A Vertical Handoff decision scheme for end-to-end QoS in heterogeneous networks: An implementation on a mobile IP testbed

A prominent function of a mobile host is seamless Vertical Handoff (VHO) that ensures application service continuity and quality. VHO decision algorithms that have been proposed in the literature consider parameters such as wireless channel quality (RSSI), cost, channel load, and available bandwidth. The mobile node runs the VHO algorithm autonomously and makes the decision. We highlight the fact that such a local decision can potentially result in a poor end-to-end application level QoS. We present a VHO scheme that takes into account end-to-end QoS as one of the key parameters in addition to other common parameters. We propose an architecture involving an external host based light-weight server (Access Link Utilization Monitor) that disseminates the available end-to-end bandwidth to the mobile node to assist it in making a decision to maintain end-to-end service quality. We describe a fuzzy logic based algorithm that has been used in the handoff decision. We present the results of our implementation on a mobile IP testbed under different realistic scenarios, that include WLAN, WiMAX and 3G access technologies to demonstrate the efficacy of the proposed scheme.