| 1. |
- Arvidsson, Åke, 1957-, et al.
(författare)
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Modelling user experience of adaptive streaming video over fixed capacity links
- 2021
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Ingår i: Performance evaluation (Print). - 0166-5316 .- 1872-745X. ; 148, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- Streaming video continues to experience unprecedented growth. This underscores the need to identify user-centric performance measures and models that will allow operators to satisfy requirements for cost-effective network dimensioning delivered with an acceptable level of user experience. This paper presents an analysis of two novel metrics in the context of fixed capacity links: (i) the average proportion of a video’s playing time during which the quality is reduced and (ii) the average proportion of videos which experience reduced quality at least once during their playing time, based on an M/M/∞ system. Our analysis is shown to hold for the more general M/G/∞ system for metric (i), but not for (ii) and simulation studies show an unexpected form of sensitivity of metric (ii) to the flow duration distribution, contrary to the norm of increasing variance causing worse performance. At typical operational loads these new metrics provide a more sensitive and information rich guide for understanding how user experience degrades, than the widely used average throughput metric does. We further show that only the combined use of this existing and our new metrics can provide a holistic perspective on overall user performance.
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| 2. |
- Arvidsson, Åke, 1957-, et al.
(författare)
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Web metrics for the next generation performance enhancing proxies
- 2019
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Ingår i: 2019 27TH INTERNATIONAL CONFERENCE ON SOFTWARE, TELECOMMUNICATIONS AND COMPUTER NETWORKS (SOFTCOM). - : IEEE. - 9789532900880 ; , s. 171-176
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Konferensbidrag (refereegranskat)abstract
- The fast growth of Internet traffic, the growing importance of cellular accesses and the escalating competition between content providers and network operators result in a growing interest in improving network performance and user experience. In terms of network transport, different solutions ranging from tuning TCP to installing middleboxes are applied. It turns out, however, that the practical results sometimes are disappointing and we believe that poor testing is one of the reasons for this. Indeed, many cases in the literature limit testing to the simple and rare use case of a single file download, while common and complex use cases like web browsing often are ignored or modelled only by considering smaller files. To facilitate better testing, we present a broader view which includes domain counts, flow counts and different forms of concurrency to better characterise the complexity around web pages, and from which the potential for different optimisation techniques can be estimated. We also derive numerical values of these metrics for a small set of popular web pages and study similarities and differences between pages with the same kind of content (newspapers, e-commerce and video) and between pages designed for the same platform (computer and smartphone).
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| 3. |
- Atxutegi, Eneko, et al.
(författare)
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On the move with TCP in current and future mobile networks
- 2017
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Ingår i: Proceedings of the 8th International Conference on the Network of the Future, London, United Kingdom, November 2017.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Mobile wireless networks constitute an indispensable part of the global Internet, and with TCP the dominating transport protocol on the Internet, it is vital that TCP works equally well over these networks as over wired ones. This paper identifies the performance dependencies by analyzing the responsiveness of TCP NewReno and TCP CUBIC when subject to bandwidth variations related to movements in different directions. The presented evaluation complements previous studies on 4G mobile networks in two important ways: It primarily focuses on the behavior of the TCP congestion control in medium- to high-velocity mobility scenarios, and it not only considers the current 4G mobile networks, but also low latency configurations that move towards the overall potential delays in 5G networks. The paper suggests that while both CUBIC and NewReno give similar goodput in scenarios where the radio channel continuously degrades, CUBIC gives a significantly better goodput in scenarios where the radio channel quality continuously increases. This is due to CUBIC probing more aggressively for additional bandwidth. Important for the design of 5G networks, the obtained results also demonstrate that very low latencies are capable of equalizing the goodput performance of different congestion control algorithms. Only in low latency scenarios that combine both large fluctuations of available bandwidths and a mobility pattern in which the radio channel quality continuously increases can some performance differences be noticed.
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| 4. |
- Cappelen, Birgitta, 1962-, et al.
(författare)
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Design for co-creation with interactive montage
- 2011
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Ingår i: Proceedings, 4th Nordic Design Research Conference, Nordes2011, School of Art and Design, Aalto University, Helsinki, Finland
May 29th - June 1st, 2011.
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Konferensbidrag (refereegranskat)abstract
- Montage in cinema means to mount images andsounds from different sources, that are interpreted together and whose oppositions drive the storyfurther. In this paper we develop the montage concept further for co-creation in interactive, tactile, spatial cross-media. As case we use the design of the interactive, tangible, cross-media installation ORFI. ORFI is developed to facilitate collaboration and co-creation between children with severe disabilities and their care persons. In this paper we focus on how we have designed for interactive montage. We present two main types of interactive montage, close and shifted in three dimensions (spatial, temporal and actorial). With the first we mean spatial and temporal closeness, depending on the roles users take and the interpretations they make. With shifted we mean how to use spatial and temporal shifting and distance between the media elements in space and over time, depending on the users’ roles and interpretations. All this to encourage co-creation over time, between a variety of users in different situations.
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| 5. |
- Cappelen, Birgitta, 1962-, et al.
(författare)
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From designing objects to designing fields : from control to freedom
- 2003
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Ingår i: Digital Creativity. - 1462-6268 .- 1744-3806. ; 14:2, s. 74-90
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we want to explore Field as a concept and as a metaphor for understanding interactive systems. By interactive systems we mean both systems and artworks, where the user by interacting changes the course of events. We intend to show why we need new terms and why we consider Field to be a fruitful concept and term. Further we will show how the Field concept changes both our understanding of what we do as designers and composers and how we acknowledge our audience. We will exemplify the design consequences of the Field concept by going through some design considerations we made when designing the audio tactile installation Mufi.
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| 6. |
- Carlsson, Bengt, et al.
(författare)
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Differences between the iterated prisoner's dilemma and the chicken game under noisy conditions
- 2002
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The prisoner's dilemma has evolved into a standard game for analyzing the success of cooperative strategies in repeated games. With the aim of investigating the behavior of strategies in some alternative games we analyzed the outcome of iterated games for both the prisoner's dilemma and the chicken game. In the chicken game, mutual defection is punished more strongly than in the prisoner's dilemma, and yields the lowest fitness. We also ran our analyses under different levels of noise. The results reveal a striking difference in the outcome between the games. Iterated chicken game needed more generations to find a winning strategy. It also favored nice, forgiving strategies able to forgive a defection from an opponent. In particular the well-known strategy tit-for-tat has a poor successrate under noisy conditions. The chicken game conditions may be relatively common in other sciences, and therefore we suggest that this game should receive more interest as a cooperative game from researchers within computer science.
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| 7. |
- Chen, Eric Zhi, 1963-
(författare)
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Constructions of 2-generator quasi-cyclic codes
- 2006
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Ingår i: Proceedings of the tenth International Workshop on Algebraic and Combinatorial Coding Theory. - Zvenigorod : Institute of Information Transmission Problems of Russian Academy of Sciences. ; , s. 60-63
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Konferensbidrag (refereegranskat)
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| 8. |
- Chen, Eric Zhi, 1963-
(författare)
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Constructions of quasi-cyclic two-weigh codes
- 2006
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Ingår i: Proc. of the tenth International Workshop on Algebraic and Combinatorial Coding Theory (ACCT-10). ; , s. 56-59
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Konferensbidrag (refereegranskat)abstract
- As a generalization of cyclic codes, quasi-cyclic (QC) codes contain many good linear codes. But quasi-cyclic codes studied so far are mainly limited to one generator (1-generator) QC codes. In this paper, 2-generator QC codes are studied, and many good 2-generator QC codes are constructed using simplex codes. A computer algorithm is given, and used to find the best possible 2-generator QC codes. Among those 2-generator QC codes constructed, some codes are two-weight codes.
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| 9. |
- Chen, Eric Zhi, 1963-
(författare)
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Further results on difference triangle sets
- 1994
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Ingår i: IEEE Transactions on Information Theory. - 0018-9448 .- 1557-9654. ; 40:4, s. 1268-1270
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Tidskriftsartikel (refereegranskat)abstract
- Further results on the upper bounds for difference tri8nglesets (DTS) are derived from disjoint difference sets and additive sequencesof permutations, whit3 greatly improve the known bounds.
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| 10. |
- Chen, Eric Zhi, 1963-
(författare)
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Good quasi-cyclic codes derived from irreducible cyclic codes
- 2005
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Ingår i: Proceedings of Optimal Codes and Related Topics (OC2005). ; , s. 74-81
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Konferensbidrag (refereegranskat)abstract
- As a generalization of cyclic codes, quasi-cyclic codes contain many good linear codes. Extensive search is made and lots of good quasi-cyclic codes are obtained from irreducible cyclic codes. A new binary [95, 13, 40] code which improves the lower bound on the minimum distance, is also constructed.
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