A QoE-Centric Analysis of Skype's FEC Mechanism
Date Issued
2011
Date
2011
Author(s)
Wang, Po-Jung
Abstract
The phenomenal growth of Skype in recent years has surpassed all expectations. Much of the application’s success is attributed to its FEC mechanism, which adds redundancy to the voice streams to sustain audio quality under network impairments. Adopting the quality-of-experience (QoE) approach, i.e., measuring the Mean Opinion Scores (MOS), we examine how much redundancy Skype adds to its voice streams and systematically explore the optimal level of redundancy for different network and codec settings. This study reveals that (1) Skype’s FEC control and coding mechanism, not so surprisingly, falls in the ballpark, but (2) a surprisingly significant margin we can improve to ensure consistent user satisfaction. By surveying packet loss patterns under different network types and environments, we found that most of the wireless loss pattern cannot be recover well by Skype’s FEC. A more sophisticated FEC mechanism adaptive to variety of loss pattern is required to achieve consistent user satisfaction.
Subjects
Forward Error Correction
Quality of Experience
Quality of Service
VoIP
Type
thesis
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ntu-100-R97942139-1.pdf
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