DiMob: Scalable and seamless mobility in SDN managed wireless networks

Wi-Fi network roaming is the act of moving a wireless device from one Wi-Fi access point (AP) to another Wi-Fi AP. In urban environments, where APs are densely deployed, users would greatly benefit from roaming between these APs. Standards for Wi-Fi-network roaming have been developed (e.g. IEEE 802.11r), but are rarely implemented. The absence of a widely used standard leads to device-dependent roaming mechanisms, which brings numerous disadvantages. 5G-EmPOWER is an example of a framework that brings the Software-Defined Networking (SDN) paradigm to wireless networks. The framework solves the problem of network roaming by allowing users to connect to their own unique virtual AP and managing their connection to the WAN behind the scenes. This allows the 5G-EmPOWER controller to seamlessly handover users from one physical AP to another. Currently, a single physical controller manages the 5G-EmPOWER control plane. The use of a single system over a distributed system has known disadvantages (e.g. greater cost, single point of failure). In this paper, we present DiMob, which distributes the SDN control plane among multiple controllers. We show that DiMob maintains a seamless handover, while offering the advantages of a distributed system. We demonstrate, for example, that adding an additional node can save approximately 30 % in CPU usage for each controller.