Mobility sensitive algorithm for vertical handovers from WiMAX to WLAN

Decisions for vertical handover in heterogeneous mobile and wireless networks are very important because they impact the QoS of the mobile users and they are also dependent upon the mobility. Choosing the right radio interface at a given moment when mobile terminal has more than one available wireless or mobile network can be based on different factors like signal strength, the power of the battery, available bandwidth, price, etc. In this paper we propose and implement an algorithm which uses mobile node´s speed as a factor for vertical handover decision between WiMAX and WLAN networks. We use IEEE 802.21 for providing the algorithm. For vertical handovers certainly the most important services are real-time services, from which the voice call continuity has primary importance. Therefore, the algorithm is tested regarding the VoIP users in WiMAX-WLAN heterogeneous environment, and it shows improvements on vertical handover latency, packet loss and average throughput of the users.