The WLAN standard IEEE 802.11ax (Wi-Fi 6) and 5G are driving wireless mobile communications in the industrial environment.
Siemens supports both technologies in order to offer optimal solutions for the most diverse requirements. The trend in automation is towards automation protocols with hard real-time requirements that are operated in parallel with data-intensive applications. To operate all applications trouble-free via a wireless connection, extensions to the mechanisms already existing in the standard are needed.
Especially in the end-to-end digitalized factory with more and more Industrial Internet of Things (IIoT) devices the number of participants in wireless networks continues to rise, and with it the need for even more flexible, efficient communication. For this, Wi-Fi 6 (IEEE 802.11ax) brings a series of high-performance functions that can be expanded. A major step towards higher efficiency is made possible by the OFDMA (orthogonal frequency-division multiple access) function, a method of data transmission already established in mobile communications but new for WLAN. With OFDMA, the communication channel is divided into multiple subchannels, so-called resource units (RUs). These subchannels can be variably bundled and used by different clients. In this way, data can be transmitted simultaneously. This can reduce latency and ultimately lead to shorter cycle and response times for automation solutions.
Another new function of Wi-Fi 6 enables a defined target wake time (TWT) to be stipulated for each participant so that clients are only addressed and “woken up” when necessary. The clients thus use less energy, which can result in longer runtimes and maintenance cycles for battery-powered WLAN devices. In complex systems, however, the more important aspect is that “sleeping” participants do not transmit and thus do not occupy the communication channel. This in turn facilitates the planning and coordination of large numbers of participants and more easily leads to a stable, interference-free communication.
The new standard function “Spatial Reuse with Basic Service Set (BSS) Coloring” aims to reuse channels that are spatially closer together. To this end, a color (in form of a number) is assigned and a dynamic channel release threshold defined for each BSS. As a result, the participants can communicate reliably even if the channel is in fact occupied by participants of another color, but they are transmitting with a lower power. This eliminates the waiting times for a free channel, and the channels can be reused more efficiently.