Vertical Handover Criteria and Algorithm in IEEE802.11 and 802.16 Hybrid Networks

Next generation wireless communications will likely rely on integrated networks consisting of multiple wireless technologies. Hybrid networks based, for instance, on systems such as WiMAX and WiFi can combine their respective advantages on coverage and data rates, offering a high Quality of Service (QoS) to mobile users. In such environment, WiFi/WiMAX dual mode terminals should seamlessly switch from one network to another, in order to obtain improved performance or at least to maintain a continuous wireless connection. This paper proposes a new user centric algorithm for vertical handover, which combines a trigger to continuously maintain the connection and another one to maximize the user throughput (taking into account the link quality and the current cell load). Moreover, we detail the implementation of that algorithm in existing standard technologies like 802.11 and 802.16. We show that, compared to more classical handover approaches, our proposed algorithm raises the system capacity, thus increasing the gain that can be achieved with a WiMAX and WiFi heterogeneous deployment.