A New Seamless Method to Support CDMA2000/WLAN Vertical Handover

This paper proposes a new protocol, Access Routers Tunneling Protocol, to facilitate seamless vertical handoff between wireless LAN and CDMA2000 access networks. A novel approach called seamless vertical handover for mobile IPv6 (SVHO) is defined to allow a mobile node to resume its real-time ongoing session with its correspondent as soon as it attaches to the new link. Traffic in progress will be redirected to the new network using mobile user´s previous care-of-address through preconfigured bidirectional tunnels. By this means, the service disruption for an ongoing real-time session could be minimized. Moreover, since the context information for the session in progress run by the mobile is kept intact at the previous access router, the delay variation (jitter) is reduced significantly during handoff. To provide certain quality of service to roaming users, new functionalities are added at access router so that it can perform not only local resource management but also call admission control as the mobile moves between subnets. To evaluate the performance, the components of handover latency are identified to demonstrate the effectiveness of our approach. Numerical results show that our new method has better performance than the brute-force handoff, the seamless handoff and the optimized seamless handoff scheme existing in the literature