NGN functional architecture for resource allocation and admission control

A technical prerequisite for a converged network is a common service delivery platform that is independent from the access networks below. The 3GPP SIP-based IP Multimedia Subsystem (IMS) is defined for this purpose. By specification, IMS is the first implementation towards reaching converged communications which allows users to communicate with video, audio and multimedia content, via any fixed, mobile and wireless access network type, with controllable QoS. This article analyzes the mechanisms of resource allocation and admission control by employing logical interfaces that carry SIP messages.