Access network controlled fast handoff for streaming multimedia in WLAN

The focus of the research presented in this paper was to develop a novel way to support voice over IP (VoIP) and streaming video applications on mobile devices over a 802.11 access network Fast handoff in a wireless local area network (WLAN) environment has been the research topic of many previous studies, the majority of which described ways to optimize the three main 802.11 handoff phases -scanning, authentication, and reassociation. In this paper however we propose a fast handoff scheme that skips all mentioned phases. Instead, the handoff is controlled and prepared by the access network and is triggered by sending a hop request message to the mobile station (STA). At the STA the three phases are reduced to a single frequency change phase. The proposed solution extends the standard 802.11 scheme; if the extension is not available at the access network or the STA, the devices will fall back on the standard handoff procedure. Because the access network fully controls the handoff process and actively invokes the frequency change on the STA, we can guarantee a minimal duration of the time the STA stays disconnected.