In this paper we firstly proved that Mobile IP protocols are designed for mobility but not for session continuity. In contradiction, mSCTP (mobile Stream Control Transmission Protocol) appears to be the best protocol with regard to session continuity support, however it does not support location management mechanisms, thus context-aware QoS as well as other mechanisms based on knowledge of location are hardly accommodated. On the other hand, the standardized IP Multimedia Subsystem (IMS) solution initially introduced by 3GPP adopts the policy-based QoS model to map user's subscription to a pre-defined QoS level, to apply service-based charging and to prevent Theft-of-Service. In this article we propose a new approach that integrates mSCTP into IMS networks to facilitate session continuity and to provide mechanisms for service control. It is realized by a proxy based on mSCTP (mobile Stream Control Transmission Protocol) that acts as an anchor point for soft vertical handover of mobile nodes, which have multiple physical interfaces (e.g., WLAN/UMTS). The mSCTP-based proxy also supports QoS provisioning and adaptation for the mobile nodes when moving in a heterogeneous wireless environment. Results show that the signaling cost for handover in our approach can be up to 23 times smaller than that in the conventional approach.
