Ändra sökning
Avgränsa sökresultatet
1234567 101 - 150 av 301
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 101.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Alfredsson, Stefan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Examining cellular access systems on trains: Measurements and change detection2017Ingår i: Proceedings of the 1st Network Traffic Measurement and Analysis Conference, New York: IEEE, 2017, s. 1-6Konferensbidrag (Refereegranskat)
    Abstract [en]

    Abstract:Access to reliable high-quality communication services on trains is important for today's mobile users. Train-mounted aggregation routers that provide WiFi access to train passengers and bundle external communication over multiple cellular modems/links is an efficient way of providing such services. Still, the characteristics of such systems have received limited attention in the literature. In this paper we examine the communication characteristics of such systems based on a large data set gathered over six months from an operational Swedish railway system. We characterize the conditions in terms of usage load, train velocity profiles, and observed throughput and delay as well as the relation between these parameters. Furthermore, we examine the data from an anomaly detection perspective. Based on a changepoint detection method, we examine how the collected metrics varies over the six months. Being able to detect shifts in the metrics over time can help detect anomalous changes in the hardware or environment, and also further helps explain the factors affecting the observed behaviors.

    Ladda ner fulltext (pdf)
    fulltext
  • 102.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Alfredsson, Stefan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Examining TCP Short Flow Performance in Cellular Networks Through Active and Passive Measurements2015Ingår i: AllThingsCellular '15 Proceedings of the 5th Workshop on All Things Cellular: Operations, Applications and Challenges / [ed] David Choffnes and Kobus Van der Merwe, Association for Computing Machinery (ACM), 2015, s. 7-12Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this study we examine the conditions in a current cellular network by examining data passively collected in the core of a cellular operator during a 24-hour period. More than 2 billion traffic measurement data points from over 500,000 cellular users are analyzed. The analysis characterizes the Time-of-Day (ToD) variations for traffic intensity and session length and serves as a complement to the active measurements also performed. A comprehensive active measurement campaign was completed in the HSDPA+ and LTE networks of the four major Swedish operators. We collect around 50,000 data points from stationary cellular modems and analyze the ToD variation pattern for underlying network layer metrics such as delay and throughput. In conjunction with the time-varying session size distribution obtained from the passive measurements, we then analyze the ToD impact on TCP flows of varying sizes. The ToD effects are examined using time series analysis with Lomb-Scargle periodograms and differential Bayesian Information Criterion to allow comparison of the relative impact of the network ToD effects. The results show that ToD effects are predominantly impacting longer-running flows, and although short flows are also impacted they are mostly constrained by other issues such as protocol efficiency.

  • 103.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Alfredsson, Stefan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Beckman, Claes
    Center for Wireless Systems, KTH.
    Train Velocity and Data Throughput: A Large Scale LTE Cellular Measurements Study2017Ingår i: Proceedings of the 2017 IEEE 86th Vehicular Technology Conference (VTC Fall), New York: IEEE, 2017, s. 1-6Konferensbidrag (Refereegranskat)
    Abstract [en]

    Train-mounted aggregation routers that provide WiFi access to train passengers and bundle external communication over multiple cellular modems/links is an efficient way of providing communication services on trains. However, the characteristics of such systems have received limited attention in the literature. In this paper we address this gap by examining the communication characteristics of such systems based on a large data set gathered over six months from an operational Swedish railway system. We focus our examination on the relationship between per link throughput and train velocity. Using Levenberg- Marquardt non-linear regression a noticeable critical point is observed for an RS-SINR of around 12 dB. At this point the impact of increased train velocity on per link throughput changes from being negative to becoming positive. Using a machine learning approach we also explore the relative importance of several observed metrics in relation to per link throughput.

    Ladda ner fulltext (pdf)
    fulltext
  • 104.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT.
    Brunstrom, Anna
    An Experimental Study on the Performance and Fairness of Loss Differentiation for TCP2004Ingår i: ICETE (3), 2004Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 105.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT.
    Brunstrom, Anna
    Checksum-based Loss Differentiation2002Ingår i: Proceedings 4th IEEE Conference on Mobile and Wireless Communications Networks, 2002Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 106.
    Garcia, Johan
    et al.
    Karlstads universitet, Institutionen för informationsteknologi.
    Brunstrom, Anna
    Karlstads universitet, Institutionen för informationsteknologi.
    Evaluation of Transport Layer Loss Notification in Wireless Environments2005Ingår i: Networking - ICN 2005: 4th International Conference on Networking, Reunion Island, France, April 17-21, 2005, Proceedings, Part I / [ed] Pascal Lorenz & Petre Dini, Springer Berlin/Heidelberg, 2005, s. 247-257Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Residual bit-errors in wireless environments are well known to cause difficulties for congestion controlled protocols like TCP. In this study we focus on a receiver-based loss differentiation approach to mitigating the problems, and more specifically on two different loss notification schemes. The fully receiver-based 3-dupack scheme uses additional dupacks to implicitly influence the retransmission behavior of the sender. The second TCP option scheme uses a TCP option to explicitly convey a corruption notification. Although these schemes look relatively simple at first glance, when examining the details several issues exist which are highlighted and discussed. A performance evaluation based on a FreeBSD kernel implementation show that the TCP option scheme works well in all tested cases and provides a considerable throughput improvement. The 3-dupack scheme also provide performance gains in most cases, but the improvements varies more between different test cases, with some cases showing no improvement over regular TCP.

  • 107.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT.
    Brunstrom, Anna
    Impact of Partial Reliability on Web Image Transport Performance2002Ingår i: Proceedings PromoteIT 2002, 2002Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 108.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Asplund, Katarina
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Application and Transport Layer Flexibility - A User-influenced Web Browsing SystemManuskript (preprint) (Övrigt vetenskapligt)
  • 109.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    A Robust JPEG Coder for a Partially Reliable Transport Service2000Konferensbidrag (Refereegranskat)
  • 110.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    An Experimental Performance Evaluation of a Partially Reliable Web Application2002Konferensbidrag (Refereegranskat)
  • 111.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    An Experimental Study on the Performance and Fairness of Loss Differentiation for TCP2004Ingår i: ICETE 3, , INSTICC Press, 2004, s. -419Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper investigates the performance and fairness of receiver-based loss differentiation for TCP. Experimentshave been performed with a FreeBSD kernel implementation. As expected, the results verify theeffectiveness of receiver-based loss differentiation when corruption losses are present. However, if the the corruptinglink is shared with users that do not employ loss differentiation, the performance gain typically comesat the expense of increased unfairness. The results show that a single loss differentiating user may in somecases reduce the bandwidth of users without loss differentiation with up to 35 percent, but there are also cases where loss differentiation has limited fairness implications. The results further show that if a user employs multiple TCP connections over the corrupting link the negative effects of corruption losses are reduced. This is true even if all connections employ regular TCP. Hence, multiple connections at the application level can to some extent be used as a simple mechanism to limit the impact of corruption losses.

  • 112.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Checksum-based Loss Differentiation2002Konferensbidrag (Refereegranskat)
    Abstract [en]

    In a wireless environment the common transport protocol assumption that all packet losses are due to congestion no longer holds true. If the transport protocols react identically to both congestion and noncongestion related losses, performance will degrade. To avoid this performance problem, transport protocols must be able to differentiate between losses that are due to congestion and losses that are due to wireless link errors. Suitable congestion avoidance behavior can then be applied as appropriate. This paper overviews previous work on loss differentiation, and proposes a checksumbased scheme. The proposed scheme reuses the checksums already available at various layers in the receiver endhost protocol stack. It is an endtoend solution for the case where the lossy link is the last hop. Header decoding, data integrity and other issues related to the implementation of our cecksumbased scheme are also discussed

  • 113.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Clustering-based separation of media transfers in DPI-classified cellular video and VoIP traffic2018Ingår i: 2018 IEEE Wireless Communications and Networking Conference (WCNC), IEEE, 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Identifying VoIP and video traffic is often useful in the context of managing a cellular network, and to perform such traffic classification deep packet inspection (DPI) approaches are often used. Commercial DPI classifiers do not necessarily differentiate between, for example, YouTube traffic that arises from browsing inside the YouTube app, and traffic arising from the actual viewing of a YouTube video. Here we apply unsupervised clustering methods on such cellular DPI-labeled VoIP and video traffic to identify the characteristic behavior of the two sub-groups of media-transfer and non media-transfer flows. The analysis is based on a measurement campaign performed inside the core network of a commercial cellular operator, collecting data for more than two billion packets in 40+ million flows. A specially instrumented commercial DPI appliance allows the simultaneous collection of per packet information in addition to the DPI classification output. We show that the majority of flows falls into clusters that are easily identifiable as belonging to one of the traffic sub-groups, and that a surprising majority of DPIlabeled VoIP and video traffic is non-media related.

    Ladda ner fulltext (pdf)
    fulltext
  • 114.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Effects of Loss Notification and Loss Differentiation on DCCP and TCP Performance2004Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper examines the effects of non-congestion related wireless link errors on transport protocol performance.

    Although link-level retransmissions to a large extent can alleviate this problem for TCP, delay-sensitive applications using DCCP may not be well served by link-level retransmissions. The loss differentiation and loss notification mechanisms in DCCP are discussed, and the TFRC congestion control is numerically evaluated for wireless loss sensitivity. The results show that the use of loss differentiation can be critical for high rate senders.

    The results, however, also show that the blind use of DCCP loss differentiation for low rate senders may be inefficient considering the communications and computational overheads involved. Further, a TCP implementation modified to provide loss differentiation and loss notification is experimentally examined. As expected there are considerable gains from using loss differentiation.

  • 115.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Efficient Image Transfer for Wireless Networks2000Konferensbidrag (Refereegranskat)
  • 116.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Impact of Partial Reliability on Web Image Transport Performance2002Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper reports on experiments with a web-browsing application using

    PRTP, a new TCP-based protocol. With PRTP it is possible for an application to

    specify, and receive, a more flexible transport service than with TCP or UDP. A web

    application using PRTP is presented, and experiments examining the performance implications

    of using PRTP instead of TCP are discussed. The experiments used actual

    implementations of TCP and PRTP to conduct web page transfers over a network capable

    of emulating different network characteristics. The JPEG part of the web pages

    were recoded using a robust JPEG coding and transmitted using the partially reliable

    transport service made possible by PRTP. A novelty in these experiments was that the

    packet loss could be controlled in detail, allowing specific packets in a stream to be lost as opposed to losing packets with a certain probability. The experiments were performed for five different network characteristics each at six different loss ratios using three different web pages. The results show that using a partially reliable transport service in conjunction with the presented application provides throughput gains in the

    majority of cases, at the expense of slightly degraded image quality. The gains relative to TCP are up to 41% with a mean of 7.2%.

  • 117.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Issues with TCP-friendly Rate Control in DCCP2004Konferensbidrag (Refereegranskat)
    Abstract [en]

    TCP-Friendly Rate Control (TFRC) is a congestion control mechanism that is proposed to be used together with the new DCCP protocol. This paper provides an overview of the issues surrounding the use of TFRC for interactive media applications. Most issues are related to speci_c TFRC mechanisms, and to the use of smaller-than-MSS packets. An analytical examination of TFRCs behavior in the presence of wireless bit errors is also presented. The results show that DCCP's builtin loss differentiation can potentially be disabled for resourceconstrained devices in order to reduce overhead

  • 118.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Progressive Parsing Transcoding of JPEG Images2000Konferensbidrag (Refereegranskat)
  • 119.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Transcoding of Image Data2004Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 120.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Transport Layer Loss Differentiation and Loss Notification2003Konferensbidrag (Refereegranskat)
  • 121.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Conchon, Emmanuel
    LAAS-CNRS / ENSICA, Toulouse, France.
    Perennou, Tanguy
    LAAS-CNRS / ENSICA, Toulouse, France.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    KauNet: Improving Reproducibility for Wireless and Mobile Research2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents the KauNet emulation system that provides pattern-based emulation. KauNet enables bit precise placement of bit-errors, exact and repeatable packet losses, delays and bandwidth variations. The design and performance of KauNet is discussed. An example is also provided of how it can be integrated in a specific emulation framework to enhance emulation for mobile and wireless systems

  • 122.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Hurtig, Per
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    KauNet: A Versatile and Flexible Emulation System2008Konferensbidrag (Refereegranskat)
  • 123.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Hurtig, Per
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    KauNet: Design and Usage2008Rapport (Refereegranskat)
    Abstract [en]

    KauNet is an emulation system that allows deterministic placement of packet losses and bit-errors as well as more precise control over bandwidth and delay changes. KauNet is an extension to the well-known Dummynet emulator in FreeBSD and allows the use of pattern and scenario files to increase control and repeatability. This report provides a comprehensive description of the usage of KauNet, as well as a technical description of the design and implementation of KauNet

  • 124.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Hurtig, Per
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    KauNet: Design and Usage2008Rapport (Övrigt vetenskapligt)
    Abstract [en]

    KauNet is an emulation system that allows deterministic placement of packet losses and bit-errors as well as more precise control over bandwidth and delay changes. KauNet is an extension to the well-known Dummynet emulator in FreeBSD and  allows the use of pattern and scenario files to increase control and repeatability. This report provides a comprehensive description of the usage of KauNet, as well as a technical description of the design and implementation of KauNet.

    Ladda ner fulltext (pdf)
    FULLTEXT02
  • 125.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Hurtig, Per
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    The Effect of Packet Loss on the Response Times of Web Services2007Ingår i: Proceedings of 3rd International Conference on Web Information Systems and Technologies (WebIST2007), INSTICC Press, 2007Konferensbidrag (Refereegranskat)
  • 126.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Sundberg, Simon
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    LTE for Trains - Performance Interactions Examined with DL, ML and Resampling2019Ingår i: 2019 IEEE Symposium on Computers and Communications (ISCC), IEEE, 2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    Current LTE networks provide a large fraction of the mobile communication needs. One recent application area that have attained additional interest is the provision of mobile communication services to train passengers. To allow more efficient use of network resources and better onboard communication experience, onboard traffic aggregation can be performed. In this work we examine a large-scale operational data set from a routerbased LTE traffic aggregation system mounted onboard more than 100 trains belonging to a major Swedish train operator. We use both deep learning (DL) with Deep Neural Networks and traditional machine learning (ML) with Random Forests to examine an observed association between train velocity and achieved throughput, which curiously varies over different radio conditions. More than 37000 train journeys are analyzed to explore for structure and learn potential explanatory features. The results indicate that the association has a limited presence on a per cell basis, and that there is only a limited amount of learnable structure per cell. A resampling evaluation shows that the association becomes apparent when cell measurements are aggregated at an order of tens to a hundred cells.

  • 127.
    Garcia, Johan
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Sundberg, Simon
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Beckman, Claes
    Icomera AB, Gothenburg, Sweden.
    Interactions Between Train Velocity andCellular Link Throughput - An Extensive Study2019Ingår i: 2019 IEEE 30th Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), 2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    Providing reliable internet connectivity to train passengers can be handled with onboard aggregation routers that use multiple external antennas to simultaneously convey user traffic over multiple links. This work studies the operational characteristics of a large-scale deployment of such a system. The examination focuses on how train velocity is associated with achieved link throughput, and how various interaction effects influence the relationship. A large data set collected over three years is analyzed, indicating that there is a systematic association between train velocity and link throughput that varies over the radio conditions and which is also linked to differences between operators.

    Ladda ner fulltext (pdf)
    fulltext
  • 128.
    Grinnemo, Karl-Johan
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Bozakov, Zdravko
    Dell EMC.
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Isabel Bueno, María
    Damjanovic, Dragana
    Mozilla.
    Rikter Evensen, Kristian
    Celerway.
    Fairhurst, Gorry
    University of Aberdeen, UK..
    Hansen, Audun
    Celerway.
    Hayes, David
    University of Oslo, Norway.
    Hurtig, Per
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Khademi, Naeem
    University of Oslo, Norway.
    Mangiante, Simone
    Dell EMC.
    Mohideen, Althaff
    University of Aberdeen, UK..
    Rajiullah, Mohammad
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Ros, David
    Simula.
    Rüngeler, Irene
    FH Münster, Germany.
    Santos, Ricardo
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Secchi, Raffaello
    University of Aberdeen, UK..
    Christian Tangenes, Tor
    Tüxen, Micheal
    FH Münster, Germany.
    Weinrank, Felix
    FH Münster, Germany.
    Welzl, Michael
    University of Oslo, Norway.
    Deliverable D3.1 - Initial Report on the Extended Transport System2017Rapport (Refereegranskat)
    Abstract [en]

    The NEAT System offers an enhanced API for applications that disentangles them from the actual transport protocol being used. The system also enables applications to communicate their service requirements to the transport system in a generic, transport-protocol independent way. Moreover, the architecture of the NEAT System promotes the evolution of new transport services. Work Package 3 (WP3) enhances and extends the core parts of the NEAT Transport. Efforts have been devoted to developing transport-protocol mechanisms that enable a wider spectrum of NEAT Transport Services, and that assist the NEAT System in facilitating several of the commercial use cases. Work has also started on the development of optimal transport-selection mechanisms; mechanisms that enable for the NEAT System to make optimal transport selections on the basis of application requirements and network measurements. Lastly, another research activity has been initiated on how to use SDN to signal application requirements to routers, switches, and similar network elements. This document provides an initial report on all these WP3 activities—both on completed and on near-termplanned work.

    Ladda ner fulltext (pdf)
    fulltext
  • 129.
    Grinnemo, Karl-Johan
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Bozakov, Zdravko
    Dell EMC.
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Isabel Sanchez Bueno, Maria
    Dreibholz, Thomas
    Simula.
    Rikter Evensen, Kristian
    Celerway.
    Fairhurst, Gorry
    University of Aberdeen, UK..
    Fosselie Hansen, Audun
    Celerway.
    Hayes, David
    University of Oslo, Norway.
    Hurtig, Per
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Rajiullah, Mohammad
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Jones, Tom
    University of Aberdeen, UK..
    Ros, David
    Simula.
    Rozensztrauch, Tomasz
    Celerway.
    Tüxen, Michael
    FH Münster, Germany.
    Vyncke, Eric
    CISCO.
    Deliverable D3.3 - Extended Transport System and Transparent Support of Non-NEAT Applications2017Rapport (Refereegranskat)
    Abstract [en]

    This deliverable summarises and concludes our work in Work Package 3 (WP3) to extend the transport services provided by the NEAT System developed in Work Package 2, and to enable non-NEAT applications to harness the transport services offered by NEAT. We have demonstrated how a policy- and information-based selection of transport protocol by NEAT could provide a more efficient transport service for web applications. The information on which NEAT makes its transport selection decisions resides in the Characteristics Information Base (CIB). The CIB is populated by various CIB sources, and in WP3 we have designed, implemented, and evaluated various CIB sources, including meta data from mobile broadband networks, passive measurements, IPv6 Provisioning Domain protocols and the Happy Eyeballs mechanism, which caches the outcome of its connection attempts. A key property of NEAT is that it not only “vertically” decouples applications from transport protocols, but also “horizontally”. Particularly, it enables applications to harness information about resource availability and policies from Software Defined Networking (SDN) controllers in managed networks, without these applications actually being SDN-aware. To extend the use of NEAT to non-NEAT applications, we have implemented a BSDcompatible sockets API on top of NEAT and a NEAT proxy that intercepts and replaces standard TCP connections with NEAT flows, i.e., with the transport solutions deemed most appropriate by NEAT.We have also proposed a way for non-NEAT applications to make use of NEAT through the deployment of NEAT-enabled virtual appliances in SDN-controlled networks: connections from these applications are routed via an SDN-controlled proxy that terminates the original connection and replaces it with a NEAT-selected connection.

    Ladda ner fulltext (pdf)
    fulltext
  • 130.
    Grinnemo, Karl-Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    A Simulation Based Performance Analysis of a TCP Extension for Best Effort Multimedia Applications2002Ingår i: Proceedings: 35th Annual Simulation Symposium, IEEE , 2002, s. 327-336Konferensbidrag (Refereegranskat)
    Abstract [en]

    Since TCP is considered unsuitable for the majority of the emerging multimedia applications, these applications primarily use UDP transport together with proprietary congestion control schemes that have better jitter and throughput characteristics. A common problem with these congestion control schemes is that they often exhibit a TCP-unfriendly and unfair behavior. As the number of applications that uses this kind of schemes increases, this could become a serious threat to the stability and performance of the Internet. In an attempt to make TCP a viable alternative to some best-effort multimedia applications, we have proposed an extension to TCP - PRTP-ECN. The performance of PRTP-ECN has been compared with TCP in an extensive factorial simulation experiment. This paper gives a detailed description of this simulation experiment with an emphasis on its statistical design and analysis. The analysis of the experiment includes, among other things, a series of ANOVA tests. These tests indicate that PRTP-ECN gives significant reductions in average interarrival jitter, while at the same time leads to improvements in average throughput and goodput, and better link utilization. In addition, the analysis suggests that PRTP-ECN is almost as fair as TCP and exhibits a TCP-friendly behavior

  • 131.
    Grinnemo, Karl-Johan
    et al.
    Karlstads universitet, Institutionen för informationsteknologi.
    Brunstrom, Anna
    Karlstads universitet, Institutionen för informationsteknologi.
    A Survey of TCP-Friendly Congestion Control Mechanisms for Multimedia Traffic2003Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The stability and performance of the Internet to date have in a large part been due tothe congestion control mechanism employed by TCP. However, while the TCP congestioncontrol is appropriate for traditional applications such as bulk data transfer, it hasbeen found less than ideal for multimedia applications. In particular, audio and videostreaming applications have difficulties managing the rate halving performed by TCP inresponse to congestion. To this end, the majority of multimedia applications use eithera congestion control scheme which reacts less drastic to congestion and therefore oftenis more aggressive than TCP, or, worse yet, no congestion control whatsoever. Sincethe Internet community strongly fears that a rapid deployment of multimedia applicationswhich do not behave in a fair and TCP-friendly manner could endanger the currentstability and performance of the Internet, a broad spectrum of TCP-friendly congestioncontrol schemes have been proposed. In this report, a survey over contemporary proposalsof TCP-friendly congestion control mechanisms for multimedia traffic in the Internetis presented. A classification scheme is outlined which shows how the majority of theproposed congestion control schemes emanate from a relatively small number of designprinciples. Furthermore, we illustrate how these design principles have been applied ina selection of congestion control scheme proposals and actual transport protocols.

  • 132.
    Grinnemo, Karl-Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Enhancing TCP for Applications with Soft Real-Time Constraints2001Ingår i: Multimedia systems and applications IV: 21-22 August 2001, Denver, USA / [ed] Andrew G. Tescher, Bhaskaran Vasudev, V. Michael Bove, Jr., Bellingham: SPIE , 2001, s. 18-31Konferensbidrag (Refereegranskat)
    Abstract [en]

    Experiences in the use of the Internet as a delivery medium for multimedia-based applications have revealed serious deficiencies in its ability to provide the QoS of Multimedia Applications. We propose an extension to TCP that addresses the QoS requirements of applications with soft real-time constraints. Although, TCP has been found unsuitable for real-time applications, it can with minor modifications be adjusted to better comply with the QoS needs of applications with soft real-time requirements. Enhancing TCP with support for this group of applications is important since the congestion control mechanism of TCP assures stability of the Internet. In contrast, specialized multimedia protocols that lack appropriate congestion control can never be deployed on a large scale basis. Two factors of great importance for applications with soft real time constraints are jitter and throughput. By relaxing the reliability offered by TCP, the extension gives better jitter characteristics and an improved throughput. The extension only needs to be implemented at the receiving side. The reliability provided is controlled by the receiving application, thereby allowing a flexible tradeoff between different QoS parameters. In this paper, our TCP extension is presented and analyzed. The analysis investigates how the different application-controlled parameters influence performance. Our analysis is supported by a simulation study that investigates the tradeoff between interarrival jitter, throughput, and reliability. The simulation results also confirm that the extended version of TCP still behaves in a TCP-friendly manner

  • 133.
    Grinnemo, Karl-Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Evaluation of the QoS Offered by PRTP-ECN: A TCP Compliant Partially Reliable Transport Protocol2001Ingår i: Proceedings: IWQoS '01 Proceedings of the 9th International Workshop on Quality of Service, London: Springer , 2001, s. 217-234Konferensbidrag (Refereegranskat)
    Abstract [en]

    The introduction of multimedia in the Internet imposes new QoS requirements on existing transport protocols. Since neither TCP nor UDP comply with these requirements, a common approach today is to use RTP/UDP and to relegate the QoS responsibility to the application. Even though this approach has many advantages, it also entails leaving the responsibility for congestion control to the application. Considering the importance of efficient and reliable congestion control for maintaining stability in the Internet, this approach may prove dangerous. Improved support at the transport layer is therefore needed. In this paper, a partially reliable transport protocol, PRTP-ECN, is presented. PRTP-ECN is a protocol designed to be both TCP-friendly and to better comply with the QoS requirements of applications with soft real-time constraints. This is achieved by trading reliability for better jitter characteristics and improved throughput. A simulation study of PRTP-ECN has been conducted. The outcome of this evaluation suggests that PRTPECN can give applications that tolerate a limited amount of packet loss significant reductions in interarrival jitter and improvements in throughput as compared to TCP. The simulations also verified the TCP-friendly behavior of PRTP-ECN

  • 134.
    Grinnemo, Karl-Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Impact of Traffic Load on SCTP Failovers in SIGTRAN2005Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    With Voice over IP (VoIP) emerging as a viable alternative to the traditional circuit-switched telephony, it is vital that the two are able to intercommunicate. To this end, the IETF Signaling Transport (SIGTRAN) group has defined an architecture for seamless transportation of SS7 signaling traffic between a VoIP network and a traditional telecom network. However, at present, it is unclear if the SIGTRAN architecture will, in reality, meet the SS7 requirements, especially the stringent availability requirements. The SCTP transport protocol is one of the core components of the SIGTRAN architecture, and its failover mechanism is one of the most important availability mechanisms of SIGTRAN. This paper studies the impact of traffic load on the SCTP failover performance in an M3UA-based SIGTRAN network. The paper shows that cross traffic, especially bursty cross traffic such as SS7 signaling traffic, could indeed significantly deteriorate the SCTP failover performance. Furthermore the paper stresses the importance of configuring routers in a SIGTRAN network with relatively small queues. For example, in tests with bursty cross traffic, and with router queues twice the bandwidth-delay product, failover times were measured which were more than 50% longer than what was measured with no cross traffic at all. Furthermore, the paper also identifies some properties of the SCTP failover mechanism that could, in some cases, significantly degrade its performance

  • 135.
    Grinnemo, Karl-Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    On the Use of CMT-SCTP to Improve the Startup Behavior of PSTN Signaling Traffic2013Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    There is currently work going on at IETF to standardize concurrent multipath transfer, i.e., simultaneous transfer of data over several network paths, for SCTP. This paper studies whether or not SCTP extended with concurrent multipath transfer (CMT-SCTP) could provide a faster startup behavior than standard SCTP. The paper complements previous work on CMT-SCTP, and extends it to PSTN signaling traffic. The paper suggests that CMT-SCTP could give a faster startup behavior over symmetrical paths, i.e., paths with similar bandwidths and round-trip times, but that its behavior is sensitive to differences in round-trip time between the paths. The paper also indicates that signaling traffic properties such as message size and burstiness contribute marginally to the startup behavior of CMT-SCTP. 

  • 136.
    Grinnemo, Karl-Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013).
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    On the Use of MPTCP to Reduce Latency for Cloud Applications2014Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    As mobile cloud usage has become more and more prevalent, with more people depending on the cloud for both their work and their leisure, cloud-to-end-user latency have risen to become a key issue. One oft-forgotten way to cost effectively improve the quality of experience is to simultaneously make use of the several network interfaces, e.g., WiFi and 3G/4G interfaces, available on most of todays mobile devices including smartphones and tablets; that is, to employ multihoming. This paper provides an initial evaluation of the latency characteristics of the multipath extensions to TCP, Multipath TCP (MPTCP), that are currently being standardized by IETF. In particular, the paper considers the possible reductions in latency that could be obtained by using MPTCP and multiple network paths between a cloud service and a mobile end user. Traffic from three cloud applications are studied, Netflix, Google Maps, and Google Docs, representing typical high-, mid-, and low- intensity cloud-to-end-user traffic. The result suggests that significant latency reductions are indeed possible, however, primarily for high- intensity video traffic such as Netflix. 

  • 137.
    Grinnemo, Karl-Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Performance of SCTP-controlled Failovers in M3UA-based SIGTRAN Networks2004Ingår i: Simulations Series, La Jolla, Ca: Society for Computer Simulation , 2004, s. 86-91Konferensbidrag (Refereegranskat)
    Abstract [en]

    There are some large economic, operational, and, to some extent, technicalincentives to replace the traditional telecom network with IP. However,such a large transition will not happen overnight maybe never. Meanwhile,IP-based and traditional TDM-based telephony will have to co-exist. To addressthis situation, the IETF SIGTRAN working group has developed an architecturefor transportation of Signaling System No. 7 (SS7) traffic over IP. Still, itremains to be shown that the introduction of the SIGTRAN architecture will notsignificantly deteriorate the performance of SS7. To this end, this paperevaluates the failover performance in SIGTRAN networks. Specifically, the paperevaluates the performance of SCTP-controlled failovers in M3UA-based SIGTRAN networks.The paper suggests that in order to obtain a failover performance with SCTPcomparable to that obtained in traditional TDM-based SS7 systems, SCTP has to abandonmany of the configuration recommendations of RFC 2960 and become much more aggressivein its failover behavior. Furthermore, the paper suggests that the SCTP parameterPath.Max.Retrans has a major impact on the SCTP failover performance. Our evaluationalso indicates that for those path propagation delays envisioned in future SIGTRAN networks,the impact of the path propagation delay on the failover performance is marginal

  • 138.
    Grinnemo, Karl-Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Some Observations on the Performance of SCTP-controlled Failovers in M3UA-based SIGTRAN Networks2004Ingår i: Proceedings of the Second Swedish National Computer Networking Workshop: SNCNW2004, Karlstad, 2004Konferensbidrag (Refereegranskat)
    Abstract [en]

    With Voice over IP (VoIP) emerging as a viable alternative totraditional circuit-switched telephony, it is vital that the twoare able to intercommunicate. To this end, the IETF SignalingTransport (SIGTRAN) group has devised an architecture forseamless transportation of SS7 signaling traffic between aVoIP network and a traditional telecom network. However,at present, it is unclear if the SIGTRAN architecture will,in reality, meet the SS7 requirements, especially the stringentavailability requirements.The SCTP transport protocol is one of the core componentsof the SIGTRAN architecture, and its failover mechanism isone of the most important of the availability mechanisms ofSIGTRAN. Currently, we are studying the performance ofSCTP-controlled failovers, and although this study is not yetcompleted some observations have been made on propertiesof the SCTP failover mechanism which could impede on itsperformance. This paper reports on these observations, andexplains their causes.

  • 139.
    Grinnemo, Karl-Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT.
    Towards the Next Generation Network: The Softswitch Solution2006Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Over the course of the last fifteen years, the telecommunication market has undergone dramatic changes. In the beginning of the nineties, the market essentially comprised a number of national monopolies. Today, yesterday's monopolies are under siege, and the incumbent operators face strong competition from newly established operators. Furthermore, in recent years broadband-based VoIP providers have entered the telecommunication market as worthy contenders to traditional operators. To be able to survive and thrive in this new, much more competitive, market, traditional wireless and wireline operators have to reduce their capital and operational expenditures. They also need to provide new revenue-generating applications and services. To this end, a large number

    of traditional operators has replaced, or seriously consider to replace, their legacy circuit-switched fixed and cellular core networks with IP. As a first step in the migration from circuit-switched technologies to IP, the softswitch solution has evolved. This report provides a comprehensive treatment of the softswitch solution from a technical viewpoint. Additionally, the report

    concludes with a brief discussion of the migration steps following the softswitch solution. In particular, an overview of the 3GPP IP Multimedia Subsystem (IMS) is given.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 140.
    Grinnemo, Karl-Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Andersson, Torbjörn
    Tieto Enator AB, Karlstad.
    Performance Benefits of Avoiding Head-of-Line Blocking in SCTP2005Ingår i: Autonomic and Autonomous Systems and International Conference on Networking and Services, 2005. ICAS-ICNS 2005. Joint International Conference on, IEEE , 2005, s. 44-Konferensbidrag (Refereegranskat)
    Abstract [en]

    Mitigating the effects of head-of-line blocking (HoLB) was one of the major reasons the IETF SIGTRAN working group developed SCTP, a new transport protocol for PSTN signaling traffic, in the first place. However, studies of the impact of HoLB blocking on TCP and SCTP have given ambiguous results as to whether HoLB has, in fact, any significantly deteriorating effect on transmission delay. To this end, we have carried out a detailed experimental study on the quantitative effects of HoLB. Our study suggests that although HoLB could indeed incur a substantial delay penalty on a small fraction of the messages in an SCTP session, it has only a marginal impact on the average end-to-end transmission delay. We only observed improvements in the range of O% to 18% in average message transmission delay of using unordered delivery as compared to ordered delivery. Furthermore, there was a large variability in between different test runs, which often made the impact of HoLB statistically insignificant

  • 141.
    Grinnemo, Karl-Johan
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Cheng, Jun
    Ericsson AB, Stockholm, Sweden.
    Using Concurrent Multipath Transfer to Improve the SCTP Startup Behavior for PSTN Signaling Traffic2014Ingår i: 2014 28TH INTERNATIONAL CONFERENCE ON ADVANCED INFORMATION NETWORKING AND APPLICATIONS WORKSHOPS (WAINA) / [ed] Barolli, L; Li, KF; Enokido, T; Xhafa, F; Takizawa, M, IEEE, 2014, s. 772-778Konferensbidrag (Refereegranskat)
    Abstract [en]

    Although latency in the Internet has gained much attention in the research community, the latency issues of mobile control signaling have received less attention, and this all the while many telecom operators are experiencing a several-hundred percent increase in signaling traffic over only a couple of years. We believe one way to address both the latency and increased signaling load of mobile networks, is to exploit concurrent transfer of signaling traffic over several paths a.k.a. concurrent multipath transfer. This paper studies whether or not SCTP extended with concurrent multipath transfer (CMT-SCTP) could provide a faster startup behavior than standard SCTP. The paper complements previous work on CMT-SCTP, and extends it to PSTN signaling traffic. The paper suggests that CMT-SCTP could give a faster startup behavior over paths with similar bandwidths and round-trip times, but that its behavior is sensitive to differences in round-trip time between the paths. Moreover, the paper suggests that provided CMT-SCTP is configured with large enough send and receive buffers, it could provide a faster startup behavior than standard SCTP over a multipath association, in spite of some of the paths having a packet-loss rate of several percent.

  • 142.
    Grinnemo, Karl-Johan
    et al.
    Karlstads universitet, Institutionen för informationsteknologi.
    Brunstrom, Anna
    Karlstads universitet, Institutionen för informationsteknologi.
    Garcia, Johan
    Karlstads universitet, Institutionen för informationsteknologi.
    A Taxonomy and Survey of Retransmission Based Partially Reliable Transport Protocols2002Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The mismatch between the services offered by the two standard transport protocols inthe Internet, TCP and UDP, and the services required by distributed multimedia applicationshas led to the development of a large number of partially reliable transportprotocols. That is, protocols which in terms of reliability places themselves betweenTCP and UDP. This paper presents a taxonomy for retransmission based, partially reliabletransport protocols, i.e., the subclass of partially reliable transport protocols thatperforms error recovery through retransmissions. The taxonomy comprises two classificationschemes: one that classifies retransmission based, partially reliable transportprotocols with respect to the reliability service they offer and one that classifies themwith respect to their error control scheme. The objective of our taxonomy is fourfold:to introduce a unified terminology; to provide a framework in which retransmissionbased, partially reliable transport protocols can be examined, compared, and contrasted;to make explicit the error control schemes used by these protocols; and, finally, to gainnew insights into these protocols and thereby suggest avenues for future research. Basedon our taxonomy, a survey was made of existing retransmission based, partially reliabletransport protocols. The survey shows how protocols are categorized according to ourtaxonomy, and exemplifies the majority of reliability services and error control schemesdetailed in our taxonomy.

  • 143.
    Grinnemo, Karl-Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    A First Study on Using MPTCP to Reduce Latency for Cloud Based Mobile Applications2015Ingår i: 2015 IEEE SYMPOSIUM ON COMPUTERS AND COMMUNICATION (ISCC), IEEE, 2015, s. 64-69Konferensbidrag (Refereegranskat)
    Abstract [en]

    Currently, Multipath TCP (MPTCP) – a modifica- tion to standard TCP that enables the concurrent use of several network paths in a single TCP connection – is being standardized by IETF. This paper provides a comprehensive evaluation of the use of MPTCP to reduce latency and thus improve the quality of experience or QoE for cloud-based applications. In particular, the paper considers the possible reductions in latency that could be obtained by using MPTCP and multiple network paths between a cloud service and a mobile end user. To obtain an appreciation of the expected latency performance for different types of cloud traffic, three applications are studied, Netflix, Google Maps, and Google Docs, representing typical applications generating high-, mid-, and low-intensity traffic. The results suggest that MPTCP could provide significant latency reductions for cloud applications, especially for applications such as Netflix and Google Maps. Moreover, the results suggest that MPTCP offers a reduced latency despite a few percent packet loss, and in spite of limited differences in the round-trip times of the network paths in an MPTCP connection. Still, larger differences in the round-trip times seem to significantly increase the application latency, especially for Netflix, Google Maps, and similar applications. Thus, to become an even better alternative to these applications, this paper suggests that the MPTCP packet scheduling policy should be changed: Apart from the round-trip times of the network paths in a connection, it should also consider the difference in round-trip time between the network paths.

    Ladda ner fulltext (pdf)
    fulltext
  • 144.
    Grinnemo, Karl-Johan
    et al.
    Karlstads universitet, Institutionen för informationsteknologi.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    A Simulation Based Performance Evaluation of PRTP2002Rapport (Övrigt vetenskapligt)
    Abstract [en]

    PRTP is proposed to address the need of a transport service that is more suitable forapplications with soft real-time requirements, e.g., video broadcasting. It is an extensionfor partial reliability to TCP. The main idea behind PRTP is to exploit the fact thatmany soft real-time applications tolerate a limited amount of packet loss. In particular,PRTP enables an application to trade some of the reliability offered by TCP for improvedthroughput and interarrival jitter. This paper describes the design of PRTP andgives a detailed description of a simulation based performance evaluation. The performanceevaluation involved the performance of PRTP compared to TCP in long- as wellas in short-lived connections and showed that PRTP probably would give significantimprovements in performance, both in terms of throughput and interarrival jitter, for awide range of applications. The performance evaluation also suggested that PRTP is notTCP-friendly and altogether fair against competing flows and thus is not suitable for usein an environment where the main reason for packet loss is congestion, e.g., in a fixedInternet environment. We believe, however, that PRTP could be a viable alternative forwireless applications in error prone environments.

  • 145.
    Grinnemo, Karl-Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT.
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    A Survey of TCP-Friendly Congestion Control Mechanisms for Multimedia Traffic2003Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The stability and performance of the Internet to date have in a large part been due tothe congestion control mechanism employed by TCP. However, while the TCP congestioncontrol is appropriate for traditional applications such as bulk data transfer, it hasbeen found less than ideal for multimedia applications. In particular, audio and videostreaming applications have difficulties managing the rate halving performed by TCP inresponse to congestion. To this end, the majority of multimedia applications use eithera congestion control scheme which reacts less drastic to congestion and therefore oftenis more aggressive than TCP, or, worse yet, no congestion control whatsoever. Sincethe Internet community strongly fears that a rapid deployment of multimedia applicationswhich do not behave in a fair and TCP-friendly manner could endanger the currentstability and performance of the Internet, a broad spectrum of TCP-friendly congestioncontrol schemes have been proposed. In this report, a survey over contemporary proposalsof TCP-friendly congestion control mechanisms for multimedia traffic in the Internetis presented. A classification scheme is outlined which shows how the majority of theproposed congestion control schemes emanate from a relatively small number of designprinciples. Furthermore, we illustrate how these design principles have been applied ina selection of congestion control scheme proposals and actual transport protocols.

    Ladda ner fulltext (pdf)
    fulltext
  • 146.
    Grinnemo, Karl-Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    An Easy way to Reduce SCTP Failover Times2005Ingår i: Proceedings of the Third Swedish National Computer Networking Workshop: SNCNW2005, 2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    To enable interoperability between the public switched telephone network and IP, the IETF SIGTRAN working group has developed an architecture for the transportation of SS7 signaling traffic over IP. The architecture is based on a new transport protocol, the Stream Control Transmission Protocol (SCTP), that is designed to meet SS7 requirements. However, recent work suggests that the SCTP failover mechanism has difficulties complying with the SS7 requirements of ITU-T. To this end, this paper suggests using a modified retransmission timeout strategy which involves using a relaxed backoff factor of less than 2, the standard value specified in RFC 2960. Through simulations, it is shown that significant improvements in failover time, and thus in increased permissible network delays, could be obtained with this backoff strategy in well-dimensioned and controlled network environments. However, the simulations also stress the importance of running signaling traffic over managed IP networks. In the simulations where the signaling traffic competed with uncontrolled cross traffic, none of the studied backoff factors made SCTP compliant with ITU-T.

  • 147.
    Grinnemo, Karl-Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Impact of SCTP-controlled Failovers for M3UA Users in a Dedicated SIGTRAN Network2003Ingår i: Proceedings of the First Swedish National Computer Networking Workshop: SNCNW2003, 2003Konferensbidrag (Refereegranskat)
  • 148.
    Grinnemo, Karl-Johan
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Fairhurst, Gorry
    University of Aberdeen, UK..
    Hayes, David
    University of Oslo, Norway.
    Hurtig, Per
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Khademi, Naeem
    University of Oslo, Norway.
    Ros, David
    Simula.
    Rüngeler, Irene
    FH Münster, Germany.
    Tüxen, Michael
    FH Münster, Germany.
    Weinrank, Felix
    FH Münster, Germany.
    Welzl, Michael
    University of Oslo, Norway.
    Deliverable D3.2 - Final Report on Transport Protocol Enhancements2017Rapport (Refereegranskat)
    Abstract [en]

    This deliverable provides a final report on the work on transport protocol enhancements done inWork Package 3. First, we report on the extensions made to the SCTP protocol that turn it into a viable alternative to TCP and allow to deliver a lower-latency transport service. Next, we describe our work to develop a framework for providing a deadline-aware, less-than-best-effort transport service, targeting background traffic and thus addressing requirements on NEAT from the EMC use case. We also present our efforts to design and implement a latency-aware scheduler for MPTCP, which enables NEAT to offer a transport service that meets the needs of latency-sensitive applications, and that efficiently utilises available network resources. Lastly, this document informs on our work on coupled congestion control for TCP, a mechanism that treats a bundle of parallel TCP flows between the same pair of hosts as a single unit. By efficiently multiplexing concurrent TCP flows, our coupled congestion control alleviates the effects of queueing, and tends to result in a more efficient usage of available bandwidth, where the flows’ aggregate capacity share can be apportioned based on application preferences.

    Ladda ner fulltext (pdf)
    fulltext
  • 149.
    Grinnemo, Karl-Johan
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Jones, Tom
    University of Aberdeen.
    Fairhurst, Gorry
    University of Aberdeen.
    Hurtig, Per
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Ros, David
    Simula Research Lab.
    NEAT - A New, Evolutive API and Transport-Layer Architecture for the Internet2016Ingår i: 12th Swedish National Computer Networking Workshop (SNCNW 2016), Sundsvall, Sweden., 2016Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    There is a growing concern that the Internet trans- port layer has become ossified in the face of emerging novel applications, and that further evolution has become very difficult. This paper identifies requirements for a new transport layer and then proposes a conceptual architecture, the NEAT system, that we believe is both flexible and evolvable. Applications interface the NEAT system through an enhanced user API that decouples them from the operation of the transport protocols and the network features being used. In particular, applications provide the NEAT system with information about their traffic requirements, pre- specified policies, and measured network conditions. On the basis of this information, the NEAT system establishes and configures appropriate connections. 

  • 150.
    Grinnemo, Karl-Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Garcia, Johan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Taxonomy and Survey of Retransmission-based Partially Reliable Transport Protocols2004Ingår i: Elsevier Computer Communications, ISSN 0140-3664, Vol. 27, nr 15, s. 1441-1452Artikel i tidskrift (Refereegranskat)
1234567 101 - 150 av 301
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf