Transport resources reservation in IMS frameworks: Terminal vs. PDF driven

摘要

IMS is a good candidate to become the service platform for next generation networks (NGN). Among one of its key characteristics is the ability to keep the Internet paradigm of application and transport separation while designing interfaces between the two layers. In IMS there is an interaction between the CSCFs (call session control function), SIP proxies managing the application setup, and the PDF (Policy Decision Function), controlling the transport network. Still, the terminals have to perform the transport resource allocation (activating the PDP context). In future networks, a similar behavior is possible but also another approach can be followed: the PDF is in charge of allocating the transport resources between the terminals, allowing to reinforce the network control. In this paper we analyze and compare both approaches, including by resorting to simulation.