Wi-Fi roaming issues are frustrating and often relate to a few key things, such as poor network design, where there is excessive cell overlap due to high access point power levels. As a result, client devices “stick” to the distant cell. Another culprit of Wi-Fi roaming issues is RF bleeding between floors, where clients connect to an access point that has a very small coverage area, therefore, the signal degrades rapidly. Finally, there are issues with client devices themselves, because in Wi-Fi, the devices always make the decisions about roaming. The device manufacturer, model or software version must all be considered. Beyond upgrading or changing devices, some Wi-Fi roaming issues may only be fixed by the manufacturer.
7signal is currently developing a new Wi-Fi roaming test, which would move sensor connections between APs and measure roaming delays. We see this as an important new feature, which would allow us to continuously benchmark Wi-Fi roaming performance and behavior offered by network.
However, we already have a number of powerful metrics to observe Wi-Fi roaming behavior. This data is based on automated passive captures where we calculate metrics on access point/client device interactions. The best results for roaming analysis are achieved when Eye sensors are configured to run only passive tests on one SSID for the duration of the Wi-Fi roaming troubleshooting. This allows the maximum amount of samples to be collected.
Below is a list of the important data elements and what to watch for when identifying Wi-Fi roaming issues:
High retry rates indicate poor RF connections. Identify specific device types or individual devices, which have issues. Also, observe uplink and downlink retry rates separately.
Low data rate/MCSs is another great indicator of a poor radio connection. Check for a proper radio-link balance by comparing uplink and downlink data rates. High output power from the access point only helps in the downlink direction. It does not help when the device is talking to the access point. In fact, when access point power is too high, it makes most devices think the connection is good, therefore, it does not want to roam. Individual devices and device models vary in their capabilities. So, by measuring, you can identify the devices struggling with Wi-Fi roaming issues.
Often terminals are supposed to operate on only one floor or area. If you catch a device “talking” with access points on different floors, then you likely have an RF leakage or propagation issue.
Observing the number of devices connecting to certain access points at certain times of the day also provides excellent insight. Staff meetings and other gatherings provide nice opportunities to observe roaming patterns.
The number of probe requests and responses and the balance between them also provides valuable insight into Wi-Fi roaming issues. An excessive amount of probe requests by a device may mean it is lacking the sufficient received signal levels, or is having trouble finding an access point to roam to.
Re-association frames provide direct information on roaming behavior for each device and device manufacturer. For example, you can identify the number of re-association requests and responses for different device manufacturers and individual devices. Also, re-association response codes indicate whether Wi-Fi roaming was successful or not successful.
After making these kinds of adjustments, you will gradually hear less Wi-Fi roaming complaints from users. Wi-Fi roaming issues can be tricky to resolve and even more difficult to find without data to understand how clients interact with your network.