Halogenated Organic Compounds - A Global Perspective

Abstract

The quality perceived by the user, a concept known as Quality of user Experience (QoE), is gaining momentum. Together with the efforts of providing appropriate architectures able to deliver the expected level of Quality of Service (QoS), users' perception of the level of quality could play a key role in making a VoIP multimedia application to succeed or to fail. QoE can be measured from different approaches; subjective ones are based on polls while objective ones are mainly based on QoS network performance parameters. Although a subjective evaluation could be costly and time consuming, it gives the most accurate results. Moreover, wireless environments incorporate new challenges in terms of QoS and QoE because of inherent wireless communication characteristics. In this way, our contribution is twofold. First, we carry out a subjective QoE assessment for VoIP applications in a real wireless environment. Skype, Gizmo5, ooVoo, and Damaka are the selected VoIP applications under study. Next, we contrast QoE results with QoS evaluation from the captured video calls made during the poll. Results show that there is no precise match on both assessments, because of QoE parameters that cannot be inferred from QoS analysis, because of the different effect of some QoS parameters which prevail, or even because of the popularity of the VoIP application. © Springer Science+Business Media, LLC 2010.