| 1. |
- Ardelius, John, et al.
(författare)
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On the effects of caching in access aggregation networks
- 2012
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Ingår i: ICN 2012, Helsinki, Finland. - : Association for Computing Machinery (ACM). - 9781450314794
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Konferensbidrag (refereegranskat)abstract
- All forecasts of Internet trac point at a substantial growth over the next few years. From a network operator perspective, efficient in-network caching of data is and will be a key component in trying to cope with and profit from this increasing demand. One problem, however, is to evaluate the performance of different caching policies as the number of available data items as well as the distribution networks grows very large.In this work, we develop an analytical model of an aggregation access network receiving a continuous flow of requests from external clients. We provide exact analytical solutions for cache hit rates, data availability and more. This enables us to provide guidelines and rules of thumb for operators and Information-Centric Network designers.Finally, we apply our analytical results to a real VoD trace from a network operator and show that substantial bandwidth savings can be expected when using in-network caching in a realistic setting.
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| 2. |
- Arvidsson, Åke, 1957-, et al.
(författare)
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Analysis of user demand patterns and locality for YouTube traffic
- 2013
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Ingår i: 25th International Teletraffic Congress. - : IEEE Communications Society. - 9781479907991
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Konferensbidrag (refereegranskat)abstract
- Video content, of which YouTube is a major part, constitutes a large share of residential Internet traffic. In this paper, we analyse the user demand patterns for YouTube in two metropolitan access networks with more than 1 million requestsover three consecutive weeks in the first network and more than 600,000 requests over four consecutive weeks in the second network.In particular we examine the existence of “local interest communities”, i.e. the extent to which users living closer to each other tend to request the same content to a higher degree, and it is found that this applies to (i) the two networks themselves; (ii) regions within these networks (iii) households with regions and (iv) terminals within households. We also find that different types of access devices (PCs and handhelds) tend to form similar interest communities.It is also found that repeats are (i) “self-generating” in the sense that the more times a clip has been played, the higher the probability of playing it again, (ii) “long-lasting” in the sense that repeats can occur even after several days and (iii) “semi regular”in the sense that replays have a noticeable tendency tooccur with relatively constant intervals.The implications of these findings are that the benefits from large groups of users in terms of caching gain may be exaggerated, since users are different depending on where they live and what equipment they use, and that high gains can be achieved in relatively small groups or even for individual users thanks totheir relatively predictable behaviour.
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| 3. |
- Arvidsson, Åke, 1957-, et al.
(författare)
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Detecting user dissatisfaction and understanding the underlying reasons
- 2013
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Ingår i: ACM SIGMETRICS / International conference on measurement and modeling of computer systems, SIGMETRICS '13, Pittsburgh, PA, USA, June 17-21, 2013. - : Association for Computing Machinery (ACM). - 9781450319003
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Konferensbidrag (refereegranskat)abstract
- Quantifying quality of experience for network applications is challenging as it is a subjective metric with multiple dimensions such as user expectation, satisfaction, and overall experience. Today, despite various techniques to support differentiated Quality of Service (QoS), the operators still lack of automated methods to translate QoS to QoE, especially for general web applications.In this work, we take the approach of identifying unsatisfactory performance by searching for user initiated early terminations of web transactions from passive monitoring. However, user early abortions can be caused by other factors such as loss of interests. Therefore, naively using them to represent user dissatisfaction will result in large false positives. In this paper, we propose a systematic method for inferring user dissatisfaction from the set of early abortion behaviors observed from identifying the traffic traces. We conduct a comprehensive analysis on the user acceptance of throughput and response time, and compare them with the traditional MOS metric. Then we present the characteristics of early cancelation from dimensions like the types of URLs and objects. We evaluate our approach on four data sets collected in both wireline network and a wireless cellular network.
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| 4. |
- Arvidsson, Åke, 1957-, et al.
(författare)
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Detecting user dissatisfaction from passive monitoring
- 2013
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Ingår i: Proceedings of Eurocon 2013, International Conference on computer as a tool, Zagreb, Croatia, July 1-4, 2013. - : IEEE Communications Society. - 9781467322300
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Konferensbidrag (refereegranskat)abstract
- In an increasingly competitive environment it is more important than ever for operators to keep their end users satisfied. User satisfaction is often characterised in terms of Quality of Experience (QoE), a subjective metric with multiple dimensions such as expectations, content, terminal, environment, cost and performance. QoE is typically quantified as MOS, mean opinion score, which is obtained by averaging the ranks of a number of voluntary users for controlled combinations content/terminals/performance etc. While this approach has many advantages, there are also a number of difficulties such as representativeness (the number of users as well as the number of objects and devices all have to be kept small); validity (the results may be biased by the situation, the setting, the renumeration and so on); and applicability (it is not clear how different numbers map to notions such as “acceptable” or “unacceptable” and operators alone cannot do very much about factors such as content).We thus investigate the possibilities of detecting user opinions in the above, simplified, terms and from the network itself; with actual expectations, content, terminals, environments, costs and performance for virtually all users all the time. To this end we revisit the earlier suggestion that user opinions be reflected in their behaviour such that poor performance may result in interrupted requests. These works have, however, considered single flows hence we extend that idea to web pages which are groups of flows. In this paper we present our methods to group flows, interpret users, and characterise performance and we make a first assessment of the correlations between web page interruptions and network performance characteristics.
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| 5. |
- Arvidsson, Åke, 1957-, et al.
(författare)
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Fast transport for edge computing in 5G networks
- 2018
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Ingår i: Proceedings of 2018 26th International Conference on Software, Telecommunications and Computer Networks (SoftCOM). - New York : IEEE Communications Society. ; , s. 41-45
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Konferensbidrag (refereegranskat)abstract
- We consider TCP performance for cloud servicesin 5G cellular networks and show that edge clouds offer the highest throughput, but that further improvements still arepossible. To this end we devise a concept where edge clouds connected directly to the radio access network can increase their transmission rates by relying on the built in re-transmissions (through quality of service features) and on the built in userfairness (through per-user buffers and scheduler policies). We use numerical examples from measurements in real networks to demonstrate that the concept is efficient and significantly improves the effective throughput beyond what placement alone can do, and we also outline possible further improvements.
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| 6. |
- Arvidsson, Åke, 1957-, et al.
(författare)
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Load transients in pooled cellular core network nodes
- 2015
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Ingår i: Performance evaluation (Print). - 0166-5316 .- 1872-745X. ; 90, s. 18-35
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Tidskriftsartikel (refereegranskat)abstract
- The coverage areas of cellular networks are logically subdivided into service areas. Each service area has a local anchor node which “hides” the mobility inside the area and the entire network has a global anchor node which “hides” the mobility between areas.The concept of unique local anchor nodes per service area was invented to simplify routing but has been found to complicate expansion. The rapidly growing demand for cellular access has therefore prompted for alternative solutions with pools of local anchor nodes per service area. Such pools are now deployed by several operators all over the world.Users in pooled service areas are mapped to specific pool members according to a load distribution policy, but the mapping can change as a result of node failures or operator interventions. Such changes take a certain time to implement and cause additional load on the anchor nodes. We study these processes in detail and derive closed form expressions which allow operators to control the trade-off between rapid changes and acceptable loads.Finally we show that the key assumptions of our model are in agreement with measured data and demonstrate how the model can be applied to investigate the effects of different network settings (timers) under different user behaviour (traffic and mobility).Contrary to current solutions to this problem, which typically are slow and/or inaccurate, our results enable fast and accurate analysis of different scenarios thereby enabling operators to maximise utilisation of the existing investments and at the same time avoid potentially dangerous situations of overload.
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| 7. |
- 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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| 8. |
- 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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| 9. |
- 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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| 10. |
- Atxutegi, Eneko, et al.
(författare)
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TCP behaviour in LTE : impact of flow start-up and mobility
- 2016
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Ingår i: Wireless and Mobile Networking Conference (WMNC), 2016 9th IFIP. - : IEEE Communications Society. - 9781467387460 - 9781467387477 ; , s. 73-80
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Konferensbidrag (refereegranskat)abstract
- Mobile internet has been widely adopted and it is expected to rise to almost 4 billion users by 2020. Despite the research effort dedicated to the enhancement of its performance, there still exists a gap in the understanding of how TCP and its many variants work over LTE. To this end, this paper evaluates the extent to which five common TCP variants, CUBIC, NewReno,Westwood+, Illinois, and CAIA Delay Gradient (CDG), are able to utilise available radio resources under hard conditions, such as during start-up and in mobile scenarios at different speeds. The paper suggests that CUBIC, due to its Hybrid Slow-Start mechanism, enters congestion avoidance prematurely, and thus experiences a prolonged start-up phase. As a result, it is unable to efficiently utilise radio resources during shorter transmissionsessions. Besides, CUBIC, Illinois and NewReno, i.e., the loss-based TCP implementations, offer better throughput, and are able to better utilise available resources during mobility than Westwood+ and CDG - the delay-based variants do.
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