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  • 151.
    Grinnemo, Karl-Johan
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Jones, Tom
    University of Aberdeen, Aberdeen, U.K.
    Fairhurst, Gorry
    University of Aberdeen, Aberdeen, U.K.
    Ros, David
    Simula Research Laboratory, Oslo, Norway.
    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).
    Towards a Flexible Internet Transport Layer Architecture2016Ingår i: The 22nd IEEE International Symposium on Local and Metropolitan Area Networks (LANMAN), Rome, Italy, June 2015 / [ed] IEEE, IEEE, 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    There is a growing concern that the Internet trans- port layer has stagnated and become less adaptive to the requirements imposed by new applications, and that further evolution has become very difficult. This is because a fundamental assumption no longer holds: it can no longer be assumed that the transport layer is only in the scope of end-hosts. The success of TCP and UDP and the ubiquity of middleboxes have led to ossification of both the network infrastructure and the API presented to applications. This has led to the development of workarounds, and a range of point solutions that fail to cover many facets of the problem. To address this issue, this paper identifies requirements for a new transport layer and then proposes a conceptual architecture that we argue is both flexible and evolvable. This new architecture requires that applications interface to the transport at a higher abstraction level, where an application can express communication preferences via a new richer API. Protocol machinery can use this information to decide which of the available transport protocols is used. By placing the protocol machinery in the transport layer, the new architecture can allow for new protocols to be deployed and enable evolution of the transport layer. 

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  • 152.
    Haile, Habtegebreil Kassaye
    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).
    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).
    Rate Change Detection in Stationary Cellular Nodes2019Ingår i: Proceedings of the Fifteenth Swedish National Computer NetworkingWorkshop (SNCNW), Luleå, Sweden. 4-5 June, 2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    An increasing number of cellular congestion controlalgorithms (CCAs) are relying on measurements of the deliveryrate observed at the receiver. Accordingly, early detection ofchanges in the receiver’s rate would improve the performanceof such algorithms. Rate measurements over short time intervalscould allow fast detection of change in the rate observed bythe upper layers of a cellular receiver. However, upper layerrate measurements for cellular receivers over a short time scaleproduce unreliable results due to the effect of underlying lowerlayer mechanisms. In this paper, we introduce a rate estimationapproach that reduces the variability observed in short timescale receiver rate measurements and allows faster rate changedetection.

  • 153.
    Haile, Habtegebreil Kassaye
    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).
    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).
    Atxutegi Narbona, Eneko
    University of the Basque Country.
    Liberal, Fidel
    University of the Basque Country.
    Arvidsson, Åke
    Kristianstad University.
    Evaluation of the Impact of TCP BBR Startup on CUBIC Traffic2018Ingår i: The Fourteenth Swedish National Computer Networking Workshop (SNCNW) 2018, 2018Konferensbidrag (Övrigt vetenskapligt)
  • 154.
    Hall, Tomas
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Hurtig, Per
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Garcia, Johan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Performance Evaluation of KauNet in Physical and Virtual Emulation Environments2012Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Evaluation of applications and protocols in the context of computer networking is often necessary to determine the efficiency and level of service they can provide. In practical testing, three different options are available for the evaluation; using a physical network as a testbed, using an emulator to simplify the infrastructure, or using a simulator to remove reliance on infrastructure entirely. As a real network is costly and difficult or even impossible to create for every scenario, emulation and simulation is often used to approximate the behavior of a network with considerably less resources required. However, while a simulator is limited only by the time required to perform the simulation, an emulator is also limited by the hardware and software used. It is therefore important to evaluate the performance of the emulator itself, to determine its ability to emulate the desired network topologies.

    The focus of this document is the KauNet emulator, an extension of Dummynet that adds several new features, primarily deterministic emulation of various network characteristics through the use of pre-generated patterns. A series of tests were per- formed using a testbed with KauNet in both physical and virtual environments, as well as a hybrid environment with both physical and virtual machines. While virtualization greatly increases the flexbility and utilization of resources compared to a pure physical setup, it may also reduce the overall performance and accuracy of the emulation.

    From the results achieved, KauNet performs well in a physical environment, with a high degree of accuracy even at high traffic loads. Virtualization on the other hand, clearly introduces several issues with both processing and packet loss that may make it undesirable for use in experiments, although it may still be sufficient for scenarios where the requirements for accuracy are lower. The hybrid environment represents a compromise, with both performance and flexibility midway between the physical and fully virtualized testbed. 

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  • 155.
    Hurtig, Per
    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).
    Evensen, Kristian
    Celerway Communications.
    Grinnemo, Karl-Johan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Fosselie Hansen, Audun
    Celerway Communications.
    Rozensztrauch, Tomasz
    Celerway Communications.
    A NEAT Approach to Mobile Communication2017Ingår i: MobiArch ’17 Proceedings of the Workshop on Mobility in the Evolving Internet Architecture, Association for Computing Machinery (ACM), 2017, s. 7-12Konferensbidrag (Refereegranskat)
    Abstract [en]

    The demands for mobile communication is ever increasing. Mobile applications are increasing both in numbers and in heterogeneity of their requirements, and an increasingly diverse set of mobile technologies are employed. This creates an urgent need for optimizing end-to-end services based on application requirements, conditions in the network and available transport solutions; something which is very hard to achieve with today's Internet architecture. In this paper, we introduce the NEAT transport architecture as a solution to this problem. NEAT is designed to offer a flexible and evolvable transport system, where applications communicate their transport-service requirements to the NEAT system in a generic, transport-protocol independent way. The best transport option is then configured at run time based on application requirements, network conditions, and available transport options. Through a set of real life mobile use case experiments, we demonstrate how applications with different properties and requirements could employ the NEAT system in multi-access environments, showing significant performance benefits as a result.

  • 156.
    Hurtig, Per
    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.
    Enhanced Metric Caching for Short TCP Flows2012Ingår i: Proceedings of the IEEE International Conference on Communications (ICC 2012), IEEE Press, 2012, s. 1209-1213Konferensbidrag (Refereegranskat)
    Abstract [en]

    Internet-based applications that require low latency are becoming more common. Such applications typically generate traffic consisting of short, or bursty, TCP flows. As TCP, instead, is designed to optimize the throughput of long bulk flows there is an apparent mismatch. To overcome this, a lot of research has recently focused on optimizing TCP for short flows as well. In this paper, we identify a performance problem for short flows caused by the metric caching conducted by the TCP control block interdependence mechanisms. Using this metric caching, a single packet loss can potentially ruin the performance for all future flows to the same destination by making them start in congestion avoidance instead of slow-start. To solve this, we propose an enhanced selective caching mechanism for short flows. To illustrate the usefulness of our approach, we implement it in both Linux and FreeBSD and experimentally evaluate it in a real test-bed. The experiments show that the selective caching approach is able to reduce the average transmission time of short flows by up to 40%.

  • 157.
    Hurtig, Per
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Enhancing SCTP Loss Recovery: An Experimental Evaluation of Early Retransmit2008Ingår i: Computer Communications, ISSN 0140-3664, E-ISSN 1873-703X, Vol. 31, nr 16, s. 3778-3788Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To reduce cost and provide more flexible services, telecommunication operators are currently replacing traditional circuit-switched telephony networks with packet-switched IP networks. To support the stringent requirements of telephony signaling (SS7), the SIGTRAN working group of the IETF specified the transport protocol SCTP. SCTP was developed to overcome a number of problems that follow from using TCP for signaling transport. However, the design of SCTP was to a great extent still based on TCP, and some problems related to signaling transport were inherited. For example, the loss recovery mechanisms in SCTP are almost identical to those of TCP. This is a problem as signaling traffic has stringent requirements on timely message delivery. TCP was not designed to meet stringent requirements on timely message delivery, and therefore the loss recovery was not optimized for it. To optimize SCTP’s loss recovery for signaling traffic, we consider the loss recovery enhancement early retransmit. To make early retransmit even better suited for signaling traffic we propose a packet-based version, which was also recently included in the early retransmit specification. By experimentally evaluating this algorithm, we show that the packet-based early retransmit algorithm, in some cases, can reduce SCTP’s loss recovery time by 62%.

  • 158.
    Hurtig, Per
    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.
    Improved Loss Detection for Signaling Traffic in SCTP2008Ingår i: IEEE International Conference on Communications (ICC 08), IEEE , 2008, s. 5886-5891Konferensbidrag (Refereegranskat)
    Abstract [en]

    The Stream Control Transmission Protocol (SCTP) was designed by the IETF as a viable solution for transportation of signaling traffic within IP-based networks. Signaling traffic is different from ordinary TCP bulk traffic in many ways. One example is that the requirement of timely delivery usually is much stricter. However, the management of the SCTP retransmission timer is not optimally designed considering this requirement. Basically, the management algorithm, unnecessarily, extends the time needed for loss detection. This paper presents a new management algorithm that is able to maintain a correct state of the retransmission timer, which eliminates this particular problem. In addition, the paper also compares the performance of the two management algorithms in an emulated signaling environment, using the lksctp implementation of SCTP. The results show that the proposed algorithm is able to provide significant reductions in loss recovery time. In some cases, the time needed to recover from packet loss is reduced with as much as 43%.

  • 159.
    Hurtig, Per
    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.
    Packet Reordering in TCP2011Ingår i: Proceedings of the IEEE GLOBECOM Workshop CCNet, IEEE Press, 2011, s. 136-141Konferensbidrag (Refereegranskat)
    Abstract [en]

    Packet reordering is now considered naturally prevalent within complex networks like the Internet. When packets are reordered, the performance of transport protocols like TCP is severely hurt. To overcome performance issues a number of mitigations have been proposed. While evaluations have shown the success of such mitigations, most have not considered realistic scenarios where other impairments are present. Furthermore, most studies only evaluate the performance of long-lived TCP flows, although short-lived flows are the most common. In this paper we evaluate Linux's built-in reordering mitigations and the TCP-NCR proposal using real protocol implementations. The results show that Linux and TCP-NCR are able to provide good protection against reordering when no other impairments are present. For flows that also experience packet loss, the performance is dominated by the negative effect of these losses. Results also indicate that short-lived flows are sensitive to how reordering mitigation is conducted. Linux was able to improve the performance of short flows slightly, while TCP-NCR performed worse than TCP without reordering protection.

  • 160.
    Hurtig, Per
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT.
    SCTP: Designed for Timely Message Delivery?2011Ingår i: Telecommunications Systems, ISSN 1018-4864, E-ISSN 1572-9451, Vol. 47, nr 3-4, s. 323-336Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To reduce cost and provide more flexible services, telecommunication operators are currently replacing traditional telephony networks with IP-networks. To support the requirements of telephony signaling in IP-networks, SCTP was standardized. SCTP solves a number of problems that follows from using TCP for telephony signaling transport. However, the design of SCTP is still largely based on TCP, and most of SCTP's data transmission mechanisms are inherited from TCP. Signaling traffic has stricter requirements of timely delivery than TCP bulk traffic. However, such requirements are not supported optimally by the inherited TCP mechanisms. We therefore argue that SCTP is not fully designed for timely message delivery. In this article we present and evaluate two loss recovery adaptations that enhance the timeliness of SCTP: Early Retransmit and a modified RTO management algorithm. In addition, we evaluate an adapted Nagle-like algorithm. The results from our evaluation show a significant reduction of message delivery times. In many of the experiments, delivery times were reduced with at least 30-50%. Furthermore, in some situations, message delivery times were reduced with up to 70%, using the modified Nagle algorithm.

  • 161.
    Hurtig, Per
    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.
    Petlund, Andreas
    Simula Research Laboratory AS.
    Welzl, Michael
    University of Oslo.
    TCP and Stream Control Transmission Protocol (SCTP) RTO Restart2016Ingår i: Internet RFCs, ISSN 2070-1721, nr 7765Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This document describes a modified sender-side algorithm for managing the TCP and Stream Control Transmission Protocol (SCTP) retransmission timers that provides faster loss recovery when there is a small amount of outstanding data for a connection. The modification, RTO Restart (RTOR), allows the transport to restart its retransmission timer using a smaller timeout duration, so that the effective retransmission timeout (RTO) becomes more aggressive in situations where fast retransmit cannot be used. This enables faster loss detection and recovery for connections that are short lived or application limited.

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  • 162.
    Hurtig, Per
    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.
    Emulation Support for Advanced Packet Reordering Models2010Ingår i: 2010 IEEE International Conference on Communications, Cape Town, South Africa: IEEE Communications Society, 2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    From being regarded as a pathological event, packet reordering is now considered to be naturally prevalent within the Internet. When packets are reordered, the performance of transport protocols like TCP can be severely hurt. To overcome performance problems a number of mitigations have been proposed. Common for most proposals is, however, the lack of evaluations using real protocol implementations and good models of packet reordering. In this paper we highlight the need for detailed reordering models, and implement support for such models in the KauNet network emulator. To demonstrate the importance of using detailed models we present an experimental example.

  • 163.
    Hurtig, Per
    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.
    Packet Loss Recovery of Signaling Traffic in SCTP2007Konferensbidrag (Refereegranskat)
  • 164.
    Hurtig, Per
    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.
    SCTP Retransmission Timer Enhancement for Signaling Traffic2008Konferensbidrag (Refereegranskat)
  • 165.
    Hurtig, Per
    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.
    Short Flows and TCP Metric Caching in Linux2011Konferensbidrag (Refereegranskat)
    Abstract

    Internet-based applications that offer (or require) user interaction are becoming more common. Such applications typically generate traffic consisting of short, or bursty, TCP flows. As TCP is designed to work better for long-lived bulk flows, a lot of research have recently focused at optimizing TCP for short flows. In this paper, we identify a performance problem for short flows, caused by the TCP metric caching in Linux. Using the cache, a single packet loss can potentially ruin the performance for all future flows to the same destination by making them start in congestion avoidance instead of slow-start. We illustrate the problem in a number of test-bed experiments and propose a modified caching strategy that explicitly considers flow lengths

  • 166.
    Hurtig, Per
    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.
    Hurtig, Per
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Message-Based Traffic Control in SCTP2009Konferensbidrag (Refereegranskat)
    Abstract

    Telecommunication operators are currently replacing traditional telephony networks with IP-networks. To support telephony signaling requirements in IP-networks, SCTP was standardized. SCTP solves a number of problems that follows from using TCP for signaling transport. However, the design of SCTP is based on inherited TCP mechanisms that were designed for bulk traffic, not for message-based traffic like telephony signaling. In this paper, we discuss the implications of this design, and exemplify the negative effects of it. In particular, we show how to adapt the SCTP message-bundling to work better for message-based traffic. Evaluations of our adapted message bundling show average reductions in message transfer times with as much as 50%, for some scenarios

  • 167.
    Hurtig, Per
    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.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    MPTCP PathFinder: Datacenter Bandwidth Aggregation2014Konferensbidrag (Refereegranskat)
  • 168.
    Hurtig, Per
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT.
    Garcia, Johan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT.
    Loss Recovery in Short TCP/SCTP Flows2006Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The Transmission Control Protocol (TCP) has been the dominant transport protocol within IP-based networks for many years, mainly due to the reliability it provide to its users and the congestion control it employs. However, as the amount of signaling traffic within IP-based networks have increased significantly in recent years, it has become clear that TCP is not suited for this kind of traffic. In order to meet the requirements of signaling traffic the Stream Control Transmission Protocol (SCTP) was developed by the Internet Engineering Task Force (IETF). SCTP is heavily influenced by TCP and is therefore similar to TCP in many ways. One example is the SCTP loss recovery and congestion control mechanisms which are almost identical to those of TCP. The primary purpose of this work is to study the performance and behavior of the TCP/SCTP loss recovery mechanisms for short flows. Using a simple client/server model, we evaluate the performance of these mechanism over a wide range of bandwidths, link delays and packet loss patterns. The experiments evaluate one TCP implementation and two SCTP implementations, and were conducted using network emulation. The experimental results show that there exist strong dependencies between the position of packet loss and the actual transmission time of the corresponding flow. In addition to these dependencies, we also found a number of implementation mistakes in the examined protocol implementations.

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  • 169.
    Hurtig, Per
    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.
    Loss Recovery in Short TCP/SCTP Flows2006Rapport (Refereegranskat)
    Abstract [en]

    The Transmission Control Protocol (TCP) has been the dominant transport protocol within IP-based networks for many years, mainly due to the reliability it provides to its users and the congestion control it employs. However, as the amount of signaling traffic within IP-based networks have increased significantly in recent years, it has become clear that TCP is not suited for this kind of traffic. In order to meet the requirements of signaling traffic the Stream Control Transmission Protocol (SCTP) was developed by the Internet Engineering Task Force (IETF). SCTP is heavily influenced by TCP and is therefore similar to TCP in many ways. One example is the SCTP loss recovery and congestion control mechanisms which are almost identical to those of TCP. The primary purpose of this work is to study the performance and behavior of the TCP/SCTP loss recovery mechanisms for short flows. Using a simple client/server model, we evaluate the performance of these mechanism over a wide range of bandwidths, link delays and packet loss patterns. The experiments evaluate one TCP implementation and two SCTP implementations, and were conducted using network emulation. The experimental results show that there exist strong dependencies between the position of packet loss and the actual transmission time of the corresponding flow. In addition to these dependencies, we also found a number of implementation mistakes in the examined protocol implementations

  • 170.
    Hurtig, Per
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Grinnemo, Karl-Johan
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Ferlin, Simone
    Ericsson Research, Stockholm.
    Alay, Özgü
    Simula Research Laboratory, Norway.
    Kuhn, Nicolas
    French National Space Centre, France.
    Low-Latency Scheduling in MPTCP2019Ingår i: IEEE/ACM Transactions on Networking, ISSN 1063-6692, E-ISSN 1558-2566, Vol. 1, s. 302-315, artikel-id 8584135Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The demand for mobile communication is continuously increasing, and mobile devices are now the communication device of choice for many people. To guarantee connectivity and performance, mobile devices are typically equipped with multiple interfaces. To this end, exploiting multiple available interfaces is also a crucial aspect of the upcoming 5G standard for reducing costs, easing network management, and providing a good user experience. Multi-path protocols, such as multi-path TCP (MPTCP), can be used to provide performance optimization through load-balancing and resilience to coverage drops and link failures, however, they do not automatically guarantee better performance. For instance, low-latency communication has been proven hard to achieve when a device has network interfaces with asymmetric capacity and delay (e.g., LTE and WLAN). For multi-path communication, the data scheduler is vital to provide low latency, since it decides over which network interface to send individual data segments. In this paper, we focus on the MPTCP scheduler with the goal of providing a good user experience for latency-sensitive applications when interface quality is asymmetric. After an initial assessment of existing scheduling algorithms, we present two novel scheduling techniques: the block estimation (BLEST) scheduler and the shortest transmission time first (STTF) scheduler. BLEST and STTF are compared with existing schedulers in both emulated and real-world environments and are shown to reduce web object transmission times with up to 51% and provide 45% faster communication for interactive applications, compared with MPTCP's default scheduler.

  • 171.
    Hurtig, Per
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    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).
    Atxutegi, Eneko
    University of the Basque Country, Spain.
    Liberal, Fidel
    University of the Basque Country, Spain.
    Arvidsson, Åke
    Kristianstad University.
    Impact of TCP BBR on CUBIC Traffic: A mixed workload evaluation2018Ingår i: Proceedings of the 30th International Teletraffic Congress, ITC 2018, IEEE, 2018, s. 218-226Konferensbidrag (Refereegranskat)
    Abstract [en]

    A recently proposed congestion control algorithm (CCA) called BBR (Bottleneck Bandwidth and Round-trip propagation time) has shown a lot of promise in avoiding some of the problems that have plagued loss-based CCAs. Nevertheless, deployment of a new alternative algorithm requires a thorough evaluation of the effect of the proposed alternative on established transport protocols like TCP CUBIC. Furthermore, evaluations that consider the heterogeneity of Internet traffic sizes would provide a useful insight into the deployability of an algorithm that introduces sweeping changes across multiple algorithm components. Yet, most evaluations of BBR's impact and competitive fairness have focused on the steady-state performance of large flows. This work expands on previous studies of BBR by evaluating BBR's impact when the traffic consists of flows of different sizes. Our experiments show that under certain circumstances BBR's startup phase can result in a significant reduction of the throughput of competing large CUBIC flows and the utilization of the bottleneck link. In addition, the steady-state operation of BBR can have negative impact on the performance of bursty flows using loss-based CCAs over bottlenecks with buffer sizes as high as two times the bandwidth-delay product. 

  • 172.
    Hurtig, Per
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    John, Wolfgang
    Department of Computer Science and Engineering, Chalmers University of Technology.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Recent Trends in TCP Packet-Level Characteristics2011Ingår i: Proceedings of the 7th International Conference on Networking and Services (ICNS), Venice/Mestre, Italy: IARIA , 2011, s. 179-195Konferensbidrag (Refereegranskat)
    Abstract [en]

    Up-to-date TCP traffic characteristics are essential for research and development of protocols and applications. This paper presents recent trends observed in 70 measurements on backbone links from 2006 and 2009. First, we provide general characteristics such as packet size distributions and TCP option usage. We confirm previous observations such as the dominance of TCP as transport and higher utilization of TCP options. Next, we look at out-of-sequence (OOS) TCP segments. OOS segments often have negative effects on TCP performance, and therefore require special consideration. While the total fraction of OOS segments is stable in our measurements, we observe a significant decrease in OOS due to packet reordering (from 22.5% to 5.2% of all OOS segments). We verify that this development is a general trend in our measurements and not caused by single hosts/networks or special temporal events. Our findings are surprising as many researchers previously have speculated in an increased amount of reordering.

  • 173.
    Hurtig, Per
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Pérennou, Tanguy
    Université de Toulouse, France.
    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.
    Using Triggers for Emulation of Opportunistic Networking2010Ingår i: Proceedings of the Second International Workshop on Mobile Opportunistic Networking, MobiOpp '10, Pisa, Italy: ACM Press, 2010, s. 155-158Konferensbidrag (Refereegranskat)
    Abstract [en]

    Opportunistic networks do not require the availability of an end-to-end path, but may instead take advantage of temporary connectivity opportunities. Opportunistic networks pose a challenge for network emulation as the traditional emulation setup where application/transport endpoints send/receive packets from the network following a black box approach is no longer applicable. Instead opportunistic networking protocols and applications need to react to the dynamics of the underlying network beyond what is conveyed through the exchange of packets. In order to support emulation evaluations for such challenging applications we in this paper introduce the concept of emulation triggers that can emulate arbitrary cross-layer feedback and that are synchronized with the emulated scenario. The design and implementation of triggers in the KauNet emulator are described. The use of triggers in the context of opportunistic networking is briefly sketched.

  • 174.
    Høiland-Jørgensen, Toke
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Ahlgren, Bengt
    SICS.
    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).
    Measuring Latency Variation in the Internet2016Ingår i: Proceedings of the 12th International on Conference on emerging Networking EXperiments and Technologies, 2016, s. 473-480Konferensbidrag (Refereegranskat)
    Abstract [en]

    We analyse two complementary datasets to quantify the latency variation experienced by internet end-users: (i) a large-scale active measurement dataset (from the Measurement Lab Network Diagnostic Tool) which shed light on long-term trends and regional differences; and (ii) passive measurement data from an access aggregation link which is used to analyse the edge links closest to the user.

    The analysis shows that variation in latency is both common and of significant magnitude, with two thirds of samples exceeding 100\,ms of variation. The variation is seen within single connections as well as between connections to the same client. The distribution of experienced latency variation is heavy-tailed, with the most affected clients seeing an order of magnitude larger variation than the least affected. In addition, there are large differences between regions, both within and between continents. Despite consistent improvements in throughput, most regions show no reduction in latency variation over time, and in one region it even increases.

    We examine load-induced queueing latency as a possible cause for the variation in latency and find that both datasets readily exhibit symptoms of queueing latency correlated with network load. Additionally, when this queueing latency does occur, it is of significant magnitude, more than 200\,ms in the median. This indicates that load-induced queueing contributes significantly to the overall latency variation.

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  • 175.
    Høiland-Jørgensen, Toke
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Grazia, Carlo Augusto
    University of Modena and Reggio Emilia.
    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).
    Flent: The FLExible Network Tester2017Ingår i: VALUETOOLS 2017: Proceedings of 11th EAI International Conference on Performance Evaluation Methodologies and Tools, New York, NY: Association for Computing Machinery (ACM), 2017, s. 1-6, artikel-id 271973Konferensbidrag (Refereegranskat)
    Abstract [en]

    Running network performance experiments on real systems is essential for a complete understanding of protocols and systems connected to the internet. However, the process of running experiments can be tedious and error-prone. In particular, ensuring reproducibility across different systems is difficult, and comparing different test runs from an experiment can be non-trivial.In this paper, we present a tool, called Flent, designed to make experimental evaluations of networks more reliable and easier to perform. Flent works by composing well-known benchmarking tools to, e.g., run tests consisting of several bulk data flows combined with simultaneous latency measurements. Tests are specified in source code, and several common tests are included with the tool. In addition, Flent contains features to automate test runs, collect relevant metadata and interactively plot and explore datasets.We showcase Flent's capabilities by performing a set of experiments evaluating the new BBR congestion control algorithm, using Flent's capabilities to reproduce experiments both in a controlled testbed and across the public internet. Our evaluation reveals several interesting features of BBR's performance.

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  • 176.
    Høiland-Jørgensen, Toke
    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).
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    The Good, the Bad and the WiFi: Modern AQMs in a residential setting2015Ingår i: Computer Networks, ISSN 1389-1286, E-ISSN 1872-7069, Vol. 89, s. 90-106Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Several new active queue management (AQM) and hybrid AQM/fairness queueing algorithms have been proposed recently. They seek to ensure low queueing delay and high network goodput without requiring parameter tuning of the algorithms themselves. However, extensive experimental evaluations of these algorithms are still lacking. This paper evaluates a selection of bottleneck queue management schemes in a test-bed representative of residential Internet connections of both symmetrical and asymmetrical bandwidths as well as WiFi. Latency under load and the performance of VoIP and web traffic patterns are evaluated under steady state conditions. Furthermore, the impact of the algorithms on fairness between TCP flows with different RTTs, and also the transient behaviour of the algorithms at flow startup is examined. The results show that while the AQM algorithms can significantly improve steady state performance, they exacerbate TCP flow unfairness. In addition, the evaluated AQMs severely struggle to quickly control queueing latency at flow startup, which can lead to large latency spikes that hurt the perceived performance. The fairness queueing algorithms almost completely alleviate the algorithm performance problems, providing the best balance of low latency and high throughput in the tested scenarios. However, on WiFi the performance of all the tested algorithms is hampered by large amounts of queueing in lower layers of the network stack inducing significant latency outside of the algorithms’ control.

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  • 177.
    Høiland-Jørgensen, Toke
    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).
    PoliFi: Airtime Policy Enforcement for WiFi2019Ingår i: IEEE Wireless Communications and Networking Conference, WCNC, IEEE, 2019, s. 1-6, artikel-id 8885440Konferensbidrag (Refereegranskat)
    Abstract [en]

    As WiFi grows ever more popular, airtime contention becomes an increasing problem. One way to alleviate this is through network policy enforcement. Unfortunately, WiFi lacks protocol support for configuring policies for its usage, and since network-wide coordination cannot generally be ensured, enforcing policy is challenging. However, as we have shown in previous work, an access point can influence the behaviour of connected devices by changing its scheduling of transmission opportunities, which can be used to achieve airtime fairness. In this work, we show that this mechanism can be extended to successfully enforce airtime usage policies in WiFi networks. We implement this as an extension our previous airtime fairness work, and present PoliFi, the resulting policy enforcement system. Our evaluation shows that PoliFi makes it possible to express a range of useful policies. These include prioritisation of specific devices; balancing groups of devices for sharing between different logical networks or network slices; and limiting groups of devices to implement guest networks or other low-priority services. We also show how these can be used to improve the performance of a real-world DASH video streaming application.

  • 178.
    Høiland-Jørgensen, Toke
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Kazior, Michał
    Tieto Poland, Szczecin, Poland.
    Täht, Dave
    TekLibre, San Francisco, CA USA.
    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).
    Ending the Anomaly: Achieving Low Latency and Airtime Fairness in WiFi2017Ingår i: Proceedings of the 2017 USENIX Annual Technical Conference (USENIX ATC ’17), USENIX - The Advanced Computing Systems Association, 2017, s. 139-151Konferensbidrag (Refereegranskat)
    Abstract [en]

    With more devices connected, delays and jitter at the WiFi hop become more prevalent, and correct functioning during network congestion becomes more important. However, two important performance issues prevent modern WiFi from reaching its potential: increased latency under load caused by excessive queueing (i.e. bufferbloat) and the 802.11 performance anomaly.

    To remedy these issues, we present a novel two-part solution. We design a new queueing scheme that eliminates bufferbloat in the wireless setting. Leveraging this queueing scheme, we then design an airtime fairness scheduler that operates at the access point and doesn't require any changes to clients.

    We evaluate our solution using both a theoretical model and experiments in a testbed environment, formulating a suitable analytical model in the process. We show that our solution achieves an order of magnitude reduction in latency under load, large improvements in multi-station throughput, and nearly perfect airtime fairness for both TCP and downstream UDP traffic. Further experiments with application traffic confirm that the solution provides significant performance gains for real-world traffic.We develop a production quality implementation of our solution in the Linux kernel, the platform powering most access points outside of the managed enterprise setting. The implementation has been accepted into the mainline kernel distribution, making it available for deployment on billions of devices running Linux today.

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  • 179.
    Jalili, Leilia
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Parichehreh, Ali
    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).
    Garcia, 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).
    Efficient traffic offloading for seamless connectivity in 5G networks onboard high speed trains2017Ingår i: IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, IEEE, 2017, s. 1-6Konferensbidrag (Refereegranskat)
    Abstract [en]

    Seamless wireless connectivity in high mobility scenarios (≥ 300 km/h), is one of the fundamental key requirements for the future 5G networks. High speed train (HST) is one of the preferred mid-range transportation systems, and highlights the challenges of providing wireless connectivity in high mobility scenarios for the 5G networks. Advanced version of Long Term Evolution (LTE-A) from the Third Generation Partnership Project (3GPP) with peak data rate up to 100 Mbps in high mobility scenarios paved the road toward high quality and cost effective onboard Internet in HSTs. However, frequent handovers (HO) of large number of onboard users increase the service interruptions that in turn inevitably decrease the experienced quality of service (QoS). In this paper, according to the two-tier architecture of the HST wireless connectivity, we propose a novel and practically viable onboard traffic offloading mechanism among the HST carriages that effectively mitigates the service interruptions caused by frequent HOs of massive number of onboard users. The proposed architecture does not imply any change on the LTE network standardization. Conclusions are supported by numerical results for realistic LTE parameters and current HST settings.

  • 180.
    Kargar Bideh, Minoo
    et al.
    Simula Research Laboratory.
    Petlund, Andreas
    Simula Research Laboratory.
    Griwodz, Carsten
    Simula Research Laboratory.
    Ahmed, Iffat
    Simula Research Laboratory.
    Halvorsen, Pål
    Simula Research Laboratory.
    Behjati, Razieh
    Simula Research Laboratory.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Alfredsson, Stefan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    TADA: An Active Measurement Tool for Automatic Detection of AQM2015Ingår i: Proceeding VALUETOOLS'15 Proceedings of the 9th EAI International Conference on Performance Evaluation Methodologies and Tools / [ed] William Knottenbelt, Katinka Wolter, Ana Busic, Marco Gribaudo and Philipp Reinecke, Brussels: The Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 2015, s. 55-60Konferensbidrag (Refereegranskat)
    Abstract [en]

    The problem of overbuffering in today's Internet (termed as bufferbloat) has recently drawn a great amount of attention from the research community. This has led to the development of various active queue management (AQM) schemes. The last years have seen a lot of effort to show the benefits of AQMs over simple tail-drop queuing and to encourage deployment. Yet it is still unknown to what extent AQMs are deployed in the Internet. In this paper, we present an end-to-end active measurement method to detect AQMs on the path bottleneck. We have developed an active measurement tool, named TADA, and evaluated our measurement methodology on a controlled experimental testbed. Experimental results show that the proposed approach provides the basis to identify whether an AQM is deployed on the bottleneck.

  • 181.
    Karlsson, Jonas
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Dimitrov, Velizar G.
    Department of Communication Networks, Technical University of Sofia, boulevard Kliment Ohridski 8, Sofia, Bulgaria.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Nilsson, Jan
    Swedish Defence Research Agency (FOI), Box 1165, SE - 581 11 Linköping, Sweden.
    Hansson, Anders
    Swedish Defence Research Agency (FOI), Box 1165, SE - 581 11 Linköping, Sweden.
    Performance Evaluation for TCP in Tactical Mobile Ad hoc Networks2012Ingår i: Proceedings of International Conference on Wireless Information Networks and Systems, SciTePress, 2012, s. 277-282Konferensbidrag (Refereegranskat)
    Abstract [en]

    Tactical networks are used in military and rescue operations to provide timely and accurate information to operating teams.  Tactical networks have traditionally used long distance narrow band radio links. However, although these links provide robust real-time communication the limited bandwidth makes them less suited for high data-rate applications.  To support high-data rate TCP applications such as providing digital images and maps, emerging tactical networks use shorter range but higher data-rate wide band radio links and multi-hop.  Due to the requirement of cheap up-front cost, most MANET research has focused on Carrier Sense Multiple Access (CSMA) networks. However, in tactical networks, where bounded delays are important, Time Division Multiple Access (TDMA) can give better possibility to support the Quality of Service needed for real-time communication.  The purpose of this paper is to assess and compare the throughput of three state-of-the-art TCP versions and two routing protocols over TDMA based MANETs.

  • 182.
    Karlsson, Jonas
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Hurtig, Per
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    MPTCP PathFinder - finding your ways to aggregated bandwidth2012Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Many  networks are multi-path; mobile devices have multiple interfaces, data centers have redundant paths and ISPs forward traffic over disjoint paths to perform load-balancing. Multi-path TCP (MPTCP) is a new mechanism that transparently divides a TCP connection into subflows and distributes them over a host's network interfaces. While this enables multi-homed systems like e.g. smartphones to use several interfaces and thus different, and mostly disjoint, network paths for a single transmission, most end-systems are still single-homed. With one interface, standard MPTCP creates only a single subflow, making single-homed systems unable to benefit from MPTCP's functionality. In this paper we propose PathFinder, an MPTCP extension that tries to estimate the number of subflows required to fully utilize  the network capacity, enabling single-homed hosts to reap the benefits of MPTCP. We evaluate MPTCP with PathFinder and compare its performance to standard MPTCP. The evaluation shows that PathFinder is able to open a limited but sufficient amount of subflows to significantly increase the throughput when compared to using standard MPTCP.

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  • 183.
    Karlsson, Jonas
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Hurtig, Per
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    di Stasi, Giovanni
    University of Naples "Federico II", Italy.
    Impact of Multi-path Routing on TCP Performance2012Ingår i: 2012 IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks (WoWMoM 2012), Washington, DC: IEEE Press, 2012, s. 1-3Konferensbidrag (Refereegranskat)
    Abstract [en]

    Routing packets over multiple disjoint paths towards a destination can increase network utilization by load-balancing the traffic over the network. The drawback of load-balancing is that different paths might have different delay properties, causing packets to be reordered. This can reduce TCP performance significantly, as reordering is interpreted as a sign of congestion. Packet reordering can be avoided by letting the network layer route strictly on flow-level. This will, however, also limit the ability to achieve optimal network throughput. There are also several proposals that try to mitigate the effects of reordering at the transport layer. In this paper, we perform an initial evaluation of such TCP reordering mitigations in multi-radio multi-channel wireless mesh networks when using multi-path routing. We evaluate two TCP reordering mitigation techniques implemented in the Linux kernel. The transport layer mitigations are compared using different multi-path routing strategies. Our findings show that, in general, flow-level routing gives the best TCP performance and that transport layer reordering mitigations only marginally can improve performance.

  • 184.
    Karlsson, Jonas
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Hurtig, Per
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    di Stasi, Giovanni
    (University of Naples "Federico II", Italy.
    Impact of Multi-path Routing on TCP Performance in Wireless Mesh Networks2012Ingår i: Proceedings of the 8th Swedish National Computer Networking Workshop (SNCNW 2012), 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    Routing packets over multiple disjoint paths to- wards a destination can increase network utilization by load- balancing the traffic over the network. The drawback of load-balancing is that different paths might have different delay properties, causing packets to be reordered. This can reduce TCP performance significantly, as reordering is interpreted as a sign of congestion. Packet reordering can be avoided by letting the network layer route strictly on flow-level. This will, however, also limit the ability to achieve optimal network throughput. There are also several proposals that try to mitigate the effects of reordering at the transport layer. In this paper, we perform an initial evaluation of such TCP reordering mitigations in multi-radio multi-channel wireless mesh networks when using multi-path routing. We evaluate two TCP reordering mitigation techniques implemented in the Linux kernel. The transport layer mitigations are compared using different multi-path routing strategies. Our findings show that, in general, flow-level routing gives the best TCP performance and that transport layer reordering mitigations only marginally can improve performance. 

  • 185.
    Karlsson, Jonas
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Hurtig, Per
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    di Stasi, Giovanni
    Department of Computer Science, University of Naples "Federico II", Italy.
    The Interaction Between TCP Reordering Mechanisms and Multi-path Forwarding in Wireless Mesh Networks2012Ingår i: 2012 IEEE 8th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob), IEEE Press, 2012, s. 276-283Konferensbidrag (Refereegranskat)
    Abstract [en]

    Routing packets over multiple disjoint paths towards a destination can increase network utilization by load-balancing the traffic over the network. In wireless mesh networks, multi-radio multi-channel nodes are often used to create a larger set of interference-free paths thus increasing the chance of load-balancing. The drawback of load-balancing is that different paths might have different delay properties, causing packets to be reordered. This can reduce TCP performance significantly, as reordering is interpreted as a sign of congestion. Packet reordering can be avoided by letting the network layer forward traffic strictly on flow-level. This would avoid the negative drawbacks of packet reordering, but will also limit the ability to achieve optimal network throughput. On the other hand, there are several proposals that try to mitigate the effects of reordering at the transport layer. In this paper, we perform an in-depth evaluation of such TCP reordering mitigations in multi-radio multi-channel wireless mesh networks when using multi-path forwarding. We evaluate two TCP reordering mitigation techniques implemented in the Linux kernel. The transport layer mitigations are compared using different multi-path forwarding strategies. Our findings show that, in general, flow-level forwarding gives the best TCP performance and that transport layer reordering mitigations only marginally can improve performance

  • 186.
    Karlsson, Jonas
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Evaluation of Packet Aggregation with TCP Traffic in Wireless Mesh Networks2010Manuskript (preprint) (Övrig (populärvetenskap, debatt, mm))
  • 187.
    Karlsson, Jonas
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Impact of Packet Aggregation on TCP performance in Wireless Mesh Networks2009Ingår i: Proceedings of the First IEEE WoWMoM Workshop on Hot Topics in Mesh Networking (HotMESH'09), IEEE , 2009, s. 1-7Konferensbidrag (Refereegranskat)
  • 188.
    Karlsson, Jonas
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    TCP Performance Evaluation in Wireless Mesh Networks using Packet Aggregation2012Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Wireless Mesh Networks (WMNs) have attracted attention as a way to provide alternative wireless Internet connectivity. In a WMN, access points communicate with each other wirelessly, forming a wireless mesh backbone network. One major problem in WMNs is low performance due to MAC and PHY layer overhead for transmission of small packets. Around 44 percent of the packets in the Internet are smaller than 100 bytes and a majority of these packets are TCP packets. The capacity of WMNs can therefore be increased significantly by packet aggregation (concatenation) of TCP packets. In this paper, we evaluate the impact of packet aggregation on TCP performance in WMNs. Using both synthetic and trace based traffic distributions we demonstrate that packet aggregation can not only increase capacity for TCP in such networks but also reduce round trip times.

  • 189.
    Karlsson, Jonas
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Kassler, Andreas
    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.
    Effect of Packet Aggregation in Wireless Mesh Networks: Analyzing TCP performance2009Ingår i: Proceedings of the 9th Scandinavian Workshop on Wireless Adhoc Networks: Adhoc'09, Uppsala: Uppsala universitet , 2009Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Recently, Wireless Mesh Networks (WMNs) have attracted attention as a way to provide alternative Internet connectivity to rural areas or communities. In WMNs, wireless access points communicate with each other wirelessly, forming a true wireless mesh based access network of mesh relay nodes (MRNs). A major problem is, however, scalability of WMNs as well as MAC and PHY layer overhead for packet transmission. Capacity of WMNs can be increased significantly by aggregating (combining) several smaller packets into larger ones. This is in particular beneficial to flows where many packets are of small sizes such as voice flows. TCP could also benefit, as by aggregating several packets together there is a reduced collision risk between TCP DATA and TCP ACKs in addition to the reduced MAC layer contention. In this paper, we investigate the impact of packet aggregation on TCP in Wireless Mesh Networks. Using several different scenarios we demonstrate that packet aggregation can not only increase capacity for TCP in such networks but also improve fairness and reduce end-to-end delay

  • 190.
    Khademi, Naeem
    et al.
    University of Oslo, Norway.
    Bozakov, Zdravko
    Dell EMC.
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Dale, Øystein
    University of Oslo, Norway.
    Damjanovic, Dragana
    Mozilla.
    Riktor Evensen, Kristian
    Celerway.
    Fairhurst, Gorry
    University of Aberdeen, UK..
    Fischer, Andreas
    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).
    Jones, Tom
    University of Aberdeen, UK.
    Mangiante, Simone
    Dell EMC.
    Petlund, Andreas
    Simula.
    Ros, David
    Simula.
    Rüngeler, Irene
    FH Münster, Germany.
    Stenberg, Daniel
    Mozilla.
    Tüxen, Michael
    FH Münster, Germany.
    Weinrank, Felix
    FH Münster, Germany.
    Welzl, Michael
    University of Oslo, Norway.
    Deliverable D2.3 - Final Version of Core Transport System2017Rapport (Refereegranskat)
    Abstract [en]

    This document presents the core transport system in NEAT, as used for development of the reference implementation of the NEAT System. The document describes the components necessary to realise the basic Transport Services provided by the NEAT User API, with the description of a set of NEAT building blocks and their related design choices. The design of this core transport system, which is the final product ofWork Package 2, is driven by the Transport Services and API design from Task 1.4, and in close coordination with the overall NEAT architecture defined in Task 1.2. To realise the Transport Services provided by the API, a set of transport functions has to be provided by the NEAT Core Transport System. These functions take the form of several building blocks, or NEAT Components, each representing an associated implementation activity. Some 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. Additional components are needed for: (a) ensuring connectivity, by means of mechanisms for discovery of path support for different protocols; (b) supporting end-to-end security; (c) the ability to apply different policies to influence the decision-making process of the transport system; (d) providing other important functionalities (e.g., a user-space SCTP stack, or gathering statistics for users or system administrators). This document updates Deliverable D2.2; in particular, the descriptions of NEAT components presented here correspond to their implementation status by the end of WP2, and as such they supersede those in D2.2.

    Ladda ner fulltext (pdf)
    fulltext
  • 191.
    Khademi, Naeem
    et al.
    University of Oslo, Norway.
    Bozakov, Zdravko
    Dell EMC.
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Dale, Øystein
    University of Oslo, Norway.
    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.
    Petlund, Andreas
    Simula.
    Ros, David
    Simula.
    Stenberg, Daniel
    Mozilla.
    Tüxen, Michael
    FH Münster, Germany.
    Weinrank,, Felix
    FH Münster, Germany.
    Welzl, Michael
    University of Oslo, Norway.
    Deliverable D2.2 - Core Transport System, with both Low-level and High-level Components2017Rapport (Refereegranskat)
    Abstract [en]

    This document presents the core transport system in NEAT, as used for development of the

    reference implementation of the NEAT System. The document describes the components

    necessary to realise the basic Transport Services provided by the NEAT User API, with the

    description of a set of NEAT building blocks and their related design choices. 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 Transport Services provided by the API, a set of transport functionalities

    has to be provided by the NEAT Core Transport System. These functionalities take the form

    of 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. Additional components are needed

    for: (a) ensuring connectivity, by means of mechanisms for discovery of path support for

    different protocols; (b) supporting end-to-end security; (c) the ability to apply different

    policies to influence the decision-making process of the transport system; (d) providing

    other important functionalities (e.g., a user-space SCTP stack, or gathering statistics for

    users or system administrators).

    This document updates Deliverable D2.1; in particular, the descriptions of NEAT components

    presented here correspond to the implementation status at the time of writing,

    and as such they replace those in D2.1.

    Ladda ner fulltext (pdf)
    fulltext
  • 192.
    Khademi, Naeem
    et al.
    University of Oslo.
    Ros, David
    Simula Research Laboratory.
    Welzl, Michael
    University of Oslo.
    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).
    Fairhurst, Gorry
    University of Aberdeen.
    Grinnemo, Karl-Johan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Hayes, David
    Simula Research Laboratory.
    Hurtig, Per
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Jones, Tom
    University of Aberdeen.
    Mangiante, Simone
    Dell EMC Research Europe.
    Tüxen, Michael
    Muenster University of Applied Sciences.
    Weinrank, Felix
    Muenster University of Applied Sciences.
    NEAT: A Platform- and Protocol-Independent Internet Transport API2017Ingår i: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 55, nr 6, s. 46-54Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The sockets Applications Programming Interface (API) has become the standard way that applications access the transport services offered by the Internet Protocol stack. This paper presents NEAT, a user-space library that can provide an alternate transport API. NEAT allows applications to request the service they need using a new design that is agnostic to the specific choice of transport protocol underneath. This not only allows applications to take advantage of common protocol machinery, but also eases introduction of new network mechanisms and transport protocols. The paper describes the components of the NEAT library and illustrates the important benefits that can be gained from this new approach. NEAT is a software platform for developing advanced network applications that was designed in accordance with the standardization efforts on Transport Services (TAPS) in the Internet Engineering Task Force (IETF), but its features exceed the envisioned functionality of a TAPS system. 

  • 193.
    Khatouni, Ali Safari
    et al.
    Politecn Torino, Turin, Italy.
    Mellia, Marco
    Politecn Torino, Turin, Italy.
    Ajmone Marsan, Marco
    Politecn Torino, Turin, Italy ; IMDEA Networks Inst, Leganes, Spain.
    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).
    Alay, Ozgu
    Simula Res Lab, Fornebu, Norway.
    Lutu, Andra
    Simula Res Lab, Fornebu, Norway.
    Midoglu, Cise
    Simula Res Lab, Fornebu, Norway.
    Mancuso, Vincenzo
    IMDEA Networks Inst, Leganes, Spain.
    Speedtest-like Measurements in 3G/4G Networks: the MONROE Experience2017Ingår i: 2017 PROCEEDINGS OF THE 29TH INTERNATIONAL TELETRAFFIC CONGRESS (ITC 29), VOL 1, IEEE, 2017, s. 169-177Konferensbidrag (Refereegranskat)
    Abstract [en]

    Mobile Broadband (MBB) Networks are evolving at a fast pace, with technology enhancements that promise drastic improvements in capacity, connectivity, coverage, i.e., better performance in general. But how to measure the actual performance of a MBB solution? In this paper, we present our experience in running the simplest of the performance test: "speedtest-like" measurements to estimate the download speed offered by actual 3G/4G networks. Despite their simplicity, download speed measurements in MBB networks are much more complex than in wired networks, because of additional factors (e.g., mobility of users, physical impairments, diversity in technology, operator settings, mobile terminals diversity, etc.). We exploit the MONROE open platform, with hundreds of multihomed nodes scattered in 4 different countries, and explicitly designed with the goal of providing hardware and software solutions to run large scale experiments in MBB networks. We analyze datasets collected in 4 countries, over 11 operators, from about 50 nodes, for more than 2 months. After designing the experiment and instrumenting both the clients and the servers with active and passive monitoring tools, we dig into collected data, and provide insight to highlight the complexity of running even a simple speedtest. Results show interesting facts, like the occasional presence of NAT, and of Performance Enhancing Proxies (PEP), and pinpoint the impact of different network configurations that further complicate the picture. Our results will hopefully contribute to the debate about performance assessment in MBB networks, and to the definition of much needed benchmarks for performance comparisons of 3G, 4G and soon of 5G networks.

  • 194.
    Klockar, Annika
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Botella, Carmen
    Universitat de València.
    Sternad, Mikael
    Uppsala University.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Svensson, Tommy
    Chalmers University of Technology.
    Utility as a User Selection Criterion for Coordinated Multi-Point Systems2013Ingår i: 2013 IEEE 24th International Symposium on Personal Indoor and Mobile Radio Communications (PIMRC), London: IEEE conference proceedings, 2013, s. 3123-3128Konferensbidrag (Refereegranskat)
    Abstract [en]

    Coordinated multipoint (CoMP) transmission and reception techniques have been proposed to combat inter-cell interference in cellular systems and, hence, to increase the data rates. Due to the overhead introduced, not all users may be served with CoMP. In this paper, we focus on how to select users for joint processing CoMP under limited backhaul capacity. The evaluated user selection schemes take user experience into account, quantified by the utility of Internet application types. We propose a heuristic algorithm utility based user selection that has low computational complexity. Utility based user selection and maximize utility, which maximizes the sum utilities, are compared to maximize rate, which maximizes the sum data rates. A range of traffic mixes and user locations are evaluated. The simulation results indicate that resources required for CoMP are more efficiently used if the user selection is based on utility rather than on maximizing the total data rate. If utility is taken into account a higher total utility can in many cases be achieved for the same limited backhaul capacity.

  • 195.
    Klockar, Annika
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Botella, Carmen
    Signals and Systems, Chalmers University of Technology, Gothenburg.
    Svensson, Tommy
    Signals and Systems, Chalmers University of Technology, Gothenburg.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Sternad, Mikael
    Signals and Systems, Uppsala University.
    Utility of Joint Processing Schemes2010Ingår i: 2010 7th International Symposium on Wireless Communication Systems (ISWCS 2010), IEEE Communications Society, 2010, s. 76-80Konferensbidrag (Refereegranskat)
    Abstract [en]

    Joint processing between base stations has been shown as an efficient technique to mitigate inter-cell interference and increase data rates, in particular at the cell edges. In this paper, we evaluate the utility of Internet applications in a joint processing enabled cluster of base stations. Utility is used to quantify system performance as experienced by the end user. In particular, the utility of three joint processing schemes for the downlink is characterized and compared within the cluster area. The qualitative results indicate that joint processing can significantly improve the utility of hard real-time and adaptive applications. For elastic applications, joint processing is not worthwhile, since almost as high utility is achieved also with conventional single base station assignment

  • 196.
    Klockar, Annika
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Sternad, Mikael
    Uppsala University.
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Apelfröjd, Rikke
    Uppsala University.
    User-centric pre-selection and scheduling for coordinated multipoint systems2014Ingår i: 2014 11th International Symposium on Wireless Communications Systems (ISWCS 2014), IEEE, 2014, s. 888-894Konferensbidrag (Refereegranskat)
    Abstract [en]

    The data traffic volumes are constantly increasing in cellular networks. Furthermore, a larger part of the traffic is generated by applications that require high data rates. Techniques including Coordinated Multipoint transmission (CoMP) can increase the data rates, but at the cost of a high overhead. The overhead can be reduced if only a subset of the users is served with CoMP. In this paper, we propose a user selection approach, including pre-selection of CoMP users and short term scheduling, that takes user requirements into account. Users that require a high data rate to reach an acceptable level of service satisfaction are selected to use coherent joint processing CoMP in some of their downlink transmission bandwidth. Simulation results show that both the number of satisfied users and fairness are improved with the proposed user selection as compared to user selection that does not consider individual user requirements.

  • 197.
    Koumaras, Harilaos
    et al.
    Natl Ctr Sci Res DEMOKRITOS, Aghia Paraskevi, Greece.
    Tsolkas, Dimitris
    Fogus Innovat & Serv, Athens, Greece.
    Gardikis, Georgios
    Space Hellas Cyprus Ltd, Athina, Greece.
    Merino Gomez, Pedro
    Univ Malaga, Malaga, Spain.
    Frascolla, Valerio
    Intel Deutschland GmbH, Neubiberg, Germany.
    Triantafyllopoulou, Dionysia
    Univ Surrey, 5GIC, Guildford, Surrey, England.
    Emmelmann, Marc
    FOKUS Fraunhofer Gesell eV, Berlin, Germany.
    Koumaras, Vaios
    INFOLYSiS PC, Athens, Greece.
    Garcia Osma, Maria L.
    Telefonica, Madrid, Spain.
    Munaretto, Daniele
    Athonet, Bolzano Vicentino, Italy.
    Atxutegi, Eneko
    Nemergent Solut SL, Bilbao, Spain.
    Suarez de Puga, Jara
    Univ Politecn Valencia, Valencia, Spain.
    Alay, Ozgu
    Simula Res Lab, Fornebu, Norway.
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Bosneag, Anne Marie Cristina
    Ericsson LMI, Dublin, Ireland.
    5GENESIS: The Genesis of a flexible 5G Facility2018Ingår i: 2018 IEEE 23RD INTERNATIONAL WORKSHOP ON COMPUTER AIDED MODELING AND DESIGN OF COMMUNICATION LINKS AND NETWORKS (CAMAD), IEEE, 2018, s. 197-202Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper describes the pathway towards the realisation of a 5G Facility that will allow the validation of the major 5G Key Performance Indicators (KPIs). It reflects the approach that the 5GENESIS consortium will adopt in this direction. More precisely, it describes the key design principles of such Facility as well as the targeted use cases for the KPIs validation. The adopted approach for the Facility realisation includes the design of a common implementation blueprint that will be instantiated in five Platforms distributed across Europe. To maximise the diversity and the efficiency of the Facility, complementary performance objectives have been selected for the Platforms, while specific characteristics from different vertical industries have been allocated to each of them.

  • 198.
    Kristensson, Per
    et al.
    Karlstads universitet, Fakulteten för humaniora och samhällsvetenskap (from 2013), Centrum för tjänsteforskning.
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Pedersen, Tore
    Bjørknes University College, Oslo, Norway.
    Affective forecasting of value creation: Professional nurses’ ability to predict and remember the experienced value of a telemedicine diagnostics ICT service2015Ingår i: Behavior and Information Technology, ISSN 0144-929X, E-ISSN 1362-3001, Vol. 34, nr 10, s. 964-975Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    New innovations that can transform societies and improve life for people are increasingly being asked for. Unfortunately, some avenues of research indicate that users of these new innovations may be inaccurate when they predict or remember the value of such new offerings. For example, the rapid development of new ICT services in areas such as health care may imply opportunities for better life conditions and well-being, but may also involve complicated predictions for users about the value they will create. New innovations may face adoption difficulties if users make inaccurate predictions or remember falsely the value that such innovations might have. In this study, 48 nurses predicted, experienced, and remembered the value of a new ICT service they used to diagnose an external skin lesion on a patient. Results showed significant differences between predicted and experienced value as well as between a service with high technical quality and the same service with lower technical quality; the value was underestimated at the time of prediction, as compared to actual experience, and the value of a high-quality ICT service was substantially more underestimated than the value of a low-quality ICT service. The results provide a novel and comprehensive understanding of how employees predict and experience the value of ICT service innovations. © 2014 Taylor & Francis.

  • 199.
    Kühlewind, Mirja
    et al.
    ETH Zurich.
    Trammell, Brian
    ETH Zurich.
    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).
    Welzl, Michael
    University of Oslo.
    Fairhurst, Gorry
    University of Aberdeen.
    TAPS: an abstract application interface for QUIC2018Ingår i: In Proceedings of CoNEXT ’18. ACM, New York, NY, USA,, 2018, s. 1-3Konferensbidrag (Refereegranskat)
    Abstract [en]

    The TAPS Architecture for Transport Services [6] providesa framework for the design of a protocol-independent asynchronousmessage-based transport API. While the traditionalBSD socket API [1] requires the user to make a choice aboutwhich protocol to use from the beginning, the TAPS APIfocuses on transport features and gives the transport stackitself the opportunity to select the most appropriate protocol.This flexibility also supports deployment of new protocols,such as QUIC, because the application does not need tochange in order to benefit from such new innovations. Thisposter defines two API mappings for QUIC, either exposingmultistreaming explicitly to the application or providing away to utilize multistreaming without application input.

  • 200.
    Lavén, Andreas
    et al.
    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.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Performance Evaluation of the Anypath Routing and Forwarding Mechanism AP-OLSR2013Ingår i: MSWiM '13 Proceedings of the 16th ACM international conference on Modeling, analysis & simulation of wireless and mobile systems, Association for Computing Machinery (ACM), 2013, s. 81-90Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Wireless mesh networks (WMNs) consist of several small routers relaying packets wirelessly toward the destination or the Internet. A dense deployment enables the rapid creation of wireless access networks at a reasonable cost. The capacity of a wireless mesh network can be increased by using a diverse set of channels to allow simultaneous transmissions without causing interference. An interesting approach is to use one fixed wireless network interface for receiving and at least one switchable interface for sending. However, such a channel assignment suffers from switching overhead.

    In order to minimize the channel switching latency, we have developed a novel packet routing and forwarding strategy, AP-OLSR, which uses multiple next hop candidates tuned to different channels. When forwarding a packet, nodes pick the neighbor which is on a channel that gives a good balance between local switching overhead and global path quality.

    In this paper, we present a thorough evaluation of AP-OLSR with scenarios involving both single and multiple gateways, as well as single and competing flows. The evaluation shows that AP-OLSR can improve performance in both latency and throughput.

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