Queueing Analysis of Simple FEC Schemes for IP Telephony

Abstract : In interactive voice applications, FEC schemes are necessary for the recovery from lost packets. These schemes need to be simple with a light coding and decoding overhead so as not to impact the interactivity. The objective of this paper is to study a well known simple FEC scheme that has been proposed and implemented, in which for every packet $n$, some redundant information is added to some subsequent packet $n + \phi$. If packet $n$ is lost, it will be reconstructed in case packet $n+\phi$ is well received. The quality of the reconstructed copy of packet $n$ will depend on the amount of information of packet $n$ carried by packet $n+\phi$. We propose a detailed queueing analysis based on a ballot theorem, and obtain simple expressions for the audio quality as a function of the amount of redundancy and its relative position with respect to the original information. For a utility function that is linear in the amount of information, the analysis shows that this FEC scheme does not scale well and any amount of added redundancy might cause a degradation in the overall quality. We then introduce and analyze other utility functions in order to obtain a quality function that is better adapted to the characteristics of this kind of applications.
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[Research Report] RR-3998, INRIA. 2000, pp.34
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Soumis le : mercredi 24 mai 2006 - 10:29:38
Dernière modification le : samedi 27 janvier 2018 - 01:31:06
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  • HAL Id : inria-00072647, version 1



Eitan Altman, Chadi Barakat, Victor Manuel Ramos Ramos. Queueing Analysis of Simple FEC Schemes for IP Telephony. [Research Report] RR-3998, INRIA. 2000, pp.34. 〈inria-00072647〉



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