User-level Performance Evaluation of VoIP Using ns-2

Abstract

Voice over IP (VoIP) is gaining an ever increasing popularity. As such, it nowadays represents one of the most studied test applications in the performance evaluation of wireline and wireless networks. However, a sound performance analysis of VoIP communications should be carried out at the user level, by computing perceptive metrics like the Mean Opinion Score (MOS) or the E-Model. In this paper, we present enhancements to the popular Network Simulator 2 (ns-2) that allow a reliable VoIP user-level performance analysis to be carried out through simulation. We show that computing performance measures at the IP level, which is usually done in ns-2, often leads to inaccurate results. Our code is publicly available at http://info.iet.unipi.it/~cng/ns2voip/.