Supporting “One Big AP” illusion in enterprise WLAN: An SDN-based solution

IEEE 802.11 standard leaves client to determine AP association selection and initiate AP handoff. This often leads to sub-optimal results in enterprise WLAN with a large number of users. Therefore, network operators expects the ability to dominate AP association selection and AP handoff initiation so that better AP/client association can be achieved. In addition, AP handoff procedure involves time-consuming packets exchange. Although many methods have been proposed to simplify AP handoff procedures, there is at least hundreds of milliseconds during which client's data transmission is blocked. In this paper, we proposed the abstraction of “One Big AP” in which unmodified 802.11-compliant client is tricked into believing that there is one access point with very large coverage, while the AP that sends and receives its packets has changed. To support the“One Big AP” illusion, we leveraged the emerging idea of Software-Defined Networking (SDN) to reform the architecture of enterprise WLAN. In the SDN-based architecture, we can easily realize network-controlled AP association and client-transparent AP handoff. We demonstrated the feasibility and efficiency of our solution through simulation.