles.

Another area of focus is further processing of position data like event detection, which evaluates the raw XYZ position data delivered by the radio based tracking systems.


Fraunhofer IIS has the full range of skills to offer complete system solutions tailored to your requirements in the area of localization and navigation.

With our longstanding and comprehensive experience in antenna and radio technology, we are in the position to objectively assess, discuss and enhance your ideas and concepts. Fraunhofer IIS is a one-stop shop for technology development ensuring measurable and sustainable success for new strategic solutions.

The propagation time measurement method provides enhanced accuracy to local systems as well as to global satellite navigation allowing for positioning in applications with extremely high precision requirements. We offer genuine expertise and access to our state-of-the-art anechoic chamber, the Test and Demonstration Center L.I.N.K., as well as various hardware and software implementations within the scope of R&D contracts or license agreements.

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