Drives and Controls Magazine
Li-Fi and TSN deliver real-time comms via light beams
Published:  03 January, 2020

German researchers have combined data transmission via light waves (Li-Fi) with TSN (Time Sensitive Networking) to allow wireless transmission of real-time and deterministic data.

Real-time transmission of data using cable-based fieldbus systems is unsuitable for mobile applications such as industrial robots and other technologies which often require messages to be transmitted in the microsecond range – for example, to synchronise machines or drives with each other. By combining Li-Fi with TSN, the researchers at the Fraunhofer IPMS organisation say that robots or dynamic manufacturing cells can communicate wirelessly in real time.

“Li-Fi is a technology for wireless data transmission by means of light and offers the possibility to realise transmission times in the microsecond range,” explains Dr Alexander Noack, Fraunhofer IPMS’ head of development. “In addition, the data connection with Li-Fi is reliable and offers consistent quality. Li-Fi is therefore an ideal medium for real-time and deterministic wireless data communication. In this way, Time Sensitive Networking can also be implemented without cables.”

TSN extends Ethernet standards to allow deterministic, real-time data transmission through a common network. It offers time-critical, prioritised control of data streams, and guarantees high bandwidths and cycle times of less than one millisecond that are needed for high-speed industrial applications.

The German researchers argue that combining Li-Fi with TSN will allow dynamic applications to communicate wirelessly in real time

“Until now, real-time data transmission for TSN was wired,” Noack adds. “Radio transmission is an alternative, but there are clear limits. With today's radio standards such as 4G, LTE, W-LAN, or the future 5G radio standard, latency times in the microsecond range required for automation cannot be achieved.” He believes that Fraunhofer researchers have overcome this problem by integrating TSN into a Li-Fi hotspot.