A framework to improve QoS and mobility management for multimedia applications in the IMS

The new IP multimedia subsystem (IMS) provides an overlay architecture for IP based core networks and enables the efficient provision of an open set of potentially highly integrated multimedia services (i.e. instant messaging, video conferencing, VoIP, application sharing, etc) on top of possibly different access technologies. However, there will be different domains and IMSs managed by different ISPs (Internet service providers) in the Internet. Each ISP has an SLA (service level agreement) established between its users, which defines what kind of resources and prices was agreed to be offered to each user. However there is no SLA between a visited domain and a mobile user. This paper analyses how to extend the QoS capabilities of the IMS offered to a mobile terminal when it roams among different domains. We propose a framework that integrates QoS and mobility management. This integration envisages the improvement of the overall end-to-end performance and the reduction of management entities in the network. The architecture presents the domain policy manager (DPM) as the decision-making and controller of a domain. The proposed architecture uses policies with inter-domain negotiation. An application scenario to show the framework functionality is described as well as the current status of the implementation.