![Page 1: A Framework for the Analysis of Adaptive Voice over IP Casetti, C.; De Martin, J.C.; Meo, M. Communications, 2000. ICC 2000. 2000 IEEE International Conference](https://reader036.vdocuments.us/reader036/viewer/2022062714/56649d635503460f94a45747/html5/thumbnails/1.jpg)
A Framework for the Analysis of Adaptive Voice over IP
Casetti, C.; De Martin, J.C.; Meo, M.
Communications, 2000. ICC 2000. 2000 IEEE International Conference on
![Page 2: A Framework for the Analysis of Adaptive Voice over IP Casetti, C.; De Martin, J.C.; Meo, M. Communications, 2000. ICC 2000. 2000 IEEE International Conference](https://reader036.vdocuments.us/reader036/viewer/2022062714/56649d635503460f94a45747/html5/thumbnails/2.jpg)
Outline
Introduction Network-driven end-to-end control over
variable bit-rate voice sources Analytical approach Case study Conclusions
![Page 3: A Framework for the Analysis of Adaptive Voice over IP Casetti, C.; De Martin, J.C.; Meo, M. Communications, 2000. ICC 2000. 2000 IEEE International Conference](https://reader036.vdocuments.us/reader036/viewer/2022062714/56649d635503460f94a45747/html5/thumbnails/3.jpg)
Introduction
Voice communication has received special attention and the possibility to offer telephony services.
How to best deliver voice over IP networks? Adaptive Voice over IP
– Solutions based on variable bit-rate speech coders that adapt to network conditions.
![Page 4: A Framework for the Analysis of Adaptive Voice over IP Casetti, C.; De Martin, J.C.; Meo, M. Communications, 2000. ICC 2000. 2000 IEEE International Conference](https://reader036.vdocuments.us/reader036/viewer/2022062714/56649d635503460f94a45747/html5/thumbnails/4.jpg)
Network-driven end-to-end control
The main goal of the algorithm– to reduce the load on the network when queue
build-ups occur.
![Page 5: A Framework for the Analysis of Adaptive Voice over IP Casetti, C.; De Martin, J.C.; Meo, M. Communications, 2000. ICC 2000. 2000 IEEE International Conference](https://reader036.vdocuments.us/reader036/viewer/2022062714/56649d635503460f94a45747/html5/thumbnails/5.jpg)
Network-driven end-to-end control
Variable-rate adaptive schemes for multimedia streams in the past– analyze the behavior of a buffer control mechanism. [Cox
and Crochiere]
– an end-to-end feedback control (the involvement of intermediate nodes is required) [Bially]
– based on the state of network [Bolot and Turetti]
– a sender-based packet loss rate estimation scheme [Sisalem and Schulzrinne]
– an analytical model for an end-to-end feedback control mechanism [Yin and Hluchyj]
![Page 6: A Framework for the Analysis of Adaptive Voice over IP Casetti, C.; De Martin, J.C.; Meo, M. Communications, 2000. ICC 2000. 2000 IEEE International Conference](https://reader036.vdocuments.us/reader036/viewer/2022062714/56649d635503460f94a45747/html5/thumbnails/6.jpg)
Network-driven end-to-end control
A feedback can be expressed as aggregate rate, traffic delay or loss rate at the receiver.
The effectiveness of the control is strongly related to the delay-load relation.
The rate control algorithm uses the information carried by cyclic RTCP receiver reports to let the source know the state of the on-going connection.
![Page 7: A Framework for the Analysis of Adaptive Voice over IP Casetti, C.; De Martin, J.C.; Meo, M. Communications, 2000. ICC 2000. 2000 IEEE International Conference](https://reader036.vdocuments.us/reader036/viewer/2022062714/56649d635503460f94a45747/html5/thumbnails/7.jpg)
Analytical Approach
Model of the source in isolation Model of the Network Interaction between a source and the network
![Page 8: A Framework for the Analysis of Adaptive Voice over IP Casetti, C.; De Martin, J.C.; Meo, M. Communications, 2000. ICC 2000. 2000 IEEE International Conference](https://reader036.vdocuments.us/reader036/viewer/2022062714/56649d635503460f94a45747/html5/thumbnails/8.jpg)
Analytical Approach
The basic assumptions– every source is modeled in isolation and is statistically
independent from the other sources.
– The interaction of the sources with the rest of the network is perceived through the feedback information conveyed back to each source.
– The model dynamics are determined by a number of driving stochastic processes:
• new call generation
• call termination
• source bit-rate increase
• source bit-rate decrease
![Page 9: A Framework for the Analysis of Adaptive Voice over IP Casetti, C.; De Martin, J.C.; Meo, M. Communications, 2000. ICC 2000. 2000 IEEE International Conference](https://reader036.vdocuments.us/reader036/viewer/2022062714/56649d635503460f94a45747/html5/thumbnails/9.jpg)
Model of the source in isolation
The user’s dynamics– idle– talking– silent
the end-to-end control mechanism– N different bit rates ( B1~BN )
– states: • I
• ( l , m ) where
I
t s
λ/2 λ/2μ μ
βα
![Page 10: A Framework for the Analysis of Adaptive Voice over IP Casetti, C.; De Martin, J.C.; Meo, M. Communications, 2000. ICC 2000. 2000 IEEE International Conference](https://reader036.vdocuments.us/reader036/viewer/2022062714/56649d635503460f94a45747/html5/thumbnails/10.jpg)
![Page 11: A Framework for the Analysis of Adaptive Voice over IP Casetti, C.; De Martin, J.C.; Meo, M. Communications, 2000. ICC 2000. 2000 IEEE International Conference](https://reader036.vdocuments.us/reader036/viewer/2022062714/56649d635503460f94a45747/html5/thumbnails/11.jpg)
Model of the network
The model of a network with K sources the state of the network
the state space for the network
![Page 12: A Framework for the Analysis of Adaptive Voice over IP Casetti, C.; De Martin, J.C.; Meo, M. Communications, 2000. ICC 2000. 2000 IEEE International Conference](https://reader036.vdocuments.us/reader036/viewer/2022062714/56649d635503460f94a45747/html5/thumbnails/12.jpg)
Model of the network
The probability that the network is in state n
The aggregate generated traffic T(n)
the delay experienced by the packets when the system is in state n
![Page 13: A Framework for the Analysis of Adaptive Voice over IP Casetti, C.; De Martin, J.C.; Meo, M. Communications, 2000. ICC 2000. 2000 IEEE International Conference](https://reader036.vdocuments.us/reader036/viewer/2022062714/56649d635503460f94a45747/html5/thumbnails/13.jpg)
Interaction between a source and the network
The probability that the network is operating in critical conditions
– where
The probability that the network is operating in underload conditions
– where
![Page 14: A Framework for the Analysis of Adaptive Voice over IP Casetti, C.; De Martin, J.C.; Meo, M. Communications, 2000. ICC 2000. 2000 IEEE International Conference](https://reader036.vdocuments.us/reader036/viewer/2022062714/56649d635503460f94a45747/html5/thumbnails/14.jpg)
Interaction between a source and the network
The round trip time is twice the packet delay in state n , 2*D(n)
Evaluating the reaction rate as the inverse of the reaction time, we can derive
![Page 15: A Framework for the Analysis of Adaptive Voice over IP Casetti, C.; De Martin, J.C.; Meo, M. Communications, 2000. ICC 2000. 2000 IEEE International Conference](https://reader036.vdocuments.us/reader036/viewer/2022062714/56649d635503460f94a45747/html5/thumbnails/15.jpg)
Case study
Three bit-rates– 8 kb/s (e.g., ITU-T G.729)– 13 kb/s (e.g., ETSI GSM-EFR)– 64kb/s (e.g., ITU-T G.711)
Pb : the probability of being in one of the states where the system is losing packets
where
![Page 16: A Framework for the Analysis of Adaptive Voice over IP Casetti, C.; De Martin, J.C.; Meo, M. Communications, 2000. ICC 2000. 2000 IEEE International Conference](https://reader036.vdocuments.us/reader036/viewer/2022062714/56649d635503460f94a45747/html5/thumbnails/16.jpg)
Case study
![Page 17: A Framework for the Analysis of Adaptive Voice over IP Casetti, C.; De Martin, J.C.; Meo, M. Communications, 2000. ICC 2000. 2000 IEEE International Conference](https://reader036.vdocuments.us/reader036/viewer/2022062714/56649d635503460f94a45747/html5/thumbnails/17.jpg)
Case study
![Page 18: A Framework for the Analysis of Adaptive Voice over IP Casetti, C.; De Martin, J.C.; Meo, M. Communications, 2000. ICC 2000. 2000 IEEE International Conference](https://reader036.vdocuments.us/reader036/viewer/2022062714/56649d635503460f94a45747/html5/thumbnails/18.jpg)
Case study
![Page 19: A Framework for the Analysis of Adaptive Voice over IP Casetti, C.; De Martin, J.C.; Meo, M. Communications, 2000. ICC 2000. 2000 IEEE International Conference](https://reader036.vdocuments.us/reader036/viewer/2022062714/56649d635503460f94a45747/html5/thumbnails/19.jpg)
Case study
![Page 20: A Framework for the Analysis of Adaptive Voice over IP Casetti, C.; De Martin, J.C.; Meo, M. Communications, 2000. ICC 2000. 2000 IEEE International Conference](https://reader036.vdocuments.us/reader036/viewer/2022062714/56649d635503460f94a45747/html5/thumbnails/20.jpg)
Case study
![Page 21: A Framework for the Analysis of Adaptive Voice over IP Casetti, C.; De Martin, J.C.; Meo, M. Communications, 2000. ICC 2000. 2000 IEEE International Conference](https://reader036.vdocuments.us/reader036/viewer/2022062714/56649d635503460f94a45747/html5/thumbnails/21.jpg)
Conclusions
We propose a framework for the analysis of adaptive, variable bit-rate sources operating in a packet network environment.
It can be useful in the preliminary phases of study of complex systems, for comparisons between different control algorithms of for tuning the parameters of the algorithm.