Practical QoS Testing of Open Source and Commercial IMS Solution for Various Wireless Access Networks

IP multimedia subsystem (IMS) is the base for convergence of mobile and fixed networks as it offers possibilities to create open infrastructure of services based on IP protocol, which will enable simpler development of a variety of multimedia services. In this paper, we present testing of a voice call performance over various wireless networks, especially UMTS, using Open IMS Core system, and analyze the functionality of selected scenarios for voice calls, comparing the so obtained results with the performance of the commercial IMS system that provides built-in enhanced QoS and other functionalities, as well. We also analyze how coding rate affects the quality of voice calls in our test systems, presenting the measurements’ results for relevant QoS parameters and stationary scenario of the observed system. The results show that the open source solution for the IMS system, while having the QoS functionalities and the server with lower performance than those of the commercial solution, still achieves excellent performance, especially for the narrowband codec, while for the wideband speech codec, the performance remains somewhat lower than the one obtained for the commercial solution. All observed solutions exhibited good results when used for speech transmission, except the GPRS and the EDGE network when used with the wideband codec.