Wireless roaming is when a wireless client (station) moves around in an area with multiple access points (APs), it can automatically switch to another AP which has better signal strength.

Traditional Roaming

However, the wireless signal handover is a decision made by the wireless clients, and we often find that wireless clients will stick to the original connected AP which has a weak wireless signal rather than roam to an AP with a stronger signal.

AP-Assisted Roaming

VigorAP provides “AP-assisted Client Roaming” which assists wireless clients to roam more effectively. Network administrators can set up conditions related to RSSI or Link rate for APs to kick out wireless clients with poor signal to help them transfer to another AP with a stronger signal.

Roaming Configuration on VigorAP

  1. To enable wireless roaming in the network, the APs must have the same SSID and use the same security mode and password phrase.

  1. The Radio Channel on each AP does not have to be the same. It is actually recommended to use different and non-overlapping channels for each AP to avoid interference between them.

  1. After preparing the SSID, go to Wireless LAN >> Roaming and set up the parameters.
  • Minimum Basic Rate
    AP will immediately disconnect the wireless client whose link speed (Mbps) is lower than the minimum rate.
  • Strictly Minimum RSSI
    AP will immediately disconnect the wireless client whose RSSI(-dBm) is lower than the minimum RSSI.
  • Minimum RSSI with Adjacent AP RSSI over
    If the wireless client ‘s RSSI (-dBm) is lower than the minimum RSSI, and there is another VigorAP on the network which has a stronger signal for them (RSSI is higher than current RSSI, and the difference is over the defined value), only then will the AP disconnect the wireless client. This mode requires information exchange between the APs, so it will work only when all the APs are VigorAPs that support this feature, are connected by Ethernet and are all under the same LAN subnet.

Note: You can enable Basic Rate and RSSI Requirement at the same time, AP will disconnect the wireless client once it meets one of the conditions.

Checking the Client’s RSSI

Network administrators can check the wireless client information such as Link Speed and RSSI from Wireless LAN >> Station List

On Android devices, we can see the signal strength of each SSID. Go to Developer Options to enable WiFi Verbose logging. Then we can check the Wifi RSSI (-dBm).

Syslog for Roaming

Network administrators can also check for the message “kick off” in the Diagnostics >> Syslog Explorer. These indicate that the AP has disconnected a wireless client due to the AP-assisted roaming settings.

Improve Handover from the Client

If your AP does not support AP-assisted roaming, you can try changing the Network adapter settings on the stations. Some wireless network adapters support a Roaming-Aggressive feature, which can be found in Device Manager > Wireless network adapter (Right Click) > Properties > Advanced. Change Roaming-Aggressiveness value to Highest.

Published On: Aug 21, 2018