A fast handoff scheme for ieee 802.11 networks using software defined networking

Due to the limited coverage range of access points (APs) and the mobility of stations (STAs), handoff occurs frequently in IEEE 802.11 wireless local area network (WLAN). However, traditional handoff mechanisms employed at STAs have inherent defects which make it hard to realize seamless handoff, it is a challenging issue for supporting seamless handoff service in WLAN. Extensions to Software Defined Networking (SDN) framework for WLAN could provide new solutions to address this issue. In this paper, we propose a pre-scan based fast handoff scheme for SDN based WLAN system. The proposed scheme can help STA obtain the best alternative AP in advance after the pre-scan process, and when the handoff is actually triggered, STA can perform the authentication and reassociation process toward the alternative AP directly. Moreover, we adopt Kalman filter to minimize the fluctuation of received signal strength (RSS), thus reducing the unnecessary pre-scan processes and handoffs. Simulation results show that the proposed scheme can effectively reduce the handoff delay.