Analysis of Delay and Jitter of Voice Traffic Over the Internet Mansour J. Karam, Fouad A. Tobagi IEEE INFOCOM 2001

The Queuing Model of Voice Traffic in a Packet Network The queuing model of voice traffic in a packet network is or M / D / 1

Voice Traffic Characteristics and Requirements Maximum tolerable round-trip delay :200-300 ms If packet loss were to occur, the number of contiguous packets which are lost is usually larger than one (clip). Clips exceeding 60 ms affect the intelligibility of the received speech.

End-to-end Delay Components for Voice Traffic

Various Delay for G.711, G.729A and G.723.1

End-to-end Delay Expression D : end-to-end delay Tf : formation delay l : lookahead Th : transmission delay Qh : queuing delay Ph : propagation delay Dplay : playout buffer delay

End-to-end Delay Expression (continued) Assuming Qmax represents the maximum queuing delay percentile incurred in the network,

General Network Topology

Model for Queuing Delay in The Network

Voice Sharing the Link with Other Traffic For a given hop, :time interval before admittance. :time interval after transmission. : perturbation introduced by lower priority packets over the hop, ranged from 0 to Tp, uniformly distributed.

Voice Sharing the Link with Other Traffic (continued) Distribution of : A triangular. As N increasing, total perturbation is normally distributed. End-to-end inter-arrival time is also normally distributed with mean Tf and standard deviation

Voice Sharing the Link with Other Traffic (continued)

Number of Hops and Link Utilization

Number of Hops and Link Utilization (continued)

Available Bandwidth

Choice of Packetization Scheme

Choice of Packetization Scheme

Conclusion In this paper, the author verified: Effect of the residual transmission time of non-voice delay Importance of bandwidth to reduce the percentile Effect of packet size on voice delay and bandwidth utilization