An experimental framework for vertical hand-over to guarantee session continuity in heterogeneous wireless environments

Mobile handsets have evolved a lot the last years and support numerous wireless interfaces for attaching to heterogeneous co-existing wireless networks. This raises new challenges and proposed solutions appear in the literature, which are listed in this work. The main focus is an extensible and robust system/framework that enables experimentation in such an environment. First seamless connectivity from the roaming on heterogeneous networks was achieved and tested using VPN tunnels. Then the system components for both network and terminal sides are presented, which provide multiple management and operation options in order to be adjustable to virtually any scenario. Additionally, a standalone and also extensible decision making framework was designed and implemented. MultiAttribute Decision Making (MADM) methods and algorithms are used to select the preferred access network for the Mobile Nodes. Finally two set of experiments performed: (1) to validate the correct operation of the system in real-life scenarios and (2) to explore the performance of the handover technique used in this system. In both of the above sets, experiments were successive, proving the feasibility of the solutions proposed and the applicability of the proposed framework to any testbed environment.