When client devices roam from one AP to another, they always need to go through an authentication process with the new AP. When AP’s act independently, the process of establishing an authentication takes place every time the client device roams.
For instance, an end user’s smartphone is connected to the airport’s WiFi – where dozens of AP’s coexist in the same network. If the end-user is on the move, without the inclusion of standards 802.11r/k, the smartphone disconnects from the existing AP before establishing a connection with the new one.
As a result, the end-user experiences WiFi disconnection and latency while trying to reconnect to a new access point. It translates into dropped WiFi-based calls, websites loading slowly, difficulties in uploading images on social networks, and other negative performance.