terena networking conference 2010

Quality of VVoIPapplications in wireless networks

Evgenie Sagatov (Samara State Aerospace University)

There is an increasing demand of voice and video applications on wireless devices due to the recent developments in smart phones and tablet PCs. To cater to this demand efficiently and reliably, it is important for the application developers and service providers to characterize and tune the performance of RTP streams that deliver the content. In addition, the area of video performance measurement is in its early stages, and developing effective techniques to measure video quality is vital. In this paper, we address both the above dimensions of requirements. We show scenarios where RTP packets are duplicated and evaluate how the video player should handle these duplicated packets. We also show a novel experimental technique to identify key frames in video, and evaluate how redundancy of those key frame packets can improve video quality. A significant contribution of our work is the development of a mathematical model for estimating video quality of codecs MPEG-2 and MPEG-4 (DivX) codecs used in open-source VLC on WiFi standards compliant wireless networks. Our model development has been done with due considerations given to the handling of duplicate packets, and adding redundancy to key video frames. The video quality measurement experimental technique and research findings presented in this paper have been implemented in our Internet video broadcasting efforts at SSAU, Togliatty branch SSAU and Internet TV service. Owing to these implementations, we have observed that our Internet video broadcasting service offering has become more automated, predictable and our service has seen notably lowered operation costs.

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