| 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. |
- Kreuger, Per, et al.
(författare)
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Zero configuration adaptive paging (zCap)
- 2012
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Ingår i: VTC Fall 2012. - : IEEE Communications Society. - 9781467318792
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Konferensbidrag (refereegranskat)abstract
- Today, cellular networks rely on fixed collections of cells (tracking areas) for handset localisation. This management parameter is manually configured and maintained and is not regularly adapted to changes in use patterns. We present a decentralised approach to localisation, based on a self-adaptive probabilistic mobility model. Estimates of model parameters are built from observations of mobility patterns collected online using a distributed algorithm. Based on these estimates, dynamic local neighbourhoods of cells are formed and maintained by the mobility management entities of the network. These neighbourhoods replace the static tracking areas used in current implementations by using the tracking area list facility of LTE. The model is also used to derive a multi phase paging scheme, where the division of cells into consecutive phases is optimal with respect to a set balance between response times and paging cost. The approach requires no manual tracking area configuration, and performs localisation efficiently in terms of number of location updates, page
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| 6. |
- Li, Jie, et al.
(författare)
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A five year perspective of traffic pattern evolution in a residential broadband access network
- 2012
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Ingår i: Future Network & MobileSummit 2012. - 9781905824304
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Konferensbidrag (refereegranskat)abstract
- In this paper we describe a systematic study on long-term evolution of residential broadband Internet traffic covering 5 calendar years from June 2007 to May 2011. The traffic evolution is characterized both in the term of the total traffic volume, as well as the traffic volumes and shares for different application categories (file sharing, video streaming etc.), with the focus on comparing the traffic on the per IP user basis and among different broadband subscription groups. The results show that the average daily total traffic generated by each private end user increased only by about 33 % during the past 5 years. Further, the results show that the P2P filesharing has been dominating the network total traffic, but the daily file-sharing traffic volume per end user largely remains the same. Also, the daily streaming-media traffic volume per end user has increased dramatically by over 500% during the studied period of time. In the meantime, the daily web-browsing traffic volume per end user has increased by about 300%. Finally, a further investigation among 4 different FTTH broadband subscription groups with 1, 10 , 30, and 100 Mbit/s symmetric access speeds shows that the lower the access speed, the more diversified the end user traffic tend to be.
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| 7. |
- Li, Jie, et al.
(författare)
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Performance analysis of local caching replacement policies for internet video streaming services
- 2014
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Ingår i: SoftCOM 2014. - : IEEE Communications Society. - 9789532900521
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Konferensbidrag (refereegranskat)abstract
- In this work, the performance of 5 representative caching replacement policies was investigated and compared for caching Internet video-on-demand (VoD) in local access networks. Two measured traces of end-user requests were used in the analyses for two typical VoD services: TV-on-demand and user generated content represented by YouTube. The studied policies range from simple least recently used (LRU) and least frequently used (LFU) algorithms to more advanced ones denoted as LFU-dynamic lifespan (LFU-DL), Adaptive replacement cache (ARC) and Greedy-dual size frequency (GDSF). Our results show that the ARC policy always outperforms the other policies due to its adaptive nature and its ability to track changes in the traffic patterns. On the other hand, the simple LRU policy can also achieve a caching performance which is comparable to that of the more advanced ARC policy especially for the TV-on-demand service when the potential caching gain is high. On the contrary, the simple LFU policy always shows the poorest performance.However, by applying a proper lifespan supplement under the LFU-DL policy, the caching performance can be effectively enhanced to the level achievable using ARC and LRU policies. Moreover, the GDSF policy does not outperform simple LRU or LFU-DL, especially for YouTube video clips when the potential caching gain is relatively low. The advantage of GDSF manifested in our analysis is, however, its outstanding cache space usage efficiency among the five studied caching algorithms.
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| 8. |
- Li, Jie, et al.
(författare)
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YouTube traffic content analysis in the perspective of clip category and duration
- 2013
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Ingår i: 2013 Fourth International Conference on the Network of the Future (NOF 2013). - : IEEE Communications Society. - 9781479916429
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Konferensbidrag (refereegranskat)abstract
- In this work, we study YouTube traffic characteristics in a medium-sized Swedish residential municipal network that has ~ 2600 mainly FTTH broadband-connected households. YouTube traffic analyses were carried out in the perspective of video clip category and duration, in order to understand their impact on the potential local network caching gains. To the best of our knowledge, this is the first time systematic analysis of YouTube traffic content in the perspective of video clip category and duration in a residential broadband network. Our results show that the requested YouTube videoclips from the end users in the studied network were imbalanced in regarding the video categories and durations. The dominating video category was Music, both in terms of the total traffic share as well as the contribution to the overall potential local network caching gain. In addition, most of the requested video clips were between 2-5 min in duration, despite video clips with durations over 15 min were also popular among certain video categories, e.g. film videos.
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| 9. |
- Nordell, Viktor, et al.
(författare)
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Concurrency and locality of content demand
- 2013
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Ingår i: 2013 International Conference on Smart Communications in Network Technologies (SaCoNeT 2013). - 9781479906956
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Konferensbidrag (refereegranskat)abstract
- Distribution of media data over the Internet is increasing in popularity and volume. This poses challenges not only for network operators but also for service providers when it comes to serving the demand in a cost-efficient way. In this paper, we approach this problem by investigating the potential of co-operative approaches where locality in space (users in the same network) and locality in time (concurrent downloads) are exploited such that as many requests as possible may behandled inside the access and metro networks. This approach may contribute not only to reducing transport costs (less traffic in core networks and at peering points) by but also improve the end user experience (by reduced round trip times and exclusion of some possible bottlenecks). To this end we develop a method to measure the possible gains from, firstly, optimal handling of concurrent downloads and, secondly, optimal utilization localavailability. We apply the method to BitTorrent data from two metropolitan access networks and find that the bandwidth savings amount to between 10% and 20% when optimizing concurrent downloads and between 56% and 66% when exploiting local availability with a simulated network cache.
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| 10. |
- Scheringer, Martin, et al.
(författare)
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Planetary boundaries for chemical pollution
- 2012
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Ingår i: Dioxin 2012 - 32nd International Symposium on Halogenated Persistent Organic Compounds.
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Konferensbidrag (refereegranskat)abstract
- Based on the concept by Rockström et al the paper discusses the principles of the concept in relation to chemical pollution and the specific challenges associated to that. The paper conclude the chemical pollution is certainly a strong anthropogenic impact of global relevance. However, because of the local or regional nature of many exposures and effects caused by chemicals, there is probably not a single tipping point for the global system that would have to be reflected by a planetary boundary. Therefore, in order to assess and manage chemical pollution, it seems to be more promising to focus on certain classes of chemicals separately and to derive boundaries of different types for these classes of chemicals, as illustrated in the paper for CFCs, POPs and food contaminants.
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