| 1. |
- Ciszkowski, Tomasz, et al.
(författare)
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Towards Quality of Experience-based Reputation Models for Future Web Service Provisioning
- 2009
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Konferensbidrag (refereegranskat)abstract
- This paper concerns the applicability of reputations systems for assessing Quality of Experience (QoE) for web services in Future Internet. Reputation systems provide mechanisms to manage subjective opinions in societies and yield general scoring of a particular behavior. Thus, they are likely to become an important ingredient of Future Internet. Parameters being under evaluation by reputation system may vary greatly and, particularly, may be chosen to assess the users’ satisfaction with (composite) web services. Currently, this satisfaction is usually expressed with QoE, which represents subjective users’ opinions. The goal is to predict users’ satisfaction based on reputation values. This may be beneficial for service providers in terms of checking the fulfillment of SLAs, for retaining QoE on the satisfaction level for other users sharing the same network or service resources, and for providing the users with indications which resource to choose in order to maximize its experience.
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| 2. |
- Ciszkowski, Tomasz, et al.
(författare)
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Towards Quality of Experience-based reputation models for future web service provisioning
- 2012
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Ingår i: Telecommunications Systems. - : Springer. - 1018-4864 .- 1572-9451. ; 51:4, s. 283-295
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Tidskriftsartikel (refereegranskat)abstract
- This paper concerns the applicability of reputations systems for assessing Quality of Experience (QoE) for web services in Future Internet. Reputation systems provide mechanisms to manage subjective opinions in societies and yield a general scoring of a particular behavior. Thus, they are likely to become an important ingredient of Future Internet. Parameters being under evaluation by a reputation system may vary greatly and, particularly, may be chosen to assess the users’ satisfaction with (composite) web services. Currently, this satisfaction is usually expressed by QoE, which represents subjective users’ opinions. The goal of this paper it to present a novel framework of web services where a reputation system is incorporated for users satisfaction tracking and prediction. This approach is a beneficial tool, which enables providers to facilitate service adaptation according to users’ expectations and maintain QoE on a satisfying level. Presented reputation system operates in an environment of composite services running on a client and server side. It makes this approach highly suitable for effective QoE differentiating and maximizing user experience for specific customer profiles even the service and network resources are shared.
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| 3. |
- Dán, György, et al.
(författare)
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Interaction Patterns between P2P Content Distribution Systems and ISPs
- 2011
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Ingår i: IEEE Communications Magazine. - 0163-6804 .- 1558-1896. ; 49:5, s. 222-230
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Tidskriftsartikel (refereegranskat)abstract
- Peer-to-peer (P2P) content distribution systems are a major source of traffic in the Internet, but the application layer protocols they use are mostly unaware of the underlying network in accordance with the layered structure of the Internet's protocol stack. Nevertheless, the need for improved network efficiency and the business interests of Internet service providers (ISPs) are both strong drivers toward a cross-layer approach in peer-to-peer protocol design, calling for P2P systems that would in some way interact with the ISPs. Recent research shows that the interaction, which can rely on information provided by both parties, can be mutually beneficial. In this article we first give an overview of the kinds of information that could potentially be exchanged between the P2P systems and the ISPs, and discuss their usefulness and the ease of obtaining and exchanging them. We also present a classification of the possible approaches for interaction based on the level of involvement of the ISPs and the P2P systems, and we discuss the potential strengths and the weaknesses of these approaches.
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| 4. |
- Egger, Sebastian, et al.
(författare)
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Waiting times in quality of experience for web based services
- 2012
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Konferensbidrag (refereegranskat)abstract
- A considerable share of applications such as web or e-mail browsing, online picture viewing and file downloads imply waiting times for their users, which is due to the turn-taking of information requests by the user and correspoding response times until each request is fulfilled. Thus, end-user quality perception in the context of interactive data services is dominated by waiting times; the longer the latter, the less satisfied the user becomes. As opposed to heavily researched multimedia experience, perception of waiting times is still not strongly explored in the context of Quality of Experience (QoE). This tutorial will contribute to closing this gap. In its first part, it addresses perception principles and discusses their applicability towards fundamental relationships between waiting times and resulting QoE. It then investigates to which extent the same relationships can also be used to describe QoE for more complex services such as web browsing. Finally, it discusses applications where waiting times determine QoE, amongst other factors. For example, the past shift from UDP media streaming to TCP media streaming (e.g. youtube.com) has extended the relevance of waiting times also to the domain of online video services. In particular, user-perceived quality suffers from initial delays when applications are launched, as well as from freezes during the delivery of the stream. These aspects, which have to be traded against each other to some extent, will be discussed mainly for HTTP video streaming in the last part of this tutorial.
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| 5. |
- Fiedler, Markus, et al.
(författare)
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A generic quantitative relationship between Quality of Experience and Quality of Service
- 2010
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Ingår i: IEEE Network. - : IEEE. - 0890-8044 .- 1558-156X. ; 24:2, s. 36-41
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Tidskriftsartikel (refereegranskat)abstract
- Quality of Experience (QoE) ties together user perception, experience and expectations to application and network performance, typically expressed by Quality of Service (QoS) parameters. Quantitative relationships between QoE and QoS are required in order to be able to build effective QoE control mechanisms onto measurable QoS parameters. On this background, this paper proposes a generic formula in which QoE and QoS parameters are connected through an exponential relationship, called IQX hypothesis. The formula relates changes of QoE with respect to QoS to the current level of QoE, is simple to match, and its limit behaviours are straighforward to interpret. It validates the IQX hypothesis for streaming services, where QoE in terms of Mean Opinion Scores (MOS) is expressed as functions of loss and reordering ratio, the latter of which is caused by jitter. For web surfing as the second application area, matchings provided by the IQX hypothesis are shown to outperform previously published logarithmic functions. We conclude that the IQX hypothesis is a strong candidate to be taken into account when deriving relationships between QoE and QoS parameters.
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| 6. |
- Fiedler, Markus, et al.
(författare)
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A natural relation between user-perceived quality and network-level perturbations
- 2006
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Extended abstract with formulae. Excerpts as follows: During the recent years, networked applications and services on top of Internet such as e-business, voice communication and media distribution and have become popular. This development has entailed a growth of interest in end-user-perceived Quality of Service (QoS). The recently proposed Quality of Experience (QoE) concept includes both end-to-end network-level Quality of Service (QoS) and user satisfaction with the service. Besides of factors such as network coverage, service offers and level of support, even subjective factors such as user experience and perception need to be taken into account. A major challenge, however, consists in quantifying losses of QoE from the users’ points of view. As far as network problems are the reason for perceived quality problems, it is worthwhile to have formulae at hand that reflect the impact of perturbations on user perception. They might be used to quantify depreciations of user perception based on comparably simple-to-measure network-level parameters. In this contribution, we propose an exponential relation between user perception and perturbations on network level, which looks like a natural law.
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| 7. |
- Fiedler, Markus, et al.
(författare)
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Quality of Experience-related differential equations and provisioning-delivery hysteresis
- 2010
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Konferensbidrag (refereegranskat)abstract
- Churn of revenue-generating and dissatisfied users has become a major point of concern for service providers and network operators. As services rely on interconnecting networks, service performance and thus user satisfaction depend on network performance. Consequently, it is of utmost importance to understand the relationships between user perception, captured by quantitative Quality of Experience (QoE) parameters, and network performance, described by Quality of Service (QoS) parameters. This paper provides insights into fundamental relationships between QoE and QoS, formulated as partial differential equations describing changes in QoE with respect to specific QoS parameters. A set of illustrating examples from the literature is given. Furthermore, the different impacts of provisioning and degree of success or failure of delivery on QoE are discussed, leading to the QoE provisioning-delivery hysteresis. This hysteresis provides a striking motivation for employing elastic adaptation mechanisms to available resources instead of suffering from uncontrolled data loss.
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| 8. |
- Fiedler, Markus, et al.
(författare)
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The Network of Excellence Euro-NF and its Specific Joint Research Projects
- 2011
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Ingår i: ICaST: ICST's Global Community Magazine (online). - : Institute for Computer Sciences, Social Informatics and Telecommunications Engineering (ICST).
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Tidskriftsartikel (refereegranskat)abstract
- This article presents the European FP7 Network of Excellence “Euro- NF” (Networks of the Future) and reviews its set of activities. Specific attention is paid to the concept of Specific Joint Research Projects (SJRP), a series of small but focused projects, integrating at least three Euro-NF partners and targeting joint seminal work, publications as well as full-size follow-up projects. Further to the description of the SJRP concept, a set of three selected SJRP from different areas are presented in detail with respect to motivation, goal, contents, results, and impact.
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| 9. |
- Hossfeld, Tobias, et al.
(författare)
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Initial delay vs. interruptions : Between the devil and the deep blue sea
- 2012
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Konferensbidrag (refereegranskat)abstract
- End user quality perception in the context of Internet applications is often characterized by waiting times before service consumption as well as interruptions during service consumption. In particular in case of bad network conditions, network and service providers have to trade off between these two impairment types, i.e. between the devil and the deep blue sea. In this paper we investigate this tradeoff in order to guide the design and development of Internet applications and network management approaches. The contribution of this paper is twofold. Firstly, we quantify the impact of initial delays on the user perceived Quality of Experience (QoE) for different application scenarios by means of subjective laboratory and crowdsourcing studies. We show that QoE for a given waiting time strongly depends on the concrete application at hand but that rating diversity remains fairly application-invariant. Secondly, using the example of YouTube video streaming we compare the influence of initial delays and interruptions (stallings) during watching. Our results demonstrate that users are extremely sensitive to interruptions and that services should be designed accordingly e.g. by increasing initial delay for prebuffering to overcome lack of resources.
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| 10. |
- Hossfeld, Tobias, et al.
(författare)
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Measurement and Analysis of Skype VoIP Traffic in 3G UMTS Systems
- 2006
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Konferensbidrag (refereegranskat)abstract
- Voice-over-IP (VoIP) telephony becomes more and more popular in the wired Internet because of easy-to-use applications with high sound quality like Skype. UMTS operators promise to offer large data rates which should also make VoIP possible in a mobile environment. However, the success of those application strongly depends on the user perceived voice quality. In this paper, we therefore analyze the achievable and the actual quality of IP-based telephony calls using Skype. This is done performing measurements in both a real UMTS network and a test environment. The latter is used to emulate rate control mechanisms and changing system conditions of UMTS networks. The results show whether Skype over UMTS is able to keep pace with existing mobile telephony systems and how it reacts to different network characteristics. The investigated performance measures comprise the Perceptual Evaluation of Speech Quality (PESQ) to evaluate the voice quality, the packet loss, the inter-packet delay, and the throughput to capture networkbased factors. In this context, the concept of the Network Utility Function (NUF) is applied to describe the impact of the network on the voice quality as perceived by the end-user.
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