Today, the computation power and storage capability on mobile devices are increasing rapidly, and together with new interactive services this creates a demand for more bandwidth. To keep track of this evolution, the use of heterogeneous networks has gained focus. Instead of only using one type of network, it is desired to utilize all carriers available on a device, and hence choose the one best suited.
This thesis describes and discusses different approaches to session continuity. The different solutions include Mobile IP, Generic Access Networks (GAN), and proposals based on the Session Initiation Protocol (SIP). Current solutions are not satisfactory in the terms of handover delay, and hence best suited for non-realtime applications.
Furthermore it is proposed an application-layer handover scheme for session continuity in heterogeneous networks, which will significantly reduce the handover time. This handover scheme has been implemented, and tests show that the handover time is significantly reduced.
Keywords: Session Continuity, Handover, Heterogeneous Networks, SIP, VoIP, GAN.