Weidmuller Wireless Ethernet Modem & Device Server WI-MOD-E-G/A User Manual
Rev.
2.16
www.weidmuller.com
49
3.16 - Roaming
Figure 38 - Roaming
In certain cases a Client may be in a mobile situation and require a method of roaming to another Access Point.
Normal network communications provides only basic roaming behavior which means as the client moves further from the
AP it will go through a period of poor communication followed by a complete disconnection of the radio link.
It is at this point that the Client will scan for Access Points and if one is in range it could take up to 10 seconds for the
client to establish a connection.
Fast Roaming will significantly reduce the time taken for a client to roam from Access Point to Access Point. Also the
discovery of AP’s is done before the existing radio link deteriorates therefore eliminating the periods of poor performance
during transition to the next AP.
The following settings/thresholds can be configured to fine tune the fast roaming process.
Fast Roaming
Fast Roaming allows a client (station) to roam to an AP with a stronger signal strength
without disrupting communications. Or roam seamlessly between multiple Access
Points based on configuration parameters such as RSSI threshold.
Passive
Scanning (STA
only)
Selecting this item stops a Client device from sending “probe request” messages when
it is searching for an access point to connect to. Instead, the client waits for a beacon
transmission from the access point.
Passive Scanning should be disabled when Fast Roaming is enabled.
Roam Scan
Threshold
Background Scan will be initiated when the RSSI to the currently connected AP drops
below this threshold and Fast Roaming (above) is enabled. Default is -90dBm
Roam
changeover
Threshold
This is the RSSI value above the Roam Scan Threshold that is required for the Client to
change to the new Access Point. In the example shown above the Access Point RSSI
would need to be above -84dB before it would changeover.
In general, the Roam Changeover Threshold should be at least 6dB, otherwise
changeovers could occur too frequently.
Roam check
Interval
If a better AP is not found, the background scan is repeated every Roam Check Interval
while the signal strength to the currently connected AP is below the Roam Scan
Threshold. Default is 30seconds
Channel Width
Selects channel width bands for background scan. If 5MHz is selected then only 5MHz
channels will be scanned during the background scan. Default is Auto, which means all
channels will be scanned.
Save Changes
Save changes to non-volatile memory. Changes will not take effect until module is reset.
Save Changes
and Reset
Save changes to non-volatile memory and reset module
