Specifications

DRM - Dynamic Radio Management
Summit WM20 Technical Reference Guide, Software Version 4.292
Now consider the case for DRM’s standard RF mode. The data Tx range from each AP is kept as low as
possible give the active clients. The area of co-channel interference in the middle of the APs is now
reduced to just co-channel interference for beacons. Beacons are regular traffic but are only sent on a
typical interval of every 0.1 seconds. Also, for co-channel interference from beacons to occur in the
center area the beacons from the co-channel APs would have to be exactly synchronized. Given the
infrequency of the beacons and the probability of an exact synchronization between co-channel APs
then it is fair to say that the dynamic RF ability of DRM’s standard mode helps significantly clean up
the co-channel interference in the center of this example diagram.
Supporting New Clients
A key characteristic of DRM Power control is how it handles new clients. When a client first associates,
DRM increases the transmit power for data frames to full power. This is done because DRM does not
know the status of the client when it first associates. DRM then evaluates the clients needs and adjusts
the transmit power to support it. If the client is far away, DRM provides more power to support it. If
the client is very close, the transmit power for data traffic is reduced significantly to minimize
interference.
RF Domain
DRM adjusts power to APs that are part of its network. Another AP is defined as being part of this
network if the SSID matches the SSID of this AP. If the APs support multiple SSIDs, then the APs are
considered part of the same network if any of the SSIDs match.
If APs are configured to suppress their SSIDs, none of the APs can determine which APs are part of the
same network. To overcome this issue, DRM has introduced the concept of an RF Domain. The RF
Domain creates a set of APs that are part of the same wireless network. To establish an RF Domain, each
AP that is to be included must have a new field added to its configuration, the RF Domain. This field is
a text string that is transmitted with each 802.11 Beacon. Clients can’t use this information to associate
or compromise security. Its purpose is to create a set of APs that DRM will include in its power control
adjustments.
DRM Shaped Power Control
DRM provides a second enterprise class power control mode called Shaped Power Control. In this
mode, DRM APs will reduce power to minimize interference between other APs operating on the same
channel. When DRM reduces power in this mode, it reduces power of all 802.11 frames including the
management frames. This shrinks the size of the cell for both management and data frames.
This mode does not adjust the power to provide better service to distant clients. If a client moves to a
position that provides marginal service from the AP it is associated to, DRM assumes that the client will
realize this and roam to a better AP.
This mode assumes that there are enough APs in the environment to provide excellent service at any
location.