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The design and implementation of a quality-based handover trigger
SICS, Kista, Sweden .
SICS, Kista.
2006 (engelsk)Inngår i: Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349, ISSN 0302-9743, Vol. 3976, s. 580-591Artikkel i tidsskrift (Fagfellevurdert) 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.

sted, utgiver, år, opplag, sider
2006. Vol. 3976, s. 580-591
Emneord [en]
802.11-Cellular convergence, Quality prediction, VoIP
HSV kategori
Identifikatorer
URN: urn:nbn:se:kth:diva-14298DOI: 10.1007/11753810_49ISI: 000238114800049Scopus ID: 2-s2.0-33745884088OAI: oai:DiVA.org:kth-14298DiVA, id: diva2:332083
Konferanse
5th International IFIP-TC6 Networking Conference, Networking 2006; Coimbra; Portugal; 15 May 2006 through 19 May 2006
Merknad

QC 20100802

Tilgjengelig fra: 2010-08-02 Laget: 2010-08-02 Sist oppdatert: 2017-12-12bibliografisk kontrollert
Inngår i avhandling
1. Quality aspects of internet telephony
Åpne denne publikasjonen i ny fane eller vindu >>Quality aspects of internet telephony
2009 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
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.

sted, utgiver, år, opplag, sider
Stockholm: KTH, 2009. s. 89
Serie
TRITA-EE, ISSN 1653-5146 ; 2009:025
Serie
SICS Dissertation Series ; 51
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-10572 (URN)978-91-7415-313-2 (ISBN)
Disputas
2009-06-05, sal D2, Stockholm, 14:00 (engelsk)
Opponent
Veileder
Merknad

QC 20100802

Tilgjengelig fra: 2009-05-27 Laget: 2009-05-27 Sist oppdatert: 2019-08-30bibliografisk kontrollert

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