Specifications

DRM - Dynamic Radio Management
Summit WM Series WLAN Switch and Altitude Access Point Software Version 4.1 Technical Reference Guide
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● Other transmitting devices on the channel
● Transmitting devices on neighboring channels
● Transmitting devices on overlapping channels (Turbo-channels)
The CQI value is designed to take into account all forms of possible interference on a particular channel.
If the noise floor is high on a channel, that channel’s CQI is adjusted to look proportionally worse than
a channel with no noise. If there are transmitters operating on adjacent channels, the overlapping
channels CQI is adjusted to take this into account.
Each channels CQI is computed and the channel with the lowest CQI is chosen as the best channel.
Negotiation Phase
Once the channel has been selected (either using the V1.0 method or the V1.2 method), the negotiation
process begins. The purpose of this process is to give the requested channel to the AP that needs it
most. APs in dense areas get priority over other APs.
During the negotiation process, DRM APs communicate their selected channel and information about
their denseness situation over the selected channel. The negotiation period lasts long enough for all APs
that have selected the same channel to receive all of the other APs channel selection information. Once
the negotiation period expires, all the APs determine if they are allowed to operate on the selected
channel. The AP with the greatest need is allowed to operate on the selected channel. All other APs
return to the scanning phase.
The APs that return to the scanning phase perform a minimal scan to detect any new APs operating on
a channel. These are typically the APs that have just won the negotiation process. The channels are
evaluated once more and the best channel is selected. A new negotiation round begins for this AP.
Operation Phase
Once an AP succeeds in acquiring its selected channel, it makes a quick check of that channel to make
sure that nothing has changed during the negotiation process (i.e. a new AP appears nearby on the
channel changing the CQI or Signal Strength measurement for that channel). If everything looks ok, the
AP enables the channel and begins operation.
Channel Selection Time
The amount of time it takes to perform the first round of channel selection is approximately 60 seconds.
NOTE
This number assumes that the regulatory domain does not require radar detection. For regulatory domains requiring
radar detection, each pass though the negotiation phase requires a radar check that lasts 60 seconds. This
significantly impacts the channel selection time for the 802.11a band due to the number of available channels. In
an 802.11a environment with 19 channels and 17 APs, it can take 30 minutes to complete channel selection.
Extreme Networks is working on solutions to improve this time.