Trane Air-Fi WCS-SB Installation, Operation And Maintenance Manual page 108

Using the Tracer® TU Service Tool with a Wireless Network
Figure 74. Channel Quality Scan screen showing channels 17 and 18 with heavy traffic that will
not support Air-Fi communication
Points to remember:
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108
The bars do not indicate signal strength.
The taller green bars indicate quieter channels which have more available bandwidth and are more
likely to get BACnet messages through.
Channels above 30% will have enough available bandwidth to support sending and receiving
BACnet messages over the Zigbee channel.
Buildings typically use Wi-Fi channels 1, 6 and 11 for their wireless networks. See
below which shows how Wi-Fi and Zigbee channels relate to each other in the 2.4 GHz spectrum.
– Wi-Fi channel 1 broadcasts in the space where Zigbee channels 11 through 14 are located.
– Wi-Fi channel 6 broadcasts in the space where Zigbee channels 16 through 19 are located.
– Wi-Fi channel 11 broadcasts in the space where Zigbee channels 21 through 24 are located.
Wi-Fi channels are about 20 MHz wide, but they seldom use all of that bandwidth. See
109. Zigbee channels that are situated near the edges of the Wi-Fi channels are able to
communicate without problem because Wi-Fi is not always using the entire channel. For instance,
Zigbee channel 11 and 14 are at the edge of Wi-Fi channel 1, but are able to communicate without
trouble as long as Wi-Fi channel 1 is not using the entire channel.
Other Zigbee channels like 12 and 13 are near the center of Wi-Fi channel 1, but if Wi-Fi channel 1
is not being used, or does not have a lot of traffic, Zigbee channels 12 and 13 will work fine.
Wi-Fi and Zigbee channels are designed to coexist with each other under typical conditions.
However, sometimes Wi-Fi channels have extraordinary traffic on them and can use up much of the
available bandwidth.
Note channels 15, 20 and 25 are not affected by Wi-Fi channels 1, 6 and 11. Channel 26 is not used
by Air-Fi.
In the Figure 74, p. 108 above, Wi-Fi channel 6 (which uses the space where Zigbee channels 16
through 19 are located) has heavy traffic and is taking up most of the bandwidth to a point where
Zigbee channels 17 and 18 are red and don't have enough bandwidth to support good Air-Fi
communication.
Figure 75, p. 109
Figure 75, p.
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