中央研究院  |  資訊科學研究所  |  多媒體網路與系統實驗室
Tuning the Redundancy Control Algorithm of Skype for User Satisfaction
(NOTE: Sheng-Wei Chen is also known as Kuan-Ta Chen.)

Abstract
Determining how to transport delay-sensitive voice data has long been a problem in multimedia networking. The difficulty arises because voice and best-effort data are different by nature. It would not be fair to give priority to voice traffic and starve its best-effort counterpart; however, the voice data delivered might not be perceptible if each voice call is limited to the rate of an average TCP flow. To address the problem, we approach it from a user-centric perspective by tuning the voice data rate based on user satisfaction.<p> Our contribution in this work is threefold. First, <b>we investigate how Skype, the largest and fastest growing VoIP service on the Internet, adapts its voice data rate (i.e., the redundancy ratio) to network conditions</b>. Second, by exploiting implementations of public domain codecs, <b>we discover that Skype's mechanism is not really geared to user satisfaction</b>. Third, based on a set of systematic experiments that quantify user satisfaction under different levels of packet loss and burstiness, <b>we derive a concise model that allows user-centric redundancy control</b>. The model can be easily incorporated into general VoIP services (not only Skype) to ensure consistent user satisfaction.<p> <font color="red"><i>Related paper: </i></font><br> - <a href="http://mmnet.iis.sinica.edu.tw/publication_detail.html?key=wu09_playout">An Empirical Evaluation of VoIP Playout Buffer Dimensioning in Skype Google Talk and MSN Messenger</a><br> - <a href="http://mmnet.iis.sinica.edu.tw/publication_detail.html?key=chen06_skype">Quantifying Skype User Satisfaction</a>

Materials
Citation
Te-Yuan Huang, Kuan-Ta Chen and Polly Huang, "Tuning the Redundancy Control Algorithm of Skype for User Satisfaction," In Proceedings of IEEE INFOCOM 2009, 2009.

BibTex
@INPROCEEDINGS{huang09:skype,
  TITLE      = {Tuning the Redundancy Control Algorithm of {Skype} for User Satisfaction},
  AUTHOR     = {Te-Yuan Huang and Kuan-Ta Chen and Polly Huang},
  BOOKTITLE  = {Proceedings of IEEE INFOCOM 2009},
  YEAR       = {2009}
}