A Seamless Handoff Mechanism for IEEE 802.11 WLANs Supporting IEEE 802.11i Security Enhancements

IEEE 802.11 wireless networks have gained great popularity. However, handoff is always a critical issue in this area. In this paper, we propose a novel seamless handoff mechanism for IEEE 802.11 wireless networks which support IEEE 802.11i security standard. Our approach consists of a Dynamic Tunnel Establishing procedure and a seamless handoff mechanism. Dynamic Tunnel Establishing is for each AP to construct trusted tunnels with its neighbor APs. In the seamless handoff method, the roaming mobile station (MS) is allowed to access the Internet via its previous AP by the tunnel between the new AP and the previous one during handoff. By our proposed approach, the continuous network connectivity and secure wireless communications of mobile users are guaranteed. In addition, no modifications are required to the standard authentication and encryption methods. Index Terms — dynamic tunnel, IEEE 802.11i, seamless handoff, wireless network.