User Manual

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Understanding Industrial WLAN – IEEE 802.11
2.6 Advanced WLAN Technologies
Dual RF Redundancy
According a recent VDC report, more than 40% of wireless users are concerned about interference. In
industrial and critical applications, this issue is even more important. Normally, interference occurs in a
dedicated frequency. So, if we can use 2 or more different frequencies to communicate at the same time, then
data transmission will not be stopped, even if there is interference in one of the frequencies. The picture below
depicts the standard architecture for wireless infrastructure. As you can see, access points (AP) can connect
many Clients to an Ethernet network.
For network redundancy, simply use APs and Clients with dual RF and keep the existing architecture (usually,
these 2 RFs are set to 2.4 GHz and 5 GHz to make sure prevent interference). To ensure that data can be
delivered between the AP and Client, even when there is interference in one of the frequencies, Moxa devices
are equipped with a special protocol with almost ‘0’ switching time for seamless redundancy. For reliability
beyond wireless redundancy, Ethernet redundancy is also required. Fast ring redundancy like RSTP or Turbo
Ring is important on the Ethernet side.
Figure: Traditional Wireless Architecture
Figure: Redundant Wireless/Ethernet Typology