With the development of the Internet of Things (IoT) era, indoor positioning has become an indispensable and important application in daily life, and positioning technology has gradually become the underlying core technology for various new scenarios. Because of the unique advantages inherent in indoor UWB positioning trackers: high positioning accuracy, low power consumption, strong anti-interference capability, strong penetration, etc., indoor UWB positioning trackers have become the most important part of the indoor positioning industry. As we all know, there are some errors in the positioning of indoor UWB positioning trackers, so how should we reduce them? Here are some of the sources of error and ways to reduce them.
Sources of error
Methods for reducing errors
Clock synchronization accuracy
The TOA localization algorithm requires accurate time synchronization between the target and reference nodes, and the TDOA localization algorithm requires accurate clock synchronization between the reference nodes, so non-accurate time synchronization will lead to localization errors in the UWB system. However, due to the limitations of indoor UWB positioning tracker hardware, fully accurate clock synchronization is not possible.
The moment at which the matched filter outputs a maximum or the moment at which the correlation maximum is used as an estimate in TOA estimation algorithms is often used. The presence of multipath causes a drift in the position of the correlation peak, resulting in a large error between the estimated and actual values.
When there is no direct propagation path between two points, only the reflected and derived components of the signal can reach the receiving end, at which point the time of the first arriving pulse is not representative of the true value of the TOA and there is a non-line-of-sight error.
In a multi-user environment, signals from other users can interfere with the target signal, thus reducing the accuracy of the indoor UWB positioning tracker estimate. One way to reduce this interference is to separate the signals from different users in time, i.e. to use different time slots for the transmission of different nodes.
Indoor UWB positioning trackers use broadband narrow pulse communication (with a very high temporal resolution to reduce positioning errors), multi-source data fusion (to improve the immunity of the positioning system) and time-series signal processing (to extract the first path signal in a complex environment with strong multipath), so that accurate positioning of the target can be achieved.
The indoor UWB positioning tracker uses a wireless synchronization method. Wireless synchronization means that each base station continuously exchanges its clock information with other base stations to achieve and maintain a consistent global time.
The wireless synchronization method relies on the measured time accuracy of the indoor UWB positioning tracker, the higher the time accuracy and the smaller the time error between the two base stations, the better the time synchronization between them. The advantage of the wireless synchronization approach is that no wired connection is required between the base stations, making deployment less difficult and less costly.
Errors in indoor UWB positioning trackers cannot be avoided, but Megastek Technologies Ltd insists on minimizing them to ensure a good user experience.