QoS architecture in IP multimedia subsystem of UMTS

IMS is the evolution of the UMTS toward an All-IP network supporting IP-based multimedia services, like VoIP, conferencing, push-to-talk or mobile gaming. As new services require high restrictions in network parameters, the support for QoS in necessary. The aim of this paper is to present the policy based architecture in IP multimedia subsystem of UMTS, its components and their interactions.