Improving Network-Assisted Roaming for Controller-Less Wi-Fi

Large Wi-Fi installations may make use of Wi-Fi controllers managing client mobility and different Virtual Local Area Networks (VLANs). However, as they might form a bottleneck, controller-less solutions are on the rise, e.g., cloud-managed solutions or mesh networks. IEEE 802.11 defines a framework for providing roaming assistance through neighbor reports and transition requests (IEEE 802.11k and IEEE 802.11v), but leaves generating meaningful candidates included in these frames open to the implementor. Without central controllers, deriving these candidates for Stations (STAs) is much more difficult. Access Points (APs) with more autonomy need to know other APs located in their proximity to provide roaming assistance for STAs. In this paper, we design and evaluate a network-assisted roaming architecture for controller-less Wi-Fi networks. APs learn roaming events in their vicinity and steer STAs by means of refined, yet standard-compliant neighbor reports and transition requests to better suited APs. Our results using a real-system prototype indicate a noticeable decrease of roaming times when comparing various reference approaches to our proposal.