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  • 1.
    Abbas, Muhammad Tahir
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Eklund, Johan
    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).
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Impact of Tunable Parameters in NB-IoT Stack onthe Energy Consumption2019Ingår i: Proceedings of Fifteenth Swedish National Computer Networking Workshop (SNCNW), 2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper studies the impact of tunable parametersin the NB-IoT stack on the energy consumption of a user equipment(UE), e.g., a wireless sensor. NB-IoT is designed to enablemassive machine-type communications for UE while providing abattery lifetime of up to 10 years. To save battery power, most oftime the UE is in dormant state and unreachable. Still, duringthe CONNECTED and IDLE state, correct tuning of criticalparameters, like Discontinuous reception (DRX), and extendedDiscontinuous reception (eDRX), respectively, are essential to savebattery power. Moreover, the DRX and eDRX actions relate tovarious parameters which are needed to be tuned in order toachieve a required UE battery lifetime. The objective of thispaper is to observe the influence of an appropriate tuning ofthese parameters to reduce the risk of an early battery drainage

  • 2.
    Abrahamsson, Henrik
    et al.
    RISE SICS.
    Abdesslem, Fehmi Ben
    RISE SICS.
    Ahlgren, Bengt
    RISE SICS.
    Björkman, Mats
    Mälardalen University.
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Marsh, Ian
    RISE SICS.
    Selecting Operator in 3G/4G Networks for Time-Critical C-ITS Applications2018Konferensbidrag (Refereegranskat)
  • 3.
    Abrahamsson, Henrik
    et al.
    RISE SICS, Stockholm, Sweden.
    Ben Abdesslem, Fehmi
    RISE SICS, Stockholm, Sweden.
    Ahlgren, Bengt
    RISE SICS, Stockholm, Sweden.
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Marsh, Ian
    RISE SICS, Stockholm, Sweden.
    Bjorkman, Mats
    Mälardalens högskola.
    Connected Vehicles in Cellular Networks: Multi-access versus Single-access Performance2018Ingår i: 2018 NETWORK TRAFFIC MEASUREMENT AND ANALYSIS CONFERENCE (TMA), IEEE, 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Connected vehicles can make roads traffic safer and more efficient, but require the mobile networks to handle time-critical applications. Using the MONROE mobile broadband measurement testbed we conduct a multi-access measurement study on buses. The objective is to understand what network performance connected vehicles can expect in today's mobile networks, in terms of transaction times and availability. The goal is also to understand to what extent access to several operators in parallel can improve communication performance. In our measurement experiments we repeatedly transfer warning messages from moving buses to a stationary server. We triplicate the messages and always perform three transactions in parallel over three different cellular operators. This creates a dataset with which we can compare the operators in an objective way and with which we can study the potential for multi-access. In this paper we use the triple-access dataset to evaluate single-access selection strategies, where one operator is chosen for each transaction. We show that if we have access to three operators and for each transaction choose the operator with best access technology and best signal quality then we can significantly improve availability and transaction times compared to the individual operators. The median transaction time improves with 6% compared to the best single operator and with 61% compared to the worst single operator. The 90-percentile transaction time improves with 23% compared to the best single operator and with 65% compared to the worst single operator.

  • 4.
    Afzal, Zeeshan
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Garcia, Johan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Lindskog, 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).
    Slice Distance: An Insert-Only Levenshtein Distance with a Focus on Security Applications2018Ingår i: Proceedings of NTMS 2018 Conference and Workshop, New York: IEEE, 2018, s. 1-5Konferensbidrag (Refereegranskat)
    Abstract [en]

    Levenshtein distance is well known for its use in comparing two strings for similarity. However, the set of considered edit operations used when comparing can be reduced in a number of situations. In such cases, the application of the generic Levenshtein distance can result in degraded detection and computational performance. Other metrics in the literature enable limiting the considered edit operations to a smaller subset. However, the possibility where a difference can only result from deleted bytes is not yet explored. To this end, we propose an insert-only variation of the Levenshtein distance to enable comparison of two strings for the case in which differences occur only because of missing bytes. The proposed distance metric is named slice distance and is formally presented and its computational complexity is discussed. We also provide a discussion of the potential security applications of the slice distance.

  • 5.
    Afzal, Zeeshan
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Garcia, Johan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Lindskog, Stefan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013). 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. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Using Partial Signatures in Intrusion Detection for Multipath TCP2019Konferensbidrag (Refereegranskat)
  • 6.
    Afzal, Zeeshan
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Lindskog, Stefan
    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).
    Lidén, Anders
    Towards Multipath TCP Aware Security Technologies2016Ingår i: 2016 8th IFIP International Conference onNew Technologies, Mobility and Security (NTMS), New York: IEEE, 2016, s. 1-8Konferensbidrag (Refereegranskat)
    Abstract [en]

    Multipath TCP (MPTCP) is a proposed extension to TCP that enables a number of performance advantages that have not been offered before. While the protocol specification is close to being finalized, there still remain some unaddressed challenges regarding the deployment and security implications of the protocol. This work attempts to tackle some of these concerns by proposing and implementing MPTCP aware security services and deploying them inside a proof of concept MPTCP proxy. The aim is to enable hosts, even those without native MPTCP support, to securely benefit from the MPTCP performance advantages. Our evaluations show that the security services that are implemented enable proper intrusion detection and prevention to thwart potential attacks as well as threshold rules to prevent denial of service (DoS) attacks.

  • 7.
    Ahlgren, Bengt
    et al.
    RISE SICS.
    Grinnemo, Karl-Johan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Arahamsson, Henrik
    RISE SICS.
    Brunström, Anna
    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).
    Latency-aware Multipath Scheduling inInformation-centric Networks2019Ingår i: Proceedings of the Fifteenth Swedish National Computer Networking Workshop (SNCNW), Luleå, Sweden. 4-5 June 2019., 2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present the latency-aware multipath schedulerZQTRTT that takes advantage of the multipath opportunities ininformation-centric networking. The goal of the scheduler is touse the (single) lowest latency path for transaction-oriented flows,and use multiple paths for bulk data flows. A new estimatorcalled zero queue time ratio is used for scheduling over multiplepaths. The objective is to distribute the flow over the paths sothat the zero queue time ratio is equal on the paths, that is,so that each path is ‘pushed’ equally hard by the flow withoutcreating unwanted queueing. We make an initial evaluation usingsimulation that shows that the scheduler meets our objectives.

  • 8.
    Ahlgren, Bengt
    et al.
    RISE SICS.
    Hurtig, Per
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Abrahamsson, Henrik
    RISE SICS.
    Grinnemo, Karl-Johan
    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. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Are MIRCC and Rate-based Congestion Control in ICN READY for Variable Link Capacity?2017Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Information-centric networking (ICN) has been introduced as a potential future networking architecture. ICN promises an architecture that makes information independent from lo- cation, application, storage, and transportation. Still, it is not without challenges. Notably, there are several outstanding issues regarding congestion control: Since ICN is more or less oblivious to the location of information, it opens up for a single application flow to have several sources, something which blurs the notion of transport flows, and makes it very difficult to employ traditional end-to-end congestion control schemes in these networks. Instead, ICN networks often make use of hop-by-hop congestion control schemes. How- ever, these schemes are also tainted with problems, e.g., several of the proposed ICN congestion controls assume fixed link capacities that are known beforehand. Since this seldom is the case, this paper evaluates the consequences in terms of latency, throughput, and link usage, variable link capacities have on a hop-by-hop congestion control scheme, such as the one employed by the Multipath-aware ICN Rate-based Congestion Control (MIRCC). The evaluation was carried out in the OMNeT++ simulator, and demonstrates how seemingly small variations in link capacity significantly deterio- rate both latency and throughput, and often result in inefficient network link usage. 

  • 9.
    Ahlgren, Bengt
    et al.
    RISE SICS.
    Hurtig, Per
    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).
    Abrahamsson, Henrik
    RISE SICS.
    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 ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    ICN Congestion Control for Wireless Links2018Ingår i: IEEE WCNC 2018 Conference Proceedings / [ed] IEEE, New York: IEEE, 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Information-centric networking (ICN) with its design around named-based forwarding and in-network caching holds great promises to become a key architecture for the future Internet. Still, despite its attractiveness, there are many open questions that need to be answered before wireless ICN becomes a reality, not least about its congestion control: Many of the proposed hop-by-hop congestion control schemes assume a fixed and known link capacity, something that rarely – if ever – holds true for wireless links. As a first step, this paper demonstrates that although these congestion control schemes are able to fairly well utilise the available wireless link capacity, they greatly fail to keep the link delay down. In fact, they essentially offer the same link delay as in the case with no hop-by-hop, only end- to-end, congestion control. Secondly, the paper shows that by complementing these congestion control schemes with an easy- to-implement, packet-train link estimator, we reduce the link delay to a level significantly lower than what is obtained with only end-to-end congestion control, while still being able to keep the link utilisation at a high level. 

  • 10.
    Alay, Özgü
    et al.
    Simula Research Laboratory, Norway.
    Lutu, Andra
    Simula Research Laboratory, Norway.
    García, Rafael
    IMDEA Networks Institute, Spain.
    Peón Quirós, Miguel
    IMDEA Networks Institute, Spain.
    Mancuso, Vincenzo
    IMDEA Networks Institute, Spain.
    Hirsch, Thomas
    Celerway AS, Norway.
    Dely, Tobias
    Celerway AS, Norway.
    Werme, Jonas
    Celerway AS, Norway.
    Evensen, Kristian
    Celerway AS, Norway.
    Hansen, Audun
    Celerway AS, 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).
    Safari Khatouni, Ali
    Politecnico di Torino.
    Mellia, Marco
    Politecnico di Torino.
    Ajmone Marsan, Marco
    Politecnico di Torino.
    Monno, Roberto
    Nextworks, Italy.
    Lønsethagen, Håkon
    Telenor R&D, Norway.
    MONROE, a distributed platform to measure and assess mobile broadband networks: demo2016Ingår i: Proceedings of the Tenth ACM International Workshop on Wireless Network Testbeds, Experimental Evaluation, and Characterization, New York, NY, USA: Association for Computing Machinery (ACM), 2016, s. 85-86Konferensbidrag (Refereegranskat)
    Abstract [en]

    This demo presents the MONROE distributed platform and how it can be used to implement measurement and assessment experiments with operational mobile broadband networks (MBBs). MONROE provides registered experimenters with open access to hundreds of nodes, distributed over several European countries and equipped with multiple MBB connections, and a backend system that collects the measurement results. Experiments are scheduled through a user-friendly web client, with no need to directly access the nodes. The platform further embeds tools for real-time traffic flow analysis and a powerful visualization tool.

  • 11.
    Alay, Özgü
    et al.
    Simula Research Laboratory, Norway.
    Lutu, Andra
    Simula Research Laboratory, Norway.
    Peón-Quirós, Miguel
    IMDEA Networks Institute, Spain.
    Mancuso, Vincenzo
    IMDEA Networks Institute, Spain.
    Hirsch, Thomas
    Celerway Communications, Norway.
    Evensen, Kristian
    Celerway Communications, Norway.
    Hansen, Audun
    Celerway Communications, 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).
    Safari Khatouni, Ali
    Politecnico di Torino, Italy.
    Mellia, Marco
    Politecnico di Torino, Italy.
    Ajmone Marsan, Marco
    IMDEA Networks Institute, Spain and Politecnico di Torino, Italy.
    Experience: An open platform for experimentation with commercial mobile broadband networks2017Ingår i: MobiCom '17 Proceedings of the 23rd Annual International Conference on Mobile Computing and Networking, New York: Association for Computing Machinery (ACM), 2017, s. 70-78Konferensbidrag (Refereegranskat)
    Abstract [en]

    Open experimentation with operational Mobile Broadband (MBB) networks in the wild is currently a fundamental requirement of the research community in its endeavor to address the need of innovative solutions for mobile communications. Even more, there is a strong need for objective data about stability and performance of MBB (e.g., 3G/4G) networks, and for tools that rigorously and scientifically assess their status. In this paper, we introduce the MONROE measurement platform: an open access and flexible hardware-based platform for measurements and custom experimentation on operational MBB networks. The MONROE platform enables accurate, realistic and meaningful assessment of the performance and reliability of 11 MBB networks in Europe. We report on our experience designing, implementing and testing the solution we propose for the platform. We detail the challenges we overcame while building and testing the MONROE testbed and argue our design and implementation choices accordingly. We describe and exemplify the capabilities of the platform and the wide variety of experiments that external users already perform using the system

  • 12.
    Alay, Özgü
    et al.
    Simula Research Laboratory, Norway.
    Lutu, Andra
    Simula Research Laboratory, Norway.
    Rafael, García
    IMDEA Networks Institute, Spain.
    Peón Quirós, Miguel
    IMDEA Networks Institute, Spain.
    Mancuso, Vincenzo
    IMDEA Networks Institute, Spain.
    Hirsch, Thomas
    Celerway AS, Norway.
    Tobias, Dély
    Celerway AS, Norway.
    Werme, Jonas
    Celerway AS, Norway.
    Evensen, Kristian
    Celerway AS, Norway.
    Fosselie Hansen, Audun
    Celerway AS, 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).
    Safari Khatouni, Ali
    Politecnico di Torino, Italy.
    Mellia, Marco
    Politecnico di Torino, Italy.
    Ajmone Marsan, Marco
    Politecnico di Torino & IMDEA Networks, Italy.
    Monno, Roberto
    Nextworks, Italy.
    Lønsethagen, Håkon
    Telenor R&D, Norway.
    Measuring and Assessing Mobile Broadband Networks with MONROE2016Ingår i: 2016 IEEE International Symposium on a World of Wireless, Mobile, and Multimedia Networks (WoWMoM), Red Hook: IEEE, 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    Mobile broadband (MBB) networks underpin numerous vital operations of the society and are arguably becoming the most important piece of the communications infrastructure. In this demo paper, our goal is to showcase the potential of a novel multi-homed MBB platform for measuring, monitoring and assessing the performance of MBB services in an objective manner. Our platform, MONROE, is composed of hundreds of nodes scattered over four European countries and a backend system that collects the measurement results. Through a user-friendly web client, the experimenters can schedule and deploy their experiments. The platform further embeds traffic analysis tools for real-time traffic flow analysis and a powerful visualization tool.

  • 13.
    Alfredsson, Stefan
    et al.
    Karlstads universitet, Institutionen för informationsteknologi.
    Brunstrom, Anna
    Karlstads universitet, Institutionen för informationsteknologi.
    Bit Error Tolerant Multimedia Transport2004Ingår i: Perspectives on Multimedia: Communication, Media and Information Technology, Chichester: John Wiley & Sons, 2004, s. 175-191Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 14.
    Alfredsson, Stefan
    et al.
    Karlstads universitet, Institutionen för informationsteknologi.
    Brunstrom, Anna
    Karlstads universitet, Institutionen för informationsteknologi.
    TCP-L: Allowing Bit Errors in Wireless TCP2003Ingår i: Proceedings of the 12th IST Summit on Mobile and Wireless Communications: Enabling a Pervasive Wireless World / [ed] Atílio Gameiro, Institute for Operations Research and the Management Sciences (INFORMS), 2003, s. 149-154Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a technique to improve the performance of TCP and the utilization of wireless networks.Wireless links exhibit high rates of bit errors, compared to communication over wireline or fiber. Since TCP cannotseparate packet losses due to bit errors versus congestion,all losses are treated as signs of congestion and congestionavoidance is initiated. This paper explores the possibility of accepting TCP packets with an erroneous checksum, toimprove network performance for those applications that can tolerate bit errors. Since errors may be in the TCP header aswell as the payload, the possibility of recovering the headeris discussed. An algorithm for this recovery is also presented.Experiments with an implementation have been performed,which show that large improvements in throughput can beachieved, depending on link and error characteristics.

  • 15.
    Alfredsson, Stefan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Institutionen för informationsteknologi.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Institutionen för informationsteknologi.
    Mikael, Sternad
    Signaler och System, Uppsala universitet.
    A 4G Link Level Emulator for Transport Protocol Evaluation2004Ingår i: Proceedings of The Second Swedish National Computer Networking Workshop (SNCNW), 2004, s. 19-23Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a wireless link and networkemulator, based upon the "Wireless IP" 4G system proposalfrom Uppsala University and partners. In wireless fading down-links (base to terminals) link-level frames are scheduled andthe transmission is adapted on a fast time scale. With fastlink adaptation and fast link level retransmission, the fading properties of wireless links can to a large extent be counteractedat the physical and link layers. A purpose of the emulatoris to investigate the resulting interaction with transport layer protocols. The emulator is built on Internet technologies, andis installed as a gateway between communicating hosts. The paper gives an overview of the emulator design, and presentspreliminary experiments with three different TCP variants. The results illustrate the functionality of the emulator by showing theeffect of changing link layer parameters on the different TCP variants.

  • 16.
    Alfredsson, Stefan
    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.
    Mikael, Sternad
    Signaler och System, Uppsala universitet.
    Cross-layer analysis of TCP performance in a 4G system2007Ingår i: Proceedings of the 15th International Conference on Software, Telecommunications and Computer Networks, IEEE Computer Society, 2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents results from an experimental study of TCP in a wireless 4G evaluation system. Test-bed results on transport layer performance are presented and analyzed in relation to several link layer aspects. The aspects investigated are the impact of channel prediction errors, channel scheduling, delay, and adaptive modulation switch level, on TCP performance. The paper contributes a cross-layer analysis of the interaction between symbol modulation levels, different scheduling strategies, channel prediction errors and the resulting frame retransmissions effect on TCP. The paper also shows that highly persistent ARQ with fast link retransmissions do not interact negatively with the TCP retransmission timer even for short round trip delays.

  • 17.
    Alfredsson, Stefan
    et al.
    Karlstads universitet, Institutionen för informationsteknologi. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Institutionen för informationsteknologi.
    Mikael, Sternad
    Signaler och System, Uppsala universitet.
    Emulation and Validation of a 4G System Proposal2005Ingår i: Proceedings of RadioVetenskap och Kommunikation 2005: Volume II, 2005, s. 357-362Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a wireless link and network emulator,along with experiments and validation against the "Wireless IP" 4G system proposal from Uppsala University and partners. In wireless fading downlinks (base to terminals) link-level frames are scheduled and the transmission is adapted on a fast time scale. With fast link adaptation and fast link level retransmission, the fading properties of wireless links can to a large extent be counteracted at thephysical and link layers. The emulator has been used to experimentally investigate the resulting interaction between the transport layer and the link layer. The paper gives an overview of the emulator design, and presents experimental results with three different TCP variants in combination with various link layer characteristics.

  • 18.
    Alfredsson, Stefan
    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.
    Mikael, Sternad
    Signaler och System, Uppsala universitet.
    Impact of 4G Wireless Link Configurations on VoIP Network Performance2008Ingår i: Proceedings of the 2008 IEEE International Symposium on Wireless Communication Systems, IEEE Communications Society, 2008, s. 708-712Konferensbidrag (Refereegranskat)
    Abstract [en]

    The performance of applications in wireless networks is partly dependent upon the link configuration. Link characteristics varies with frame retransmission persistency, link frame retransmission delay, adaptive modulation strategies, coding, and more. The link configuration and channel conditions can lead to packet loss, delay and delay variations, which impact different applications in different ways. A bulk transfer application may tolerate delays to a large extent, while packet loss is undesirable. On the other hand, real-time interactive applications are sensitive to delay and delay variations, but may tolerate packet loss to a certain extent. This paper contributes a study of the effect of link frame retransmission persistency and delay on packet loss and latency for real-time interactive applications. The results indicate that a reliable retransmission mechanism with fast link retransmissions in the range of 2-8 ms is sufficient to provide an upper delay bound of 50 ms over the wireless link, which is well within the delay budget of voice over IP applications.

  • 19.
    Alfredsson, Stefan
    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.
    Mikael, Sternad
    Signaler och System, Uppsala universitet.
    Transport Protocol Performance over 4G Links: Emulation Methodology and Results2006Ingår i: Proceedings of the International Symposium on Wireless Communication Systems (ISWCS), IEEE Computer Society, 2006, s. 327-332Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a wireless link and network emulator for the "Wireless IP" 4G system proposal from Uppsala University and partners. In wireless fading downlinks (base to terminals) link-level frames are scheduled and the transmission is adapted on a fast time scale. With fast link adaptation and fast link level retransmission, the fading properties of wireless links can to a large extent be counteracted at the physical and link layers. The emulator has been used to experimentally investigate the resulting interaction between the transport layer and the physical/link layer in such a downlink. The paper introduces the Wireless IP system, describes the emulator design and implementation, and presents experimental results with TCP in combination with various physical/link layer parameters. The impact of link layer ARQ persistency, adaptive modulation, prediction errors and simple scheduling are all considered.

  • 20.
    Alfredsson, Stefan
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Del Giudice, Giacomo
    Politecnico di Bari, Italy.
    Garcia, Johan
    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.
    De Cicco, Luca
    Ecole superieure d'Electricite, France; Politecnico di Bari, Italy.
    Mascolo, Saverio
    Politecnico di Bari, Italy.
    Impact of TCP Congestion Control on Bufferbloat in Cellular Networks2013Ingår i: Proceedings of the 14th IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks (WoWMoM 2013) / [ed] Angelos Lazaris, Balaji Rengarajan, IEEE Press, 2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    The existence of excessively large and too filled network buffers, known as bufferbloat, has recently gained attention as a major performance problem for delay-sensitive applications. One important network scenario where bufferbloat may occur is cellular networks.

    This paper investigates the interaction between TCP congestion control and buffering in cellular networks. Extensive measurements have been performed in commercial 3G, 3.5G and 4G cellular networks, with a mix of long and short TCP flows using the CUBIC, NewReno and Westwood+ congestion control algorithms. The results show that the completion times of short flows increase significantly when concurrent long flow traffic is introduced. This is caused by increased buffer occupancy from the long flows. In addition, for 3G and 3.5G the completion times are shown to depend significantly on the congestion control algorithms used for the background flows, with CUBIC leading to significantly larger completion times.

  • 21.
    Alfredsson, Stefan
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Del Giudice, Giacomo
    Politecnico di Bari, Italy.
    Garcia, Johan
    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.
    De Cicco, Luca
    Ecole superieure d'Electricite, France; Politecnico di Bari, Italy.
    Mascolo, Saverio
    Politecnico di Bari, Italy.
    Observations of Bufferbloat in Swedish Cellular Networks2013Ingår i: Proceedings of the 9th Swedish National Computer Networking Workshop (SNCNW 2013) / [ed] Bengt Ahlgren, 2013Konferensbidrag (Refereegranskat)
  • 22.
    Arvidsson, Åke
    et al.
    Kristianstad University, Kristianstad, Sweden..
    Grinnemo, Karl-Johan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Chen, Eric
    Kristianstad University, Kristianstad, Sweden..
    Qinghua, Wang
    Kristianstad University, Kristianstad, Sweden..
    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).
    Web metrics for the next generation performance enhancing proxies2019Ingår i: SoftCOM 2019 Papers, 2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    The fast growth of Internet traffic, the growingimportance of cellular accesses and the escalating competitionbetween content providers and network operators result in agrowing interest in improving network performance and userexperience. In terms of network transport, different solutionsranging from tuning TCP to installing middleboxes are applied.It turns out, however, that the practical results sometimes aredisappointing and we believe that poor testing is one of thereasons for this. Indeed, many cases in the literature limittesting to the simple and rare use case of a single file download,while common and complex use cases like web browsing oftenare ignored or modelled only by considering smaller files. Tofacilitate better testing, we present a set of metrics by whichthe complexity around web pages can be characterised andthe potential for different optimisations can be estimated. Wealso derive numerical values of these metrics for a small set ofpopular web pages and study similarities and differences betweenpages with the same kind of content (newspapers, e-commerceand video) and between pages designed for the same platform(computer and smartphone).

  • 23.
    Asplund, Katarina
    et al.
    Karlstads universitet, Institutionen för informationsteknologi.
    Brunstrom, Anna
    Karlstads universitet, Institutionen för informationsteknologi.
    Partially Reliable Multimedia Transport2004Rapport (Övrigt vetenskapligt)
  • 24.
    Asplund, Katarina
    et al.
    Karlstads universitet, Institutionen för informationsteknologi.
    Brunstrom, Anna
    The trade-off Between Latency and Image Quality: A User PerspectiveManuskript (preprint) (Övrig (populärvetenskap, debatt, mm))
  • 25.
    Asplund, Katarina
    et al.
    Karlstads universitet, Institutionen för informationsteknologi.
    Brunstrom, Anna
    Karlstads universitet, Institutionen för informationsteknologi.
    Garcia, Johan
    Karlstads universitet, Institutionen för informationsteknologi.
    Schneyer, Sean
    Karlstads universitet, Institutionen för informationsteknologi.
    Grinnemo, Karl-Johan
    Karlstads universitet, Institutionen för informationsteknologi.
    PRTP: A Partially Reliable Transport Protocol for Multimedia Applications: Background, Information and Analysis1999Rapport (Övrigt vetenskapligt)
  • 26.
    Asplund, Katarina
    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.
    An Evaluation of User Web Service Requirements2002Konferensbidrag (Refereegranskat)
  • 27.
    Asplund, Katarina
    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.
    Partially Reliable Multimedia Transport2004Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The ongoing deployment of applications that transmit multimedia data makes it important for the Internet to better accommodate the service requirements of this type of applications. One approach is to provide a partially reliable service, i.e. a service that does not insist on recovering all but only some of the packet losses, thus providing less delay than a reliable transport service. This technical report describes a transport protocol that provides a partially reliable service. The protocol, called PRTP, is especially aimed at applications with soft real-time requirements. The report also presents performance results from a number of different experiments investigating different aspects of PRTP. The results indicate that transfer times can be significantly decreased when using PRTP as opposed to TCP when packets are lost in the network.

  • 28.
    Asplund, Katarina
    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.
    The QoS Trade-off Between Latency and Image Quality on the Web: A User Perspective2002Konferensbidrag (Refereegranskat)
  • 29.
    Asplund, Katarina
    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.
    The Trade-off Between Latency and Image Quality on the Web: A User Perspective2003Ingår i: / [ed] John Sören Pettersson, 2003Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 30.
    Asplund, Katarina
    et al.
    Karlstads universitet, Institutionen för informationsteknologi.
    Garcia, Johan
    Brunstrom, Anna
    Schneyer, Sean
    Decreasing Transfer Delay Through Partial ReliabilityManuskript (preprint) (Övrig (populärvetenskap, debatt, mm))
  • 31.
    Asplund, Katarina
    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. 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.
    Schneyer, S.
    Decreasing Transfer Delay Through Partial Reliability2000Konferensbidrag (Refereegranskat)
  • 32.
    Atxutegi, Eneko
    et al.
    University of the Basque Country, Spain.
    Grinnemo, Karl-Johan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Izurza, Andoni
    University of the Basque Country, Spain.
    Arvidsson, Åke
    Kristianstad University, Sweden.
    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).
    On the move with TCP in current and future mobile networks2017Ingår i: Proceedings of the 2017 8th International Conference on the Network of the Future (NOF). / [ed] T. Mahmoodi, S. Secci, A. Cianfrani, F. Idzikowski, New York, USA: IEEE, 2017, s. 66-72Konferensbidrag (Refereegranskat)
    Abstract [en]

    Mobile wireless networks constitute an indispensable part of the global Internet, and with TCP the dominating transport protocol on the Internet, it is vital that TCP works equally well over these networks as over wired ones. This paper identifies the performance dependencies by analyzing the responsiveness of TCP NewReno and TCP CUBIC when subject to bandwidth variations related to movements in different directions. The presented evaluation complements previous studies on 4G mobile networks in two important ways: It primarily focuses on the behavior of the TCP congestion control in medium- to high-velocity mobility scenarios, and it not only considers the current 4G mobile networks, but also low latency configurations that move towards the overall potential delays in 5G networks. The paper suggests that while both CUBIC and NewReno give similar goodput in scenarios where the radio channel continuously degrades, CUBIC gives a significantly better goodput in scenarios where the radio channel quality continuously increases. This is due to CUBIC probing more aggressively for additional bandwidth. Important for the design of 5G networks, the obtained results also demonstrate that very low latencies are capable of equalizing the goodput performance of different congestion control algorithms. Only in low latency scenarios that combine both large fluctuations of available bandwidths and a mobility pattern in which the radio channel quality continuously increases can some performance differences be noticed.

  • 33.
    Atxutegi, Eneko
    et al.
    University of the Basque Country.
    Liberal, Fidel
    University of the Basque Country.
    Grinnemo, Karl-Johan
    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).
    Arvidsson, Åke
    Kristianstad University.
    TCP Performance over Current Cellular Access: A Comprehensive Analysis2018Ingår i: Autonomous Control for a Reliable Internet of Services: Methods, Models, Approaches, Techniques, Algorithms and Tools / [ed] Ivan Ganchev, R. D. van der Mei, Hans van den Berg, Cham: Springer, 2018, s. 371-400Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Mobile internet usage has significantly raised over the last decade and it is expected to grow to almost 4 billion users by 2020. Even after the great effort dedicated to the improvement of the performance, there still exist unresolved questions and problems regarding the interaction between TCP and mobile broadband technologies such as LTE. This chapter collects the behavior of distinct TCP implementation under various network conditions in different LTE deployments including to which extent the performance of TCP is capable of adapting to the rapid variability of mobile networks under different network loads, with distinct flow types, during start-up phase and in mobile scenarios at different speeds. Loss-based algorithms tend to completely fill the queue, creating huge standing queues and inducing packet losses both under stillness and mobility circumstances. On the other side delay-based variants are capable of limiting the standing queue size and decreasing the amount of packets that are dropped in the eNodeB, but they are not able under some circumstances to reach the maximum capacity. Similarly, under mobility in which the radio conditions are more challenging for TCP, the loss-based TCP implementations offer better throughput and are able to better utilize available resources than the delay-based variants do. Finally, CUBIC under highly variable circumstances usually enters congestion avoidance phase prematurely, provoking a slower and longer start-up phase due to the use of Hybrid Slow-Start mechanism. Therefore, CUBIC is unable to efficiently utilize radio resources during shorter transmission sessions.

  • 34.
    Atxutegi, Eneko
    et al.
    University of the Basque Country.
    Liberal, Fidel
    University of the Basque Country.
    Grinnemo, Karl-Johan
    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.
    Arvidsson, Åke
    Kristianstad University.
    Robert, Remi
    Ericsson AB.
    TCP behaviour in LTE: impact of flow start-up and mobility2016Ingår i: Wireless and Mobile Networking Conference (WMNC), 2016 9th IFIP, IEEE, 2016, s. 73-80Konferensbidrag (Refereegranskat)
    Abstract [en]

    Nowadays, more than two billion people uses the mobile internet, and it is expected to rise to almost 4 billion by 2020. Still, there is a gap in the understanding of how TCP and its many variants work over LTE. To this end, this paper evaluates the extent to which five common TCP variants, CUBIC, NewReno, Westwood+, Illinois, and CAIA Delay Gradient (CDG), are able to utilise available radio resources under hard conditions, such as during start-up and in mobile scenarios at different speeds. The paper suggests that CUBIC, due to its Hybrid Slow- Start mechanism, enters congestion avoidance prematurely, and thus experiences a prolonged start-up phase, and is unable to efficiently utilise radio resources during shorter transmission sessions. Still, CUBIC, Illinois and NewReno, i.e., the loss-based TCP implementations, offer better throughput, and are able to better utilise available resources during mobility than Westwood+ and CDG – the delay-based variants do. 

  • 35.
    Atxutegi, Eneko
    et al.
    University of the Basque Country, Spain.
    Liberal, Fidel
    University of the Basque Country, Spain.
    Haile, Habtegebreil Kassaye
    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).
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Arvidsson, Åke
    Kristianstad University, Sweden.
    On the use of TCP BBR in cellular networks2018Ingår i: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, nr 3, s. 172-179Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    TCP BBR (Bottleneck Bandwidth and Round-trip propagation time) is a new TCP variant developed at Google, and which, as of this year, is fully deployed in Googles internal WANs and used by services such as Google.com and YouTube. In contrast to other commonly used TCP variants, TCP BBR is not loss-based but model-based: It builds a model of the network path between communicating nodes in terms of bottleneck bandwidth and minimum round-trip delay and tries to operate at the point where all available bandwidth is used and the round-trip delay is at minimum. Although, TCP BBR has indeed resulted in lower latency and a more efficient usage of bandwidth in fixed networks, its performance over cellular networks is less clear. This paper studies TCP BBR in live mobile networks and through emulations, and compares its performance with TCP NewReno and TCP CUBIC, two of the most commonly used TCP variants. The results from these studies suggest that in most cases TCP BBR outperforms both TCP NewReno and TCP CUBIC, however, not so when the available bandwidth is scarce. In these cases, TCP BBR provides longer file completion times than any of the other two studied TCP variants. Moreover, competing TCP BBR flows do not share the available bandwidth in a fair way, something which, for example, shows up when shorter TCP BBR flows struggle to get its fair share from longer ones. 

  • 36.
    Bajpai, Vaibhav
    et al.
    Technical University of Munich, Germany.
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Feldmann, Anja
    Max Planck Society, Germany.
    Kellerer, Wolfgang
    Technical University of Munich, Germany.
    Pras, Aiko
    University of Twente, Netherlands .
    Schulzrinne, Henning
    Columbia University, USA.
    Smaragdakis, Georgios
    Technical University of Berlin, Germany.
    Waehlisch, Matthias
    Free University of Berlin, Germany.
    Wehrle, Klaus
    RWTH Aachen University, Germany .
    The Dagstuhl Beginners Guide to Reproducibility for Experimental Networking Research2019Ingår i: Computer communication review, ISSN 0146-4833, E-ISSN 1943-5819, Vol. 49, nr 1, s. 24-30Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Reproducibility is one of the key characteristics of good science, but hard to achieve for experimental disciplines like Internet measurements and networked systems. This guide provides advice to researchers, particularly those new to the field, on designing experiments so that their work is more likely to be reproducible and to serve as a foundation for follow-on work by others.

  • 37.
    Baucke, Stephan
    et al.
    Ericsson Research, Germany.
    Grinnemo, Karl-Johan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Ludwig, Reiner
    Ericsson Research, Germany.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Wolisz, Adam
    Department of Electrical Engineering, Technical University Berlin, Germany.
    Using Relaxed Timer Backoff to Reduce SCTP Failover TimesManuskript (Övrigt vetenskapligt)
  • 38.
    Beckman, Claes
    et al.
    KTH, Center for Wireless Systems.
    Garcia, Johan
    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).
    On the Impact of Velocity on the Train-to-Earth MIMO Propagation Channel: Statistical Observations and Qualitative Analysis2017Ingår i: 2017 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting, IEEE, 2017, s. 1865-1866Konferensbidrag (Refereegranskat)
    Abstract [en]

    We provide measured data collected from 97 trains completing over 7000 journeys in Sweden showing that the throughput over LTE is impacted by train velocity. In order to explain these observations we assume that the underlying causes can be found in the implementation of the MIMO system into LTE Rel. 8 and the diffuse scattering of signals from ground reflections.

  • 39.
    Blom, Martin
    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.
    Nordby, Eivind J
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    A Software Engineering Course that Integrates Education and Research2000Konferensbidrag (Refereegranskat)
  • 40.
    Blom, Martin
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Nordby, Eivind J
    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.
    An Experimental Evaluation of Documentation Methods and Reusability2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents an experimental evaluation carried out in an academic environment. The goal of the experiment was to compare how different methods of documenting semantic information affect software reuse. More specifically, the goal was to measure if there were any differences between the methods with regard to the time needed to implement changes to existing software. Four methods of documentation were used; executable contracts, non-executable contracts, Javadoc-style documentation and sequence diagrams. The results indicate that executable contracts demanded more time than the other three methods and that sequence diagrams and Javadoc demanded the least time

  • 41.
    Blom, Martin
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Nordby, Eivind J
    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.
    An Experimental Evaluation of Programming by Contract2002Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents an experiment designed to compare a contract-based programming method with a standard programming method based on exceptions. The purpose was to evaluate if using contracts would shorten development time, if contracts would improve work satisfaction and if contracts would increase the quality of the resulting software program. The experiment was performed in a project work course for students in the computer science program at Karlstad University. The students were to solve an assignment in groups of four within a period of ten weeks. Half of the groups used the contract-based method and the other half used the exception-based method. We gathered data on time consumption and work satisfaction on daily forms for statistical analysis. The results indicate that there is a gain in the time spent on implementation of the assignment if the contract-based method is used, but no significant difference in total time consumption was found. The results also indicate that the work satisfaction was slightly higher in the groups using the contract-based method. The resulting program was analyzed for a range of quality metrics, but no significant differences were found

  • 42.
    Blom, Martin
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Nordby, Eivind J
    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.
    Introducing Contract-Based Programming in Industry - A Case Study2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a case study performed in an industrial project where we introduced and evaluated a method for supporting contract-based program development. The project constructed a large software system and involved around 30 people for 8 months. This paper reports on the designers' and programmers' attitudes towards programming by contract and how they perceived the effect the method had on their work. The results show that the designers and programmers were generally positive to contract-based program development and believed that the quality of their products would improve as an effect of the method

  • 43.
    Blom, Martin
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Nordby, Eivind J
    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.
    Method Description for Semla - A Software Design Method with a Focus on Semantics2000Rapport (Refereegranskat)
  • 44.
    Blom, Martin
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Nordby, Eivind J
    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.
    Systemarkitektur och -design2000Ingår i: Del av kapitel 3 i "Industriell Programvaruteknik. Forskningsresultat i kortform", NUTEK Förlag Nr: B 2000:01 (www.nutek.se), ([MS Word]) , 2000Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 45.
    Blom, Martin
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Nordby, Eivind J
    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.
    Teaching Semantic Aspects of OO Programming2002Konferensbidrag (Refereegranskat)
  • 46.
    Bozakov, Zdravko
    et al.
    Dell EMC.
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Damjanovic, Dragana
    Mozilla.
    Riktor Evensen, Kristian
    Celerway.
    Fairhurst, Gorry
    University of Aberdeen, UK..
    Grinnemo, Karl-Johan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Jones, Tom
    University of Aberdeen, UK..
    Mangiante, Simone
    Dell EMC.
    Papastergiou, Giorgos
    Simula.
    Ros, David
    Simula.
    Tüxen, Michael
    FH Münster, Germany.
    Welzl, Michael
    University of Oslo, Norway.
    Deliverable D2.1 - First Version of Low-Level Core Transport System2016Rapport (Refereegranskat)
    Abstract [en]

    This document presents the first version of the low-level Core Transport System in NEAT, to be used for development of a reference implementation of the NEAT System. The design of this core transport system takes into consideration the Transport Services and the API defined in Task 1.3 and in close coordination with the overall architecture (Task 1.2). To realise the basic Transport Services provided by the API, a set of low-level transport functionalities has to be provided by the NEAT core transport system. These functionalities take the formof several building blocks, or NEAT Components, each representing an associated implementation activity. Some of the components are needed to ensure the basic operation of the NEAT System—e.g., a NEAT Flow Endpoint, a callback-based NEAT API Framework, the NEAT Logic and the functionality to Connect to a name. Some other components are needed to ensure connectivity usingMiddlebox Traversal techniques (e.g., TURN), discovery of path support for different transport protocols using Happy Eyeballs mechanisms, offering end-to end Security (e.g., (D)TLS over transport), gather statistics for the users or system administrators, and the ability to apply different policies in order to influence the decision-making process of the transport system. This document describes each of these building blocks and related design choices.

  • 47.
    Bozakov, Zdravko
    et al.
    Dell EMC, Ireland.
    Mangiante, Simone
    Dell EMC, Ireland.
    Hernandez Benet, Cristian
    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). Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Santos, Ricardo
    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).
    Buckley, Donagh
    Dell EMC, Ireland.
    A NEAT framework for enhanced end-host integration in SDN environments2017Ingår i: 2017 IEEE Conference on Network Function Virtualization and Software Defined Networks (NFV-SDN), IEEE, 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    SDN aims to facilitate the management of increasingly complex, dynamic network environments and optimize the use of the resources available therein with minimal operator intervention. To this end, SDN controllers maintain a global view of the network topology and its state. However, the extraction of information about network flows and other network metrics remains a non-trivial challenge. Network applications exhibit a wide range of properties, posing diverse, often conflicting, demands towards the network. As these requirements are typically not known, controllers must rely on error-prone heuristics to extract them. In this work, we develop a framework which allows applications deployed in an SDN environment to explicitly express their requirements to the network. Conversely, it allows network controllers to deploy policies on end-hosts and to supply applications with information about network paths, salient servers and other relevant metrics. The proposed approach opens the door for fine grained, application-aware resource optimization strategies in SDNs

  • 48.
    Briscoe, Bob
    et al.
    BT, Ipswich IP5 3RE, Suffolk, England.
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013). Karlstad Univ, S-65188 Karlstad, Sweden..
    Petlund, Andreas
    Simula Res Lab AS, N-1364 Fornebu, Norway..
    Hayes, David
    Univ Oslo, N-0316 Oslo, Norway..
    Ros, David
    Simula Res Lab AS, N-1364 Fornebu, Norway..
    Tsang, Ing-Jyh
    Alcatel Lucent, Bell Labs, B-2018 Antwerp, Belgium..
    Gjessing, Stein
    Univ Oslo, N-0316 Oslo, Norway..
    Fairhurst, Gorry
    Univ Aberdeen, Aberdeen AB24 3FX, Scotland..
    Griwodz, Carsten
    Simula Res Lab AS, N-1364 Fornebu, Norway..
    Welzl, Michael
    Univ Oslo, N-0316 Oslo, Norway..
    Reducing Internet Latency: A Survey of Techniques and Their Merits2016Ingår i: IEEE Communications Surveys and Tutorials, ISSN 1553-877X, E-ISSN 1553-877X, Vol. 18, nr 3, s. 2149-2196Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Latency is increasingly becoming a performance bottleneck for Internet Protocol (IP) networks, but historically, networks have been designed with aims of maximizing throughput and utilization. This paper offers a broad survey of techniques aimed at tackling latency in the literature up to August 2014, as well as their merits. A goal of this work is to be able to quantify and compare the merits of the different Internet latency reducing techniques, contrasting their gains in delay reduction versus the pain required to implement and deploy them. We found that classifying techniques according to the sources of delay they alleviate provided the best insight into the following issues: 1) The structural arrangement of a network, such as placement of servers and suboptimal routes, can contribute significantly to latency; 2) each interaction between communicating endpoints adds a Round Trip Time (RTT) to latency, particularly significant for short flows; 3) in addition to base propagation delay, several sources of delay accumulate along transmission paths, today intermittently dominated by queuing delays; 4) it takes time to sense and use available capacity, with overuse inflicting latency on other flows sharing the capacity; and 5) within end systems, delay sources include operating system buffering, head-of-line blocking, and hardware interaction. No single source of delay dominates in all cases, and many of these sources are spasmodic and highly variable. Solutions addressing these sources often both reduce the overall latency and make it more predictable.

  • 49.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Reliable and Secure Communication in SCTP2010Konferensbidrag (Refereegranskat)
  • 50.
    Brunström, Anna
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Alfredsson, Stefan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Garcia, Johan
    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.
    NEWCOM DR6.2: First report on frameworks/models matching Department 6 needs2005Rapport (Refereegranskat)
    Abstract [en]

    During the first phase of NEWCOM the focus areas of Department 6 were identified and refined. A number of relevant knowledge gaps were identified for the areas transport protocols, architectures and cross-layer aspects, and modelling. In this deliverable we describe a first set of frameworks/models to support research integration within the Department. The integration approach and the defined models/frameworks are described for each one of the selected knowledge gaps. The deliverable also includes a report on tools, software libraries and traces that can be shared between the partners

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