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The design and implementation of a quality-based handover trigger
SICS, Kista, Sweden .
SICS, Kista.
2006 (English)In: Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349, ISSN 0302-9743, Vol. 3976, 580-591 p.Article in journal (Refereed) Published
Abstract [en]

Wireless connectivity is needed to bring IP-based telephony into serious competition with the existing cellular infrastructure. However it is well known that voice quality problems can occur when used with unlicensed spectrum technologies such as the popular IEEE 802.11 standards. The cellular infrastructure could provide alternative network access should users roam out of 802.11 coverage or if heavy traffic loads are encountered in the 802.11 cell. Therefore, our goal is to design a handover mechanism to switch ongoing calls to the cellular network when the 802.11 network cannot sustain sufficient call quality. We have investigated load and coverage scenarios and designed, implemented and evaluated the performance of an 802.11 quality-based trigger for the handover of voice calls to the cellular network. We show that our predictive solution addresses the coverage problem and evaluate it within a real setting.

Place, publisher, year, edition, pages
2006. Vol. 3976, 580-591 p.
Keyword [en]
802.11-Cellular convergence, Quality prediction, VoIP
National Category
Telecommunications
Identifiers
URN: urn:nbn:se:kth:diva-14298DOI: 10.1007/11753810_49ISI: 000238114800049Scopus ID: 2-s2.0-33745884088OAI: oai:DiVA.org:kth-14298DiVA: diva2:332083
Conference
5th International IFIP-TC6 Networking Conference, Networking 2006; Coimbra; Portugal; 15 May 2006 through 19 May 2006
Note

QC 20100802

Available from: 2010-08-02 Created: 2010-08-02 Last updated: 2017-12-12Bibliographically 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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Citation style
  • apa
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  • Other locale
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Output format
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