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  • 251. Ottosson, T.
    et al.
    Sternad, M.
    Ahlén, A.
    Svensson, A.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Towards a 4G IP-based Wireless Systems Proposal2002Konferensbidrag (Refereegranskat)
    Abstract [en]

    A packet switched wireless cellular system with wide area coverage, high throughput and high spectral efficiency is proposed. Smart antennas at both base stations and mobiles improve the antenna gain and improve the signal to interference ratio. The small-scale fading is predicted in both time and frequency and a slotted OFDM radio interface is used, in which time-frequency bins are allocated adaptively to different mobile users, based on their predicted channel quality. This enables efficient scheduling among sectors and users as well as fast adaptive modulation and power control.

    We here estimate the spectral efficiency of the suggested downlink. The resulting channel capacity grows with the number of simultaneous users and with the number of antenna elements in terminals. A high efficiency, around 4 bits/s/Hz, is attained already for moderate numbers of users and terminal antennas. An outline is given of research pursued within the PCC Wireless IP Project to improve and investigate this type of system.

  • 252. Palazzo, S.
    et al.
    Scopigno, R.
    Spirito, M.
    Korpeoglu, I.
    Ulucinar, A. R.
    Moustakas, A. L.
    Galluccio,, L.
    Leonardi, A.
    Fabbri, F.
    Verdone, R.
    Chiasserini, C.F.
    Zanella, A.
    Zorzi, F.
    Ferrus, R.
    Riihijarvi, J.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Cavalcanti de Castro, Marcel
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    DR.11.1: State of the art of research on opportunistic networks, and definition of a common framework for reference models and performance metrics2008Rapport (Refereegranskat)
  • 253.
    Papastergiou, Georgios
    et al.
    Simula Research Laboratory (SRL).
    Grinnemo, Karl-Johan
    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 (from 2013).
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Ros, David
    Simula Research Laboratory (SRL).
    Tuexen, Michael
    Fachhochschule Münster.
    Khademi, Naeem
    University of Oslo.
    Hurtig, Per
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    On the Cost of Using Happy Eyeballs for Transport Protocol Selection2016Ingår i: PROCEEDINGS OF THE ACM, IRTF & ISOC APPLIED NETWORKING RESEARCH WORKSHOP (ANRW'16), Association for Computing Machinery (ACM), 2016, s. 45-51Konferensbidrag (Refereegranskat)
    Abstract [en]

    Concerns have been raised in the past several years that introducing new transport protocols on the Internet has be- come increasingly difficult, not least because there is no agreed-upon way for a source end host to find out if a trans- port protocol is supported all the way to a destination peer. A solution to a similar problem—finding out support for IPv6—has been proposed and is currently being deployed: the Happy Eyeballs (HE) mechanism. HE has also been proposed as an efficient way for an application to select an appropriate transport protocol. Still, there are few, if any, performance evaluations of transport HE. This paper demonstrates that transport HE could indeed be a feasible solution to the transport support problem. The paper evaluates HE between TCP and SCTP using TLS encrypted and unencrypted traffic, and shows that although there is indeed a cost in terms of CPU load to introduce HE, the cost is rel- atively small, especially in comparison with the cost of using TLS encryption. Moreover, our results suggest that HE has a marginal impact on memory usage. Finally, by introduc- ing caching of previous connection attempts, the additional cost of transport HE could be significantly reduced. 

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  • 254.
    Papastergiou, Giorgos
    et al.
    Simula Research Laboratory, Norway.
    Fairhurst, Gorry
    University of Aberdeen, U.K.
    Ros, David
    Simula Research Laboratory, Norway.
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Grinnemo, Karl-Johan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013). Distributed Systems and Communication (DISCO).
    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.
    Tüxen, Michael
    Münster University of Applied Sciences, Steinfurt, Germany.
    Welzl, Michael
    University of Oslo, Norway.
    Damjanovic, Dragana
    Mozilla Corporation, Mountain View, CA, USA.
    Mangiante, Simone
    EMC Corporation, Ovens, Ireland.
    De-Ossifying the Internet Transport Layer: A Survey and Future Perspectives2017Ingår i: IEEE Communications Surveys and Tutorials, ISSN 1553-877X, E-ISSN 1553-877X, Vol. 19, nr 1, s. 619-639Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is widely recognized that the Internet transport layer has become ossified, where further evolution has become hard or even impossible. This is a direct consequence of the ubiquitous deployment of middleboxes that hamper the deployment of new transports, aggravated further by the limited flexibility of the application programming interface (API) typically presented to applications. To tackle this problem, a wide range of solutions have been proposed in the literature, each aiming to address a particular aspect. Yet, no single proposal has emerged that is able to enable evolution of the transport layer. In this paper, after an overview of the main issues and reasons for transport-layer ossification, we survey proposed solutions and discuss their potential and limitations. The survey is divided into five parts, each covering a set of point solutions for a different facet of the problem space: (1) designing middlebox-proof transports; (2) signaling for facilitating middlebox traversal; (3) enhancing the API between the applications and the transport layer; (4) discovering and exploiting end-to-end capabilities; and (5) enabling user-space protocol stacks. Based on this analysis, we then identify further development needs toward an overall solution. We argue that the development of a comprehensive transport layer framework, able to facilitate the integration and cooperation of specialized solutions in an application-independent and flexible way, is a necessary step toward making the Internet transport architecture truly evolvable. To this end, we identify the requirements for such a framework and provide insights for its development

  • 255.
    Parichehreh, Ali
    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).
    Measurement Analysis of TCP Congestion Control Algorithms in LTE Uplink2018Ingår i: 2018 Network Traffic Measurement and Analysis Conference (TMA), New York: IEEE, 2018, s. 1-8Konferensbidrag (Refereegranskat)
    Abstract [en]

    The unprecedented growth of user generated con- tents yielded by the proliferation of social networks applications, cellular based video surveillance and device-to-device (D2D) communication, makes the cellular uplink communication an attractive topic. In this paper we conduct a systematic evaluation and measurement analysis to characterize cellular uplink traffic and compare its interplay with different TCP congestion control algorithms (CCA), namely NewReno, Cubic, and BBR, in both stationary and mobility scenarios. The evaluation encompasses average throughput, average round trip time (RTT), fairness among simultaneous flows, and packet retransmission. The in- tended behavior of BBR has been observed in LTE uplink, but some severe issues such as lack of fairness among simultaneous flows and massive on device packet losses have been observed. It is observed that the lack of fairness among simultaneous flows can unpredictably change the throughput of multi-flow applications.

  • 256.
    Parichehreh, Ali
    et al.
    Ericsson Research, Sweden.
    Moosavi, Reza
    Ericsson Research, Sweden.
    Ramachandra, Pradeepa
    Ericsson Research, Sweden.
    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).
    LTE as a Road Toward 5G: QoS Analysis in Mobility Scenario Using The Monroe Platform2019Ingår i: IEEE Wireless Communications and Networking Conference, WCNC, IEEE, 2019, s. 1-7Konferensbidrag (Refereegranskat)
    Abstract [en]

    Seamless wireless connectivity and low latency com- munication in mobility scenarios are two fundamental require- ments in the fifth generation networks to effectively cover a broader range of use cases such as massive machine type communications and ultra-reliable low-latency communications for new industrial/potential users, as well as enhanced mobile broadband for conventional users.

    In this paper, we aim at measuring certain key performance indicators in mobility scenarios, highlighting some practical inefficiencies that require more careful consideration when de- signing and enhancing mobility features of 5G networks. We investigate the round trip time, uplink throughput and the impact of handover interruption time on these metrics. Our results are based on three months experiment campaign in a mix of rural, suburban, and urban environment using the geographically distributed MONROE platform. Based on the observed discrep- ancies between measured and standardized LTE performance, we conclude the paper with a discussion of techniques that may need more attention for mobility scenarios in fifth generation mobile networks.

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  • 257. Perennou, Tanguy
    et al.
    Bouabdallah, Amine
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Garcia, Johan
    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.
    IP-Level Satellite Link Emulation with KauNet2009Ingår i: International Workshop on Satellite and Space Communications, Siena, Italy: IEEE Communications Society, 2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    Distributed applications and transport protocolscommunicating over a satellite link may react very strongly to conditions specific to that kind of link. Providing an evaluation framework to allow tests of real implementations of such software in that context is quite a challenging task. In this paper we show how the use of the general-purpose KauNet IP-level emulator combined with satellite-specific packet loss patterns can help by reproducing losses and delays experienced on a satellite link with a simple Ethernet LAN setup. We also describe a simple experimentation platform and how a typical demonstration is carried out. Such a platform is an essential tool for developers performing continuous testing as they provide new features for e.g. video codecs or transport-level software like DCCP and its congestion control components

  • 258. Persson, Hannes
    et al.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Ottosson, T
    Evaluation of Soft Information based JPEG2000 Decoders2004Konferensbidrag (Refereegranskat)
    Abstract [en]

    Error free transmission is not always possible in todays nor future's communication networks without making retransmissions. Retransmissions, however, introduce delay. To delay sensitive applications the concept of soft information, i.e. lower layer knowledge about the channel conditions, could reduce the number of retransmissions. This paper explores the utilization of soft information in image decoding. It is not sufficient to treat the soft information and the image decoder separately. By combining soft information and error resilience in the decoder the image quality can be improved. Two modified JPEG2000 image decoders that utilize soft information have been developed. Experiment results with images transmitted over a simulated wireless channel show that a simple decoding process which utilizes soft information can give high gains in image quality. Only marginally higher gains are observed with a more complex decoding process

  • 259. Persson, Hannes
    et al.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Ottosson, Tony
    Utilizing Cross-Layer Information to Improve Performance in JPEG2000 Decoding2007Ingår i: Advances in Multimedia, vol. 2007Artikel i tidskrift (Refereegranskat)
  • 260. Persson, Hannes
    et al.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Ottosson, Tony
    Utilizing Soft Information at the Application Layer: Quality Enhanced JPEG2000 Decoding2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we focus on wireless multimedia communication and investigate how soft information from the physical layer can be used at the application layer. The soft information yields reliability measures for the received bits and is incorporated into two soft input iterative JPEG2000 image decoders. These decoders use the soft information together with the error detection mechanisms in JPEG2000. When errors occur the decoders can increase the image quality and minimize the negative effect of error concealment without making time consuming retransmissions. Experiment results with images transmitted over a simulated wireless channel show that a simple decoding algorithm that utilizes soft information can give high gains in image quality. Only marginally higher gains are observed with a more complex decoding algorithm

  • 261. Persson, Hannes
    et al.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Ottosson, Tony
    Utilizing Soft Information in Image Decoding2003Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper explores the utilization of soft information in image decoding. Error free transmission is not always possible in today's nor future's communication networks without retransmissions. Retransmissions, however, introduce delay. To delay sensitive applications the concept of soft information, i.e. lower layer knowledge about the channel conditions, could reduce the number of retransmissions. It is not sufficient to treat the soft information and the image decoder separately. By combining soft information and the knowledge of the image structure in the decoding process image quality can be improved. A modified JPEG2000 image decoder that utilizes soft information has been developed. Experimental results with images transmitted over a simulated wireless channel show that iterative decoding with soft information can give high gains in image quality.

  • 262.
    Pettersson, John Sören
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för informatik och projektledning. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Johansson-Hidén, Birgitta
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för psykologi. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Clerwall, Christer
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för medie- och kommunikationsvetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Zuccato, Albin
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    HumanIT 20032003Bok (Refereegranskat)
    Abstract [sv]

    The Centre for HumanIT at Karlstad University aims at strengthening research on "the Human aspects of IT". The present volume consists of contributions from seventeen of the researchers and research students involved in HumanIT activities during the last three years. Some chapters report past activities, some are directed more towards future research activities. The contributions span from the linguistic details of Internet chats, over IT-related stress and privacy risk management, to using ICT to alleviate poverty in the large portions of the world where no-one has ever used any kind of IT appliance. The volume also includes an introduction to the Centre itself.The Swedish Knowledge Foundation (KK-Stiftelsen) has supported HumanIT by a special Platform grant to Karlstad University during January 2001-August 2003. The mentors of this Platform project have provided a preface to the present volume.ContentsBridging the Digital Divide - ICT Solutions Supporting Economic and Social Development for the Unseen MajoritySusanne Sundén & Gudrun WicanderReflecting on ICT and Stress: Conceptual Connections and a Suggested ApplicationBirgitta Johansson-Hidén, Erik Wästlund & Susanne WallinLearning and Understanding E-commerceSten CarlssonPrivacy Risk Management in a Business EnvironmentAlbin ZuccatomCrowds: Anonymity for the Mobile InternetChrister Andersson, Simone Fischer-Hübner & Reine LundinInformation Architecture - a Descriptive OverviewChrister ClerwallThe Trade-off Between Latency and Image Quality on the Web: A User PerspectiveKatarina Asplund & Anna BrunströmTowards a Better System for Text Predicition in Mobile PhonesYlva Hård af SegerstadThe Significance of English Content in a Swedish Web ChatMalin SveningssonOzlab - a System Overview with an Account of Two Years of ExperiencesJohn Sören PetterssonEnterprise Modeling Approach for Information Systems EngineeringPrima Gustiene

  • 263.
    Peón-Quirós, Miguel
    et al.
    IMDEA Networks, Madrid, Spain .
    Mancuso, Vincenzo
    IMDEA Networks, Madrid, Spain .
    Comite, Vincenzo
    La Sapienza University, Italy.
    Lutu, Andra
    Simula Research Lab, Norway.
    Alay, Özgü
    Simula Research Lab, Norway.
    Alfredsson, Stefan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Karlsson, Jonas
    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).
    Mellia, Marco
    Politecnico di Torino, Italy.
    Khatouni, Ali Safari
    Politecnico di Torino, Italy.
    Hirsch, Thomas
    Celerway, Oslo, Norway .
    Results from Running an Experiment as a Service Platform for Mobile Networks2017Ingår i: WiNTECH '17 Proceedings of the 11th Workshop on Wireless Network Testbeds, Experimental evaluation & CHaracterization, New York, USA: Association for Computing Machinery (ACM), 2017, s. 9-16Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we present a selection from a vast range of experiments run with MONROE, our experiment as a service platform open to external researchers. We show that the platform can be used to benchmark network performance in a repeatable and controlled manner thanks to the collection of a rich set of geotagged metadata and the execution of discretionary user experiments. Indeed, with the sheer amount of data collected from 12 commercial mobile operators across Europe, MONROE offers an unprecedented opportunity to monitor, analyze and ultimately improve the status of current and future mobile broadband networks. We also show how flexibly the platform allows combining metadata and experimental data series during the experiments or by means of post-processing, and show results produced by our own experiments as well as by external research groups and developers that have been granted access to the platform

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  • 264. Pérennou, Tanguy
    et al.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Hall, Tomas
    Garcia, Johan
    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.
    Emulating Opportunistic Networks with KauNet Triggers2011Ingår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2011Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In opportunistic networks, the availability of an end-to-end path is no longer required. Instead opportunistic networks may take advantage of temporary connectivity opportunities. Opportunistic networks present a demanding environment for network emulation as the traditional emulation setup, where application/transport endpoints only send and receive packets from the network following a black box approach, is no longer applicable. Opportunistic networking protocols and applications additionally need to react to the dynamics of the underlying network beyond what is conveyed through the exchange of packets. In order to support IP-level emulation evaluations of applications and protocols that react to lower layer events, we have proposed the use of emulation triggers. Emulation triggers can emulate arbitrary cross-layer feedback and can be synchronized with other emulation effects. After introducing the design and implementation of triggers in the KauNet emulator, we describe the integration of triggers with the DTN2 reference implementation and illustrate how the functionality can be used to emulate a classical DTN data-mule scenario.

  • 265.
    Rabitsch, Alexander
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Hurtig, Per
    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).
    A Stream-Aware Multipath QUIC Scheduler for Heterogeneous Paths2018Ingår i: EPIQ 2018 - Proceedings of the 2018 Workshop on the Evolution, Performance, and Interoperability of QUIC, Part of CoNEXT 2018, Association for Computing Machinery (ACM), 2018, s. 29-35Konferensbidrag (Refereegranskat)
    Abstract [en]

    Multipath communication is an attractive solution to the increasing need for improving web performance, by allowing devices to aggregate the capacity of different network paths, which can thus lead to lower latencies. However, path asymmetry is known to incur performance issues for multipath transport protocols, such as head-of-line blocking (HoLB), as well as other issues. We propose a proof-of-concept algorithm for a stream-aware packet scheduler for Multipath QUIC, called Stream-Aware Earliest Completion First (SA-ECF). SA-ECF schedules the sending of stream data so that the completion of individual streams are not delayed by slower paths, while providing a fair allocation of the aggregated bandwidth based on stream priority information from HTTP/2. We compare the performance of SA-ECF with other packet schedulers for MPQUIC using measurements from a virtualized testbed. Our results show that SA-ECF is able to handle path heterogeneity well, and can provide lower stream completion times than non stream-aware schedulers.

  • 266.
    Rajiullah, Mohammad
    et al.
    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 ekonomi, kommunikation och IT, Centrum för HumanIT.
    Evaluation and Analysis of NR-SACKs based PR-SCTP2012Konferensbidrag (Refereegranskat)
  • 267.
    Rajiullah, Mohammad
    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. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    On the Effectiveness of PR-SCTP in Networks with Competing Traffic2011Ingår i: 2011 IEEE SYMPOSIUM ON COMPUTERS AND COMMUNICATIONS (ISCC), Corfu, Greece: IEEE conference proceedings, 2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    PR-SCTP is an extension to SCTP for partial reliability that enables a content sensitive transport service where the reliability of messages can be individually controlled. In previous work, PR-SCTP has been applied for prioritization of messages and trading of reliability against timeliness for applications such as real time video streaming, IPTV transmission, SIP signaling, and syslog. As compared to TCP, it has been shown to provide significant reductions in message transfer delay and gains in application performance. Much of the previous work has, however, considered artificial loss scenarios without competing traffic. Experiments presented in this paper show that although PR-SCTP clearly outperforms TCP in artificial loss scenarios, the performance gain is not as evident in scenarios where PR-SCTP shares a bottleneck link with competing traffic. Our analysis shows that inefficiencies in the \emph{forward\_tsn} mechanism of PR-SCTP, overhead due to small messages, and a higher loss rate per byte encountered by PR-SCTP are contributing factors to the reduced performance when network resources are shared. Finally, a proposal for a more efficient \emph{forward\_tsn} mechanism is introduced

  • 268.
    Rajiullah, Mohammad
    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.
    Optimizing PR-SCTP Performance using NR-SACKs2012Ingår i: 2012 2nd Baltic Congress on Future Internet Communications, Vilnius: IEEE conference proceedings, 2012, s. 222-229Konferensbidrag (Refereegranskat)
    Abstract [en]

    A partially reliable extension of SCTP, PR-SCTP, has been considered as a candidate for prioritizing content sensitive traffic at the transport layer. PR-SCTP offers a flexible QoS trade-off between timeliness and reliability. Several applications such as streaming multimedia, IPTV transmission, and SIP signaling have been shown to benefit from this. Our previous work, however, suggests that the performance gain can be very much reduced in a network with competing traffic. One of the most important factors in this case is the inefficiency in the forward_tsn mechanism in PR-SCTP. In this paper, we thoroughly examine the forward_tsn inefficiency and propose a solution to overcome it that takes advantage of the NR-SACKs mechanism available in FreeBSD. Moreover, we implement and evaluate the proposed solution. Our initial set of results show a significant performance gain for PR-SCTP with NR-SACKs. In some scenarios the average message transfer delay is reduced by more than 75%.

  • 269.
    Rajiullah, Mohammad
    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.
    Performance Optimization of PR-SCTP for Small Messages2011Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Stream Control Transmission Protocol (SCTP) was defined by the IETF Signaling Transport (SIGTRAN) working group to transport SS7 signaling traffic over the Internet. SCTP can also be used as a general purpose message based transport protocol. A partially reliable extension of SCTP, PR-SCTP has been considered as a candidate for prioritizing content sensitive traffic at the transport layer. By using PR-SCTP, it is possible to define various reliability policies for different application messages. An application chooses (re)transmission policy on a per message basis. A special control chunk called Forward Cumulative TSN (forward_tsn) is used to provide partial reliability. When a message is abandoned by PR-SCTP, for instance the associated lifetime is over, a forward_tsn chunk is sent to the receiver to tell it not to expect that particular message any more. PR-SCTP can offer a trade-off between timeliness and reliability for application messages when network resources become congested. Several applications such as streaming multimedia, IPTV transmission, and SIP signaling have been shown to benefit from this. Our previous work, however, suggests that the performance gain can be very limited in a network with competing traffic when message sizes are small. In this case, the most important factor is the inefficiency in the forward_tsn mechanism of PR-SCTP. In this work, we examine the forward_tsn inefficiency in detail and propose several solutions to overcome it. Moreover, we implement and evaluate one of the proposed solutions that takes advantage of the Non-Renegable Selective Acknowledgement (NR-SACK) mechanism available in the current FreeBSD OS. A receiver can use NR-SACKs to selectively acknowledge out-of-order but non-renegable data. Our results show a significant performance gain for PR-SCTP with NR-SACKs for small messages. In some scenarios the average message transfer delay is reduced by more than 75%.

  • 270.
    Rajiullah, Mohammad
    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. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Lindskog, Stefan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Priority Based Delivery of PR-SCTP Messages in a Syslog Context2011Ingår i: Access networks, Springer, 2011, s. 299-310Konferensbidrag (Refereegranskat)
    Abstract [en]

    Unquestionably, syslog provides the most popular and easily manageable computer system logging environment. In a computer network, syslog messages are used for several purposes such as for optimizing system performance, logging user's actions and investigating malicious activities. Due to all these essential utilities, a competent transport service for syslog messages becomes important. Most of the current syslog implementations use either the unreliable UDP protocol or the more costly reliable TCP protocol. Neither of these protocols can provide both timeliness and reliability, while transporting inherently prioritized syslog messages in a congested network. In this paper, we both propose and evaluate the use of PR-SCTP, an existing partial reliability extension of the SCTP transport protocol, as a candidate transport service for the next generation syslog standard. In our emulation based experimental results, PR-SCTP shows better performance than TOP in terms of average delay for message transfer. Furthermore, PR-SCTP exhibits less average packet loss than UDP. In both cases, PR-SCTP exploits priority properties of syslog messages during loss recovery.

  • 271.
    Rajiullah, Mohammad
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Petlund, Andreas
    Simula research lab.
    Reducing Internet Transport Latency for Thin Streams and Short Flows2013Ingår i: Future Network & Mobile Summit 2013, 2013Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The present Internet limits the performance of applications that need real- time interaction. This is in part because the design of the network has been optimised to boost throughput, maximising efficiency for bulk applications. However, changes in use have resulted in that an increasing number of applications now depend on timely delivery. One of the targets of the RITE project is to reduce internet transport latency in support of such applications. Initial results from the project on how end nodes can be optimized for more timely error recovery are presented in this poster. 

  • 272.
    Rajiullah, Mohammad
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Hurtig, Per
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Petlund, Andreas
    Simula Research Laboratory.
    Welzl, Michael
    Oslo University.
    An Evaluation of Tail Loss Recovery Mechanisms for TCP2015Ingår i: Computer communication review, ISSN 0146-4833, E-ISSN 1943-5819, Vol. 45, nr 1, s. 6-11Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Interactive applications do not require more bandwidth to go faster. Instead, they require less latency. Unfortunately, the current design of transport protocols such as TCP limits possible latency reductions. In this paper we evaluate and compare different loss recovery enhancements to fight tail loss latency. The two recently proposed mechanisms "RTO Restart" (RTOR) and "Tail Loss Probe" (TLP) as well as a new mechanism that applies the logic of RTOR to the TLP timer management (TLPR) are considered. The results show that the relative performance of RTOR and TLP when tail loss occurs is scenario dependent, but with TLP having potentially larger gains. The TLPR mechanism reaps the benefits of both approaches and in most scenarios it shows the best performance.

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  • 273.
    Rajiullah, Mohammad
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Lundin, Reine
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Lindskog, Stefan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Performance Analysis and Improvement of PR-SCTP for Small Messages2013Ingår i: Computer Networks, ISSN 1389-1286, Vol. 57, nr 18, s. 3967-3986Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    PR-SCTP, a partially reliable extension of SCTP, provides a flexible QoS trade-off between timeliness and reliability for application traffic. However, the performance of PR-SCTP can be reduced due to certain traffic characteristics and network scenarios. Previously, we proposed a NR-SACK based optimization for PR-SCTP. In this work we extensively evaluate and analyze the performance of PR-SCTP with NR-SACKs using different network scenarios. Moreover, we compare the performance of our NR-SACK based PR-SCTP with existing transport protocols for syslog traffic. In the evaluation, we use real syslog traces from an operational syslog system. The results indicate that NR-SACKs based PR-SCTP significantly improves the overall message transfer delay as compared to SCTP and TCP.

  • 274.
    Rajiullah, Mohammad
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Lundin, Reine
    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.
    Lindskog, Stefan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Data Modeling and Transport of Syslog Messages2011Konferensbidrag (Refereegranskat)
  • 275.
    Rajiullah, Mohammad
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Lundin, Reine
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Lindskog, Stefan
    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.
    Syslog Performance: Data Modeling and Transport2011Ingår i: Proceedings of the 3rd International Workshop on Security and Communication Networks (IWSCN 2011), Norway: IEEE Press, 2011, s. 31-37Konferensbidrag (Refereegranskat)
    Abstract [en]

    Syslog is one of the basic methods for event logging in computer networks. Log messages that are generated by syslog can be used for a number of purposes, including optimizing system performance, system auditing, and investigating malicious activities in a computer network. Considering all these attractive uses, both timeliness and reliability is needed when syslog messages are transported over a network. The unreliable transport protocol UDP was specified in the original syslog specification; later a reliable transport service based on TCP was also proposed. However, TCP is a costly alternative in terms of delay. In our previous work, we introduced the partially reliable extension of SCTP, PR-SCTP, as a transport service for syslog, trading reliability against timeliness by prioritizing syslog messages. In this work, we first model syslog data using real syslog traces from an operational network. The model is then used as input in the performance evaluation of PR-SCTP. In the experiments, real congestion is introduced in the network by running several competing flows. Although PR-SCTP clearly outperformed TCP and SCTP in our previous work, our present evaluations show that PR-SCTP performance is largely influenced by the syslog data size characteristics

  • 276.
    Rajiullah, Mohammad
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Lutu, Andra
    Telefonica Research, Spain.
    Ali, Safari Khatouni
    Dalhousie University, Canada.
    Fida, Mah-rukh
    Simula Metropolitan, Norway.
    Mellia, Marco
    Politecnico di Torino, Italy.
    Alay, Özgü
    Simula Metropolitan, Norway.
    Brunström, Anna
    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).
    Mancuso, Vincenzo
    IMDEA Networks Institute, Spain.
    Web Experience in Mobile Networks: Lessons from Two Million Page Visits2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    Measuring and characterizing web page performance is a challeng- ing task. When it comes to the mobile world, the highly varying technology characteristics coupled with the opaque network con- figuration make it even more difficult. Aiming at reproducibility, we present a large scale empirical study of web page performance collected in eleven commercial mobile networks spanning four countries. By digging into measurement from nearly two million web browsing sessions, we shed light on the impact of different web protocols, browsers, and mobile technologies on the web per- formance. We found that the impact of mobile broadband access is sizeable. For example, the median page load time using mobile broadband increases by a third compared to wired access. Mobility clearly stresses the system, with handover causing the most evi- dent performance penalties. Contrariwise, our measurements show that the adoption of HTTP/2 and QUIC has practically negligible impact. To understand the intertwining of all parameters, we adopt state-of-the-art statistical methods to identify the significance of different factors on the web performance. Our analysis confirms the importance of access technology and mobility context as well as webpage composition and browser. Our work highlights the importance of large-scale measurements. Even with our controlled setup, the complexity of the mobile web ecosystem is challenging to untangle. For this, we are releasing the dataset as open data for validation and further research.

  • 277.
    Rajiullah, Mohammad
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Mohideen, A. C.
    University of Aberdeen, UK.
    Weinrank, Felix
    Münster University of Applied Sciences.
    Seechi, Raffaello
    University of Aberdeen, UK.
    Fairhurst, Gorry
    University of Aberdeen, UK.
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Understanding Multistreaming for Web Traffic: An Experimental Study2017Ingår i: 16th International IFIP TC6 Networking Conference, Networking 2017 / [ed] Gunnar Karlsson, Anna Brunstrom, Hongbo Jiang, Tilman Wolf, Viktoria Fodor, IEEE, 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper explores the design trade-offs needed for an Internet transport protocol to effectively support web access over HTTP/1.1. It explores use of a multistreaming transport protocol mechanism and studies these using a practical methodology utilising the transport features of TCP and SCTP. This is used to evaluate the relative benefit of key transport mechanisms and analyse how these impact web access performance. Our conclusions help identify the root causes of performance impairments and suggest appropriate choices when selecting a suitable transport protocol.

  • 278.
    Robert, Rémi
    et al.
    Ericsson AB.
    Atxutegi, Eneko Narbona
    University of the Basque Country, Spain.
    Arvidsson, Åke
    Kristianstad University, Sweden & Ericsson AB.
    Liberal, Fidel
    University of the Basque Country, Spain.
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Grinnemo, Karl-Johan
    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 (from 2013).
    Behaviour of common TCP variants over LTE2016Ingår i: Global Communications Conference (GLOBECOM), 2016 IEEE, IEEE, 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper aims at increasing our understanding of the behaviour of some of the major TCP variants in LTE networks. A simulation study on the behaviour of seven TCP variants is performed. The evolution of the throughput, congestion window and queuing delay are studied for four scenarios with different network loads and flow types. Our measurements show that, in average radio conditions, most variants are able to quickly reach full link utilisation. However, to achieve the same throughput, they create different amounts of queuing delay. On the one hand, loss-based algorithms tend to completely fill the queue, creating huge queuing delays and inducing packet losses. On the other hand, delay-based variants manage to limit the queue size and decrease the amount of packets dropped by the eNodeB, but struggle to reach the maximum throughput in some circumstances.

  • 279.
    Santos, Ricardo
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Bozakov, Zdravko
    DELL EMC Research Europe, Ovens, Ireland.
    Mangiante, Simone
    DELL EMC Research Europe, Ovens, Ireland.
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Kassler, Andreas
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    A NEAT framework for application-awareness in SDN environments2017Ingår i: 2017 IFIP Networking Conference (IFIP Networking) and Workshops, IEEE, 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    Software-Defined Networking (SDN) has led to a paradigm shift in the way how networks are managed and operated. In SDN environments the data plane forwarding rules are managed by logically centralized controllers operating on global view of the network. Today, SDN controllers typically posses little insight about the requirements of the applications executed on the end-hosts. Consequently, they rely on heuristics to implement traffic engineering or QoS support. In this work, we propose a framework for application-awareness in SDN environments where the end-hosts provide a generic interface for the SDN controllers to interact with. As a result, SDN controllers may enhance the end-host’s view of the attached network and deploy policies into the edge of the network. Further, controllers may obtain information about the specific requirements of the deployed applications. Our demonstration extends the OpenDaylight SDN controller to enable it to interact with end-hosts running a novel networking stack called NEAT. We demonstrate a scenario in which the controller distributes policies and path information to manage bulk and low-latency flows. 

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  • 280. Schneyer, S.
    et al.
    Garcia, Johan
    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.
    Asplund, Katarina
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    PRTP: A Partially Reliable Transport Protocol for Multimedia Applications1999Konferensbidrag (Refereegranskat)
  • 281.
    Schneyer, Sean
    et al.
    Karlstads universitet, Institutionen för informationsteknologi.
    Garcia, Johan
    Karlstads universitet, Institutionen för informationsteknologi.
    Brunstrom, Anna
    Karlstads universitet, Institutionen för informationsteknologi.
    Asplund, Katarina
    Karlstads universitet, Institutionen för informationsteknologi.
    PRTP: A Partially Reliable Transport Protocol for Multimedia Applications1999Ingår i: Proceedings of ISIMADE, 1999Konferensbidrag (Övrigt vetenskapligt)
  • 282. Sternad, M.
    et al.
    Svensson, T.
    Ottosson, T.
    Ahlen, A.
    Svensson, A.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Towards Systems Beyond 3G Based on Adaptive OFDMA Transmission2007Ingår i: Proceedings of the IEEE, Volume 95, Issue 12, Page(s):2432 - 2455Artikel i tidskrift (Refereegranskat)
  • 283. Svensson, A.
    et al.
    Ahlén, A.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Ottosson, T.
    Sternad, M.
    An OFDM Based System Proposal for 4G Downlinks2003Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we describe an OFDM based 4G downlink for a wide area coverage and high mobility system. User data are multiplexed and OFDM modulated such that the user with the best predicted channel conditions are always using the channel. This user employs the linear modulation scheme that maximizes the spectral efficiency. We show that the system obtains a sector capacity that is significantly better than current 3G systems.

    Various combinations of OFDM and CDMA are also discussed and it is concluded that it is difficult to motivate the significantly increased complexity of such schemes. Moreover, we also doubt that these combinations can increase spectral efficiency when predicted channel information is utilized at the transmitter

  • 284.
    Söderman, Pehr
    et al.
    KTH Royal Institute of Technology.
    Eklund, Johan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Grinnemo, Karl-Johan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Hidell, Marcus
    KTH.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Handover in the Wild: The Feasibility of Vertical Handover in Commodity Smartphones2013Ingår i: Proceedings of the IEEE International Conference on Communications (ICC), IEEE, 2013, s. 6401-6406Konferensbidrag (Refereegranskat)
    Abstract [en]

    Today commodity mobile devices are frequently equipped with two wireless access technologies,WiFi and 3G/4G. To enable continuous connectivity it is vital that these terminals provide for vertical handover between different technologies. Particularly, they should provide a vertical handover that complies with the timeliness requirements of soft real-time applications. Considering aspects such as cost and ease-of-deployment, ap- plication neutrality, and, not least, the emergence of transport protocols that support multi-homing such as mobile SCTP and multi-path TCP, we think it would be beneficial to handle vertical handover in the transport layer of the mobile terminal. This paper demonstrates through several real-world experiments, the feasibility of using a lightweight vertical handover scheme in smart mobile terminals for live video streaming. The vertical handover criteria is based on the received signal strength. Our experiments suggest that the scheme indeed provides for seamless vertical handover at walking speed – our target scenario. However, the experiments also suggest that the scheme gives significant reductions in handover time, as compared to mobile SCTP without improvements, at higher speeds.

  • 285.
    Söderman, Pehr
    et al.
    The KTH Royal Institute of Technology, Communication: Infrastructure and Services.
    Grinnemo, Karl-Johan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Cheimonidis, Georgios
    PrimeTel PLC, Nicosia, CYPRUS.
    Ismailov, Yuri
    Ericsson Research, Stockholm, SWEDEN.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    An SCTP-based Mobility Management Framework for Smartphones and Tablets2012Ingår i: Advanced Information Networking and Applications Workshops (WAINA), 2012, 26th International Conference on, IEEE Press, 2012, s. 1107-1112Konferensbidrag (Refereegranskat)
    Abstract [en]

    The current wireless network landscape comprisesa plethora of technologies including WLAN, WiMAX and 3G, and not much speaks for a radical change of the state of affairs in the near future. In light of this, it becomes pivotal to facilitate vertical handover between different types of wireless networks. Although, a large number of vertical handover schemes have been proposed in the past several years, the majority of the proposed solutions reside in the network and/or link layer– e.g., Mobile IP and various IEEE 802.21 schemes – and relatively few are transport-layer solutions. However, we think transport-layer solutions many times are attractive, particularly in cases where there are no economic incentives to upgrade the existing network infrastructure. To this end, we have designed a lightweight, transport-level mobility framework based on the Stream Control Transmission Protocol (SCTP) and its extension for dynamic address reconfiguration. The framework API has been kept very small and closely aligned with the SCTP sockets extensions, which makes porting of existing applications fairly straightforward. To demonstrate its usefulness for low-power tablets and smart phones, we have implemented our frameworkon a Motorola Xoom tablet running the Android OS. Our initial proof-of-concept experiment gave satisfactory results witha handover performance on par with that of other vertical handover solutions.

  • 286.
    Söderman, Pehr
    et al.
    School of Information and Communication Technology, KTH Royal Institute of Technology.
    Hidell, Markus
    School of Information and Communication Technology, KTH Royal Institute of Technology.
    Grinnemo, Karl-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.
    SCTP: Fast Transport Layer Vertical Handover in Android Mobile Devices2012Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Contemporary mobile devices such as smartphones and tablets are increasingly equipped with multiple network interfaces that enable automatic vertical handover between heterogeneous wireless networks including WiFi and cellular 3G and 4G networks. However, the employed vertical handover schemes are mostly quite simple, and incur non-negligible service disruptions to ongoing sessions, e.g., video streaming and live conferencing sessions. A number of improved mobility management frameworks for these lightweight mobile devices have been proposed in the past recent years. Although these may result in negligible service disruptions, the vast majority of them are network- or integrated network- and link-layer based, and require support in the infrastructure to be successfully deployed. In this paper, we demonstrate, through the use of an Android-based mobility framework, the feasibility of using an infrastructure-independent, transport-level vertical handover scheme on a smartphone for an application as demanding as video streaming. Particularly, we show that a standardized mobility solution based on the Stream Control Transmission Protocol (SCTP) and its extension for Dynamic Address Reconfiguration (DAR) incurs a service disruption on par with comparable proposed network- and link- layer solutions.

  • 287.
    Söderman, Pehr
    et al.
    The KTH Royal Institute of Technology.
    Hidell, Markus
    The KTH Royal Institute of Technology.
    Grinnemo, Karl-Johan
    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.
    Sub-Second Transport Layer Vertical Handover Using mSCTP in Android Mobile Devices2012Ingår i: 2012 International Symposium on Wireless Communication Systems (ISWCS 2012), IEEE Press, 2012, s. 661-665Konferensbidrag (Refereegranskat)
    Abstract [en]

    Contemporary mobile devices such as smartphones and tablets are increasingly equipped with multiple network interfaces that enable automatic vertical handover between heterogeneous wireless networks including WiFi and cellular 3G and 4G networks. However, the employed vertical handover schemes are mostly quite simple, and incur non-negligible service disruptions to ongoing sessions, e.g., video streaming and live conferencing sessions. A number of improved mobility management frameworks for these lightweight mobile devices have been proposed in the past recent years. Although these may result in negligible service disruptions, the vast majority of them are network- or integrated network- and link-layer based, and require support in the infrastructure to be successfully deployed. This paper demonstrates the feasibility of using an infrastructure-independent, transport-level vertical handover scheme on a smartphone for an application as demanding as video streaming. In our study, we used a previously developed Android-based mobility framework. The study shows that astandardized mobility solution based on the Stream ControlTransmission Protocol (SCTP) and its extension for DynamicAddress Reconfiguration (DAR), incurs a service disruption on par with comparable proposed network- and link-layer solutions.

  • 288.
    Weinrank, Felix
    et al.
    Münster University of Applied Sciences.
    Grinnemo, Karl-Johan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Bozakov, Zdravko
    Dell EMC Research Europe.
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Dreibholz, Thomas
    Simula Research Laboratory.
    Fairhurst, Gorry
    University of Aberdeen.
    Hurtig, Per
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Khademi, Naeem
    University of Oslo.
    Tüxen, Michael
    Münster University of Applied Sciences.
    A NEAT Way to Browse the Web2017Ingår i: Applied Networking Research Workshop (ANRW) 2017, Prague, Czech Republic, July 15, 2017., Thomas Dreibholz , 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    There is a growing concern that the Internet transport layer has become ossified in the face of emerging novel applications, and that further evolution has become very difficult. The NEAT system is a novel and evolvable transport system that decouples applications from the underlying transport layer and network services. In so doing, it facilitates dynamic transport selection. This demo shows how the NEAT system is able to dynamically select the most appropriate transport solution for the Mozilla Firefox web browser.

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  • 289.
    Wennström (Klockar), Annika
    et al.
    Karlstads universitet, Institutionen för informationsteknologi.
    Alfredsson, Stefan
    Karlstads universitet, Institutionen för informationsteknologi.
    Brunstrom, Anna
    Karlstads universitet, Institutionen för informationsteknologi.
    TCP over Wireless Networks2004Rapport (Övrigt vetenskapligt)
    Abstract [en]

    This report provides an overview of common wireless network technologies used today, with emphasis on data transmission. Wireless networks are becoming increasingly used for Internet communications. As discussed in the report, the TCP protocol may experience performance degradations over wireless networks, due to non-congestion related packet loss and varying round trip times. To this end, many enhancements for TCP to the link and transport layer have been proposed. A selection of these are presented and discussed in relation to the wireless network technologies.

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  • 290.
    Wennström (Klockar), Annika
    et al.
    Karlstads universitet, Institutionen för informationsteknologi.
    Brunstrom, Anna
    Karlstads universitet, Institutionen för informationsteknologi.
    Garcia, Johan
    Karlstads universitet, Institutionen för informationsteknologi.
    Gustafsson, Jan H.
    Telia Mobile AB, Karlstad, Sweden.
    A GSM/GPRS Testbed for TCP Performance Evaluation2002Ingår i: Proceedings of International Workshop on Wired/Wireless Internet Communications / [ed] Hamid R. Arabnia, Youngsong Mun, CSREA Press, 2002, s. 19-26Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Investigating the wireless Internet is a nontrivial task dueto the complexity of wireless systems and the many protocolinteractions that appear. In this paper we present a measurementtestbed that allows us to investigate the performanceof Internet traffic over a real GSM network but witha controlled radio environment and traffic load. A detailedperformance evaluation of TCP over GSM is presented. Arange of radio conditions are considered with a focus on theinteraction between TCP and the GSM link layer. With respectto efficient protocol layer interaction, the results showthat high variability in round trip times is more problematicthan poor radio conditions. How the testbed has been extendedfor GPRS and planned measurements for this systemare also discussed.

  • 291.
    Wennström (Klockar), Annika
    et al.
    Karlstads universitet, Institutionen för informationsteknologi.
    Brunström, Anna
    Karlstads universitet, Institutionen för informationsteknologi.
    TCP over GPRS: The Effect of Preemption2003Konferensbidrag (Refereegranskat)
    Abstract [en]

    GPRS extends the widely deployed GSM system with a more efficient wireless Internet access. In this paper we present measurements of GPRS traffic when preempted by circuit-switched calls. The results indicate that TCP performance is degraded more than necessary, as buffered data is flushed immediately when the GPRS traffic is preempted. The time required for error recovery is considerable also for very short preemtion periods.

  • 292.
    Wennström (Klockar), Annika
    et al.
    Karlstads universitet, Institutionen för informationsteknologi.
    Brunström, Anna
    Karlstads universitet, Institutionen för informationsteknologi.
    Rendón, Juan
    Impact of GPRS buffering on TCP performance2004Ingår i: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, IEE Electronics Letters Volume 40, Issue 20, 30 Sept. 2004 Page(s): 1279-1281, Vol. 40, nr 20, s. 1279-1281Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    GPRS networks, excessive buffering has a negative effect on TCP as the round trip times become very long. Measurements with different buffer settings indicate that the queueing delay can be reduced by orders of magnitude with a smaller buffer, without significantly degrading TCP throughput. The measurements are conducted in a GPRS testbed consisting of real network nodes.

  • 293.
    Wennström (Klockar), Annika
    et al.
    Karlstads universitet, Institutionen för informationsteknologi.
    Brunström, Anna
    Karlstads universitet, Institutionen för informationsteknologi.
    Rendón, Juan
    Technology Dept., Pompeu Fabra University, Barcelona, Spain.
    Gustafsson, J. H.
    Telia Mobile AB, Karlstad, Sweden.
    The Impact of Preemptive Priority in GPRS on TCP Performance: A Measurement Study2004Ingår i: The first International Workshop on TCP and MAC Protocols in Wireless and Wired Networks, 2004, s. 430-436Konferensbidrag (Refereegranskat)
    Abstract [en]

    GPRS extends the widely deployed GSM system with a more effecient wireless Internet access. In this paper we investigate how a TCP transmission over GPRS is affected when it loses all its resources due to preemption by circuit-switched calls with higher priority. The results indicate that TCP performance is degraded more than necessary, as buffered data is flushed immediately when the GPRS traffic is preempted. The time required for error recovery is considerable also for very short preemption periods. The situation would improve if data was buffered during preemption and if the data was transmitted immediately as GPRS resources become available again.

  • 294.
    Wennström (Klockar), Annika
    et al.
    Karlstads universitet, Institutionen för informationsteknologi.
    Brunström, Anna
    Karlstads universitet, Institutionen för informationsteknologi.
    Rendón, Juan
    Technology Dept., Pompeu Fabra University, Barcelona, Spain.
    Gustafsson, Jan H.
    Telia Mobile, Karlstad, Sweden.
    A GPRS Testbed for TCP Performance Measurements2002Ingår i: 4th International Workshop on Mobile and Wireless Communications Network, IEEE conference proceedings, 2002, s. 320-324Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper a GPRS measurement testbed for TCP performance evaluation is presented. Unlike simulations and live measurements, the testbed combines the use of real network equipment and protocol implementations with a precise control over radio channel conditions. Some initial TCP measurements obtained with the GPRS testbed are also presented. The effect of varying numbers of PDCH and of buffering in the GPRS system is investigated.

  • 295.
    Wennström (Klockar), Annika
    et al.
    Karlstads universitet, Institutionen för informationsteknologi.
    Brunström, Anna
    Karlstads universitet, Institutionen för informationsteknologi.
    Rendón, Juan
    Gustafsson, Jan H.
    The Impact of GPRS Buffering on TCP Performance2003Rapport (Refereegranskat)
    Abstract [en]

    Wireless Internet access over GPRS, the packet-oriented extension to GSM, provides for higher data rates and more efficient network utilization compared to circuit-switched access. The performance of the Internet protocols in GPRS is dependent not only on the quality of the radio link, but also on the buffering in the GPRS network. In this paper we investigate the impact of buffering on TCP performance. Measurements are conducted in a GPRS testbed consisting of real network nodes with real protocol implementations. When the buffer between the fixed and the wireless networks is large, then the round trip times may become very long. Measurements with different buffer settings indicate that the buffer could be decreased in order to reduce the queuing delay, without degrading the throughput. Measurements of concurrent packet- and circuit-switched traffic show that buffered data is flushed immediately as the GPRS traffic is preempted by circuit-switched calls. When resources are available again, the lost data must be retransmitted. In many cases this could be avoided by guarding the data with a timer

  • 296.
    Wennström (Klockar), Annika
    et al.
    Karlstads universitet, Institutionen för informationsteknologi.
    Garcia, Johan
    Karlstads universitet, Institutionen för informationsteknologi.
    Brunström, Anna
    Karlstads universitet, Institutionen för informationsteknologi.
    Gustafsson, Jan H.
    Telia Mobile AB, Karlstad, Sweden.
    TCP and GSM Link Layer Interactions: Implications for the Wireless Internet2001Ingår i: IEEE VTS 53rd Vehicular Technology Conference, 2001, IEEE conference proceedings, 2001, s. 2198-2202Konferensbidrag (Refereegranskat)
    Abstract [en]

    The demand for wireless access to the Internet has grown rapidly making the performance of TCP in wireless environments an important issue. We present experimental measurements of the performance of TCP over GSM. The measurements were captured over a real GSM network connected to a controlled radio environment. A range of radio conditions were considered with a focus on the interaction between TCP and the GSM link layer. Even for very poor radio conditions, only neglible negative interaction effects were found.

  • 297.
    Yedugundla, Kiran
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Hurtig, Per
    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).
    Handling Packet Losses in Cloud-Based Application Traffic2019Ingår i: Proceedings of the 9th International Conference on Cloud Computing and Services Science - Volume 1: CLOSER, SciTePress, 2019, s. 111-119Konferensbidrag (Refereegranskat)
    Abstract [en]

    Internet traffic is comprised of data flows from various applications with unique traffic characteristics. For many cloud applications, end-to-end latency is a primary factor affecting the perceived user experience. As packet losses cause delays in the communication they impact user experience, making efficient handling of packet losses an important function of transport layer protocols. Multipath TCP (MPTCP) is a modification to TCP that enables simultaneous use of several paths for a TCP flow. MPTCP is known to improve throughput. However, the performance of MPTCP is not optimal when handling certain loss scenarios. Efficient packet loss recovery is thus important to achieve desirable flow completion times for interactive cloud-based applications. In this paper we evaluate the performance of MPTCP in handling tail losses using traffic traces from various cloud-based applications. Tail losses, losses that occur at the end of a flow or traffic burst, are particularly challenging from a latency perspective as they are difficult to detect and recover in a timely manner. Tail losses in TCP are handled by using a tail loss probe (TLP) mechanism which was adapted to MPTCP from TCP. We investigate the performance of TLP in MPTCP, comparing the standard implementation to a recently proposed, less conservative approach. Our experimental results show that a less conservative implementation of TLP performs significantly better than the standard implementation in handling tail losses, reducing the average burst completion time of cloud based applications when tail loss occurs by up to 50% in certain cases.

  • 298.
    Yedugundla, Kiran
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Hurtig, Per
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Multipath TCP: Can it Reduce Transport Latency for Web Traffic?2015Konferensbidrag (Refereegranskat)
  • 299.
    Yedugundla, Kiran
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Hurtig, Per
    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.
    Probe or Wait: Handling tail losses using Multipath TCP2017Ingår i: 2017 IFIP Networking Conference (IFIP Networking) and Workshops, IEEE, 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    Packet losses are known to affect the performance of latency sensitive Internet applications such as media streaming and gaming. Transport protocols recover from packet loss in order to provide reliable end-to-end communication and improve user experience. The efficiency of loss recovery mechanisms influences the completion time of flows, and thus also the application performance as perceived by the end user. In this paper we focus on state-of-the-art loss recovery mechanisms for TCP and Multipath TCP. We use controlled tail loss scenarios to evaluate the performance of loss recovery mechanisms and, based on the observations, we propose an enhanced tail loss recovery mechanism for Multipath TCP, to improve the loss recovery time. Our experiment results, using the Linux Multipath TCP implementation, show consistent end-to-end latency performance improvement in considered scenarios.

  • 300.
    Yedugundla, Venkata Kiran
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Ferlin, Simone
    Simula Research Laboratory, Oslo, Norway.
    Dreibholz, Thomas
    Simula Research Laboratory, Oslo, Norway.
    Alay, Özgü
    Simula Research Laboratory, Oslo, Norway.
    Kuhn, Nicolas
    IMT Télécom Bretagne, IRISA, Cesson-Sévigné, France.
    Hurtig, Per
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Is Multi-Path Transport Suitable for Latency Sensitive Traffic?2016Ingår i: Computer Networks, ISSN 1389-1286, E-ISSN 1872-7069, Vol. 105, s. 1-21Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper assesses whether multi-path communication can help latency-sensitive applications to satisfy the requirements of their users. We consider Concurrent Multi-path Transfer for SCTP (CMT-SCTP) and Multi-path TCP (MPTCP) and evaluate their proficiency in transporting video, gaming, and web traffic over combinations of WLAN and 3G interfaces. To ensure the validity of our evaluation, several experimental approaches were used including simulation, emulation and live experiments. When paths are symmetric in terms of capacity, delay and loss rate, we find that the experienced latency is significantly reduced, compared to using a single path. Using multiple asymmetric paths does not affect latency - applications do not experience any increase or decrease, but might benefit from other advantages of multi-path communication. In the light of our conclusions, multi-path transport is suitable for latency-sensitive traffic and mature enough to be widely deployed. 

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