Roaming - Weidmuller WI-MOD-E-G User Manual

Weidmuller Wireless Ethernet Modem & Device Server WI-MOD-E-G/A User Manual

3.16 - 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 allows a client (station) to roam to an AP with a stronger signal strength
Fast Roaming
without disrupting communications. Or roam seamlessly between multiple Access
Points based on configuration parameters such as RSSI threshold.
Passive Selecting this item stops a Client device from sending "probe request" messages when
Scanning (STA it is searching for an access point to connect to. Instead, the client waits for a beacon
only) transmission from the access point.
Passive Scanning should be disabled when Fast Roaming is enabled.
Roam Scan Background Scan will be initiated when the RSSI to the currently connected AP drops
Threshold below this threshold and Fast Roaming (above) is enabled. Default is -90dBm
Roam This is the RSSI value above the Roam Scan Threshold that is required for the Client to
changeover change to the new Access Point. In the example shown above the Access Point RSSI
Threshold 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 If a better AP is not found, the background scan is repeated every Roam Check Interval
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 Save changes to non-volatile memory and reset module
and Reset
Rev. 2.16
Figure 38 - Roaming
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