When client devices roam between APs to gain the best performance, they are indirectly helping the capacity of the whole Wi-Fi network. However, if AP power levels and antennas are not arranged properly, then roaming does not work properly. As we saw previously, a strong signal from an AP prevents a client device from roaming to another, possibly nearer AP, which could offer a better Wi-Fi service and so deliver better performance.

The diagram below shows the result of some client roaming tests, where problems with AP power levels and antennas prevent roaming.

The paths taken for the roaming tests are shown as arrows, and the AP to which the client is associated is shown with a colour code.

Some anomalies were not expected, but are immediately obvious from the roaming tests:

• There is a strong dependence of the client on the Red AP (HGE-R2) even when the client is at the opposite side of the building,
• There is a strong dependence of the client on the Mauve AP (HGW-R4), again even when the client is at the opposite side of the building.
• When the client is in a corridor, it only associates to the Yellow AP (JH-R3), in another room.

There are reasons for all of this behaviour, and they need to be understood, so that the Wi-Fi design, its installation and its configuration can be set up properly for the Wi-Fi to perform properly, particularly when it is under a heavy load. When we do a proper Wi-Fi design, using an AP-on-a-Stick, our multiple APs allow us to test the roaming performance of the design in-situ.