End-to-end performance of the IP multimedia subsystem over various wireless networks

The IP Multimedia Subsystem (IMS) as an overlay architecture for IP based core networks is the target of many trials with mobile and fixed network operators these days since it promises to enable fixed mobile convergence. The Open IMS Core project of the Fraunhofer Institute for Open Communication Systems (FOKUS) is based upon Open-Source software and offers the core network functionality of an IMS, while being fully conformant on the signaling plane to existing IMS standards. In its setup, the Open IMS Core resembles future IMS networks at the needed detail level and allows to produce first IMS performance results. This paper will present the performance results of the signaling plane based upon the Open IMS Core in the most common usage of an IMS network -a voice call - when the clients are communicating over different wireless technologies like Wireless LAN 802.11b and 802.11g, 3G CDMA (UMTS) and GPRS. From the results we will draw orientative conclusions whether eac h of those technologies is suitable to sustain an IMS network on top.