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Modelling the arrival process for packet audio
(CNA Lab, SICS, Sweden)
Uppsala Universitet.
2003 (English)In: QUALITY OF SERVICE IN MULTISERVICE IP NETWORKS, PROCEEDINGS, 2003, Vol. 2601, 35-49 p.Conference paper, Published paper (Refereed)
Abstract [en]

Packets in an audio stream can be distorted relative to one another during the traversal of a packet switched network. This distortion can be mainly attributed to queues in routers between the source and the destination. The queues can consist of packets either from our own flow, or from other flows. The contribution of this work is a Markov model for the time delay variation of packet audio in this scenario. Our model is extensible, and show this by including sender silence suppression and packet loss into the model. By comparing the model to wide area traffic traces we show the possibility to generate an audio arrival process similar to those created by real conditions. This is done by comparing the probability density functions of our model to the real captured data.

Place, publisher, year, edition, pages
2003. Vol. 2601, 35-49 p.
Series
LECTURE NOTES IN COMPUTER SCIENCE, ISSN 0302-9743
Keyword [en]
packet delay, WIP, Markov chain, steady state
National Category
Computer Sciences
Identifiers
URN: urn:nbn:se:kth:diva-14294ISI: 000182655700003ISBN: 3-540-00604-4 (print)OAI: oai:DiVA.org:kth-14294DiVA: diva2:332074
Note
QC 20100802Available from: 2010-08-02 Created: 2010-08-02 Last updated: 2018-01-12Bibliographically approved
In thesis
1. Quality aspects of internet telephony
Open this publication in new window or tab >>Quality aspects of internet telephony
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Internet telephony has had a tremendous impact on how people communicate.Many now maintain contact using some form of Internet telephony.Therefore the motivation for this work has been to address the quality aspectsof real-world Internet telephony for both fixed and wireless telecommunication.The focus has been on the quality aspects of voice communication,since poor quality leads often to user dissatisfaction. The scope of the workhas been broad in order to address the main factors within IP-based voicecommunication.

The first four chapters of this dissertation constitute the backgroundmaterial. The first chapter outlines where Internet telephony is deployedtoday. It also motivates the topics and techniques used in this research.The second chapter provides the background on Internet telephony includingsignalling, speech coding and voice Internetworking. The third chapterfocuses solely on quality measures for packetised voice systems and finallythe fourth chapter is devoted to the history of voice research.

The appendix of this dissertation constitutes the research contributions.It includes an examination of the access network, focusing on how calls are multiplexed in wired and wireless systems. Subsequently in the wireless case, we consider how to handover calls from 802.11 networks to the cellularinfrastructure. We then consider the Internet backbone where most of ourwork is devoted to measurements specifically for Internet telephony. The applications of these measurements have been estimating telephony arrival processes, measuring call quality, and quantifying the trend in Internet telephony quality over several years. We also consider the end systems, since they are responsible for reconstructing a voice stream given loss and delay constraints. Finally we estimate voice quality using the ITU proposal PESQ and the packet loss process.

The main contribution of this work is a systematic examination of Internet telephony. We describe several methods to enable adaptable solutions for maintaining consistent voice quality. We have also found that relatively small technical changes can lead to substantial user quality improvements.A second contribution of this work is a suite of software tools designed to a certain voice quality in IP networks. Some of these tools are in use within commercial systems today.

Place, publisher, year, edition, pages
Stockholm: KTH, 2009. 89 p.
Series
Trita-EE, ISSN 1653-5146 ; 2009:025
Series
SICS Dissertaion Series, ISSN 1101-1335 ; 51
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-10572 (URN)978-91-7415-313-2 (ISBN)
Public defence
2009-06-05, sal D2, Stockholm, 14:00 (English)
Opponent
Supervisors
Note
QC 20100802Available from: 2009-05-27 Created: 2009-05-27 Last updated: 2013-09-09Bibliographically approved

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CiteExportLink to record
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Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
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More styles
Language
  • de-DE
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Output format
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