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  • 351.
    Hernandez Benet, Cristian
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Alizadeh Noghani, Kyoomars
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Taheri, Javid
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    SDN implementations and protocols2018In: Big Data and Software Defined Networks / [ed] Javid Taheri, IET Digital Library, 2018, 1, p. 27-48Chapter in book (Refereed)
    Abstract [en]

    This chapter begins by explaining the main SDN concepts with the focus on a SDN controller. It presents the most important aspects to consider when we desire to go from traditional network to a SDN networks. We present an in-depth analysis of the most commonly used and modern SDN controllers and analyse the main features, capabilities and requirements of one of the presented controllers. OpenFlow is the standard leading in the market allowing the management of the forwarding plane devices such as routers or switches. While there are other standards with the same aim, OpenFlow has secured a position in the market and has been expanded rapidly. Therefore, an analysis is presented on a different OpenFlow compatible device for the implementation of an SDN network. This study encompasses both software and hardware solutions along with the scope of implementation or use of these devices. This chapter ends up presenting a description of OpenFlow protocol alternatives, a more detailed description of OpenFlow and its components and other wellknown southbound protocols involved for the management and configuration of the devices.

  • 352.
    Hernandez Benet, Cristian
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    FlowDyn: Towards a Dynamic Flowlet Gap Detection using Programmable Data Planes2019Conference paper (Refereed)
    Abstract [en]

    Data center networks offer multiple disjoint paths between Top-of-Rack (ToR) switches to connect server racks providing large bisection bandwidth. An effective load-balancing mechanism is required in order to fully utilize the available capacity of the multiple paths. While packet-based loadbalancing can achieve high utilization, it suffers from reordering. Flow-based load-balancing such as equal-cost multipath routing (ECMP) spreads traffic uniformly across multiple paths leading to frequent hash collisions and suboptimal performance. Finally, flowlet based load-balancing such as CONGA or HULA splits flows into smaller units, which are sent on different paths. Most flowlet based load-balancing schemes depend on a proper static setting of the flowlet gap, which decides when new flowlets are detected. While a too small gap may lead to reordering, a too large gap results in missed load-balancing opportunities. In this paper,weproposeFlowDyn,whichdynamicallyadaptstheflowlet gap to increase the efficiency of the load-balancing schemes while avoiding the reordering problem. Using programmable data planes, FlowDyn uses active probes together with telemetry informationtotrackpathlatencybetweendifferentToRswitches. FlowDyn calculates dynamically a suitable flowlet gap that can be used for flowlet based load-balancing mechanism. We evaluate FlowDyn extensively in simulation, showing that it achieves 3.19 times smaller flow completion time at 10% load and 1.16x at 90% load.

  • 353.
    Hernandez Benet, Cristian
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Benson, T.
    Brown University, United States.
    Pongracz, G.
    Networking Research - Ericsson, United States.
    MP-HULA: Multipath transport aware load balancing using programmable data planes2018In: NetCompute 2018 - Proceedings of the 2018 Morning Workshop on In-Network Computing, Part of SIGCOMM 2018, Association for Computing Machinery, Inc , 2018, p. 7-13Conference paper (Refereed)
    Abstract [en]

    Datacenter networks ofer a large degree of multipath in order to provide large bisectional bandwidth. The end-to-end performance is determined by the load-balancing strategy which needs to be designed to efectively manage congestion. Consequently, congestion aware load-balancing strategies such as CONGA or HULA have been designed. Recently, more and more applications that are hosted on cloud servers use multipath transport protocols such as MPTCP. However, in the presence of MPTCP, existing load-balancing schemes including ECMP, HULA or CONGA may lead to suboptimal forwarding decisions where multiple MPTCP subfows of one connection are pinned on the same bottleneck link. In this paper, we present MP-HULA, a transport layer multi-path aware load-balancing scheme using Programmable Data Planes. First, instead of tracking congestion information for the best path towards the destination, each MP-HULA switch tracks congestion information for the best-k paths to a destination through the neighbor switches. Second, we design MP-HULA using Programmable Data Planes, where each leaf switch can identify, using P4, which MPTCP subfow belongs to which connection. MP-HULA then load-balances diferent MPTCP subfows of a MPTCP connection on diferent next hops considering congestion state while aggregating bandwidth. Our evaluation shows that MP-HULA with MPTCP outperforms HULA in average flow completion time (2.1x at 50% load, 1.7x at 80% load).

  • 354.
    Hernandez Benet, Cristian
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Zola, Enrica
    Univ Politecn Cataluna, C Jordi Girona 1-3, Barcelona, Spain..
    Predicting expected TCP throughput using genetic algorithm2016In: Computer Networks, ISSN 1389-1286, E-ISSN 1872-7069, Vol. 108, p. 307-322Article in journal (Refereed)
    Abstract [en]

    Predicting the expected throughput of TCP is important for several aspects such as e.g. determining handover criteria for future multihomed mobile nodes or determining the expected throughput of a given MPTCP subflow for load-balancing reasons. However, this is challenging due to time varying behavior of the underlying network characteristics. In this paper, we present a genetic-algorithm-based prediction model for estimating TCP throughput values. Our approach tries to find the best matching combination of mathematical functions that approximate a given time series that accounts for the TCP throughput samples using genetic algorithm. Based on collected historical datapoints about measured TCP throughput samples, our algorithm estimates expected throughput over time. We evaluate the quality of the prediction using different selection and diversity strategies for creating new chromosomes. Also, we explore the use of different fitness functions in order to evaluate the goodness of a chromosome. The goal is to show how different tuning on the genetic algorithm may have an impact on the prediction. Using extensive simulations over several TCP throughput traces, we find that the genetic algorithm successfully finds reasonable matching mathematical functions that allow to describe the TCP sampled throughput values with good fidelity. We also explore the effectiveness of predicting time series throughput samples for a given prediction horizon and estimate the prediction error and confidence. 

  • 355.
    Hernandez Benet, Cristian
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Nasim, Robayet
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Alizadeh Noghani, Kyoomars
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    OpenStackEmu - A Cloud Testbed Combining Network Emulation with OpenStack and SDN2017In: Consumer Communications & Networking Conference (CCNC), 2017 14th IEEE Annual, IEEE, 2017, p. 566-568Conference paper (Refereed)
    Abstract [en]

    OpenStack has been widely acknowledged to be one of the most important open source cloud platforms. In order to perform experimentally driven research in the area of cloud and cloud networking, there is however a big gap, because most researchers do not have access to a large cloud deployment and cannot change networking or compute infrastructure in order to test their algorithms and protocols on a large-scale. We developed OpenStackEmu, which is to the best of our knowledge the first attempt that combines OpenStack infrastructure with a Software Defined Networking (SDN) based controller such as OpenDaylight and a large-scale network emulator CORE (Common Open Research Emulator). The OpenStack compute and control nodes are connected to the CORE emulation server using TUN/TAP interfaces that inject the control (e.g. for VM migration) and data (VM-to-VM traffic) packets into a customizable network topology that is emulated using configurable Open vSwitches using CORE emulator. Experimenters can define e.g. fat-tree or distributed data center topologies and study the behavior of real VMs and services in those VMs under different background loads and SDN routing policies. We integrated the data center traffic generator DCT2Gen that allows to generate realistic background traffic based on traces from real data centers. Experimenters can study the performance impact of different VM migration strategies or different routing and load balancing schemes on real VM and application performance using different emulated topologies. We believe that OpenStackEmu is an important tool for both the SDN and OpenStack community in order to evaluate the performance of novel algorithms and protocols in the area of cloud networking.

  • 356.
    Herold, Sebastian
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Blom, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Buckley, Jim
    University of Limerick / Lero, Ireland.
    Evidence in Architecture Degradation and Consistency Checking Research: Preliminary Results from a Literature Review2016In: Proceeding ECSAW '16 Proccedings of the 10th European Conference on Software Architecture Workshops, Association for Computing Machinery (ACM), 2016Conference paper (Refereed)
  • 357.
    Him-Jensen, Ida
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Sinnrik matematik: En läromedelsanalys med fokus på uppgifters visuella, auditiva och kinestetiska/taktila stöd2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of the essay is to examine the possibilities for students to learn mathematics with a variety of senses through the tasks in the teaching materials Nya matematikboken, Singma and Favorit matematik during school year 1. The focus is on visual, auditory and kinesthetic/tactile support. Furthermore, the aim is to investigate the different elements of the teaching material and the extent of the different support in them. With categories based on different sensory input, a thorough content analysis has been made to compare the three chosen teaching materials. The result shows that there are good grounds for learning through many senses. However, the support varies in total and in the different elements. Both similarities and differences have been distinguished. The results also clearly show the benefits of using the teaching materials fully.

  • 358.
    Honnér, Tina
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Var håller talfamiljer hus i läroboksuppgifter?: En läromedelsanalys av läroboksuppgifter i årskurs 1 som fokuserar på talfamiljer upp till 10, utifrån ett problemlösningsperspektiv.2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this essay is to illustrate how fact families are present and form part of teaching materials in Swedish schools` year 1. This study focuses on how text book assignments teaches number sense, number ability and fact families up to 10, from a problem-solving perspective. To fulfill the purpose of the essay, textbook assignments with fact families and parts of fact families are analyzed using Cummins´ analysis model, where the framework is sorted into four distinct levels depending on context and cognitive difficulty after categorization. The result was analyzed both quantitatively and qualitatively and showed that teaching materials train students in the part of facts completely independently. Very few teaching materials showed the relationship between the fact family and the whole and parts of addition and subtraction. The most common textbook task is a bare task with addition or subtraction that counts from left to right without the support of context. The study also raises thoughts about what the research shows versus how school books assignments are designed and also what the individual teacher needs to think about when making his or her choice of text book tasks for students.

  • 359.
    Hoseiny Farahabady, Mohammad Reza
    et al.
    Sch. of IT, Univ. of Sydney, Sydney, NSW, Australia.
    Taheri, Javid
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Tari, Zahir
    Sch. of Sci., RMIT Univ., Melbourne, VIC, Australia.
    Zomaya, Albert Y
    School of Information Technologies, University of Sydney.
    A Dynamic Resource Controller for a Lambda Architecture2017In: 2017 46th International Conference on Parallel Processing (ICPP), Piscataway: IEEE, 2017, p. 332-341Conference paper (Refereed)
    Abstract [en]

    Lambda architecture is a novel event-driven serverless paradigm that allows companies to build scalable and reliable enterprise applications. As an attractive alternative to traditional service oriented architecture (SOA), Lambda architecture can be used in many use cases including BI tools, in-memory graph databases, OLAP, and streaming data processing. In practice, an important aim of Lambda's service providers is devising an efficient way to co-locate multiple Lambda functions with different attributes into a set of available computing resources. However, previous studies showed that consolidated workloads can compete fiercely for shared resources, resulting in severe performance variability/degradation. This paper proposes a resource allocation mechanism for a Lambda platform based on the model predictive control framework. Performance evaluation is carried out by comparing the proposed solution with multiple resource allocation heuristics, namely enhanced versions of spread and binpack, and best-effort approaches. Results confirm that the proposed controller increases the overall resource utilization by 37% on average and achieves a significant improvement in preventing QoS violation incidents compared to others.

  • 360.
    Hoseinyfarahabady, M. Reza
    et al.
    The University of Sydney, Australia.
    Bastani, Saeed
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Taheri, Javid
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Zomaya, Albert Y.
    The University of Sydney, Australia.
    Tari, Zahir
    RMIT University, Australia.
    Khan, Samee Ullah
    North Dakota State University, United States.
    Toward designing a dynamic CPU cap manager for timely dataflow platforms2018In: HPC '18 Proceedings of the High Performance Computing Symposium / [ed] Watson L.T., Thacker W.I., Sosonkina M., Rupp K., Weinbub J., Association for Computing Machinery (ACM), 2018, Vol. 50, no 4, p. 60-70, article id 6Conference paper (Refereed)
    Abstract [en]

    In this work, we propose a control-based solution for the problem of CPU resource allocation in data-flow platform that considers the degradation of performance caused by running concurrent data-flow processes. Our aim is to cut the QoS violation incidents for applications belonging to the highest QoS class. The performance of the proposed solution is bench-marked with the famous round robin algorithm. The experimental results confirms that the proposed algorithm can decrease the latency of processing data records for applications by 48% compared to the round robin policy.

  • 361.
    Huang, Peter
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Gagnero, Pontus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Seamlessly Displaying Models in Virtual Reality2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 362.
    Hurtig, Per
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Alay, Ozgu
    Simula Research Laboratory.
    Ferlin, Simone
    Simula Research Laboratory.
    Yedugundla, Kiran
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Reducing Transport Latency using Multipath Protocols2015Conference paper (Refereed)
  • 363.
    Hurtig, Per
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Alfredsson, Stefan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Brunström, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Evensen, Kristian
    Celerway Communications.
    Grinnemo, Karl-Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Fosselie Hansen, Audun
    Celerway Communications.
    Rozensztrauch, Tomasz
    Celerway Communications.
    A NEAT Approach to Mobile Communication2017In: MobiArch ’17 Proceedings of the Workshop on Mobility in the Evolving Internet Architecture, Association for Computing Machinery (ACM), 2017, p. 7-12Conference paper (Refereed)
    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.

  • 364.
    Hurtig, Per
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Grinnemo, Karl-Johan
    Brunström, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Ferlin, Simone
    Ericsson Research, Stockholm.
    Alay, Özgü
    Simula Research Laboratory, Norway.
    Kuhn, Nicolas
    French National Space Centre, France.
    Low-Latency Scheduling in MPTCP2019In: IEEE/ACM Transactions on Networking, ISSN 1063-6692, E-ISSN 1558-2566, Vol. 1, p. 302-315, article id 8584135Article in journal (Refereed)
    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.

  • 365.
    Hurtig, Per
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Haile, Habtegebreil Kassaye
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Grinnemo, Karl-Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Brunström, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (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 evaluation2018In: Proceedings of the 30th International Teletraffic Congress, ITC 2018, IEEE, 2018, p. 218-226Conference paper (Refereed)
    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. 

  • 366.
    Häger, Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science. Karlstad University.
    An Evaluation of Google Glass: Design, Implementation and Evaluation of a Product Assembly Application for Google Glass and Smartphones2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Assembling components in a production line could potentially be a tedious task, if performed stepwise by the book. However, an employee who is assembling many different products may not know all the steps by heart. As such they will be reliant on an instruction manual. However, an instruction manual must be carried around and, while assembling components, placed in the assembler's line of sight. Instead new technology could make the process more efficient. Google Glass places a display slightly above the user's line of sight and can be controlled via voice commands, and as such solves many of the problems associated with carrying around instruction manuals. This dissertation is an evaluation of Google Glass and describes the design, implementation and evaluation of an product assembly application for both Google Glass and smartphones. The smartphone version was implemented in order to provide a reference point as well as means of comparison with the Google Glass application. The test application used in the study was to read a QR code and download a set of assembly instructions. Testing was carried out on the different steps of the application, from when the QR code had been scanned until the information was displayed to the user. The results show that Google Glass is almost always slower, in all steps, compared to the smartphone equivalents. The conclusion is that Google must upgrade and improve on Google Glass and in particular the hardware. Google Glass overheats easily and the camera is of inferior quality. Google's implementation restrictions also limits what developers might be able to do with the device. However, Google Glass is easy to use and has potential to become a more useful device in the future.

  • 367. Häggström, Johan
    et al.
    Norén, Evavan Bommel, JorrytKarlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).Sayers, JudyHelenius, OlaLiljekvist, YvonneKarlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    ICT in mathematics education: the future and the realities. Proceedings of MADIF 10
  The tenth research seminar of the Swedish Society for Research in Mathematics Education,
Karlstad, January 26–27, 20162017Conference proceedings (editor) (Refereed)
  • 368.
    Håkman, Olof
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Boltzmann Equation and Discrete Velocity Models: A discrete velocity model for polyatomic molecules2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In the study of kinetic theory and especially in the study of rarefied gas dynamics one often turns to the Boltzmann equation. The mathematical theory developed by Ludwig Boltzmann was at first sight applicable in aerospace engineering and fluid mechanics. As of today, the methods in kinetic theory are extended to other fields, for instance, molecular biology and socioeconomics, which makes the need of finding efficient solution methods still important. In this thesis, we study the underlying theory of the continuous and discrete Boltzmann equation for monatomic gases. We extend the theory where needed, such that, we cover the case of colliding molecules that possess different levels of internal energy. Mainly, we discuss discrete velocity models and present explicit calculations for a model of a gas consisting of polyatomic molecules modelled with two levels of internal energy.

  • 369.
    Høiland-Jørgensen, Toke
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Analyzing the Latency of Sparse Flows in the FQ-CoDel Queue Management Algorithm2018In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 22, no 11, p. 2266-2269Article in journal (Refereed)
    Abstract [en]

    The FQ-CoDel queue management algorithm was recently published as an IETF RFC.It achieves low latency especially for low-volume (or sparse) traffic flowscompeting with bulk flows. However, the exact conditions for when a particularflow is considered to be sparse has not been well-explored.

    In this work, we analyse the performance characteristics of the sparse flowoptimisation of FQ-CoDel, formulating the constraints that flows must satisfy tobe considered sparse in a given scenario. We also formulate expressions for theexpected queueing latency for sparse flows.

    Then, using a numerical example, we show that for a given link and a given typeof sparse flows (VoIP traffic), the number of sparse flows that a givenbottleneck can service with low sparse flow latency is only dependent on thenumber of backlogged bulk flows at the bottleneck. Furthermore, as long as themaximum number of sparse flows is not exceeded, all sparse flows can expect avery low queueing latency through the bottleneck.

  • 370.
    Høiland-Jørgensen, Toke
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Bufferbloat and Beyond: Removing Performance Barriers in Real-World Networks2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The topic of this thesis is the performance of computer networks. While network performance has generally improved with time, over the last several years we have seen examples of performance barriers limiting network performance. In this work we explore such performance barriers and look for solutions.

    The problem of excess persistent queueing latency, known as bufferbloat, serves as our starting point; we examine its prevalence in the public internet, and evaluate solutions for better queue management, and explore how to improve on existing solutions to make them easier to deploy.

    Since an increasing number of clients access the internet through WiFi networks, examining WiFi performance is a natural next step. Here we also look at bufferbloat, as well as the so-called performance anomaly, where stations with poor signal strengths can severely impact the performance of the whole network. We present solutions for both of these issues, and additionally design a mechanism for assigning policies for distributing airtime between devices on a WiFi network. We also analyse the “TCP Small Queues” latency minimisation technique implemented in the Linux TCP stack and optimise its performance over WiFi networks.

    Finally, we explore how high-speed network processing can be enabled in software, by looking at the eXpress Data Path framework that has been gradually implemented in the Linux kernel as a way to enable high-performance programmable packet processing directly in the operating system’s networking stack.

    A special focus of this work has been to ensure that the results are carried forward to the implementation stage, which is achieved by releasing implementations as open source software. This includes parts that have been accepted into the Linux kernel, as well as a separate open source measurement tool, called Flent, which is used to perform most of the experiments presented in this thesis, and also used widely in the bufferbloat community.

  • 371.
    Høiland-Jørgensen, Toke
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Flent: The FLExible Network Tester2015Conference paper (Other academic)
  • 372.
    Høiland-Jørgensen, Toke
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    On the Bleeding Edge: Debloating Internet Access Networks2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    As ever more devices are connected to the internet, and applications turn ever more interactive, it becomes more important that the network can be counted on to respond reliably and without unnecessary delay. However, this is far from always the case today, as there can be many potential sources of unnecessary delay. In this thesis we focus on one of them: Excess queueing delay in network routers along the path, also known as bufferbloat.

    We focus on the home network, and treat the issue in three stages. We examine latency variation and queueing delay on the public internet and show that significant excess delay is often present. Then, we evaluate several modern AQM algorithms and packet schedulers in a residential setting, and show that modern AQMs can almost entirely eliminate bufferbloat and extra queueing latency for wired connections, but that they are not as effective for WiFi links. Finally, we go on to design and implement a solution for bufferbloat at the WiFi link, and also design a workable scheduler-based solution for realising airtime fairness in WiFi.

    Also included in this thesis is a description of Flent, a measurement tool used to perform most of the experiments in the other papers, and also used widely in the bufferbloat community.

  • 373.
    Høiland-Jørgensen, Toke
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Ahlgren, Bengt
    SICS.
    Hurtig, Per
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Brunström, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Measuring Latency Variation in the Internet2016In: Proceedings of the 12th International on Conference on emerging Networking EXperiments and Technologies, 2016, p. 473-480Conference paper (Refereed)
    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.

  • 374.
    Høiland-Jørgensen, Toke
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Brouer, Jesper Dangaard
    Red Hat.
    Borkmann, Daniel
    Cilium.io.
    Fastabend, John
    Cilium.io.
    Herbert, Tom
    Quantonium Inc..
    Ahern, David
    Cumulus Networks.
    Miller, David
    Red Hat.
    The eXpress Data Path: Fast Programmable Packet Processing in the Operating System Kernel2018In: CoNEXT '18 Proceedings of the 14th International Conference on emerging Networking EXperiments and Technologies, Association for Computing Machinery (ACM), 2018, p. 54-66Conference paper (Refereed)
    Abstract [en]

    Programmable packet processing is increasingly implemented using kernel bypass  techniques, where a userspace application takes complete control of the  networking hardware to avoid expensive context switches between kernel and  userspace. However, as the operating system is bypassed, so are its  application isolation and security mechanisms; and well-tested configuration,  deployment and management tools cease to function.  To overcome this limitation, we present the design of a novel approach to  programmable packet processing, called the eXpress Data Path (XDP). In XDP,  the operating system kernel itself provides a safe execution environment for  custom packet processing applications, executed in device driver context. XDP  is part of the mainline Linux kernel and provides a fully integrated solution  working in concert with the kernel's networking stack. Applications are  written in higher level languages such as C and compiled into custom byte code  which the kernel statically analyses for safety, and translates into native  instructions.  We show that XDP achieves single-core packet processing performance as high as  24 million packets per second, and illustrate the flexibility of the  programming model through three example use cases: layer-3 routing, inline  DDoS protection and layer-4 load balancing.

  • 375.
    Høiland-Jørgensen, Toke
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Grazia, Carlo Augusto
    University of Modena and Reggio Emilia.
    Hurtig, Per
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Brunström, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Flent: The FLExible Network Tester2017In: VALUETOOLS 2017: Proceedings of 11th EAI International Conference on Performance Evaluation Methodologies and Tools, New York, NY: Association for Computing Machinery (ACM), 2017, p. 1-6, article id 271973Conference paper (Refereed)
    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.

  • 376.
    Høiland-Jørgensen, Toke
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Hurtig, Per
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Brunstrom, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    The Good, the Bad and the WiFi: Modern AQMs in a residential setting2015In: Computer Networks, ISSN 1389-1286, E-ISSN 1872-7069, Vol. 89, p. 90-106Article in journal (Refereed)
    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.

  • 377.
    Høiland-Jørgensen, Toke
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Hurtig, Per
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Brunström, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    PoliFi: Airtime Policy Enforcement for WiFi2019In: IEEE Wireless Communications and Networking Conference, WCNC, IEEE, 2019, p. 1-6, article id 8885440Conference paper (Refereed)
    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.

  • 378.
    Høiland-Jørgensen, Toke
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Kazior, Michał
    Tieto Poland, Szczecin, Poland.
    Täht, Dave
    TekLibre, San Francisco, CA USA.
    Hurtig, Per
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Brunström, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Ending the Anomaly: Achieving Low Latency and Airtime Fairness in WiFi2017In: Proceedings of the 2017 USENIX Annual Technical Conference (USENIX ATC ’17), USENIX - The Advanced Computing Systems Association, 2017, p. 139-151Conference paper (Refereed)
    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.

  • 379.
    Høiland-Jørgensen, Toke
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Täht, Dave
    Teklibre, Usa.
    Morton, Jonathan
    Piece of CAKE: A Comprehensive Queue Management Solution for Home Gateways2018In: 2018 IEEE INTERNATIONAL SYMPOSIUM ON LOCAL AND METROPOLITAN AREA NETWORKS (LANMAN), IEEE, 2018, p. 37-42Conference paper (Refereed)
    Abstract [en]

    The last several years has seen a renewed interest in smart queue management tocurb excessive network queueing delay, as people have realised the prevalence of bufferbloat in real networks.

    However, for an effective deployment at today's last mile connections, animproved queueing algorithm is not enough in itself, as often the bottleneckqueue is situated in legacy systems that cannot be upgraded. In addition,features such as per-user fairness and the ability to de-prioritise backgroundtraffic are often desirable in a home gateway.

    In this paper we present Common Applications Kept Enhanced (CAKE), a comprehensive network queue management system designed specifically for homeInternet gateways. CAKE packs several compelling features into an integratedsolution, thus easing deployment. These features include: bandwidth shaping withoverhead compensation for various link layers; reasonable DiffServ handling;improved flow hashing with both per-flow and per-host queueing fairness; andfiltering of TCP ACKs.

    Our evaluation shows that these features offer compelling advantages, andthat CAKE has the potential to significantly improve performance of last-mileinternet connections.

  • 380.
    Hübsch, Jacob
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Persson, Magnus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Förstärkt verklighet med ARCore: Utveckling av en förstärkt verklighetsapplikation i Android med Kotlin och Azure2019Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The technology of “augmented reality” has existed in an experimental stage since the early 1990s, but it is not until around year 2010 that commercial use in the form of both hardware and software became available, for example, when Pokémon GO and Google Glass were announced.

    The aim of this thesis is to develop a mobile application that utilizes the technique of augmented reality to gain an insight into the technique’s potential, as well as the various tools available in this type of development. The project resulted in an augmented reality application, written in the program language Kotlin for the mobile operating system Android. The main use of the application includes group activities such as tourism, as the main functionality is to visualize other users' location via the mobile camera using the tools ARCore and Azure’s database Cosmos DB. Even though the technology is relatively new, the work has progressed without major difficulties, and even with basic programming knowledge it is possible to do software development in this area.

  • 381.
    Ijioma, Ekeoma R.
    et al.
    University of Limerick.
    Muntean, Adrian
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Fast Drift Effects In The Averaging Of A Filtration Combustion System: A Periodic Homogenization Approach2019In: Quarterly of Applied Mathematics, ISSN 0033-569X, E-ISSN 1552-4485, Vol. 77, no 1, p. 71-104Article in journal (Refereed)
    Abstract [en]

    We target the periodic homogenization of a semi-linear reaction-diffusion-convection system describing filtration combustion, where fast drifts are triggered by the competition between heat and mass transfer processes in an asymptotic regime of dominant convection. In addition, we consider the interplay between surface nonlinear chemical reactions and transport processes. To handle the oscillations occurring due to the heterogeneity of the medium, we rely on the concept of two-scale convergence with drift to obtain, for suitably scaled model parameters, the upscaled system of equations together with effective transport parameters. The main difficulty is to treat the case of a coupled multi-physics problem. We proceed by extending the results reported by G. Allaire et al. and other related papers in this context to the case of a coupled system of evolution equations pertinent to filtration combustion.

  • 382.
    Iwaya, L H
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Fausto, Giunchiglia
    Trento University, Italy.
    Martucci, Leonardo
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Hume, Alethia
    Trento University, Italy.
    Fischer-Hübner, Simone
    Karlstad University, Division for Information Technology.
    Chenu-Abente, Ronald
    Trento University, Italy.
    Ontology-based Obfuscation and Anonymisation for Privacy: A Case Study on Healthcare2016In: Privacy and Identity Management: Time for a Revolution? / [ed] David Aspinal, Marit Hansen, Jan Camenisch, Simone Fischer-Hübner, Charles Raab, Springer, 2016, p. 343-358Conference paper (Refereed)
  • 383.
    Iwaya, Leonardo H
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Engineering Privacy for Mobile Health Data Collection Systems in the Primary Care2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Mobile health (mHealth) systems empower Community Health Workers (CHWs) around the world, by supporting the provisioning of Community-Based Primary Health Care (CBPHC) – primary care outside the health facility into people’s homes. In particular, Mobile Health Data Collection Systems (MDCSs) are used by CHWs to collect health-related data about the families that they treat, replacing paper-based approaches for health surveys. Although MDCSs significantly improve the overall efficiency of CBPHC, existing and proposed solutions lack adequate privacy and security safeguards. In order to bridge this knowledge gap between the research areas of mHealth and privacy, the main research question of this thesis is: How to design secure and privacy-preserving systems for Mobile Health Data Collection Systems? To answer this question, the Design Method is chosen as an engineering approach to analyse and design privacy and security mechanisms for MDCSs. Among the main contributions, a comprehensive literature review of the Brazilian mHealth ecosystem is presented. This review led us to focus on MDCSs due to their impact on Brazil’s CBPHC, the Family Health Strategy programme. On the privacy engineering side, the contributions are a Privacy Impact Assessment (PIA) for the GeoHealth MDCS and three mechanisms: (a) SecourHealth, a security framework for data encryption and user authentication; (b) an Ontology-based Data Sharing System (O-DSS) that provides obfuscation and anonymisation functions; and, (c) an electronic consent (e-Consent) tool for obtaining and handling informed consent. Additionally, practical experience is shared about designing a MDCS, GeoHealth, and deploying it in a large-scale experimental study. In conclusion, the contributions of this thesis offer guidance to mHealth practitioners, encouraging them to adopt the principles of privacy by design and by default in their projects.

  • 384.
    Iwaya, Leonardo H
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Secure and Privacy-aware Data Collection and Processing in Mobile Health Systems2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Healthcare systems have assimilated information and communication technologies in order to improve the quality of healthcare and patient's experience at reduced costs. The increasing digitalization of people's health information raises however new threats regarding information security and privacy. Accidental or deliberate data breaches of health data may lead to societal pressures, embarrassment and discrimination. Information security and privacy are paramount to achieve high quality healthcare services, and further, to not harm individuals when providing care. With that in mind, we give special attention to the category of Mobile Health (mHealth) systems. That is, the use of mobile devices (e.g., mobile phones, sensors, PDAs) to support medical and public health. Such systems, have been particularly successful in developing countries, taking advantage of the flourishing mobile market and the need to expand the coverage of primary healthcare programs. Many mHealth initiatives, however, fail to address security and privacy issues. This, coupled with the lack of specific legislation for privacy and data protection in these countries, increases the risk of harm to individuals. The overall objective of this thesis is to enhance knowledge regarding the design of security and privacy technologies for mHealth systems. In particular, we deal with mHealth Data Collection Systems (MDCSs), which consists of mobile devices for collecting and reporting health-related data, replacing paper-based approaches for health surveys and surveillance. This thesis consists of publications contributing to mHealth security and privacy in various ways: with a comprehensive literature review about mHealth in Brazil; with the design of a security framework for MDCSs (SecourHealth); with the design of a MDCS (GeoHealth); with the design of Privacy Impact Assessment template for MDCSs; and with the study of ontology-based obfuscation and anonymisation functions for health data.

  • 385.
    Iwaya, Leonardo H
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Fischer-Hübner, Simone
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Åhlfeldt, Rose-Mharie
    School of Informatics, University of Skövde, Skövde, Sweden.
    Martucci, Leonardo
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    mHealth: A Privacy Threat Analysis for Public Health Surveillance Systems2018In: 2018 IEEE 31st International Symposium on Computer-Based Medical Systems / [ed] Bridget Kane, Karlstad, Sweden: IEEE, 2018Conference paper (Refereed)
    Abstract [en]

    Community Health Workers (CHWs) have been using Mobile Health Data Collection Systems (MDCSs) for supporting the delivery of primary healthcare and carrying out public health surveys, feeding national-level databases with families’ personal data. Such systems are used for public surveillance and to manage sensitive data (i.e., health data), so addressing the privacy issues is crucial for successfully deploying MDCSs. In this paper we present a comprehensive privacy threat analysis for MDCSs, discuss the privacy challenges and provide recommendations that are specially useful to health managers and developers. We ground our analysis on a large-scale MDCS used for primary care (GeoHealth) and a well-known Privacy Impact Assessment (PIA) methodology. The threat analysis is based on a compilation of relevant privacy threats from the literature as well as brain-storming sessions with privacy and security experts. Among the main findings, we observe that existing MDCSs do not employ adequate controls for achieving transparency and interveinability. Thus, threatening fundamental privacy principles regarded as data quality, right to access and right to object. Furthermore, it is noticeable that although there has been significant research to deal with data security issues, the attention with privacy in its multiple dimensions is prominently lacking.

  • 386.
    Iwaya, Leonardo H
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Fischer-Hübner, Simone
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Åhlfeldt, Rose-Mharie
    School of Informatics, University of Skövde, Skövde, Sweden.
    Martucci, Leonardo
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Mobile Health Systems for Community-Based Primary Care: Identifying Controls and Mitigating Privacy Threats2019In: JMIR mhealth and uhealth, E-ISSN 2291-5222, Vol. 7, no 3, p. 1-16, article id e11642Article in journal (Refereed)
    Abstract [en]

    Background: Community-based primary care focuses on health promotion, awareness raising, and illnesses treatment and prevention in individuals, groups, and communities. Community Health Workers (CHWs) are the leading actors in such programs, helping to bridge the gap between the population and the health system. Many mobile health (mHealth) initiatives have been undertaken to empower CHWs and improve the data collection process in the primary care, replacing archaic paper-based approaches. A special category of mHealth apps, known as mHealth Data Collection Systems (MDCSs), is often used for such tasks. These systems process highly sensitive personal health data of entire communities so that a careful consideration about privacy is paramount for any successful deployment. However, the mHealth literature still lacks methodologically rigorous analyses for privacy and data protection.

    Objective: In this paper, a Privacy Impact Assessment (PIA) for MDCSs is presented, providing a systematic identification and evaluation of potential privacy risks, particularly emphasizing controls and mitigation strategies to handle negative privacy impacts.

    Methods: The privacy analysis follows a systematic methodology for PIAs. As a case study, we adopt the GeoHealth system, a large-scale MDCS used by CHWs in the Family Health Strategy, the Brazilian program for delivering community-based primary care. All the PIA steps were taken on the basis of discussions among the researchers (privacy and security experts). The identification of threats and controls was decided particularly on the basis of literature reviews and working group meetings among the group. Moreover, we also received feedback from specialists in primary care and software developers of other similar MDCSs in Brazil.

    Results: The GeoHealth PIA is based on 8 Privacy Principles and 26 Privacy Targets derived from the European General Data Protection Regulation. Associated with that, 22 threat groups with a total of 97 subthreats and 41 recommended controls were identified. Among the main findings, we observed that privacy principles can be enhanced on existing MDCSs with controls for managing consent, transparency, intervenability, and data minimization.

    Conclusions: Although there has been significant research that deals with data security issues, attention to privacy in its multiple dimensions is still lacking for MDCSs in general. New systems have the opportunity to incorporate privacy and data protection by design. Existing systems will have to address their privacy issues to comply with new and upcoming data protection regulations. However, further research is still needed to identify feasible and cost-effective solutions.

  • 387.
    Iwaya, Leonardo H.
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Fischer-Hübner, Simone
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Åhlfeldt, Rose-Mharie
    School of Informatics, University of Skövde, Skövde, Sweden.
    Martucci, Leonardo
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Overview of Privacy Challenges in Mobile Health Data Collection Systems2018Conference paper (Refereed)
    Abstract [en]

    Community Health Workers (CHWs) have been using Mobile HealthData Collection Systems (MDCSs) for public health surveys, feeding the national-level databases with the families’ personal data. Since such systems are inherentlyused for public surveillance and manage sensitive data (i.e., health data), deal-ing with the privacy issues is crucial to successful deployments. In this poster wepresent the privacy challenges related to MDCSs, providing a summary speciallyimportant to health managers and developers.

  • 388.
    Iwaya, Leonardo H
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Li, Jane
    Health and Biosecurity, Commonwealth Scientific and Industrial Research Organization, Australia.
    Fischer-Hübner, Simone
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Åhlfeldt, Rose-Mharie
    University of Skövde.
    Martucci, Leonardo
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    E-Consent for Data Privacy: Consent Management for Mobile Health Technologies in Public Health Surveys and Disease Surveillance2019In: MEDINFO 2019: Health and Wellbeing e-Networks for All / [ed] Lucila Ohno-Machado, Brigitte Séroussi, IOS Press, 2019, Vol. 264, p. 1224-1227Conference paper (Refereed)
    Abstract [en]

    Community health workers in primary care programs increasingly use Mobile Health Data Collection Systems (MDCSs) to report their activities and conduct health surveys, replacing paper-based approaches. The mHealth systems are inherently privacy invasive, thus informing individuals and obtaining their consent is important to protect their right to privacy. In this paper, we introduce an e-Consent tool tailored for MDCSs. It is developed based on the requirement analysis of consent management for data privacy and built upon the solutions of Participant-Centered Consent toolkit and Consent Receipt specification. The e-Consent solution has been evaluated in a usability study. The study results show that the design is useful for informing individuals on the nature of data processing, privacy and protection and allowing them to make informed decisions

  • 389.
    Iwaya, Leonardo H
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Martucci, Leonardo
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Fischer-Hübner, Simone
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Towards a Privacy Impact Assessment Template for Mobile Health Data Collection Systems2016In: Proceedings of the 5th International Conference on M4D Mobile Communication Technology for Development: M4D 2016, General Tracks / [ed] Orlando P Zacarias and Caroline W. Larsson, 2016, p. 189-200Conference paper (Refereed)
  • 390.
    Iwaya, Leonardo H.
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Voronkov, Artem
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Martucci, Leonardo A.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Lindskog, Stefan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Fischer-Hübner, Simone
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Firewall Usability and Visualization: A Systematic Literature Review2016Report (Refereed)
    Abstract [en]

    Firewalls are network security components that allow administrators to handle incoming and outgoing traffic based on a set of rules. Such security appliances are typically the first line of defense, creating a barrier between organization’s internal network and the outside network (e.g., Internet). The process of correctly configuring a firewall is complex and error prone, and it only gets worse as the complexity of the network grows. A vulnerable firewall configuration will very likely result in major threats to the organization’s security. In this report we aim to investigate how to make administrator task of planning and implementing firewall solutions easier, from the stand points of usability and visualization. Our scientific investigation starts with the understanding of the state-of-the-art on this specific field. To do so, we conducted a Systematic Literature Review (SLR), a strict methodology to plan a literature review, to gather relevant information, to synthesize and compare approaches, and to report findings. During the initial search process thousands of papers were screened, leading us to 125 papers carefully selected for further readings. In the secondary study, ten relevant works were identified and assessed, in which authors tackled the issues of usability and visualization for Firewalls and Personal Firewalls. Among the main findings, we perceive that there is a lack (or even absence) of user studies to validate the proposed models. This leads us to a series of unwarranted solutions, that need to be prototyped and tested with real users. We also see an huge opportunity for integrative approaches, that could combine firewall research areas, such as automatic anomaly detection, advisory systems, and varying visualization schemes.

  • 391.
    Iwaya, Leonardo
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013). University of Sao Paulo, Brazil.
    Rosso, R S U
    Universidade do Estado de Santa Catarina, Brazli.
    Hounsell, M S
    Universidade do Estado de Santa Catarina, Brazil.
    A Design for Assembly Application with Dynamic Information Retrieval from Case Database2013In: Intelligent Manufacturing Systems / [ed] Marcos de Sales Guerra Tsuzuki and José Reinaldo Silva, Elsevier, 2013, Vol. 11, p. 186-191Conference paper (Refereed)
    Abstract [en]

    Design for Assembly (DFA) is a Concurrent Engineering constituent that gained a lot of attention due to fast and measurable benets. The main principle of DFA is to foresee assembly problems at the design stage based on the experience regarding functionality, materials and machine availability. The work presented in this paper, named RFA - Redesign for Assembly, adds a way to explicitly register and retrieve experiences as part of the design process. It starts from an initial design, then RFA leads the designer through a detailed assessment towards an improved design according to previous experiences. Experience representation was done using a Group Technology classication concept that helps assign a primary-key for a Case Based Teaching underlying system. A supporting system has been implemented in order to try out RFA. DFA scholars have used RFA and proved that experience retrieval is easily and intuitively incorporated in the design process. The paper presents a study about the DFA methodology, reviews existing solutions (methods and software) from the literature and details the RFA architecture, implementation and tests. RFA shows potential for a new design culture based on knowledge sharing, but also, as a repository for a very valuable asset, i.e. problem-oriented assembly-related design experience.

  • 392.
    Jain, P
    et al.
    South Asian University.
    Kanjilal, S
    South Asian University.
    Persson, Lars-Erik
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Hardy-type inequalities over balls in R^N for some bilinear and iterated operators2019In: Journal of Inequalities and Special Functions, ISSN 2217-4303, E-ISSN 2217-4303, Vol. 10, no 2, p. 35-48Article in journal (Refereed)
    Abstract [en]

    Some new multidimensional Hardy-type inequalites are proved and discussed. The cases with bilinear and iterated operators are considered and some equivalence theorems are proved.

  • 393.
    Jalili, Leilia
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Parichehreh, Ali
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Alfredsson, Stefan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Garcia, Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Brunström, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Efficient traffic offloading for seamless connectivity in 5G networks onboard high speed trains2017In: IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, IEEE, 2017, p. 1-6Conference paper (Refereed)
    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.

  • 394.
    Jankvist, Uffe
    et al.
    University of Southern Denmark.
    Ryve, Andreas
    Mälardalen University.
    van Bommel, Jorryt
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Waege, Kjersti
    Norvegian University of Science and Technology.
    Future challenges of mathematics education research in the Nordic region: Young researchers’ perspective2011In: Proceedings of NORMA 11: the sixth Nordic Conference on Mathmatics Education / [ed] Guðný Helga Gunnarsdóttir, Reijkjavik: University of Iceland Press, 2011Conference paper (Refereed)
    Abstract [en]

     In the last decade research in mathematics education has grown and consolidated in the Nordic countries. New and younger researchers are entering the field as a result of the organization of solid doctoral programs and the growth of teaching and research environments in higher education institutions. The social, cultural and economic contexts of our countries have also changed in the last decade. The question of which are the main challenges for research in the years to come is worth exploring for a community starting a new decade of work. The intention of the panel is to generate a discussion in the community by having young researchers present their views on: (1) which topics of research the Nordic region has contributed to the world and that deserve being strengthened in the future; (2) which new topics of research that may become relevant as social changes pose new demands on our knowledge and understanding of the practices of mathematics education in the educational system; and (3) which institutional affordances and constraints young researchers experience for the development of research 

  • 395.
    Johansson, David
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Construction of Superimposed Codes Using Graphs and Galois Fields2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this thesis some constructions of superimposed codes are presented. Many of the known nontrivial constructions arise from t−designs, and the constructions discussed in this thesis is also based on a block design idea. Superimposed codes are rather combinatorial in nature, so the connection to t−designs is not too surprising. What may be a little surprise, however, is the connection between superimposed codes and linear codes and Galois elds. Linear codes are quite intuitive and have nice properties, as is the case for Galois elds; combinatorial structures are quite often the contrary, not intuitive and quite dicult to understand. Because of this, it is interesting that a combinatorial structure like superimposed codes can be constructed from structures like linear codes and Galois elds. The main goal of this thesis is to present two possibly new approaches to construct superimposed codes. The constructions are described, but not proved to be correct. The rst construction presented is using graphs. In practice, this is not a good way to construct codes, since it requires the construction of a graph and nding certain cycles in the graph. It is still an interesting construction, however, since it provides a connection between constant weight codes and superimposed codes. Another construction is presented, one that seems much more useful when constructing codes. In [7] one particular superimposed code is constructed from a Galois eld. In this thesis we will see that this construction using Galois elds can be generalized.

  • 396.
    Johansson, David
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Taheri, Javid
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    On the Energy Cost of Robustness and Resiliency for Virtual Network Function Placement2018In: 2018 IEEE Conference on Network Function Virtualization and Software Defined Networks (NFV-SDN), IEEE, 2018Conference paper (Refereed)
    Abstract [en]

    The placement of Virtual Network Functions (VNF) in distributed data centers is an important problem to solve for the next generation cloud based telecom architectures. This is because where to place the VNFs and how to route the traffic in the physical network impacts the energy consumption of the cloud infrastructure, the resiliency of the service chains and the SLA with the tenants. For network operators, it is important to minimize the operational costs of their infrastructure, provide robustness of the placement and routing in order to cope with potential hardware failures and imprecise resource demand specifications. In this paper, we develop a new optimization model for the green multi-period VNF placement and traffic routing problem, where different service chain configurations exist over time. The model is formulated as a Mixed Integer Linear Program (MILP), considers latency due to network propagation and VNF processing and provides different protection methods for the NFV traffic routing to cope with link failures. By applying Soyster's robustness principle, the model yields a network configuration that can cope with load that deviates from the expected demand. Because the MILP is complex to solve, we develop a fast variable fixing heuristic. In our numerical evaluation, we use the virtualized Evolved Packet Core and study the energy cost of different robustness levels and protection schemes for VNF service flow routing.

  • 397.
    Johansson, Gustav
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Persson, Fredrik
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Photograph labeling application: An Android application for labeling and uploading of photographs2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The project’s goal was to solve a technical problem for Elonservice in Värmland, wheretheir technicians have the need for an upload solution for labeled photographs in connectionwith warranty claims. The solution to the problem was to develop an Android applicationthat label photographs and then automatically uploads them to a selected storage service.The end result of the project is a working Android application. Users can take photographsthrough the application and is then forced to name them in a correct manner. Theapplication automatically handles the uploading of photographs and deletion of uploadedphotographs. In addition to this there is also a gallery where all photographs are displayedwith their upload state and the opportunity to see all photos in full screen. The applicationhas future development possibilities such as more options for storage services , labelingalternative to photographs and a more attractive design.

  • 398.
    Johansson, Simon
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Andersson, Hugo
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Chicago: A multiplayer card game based on Client – Server architecture2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 399.
    Johansson, Viktor
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Jeppesen, Christian
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Utveckling av internordersystem för SharePoint2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    SharePoint is a web based platform designed to provide internal communications and file sharing for businesses and organizations.

    In this project, we created a system consisting of multiple applications to be used together with SharePoint. These applications are meant to simplify the workflow for internal orders of products. The system is targeted towards companies that do not have a flexible approach to digital orders or companies that want to integrate this functionality into their SharePoint platform.

     

    The project includes, in addition to the creation of the system, installation of the software and the servers needed to run a SharePoint environment and their configurations.

    The system consists of four applications where one of these, the store application, is required for the system to be used at all. The other applications are an order management application, a purchase application and an incoming delivery application. Of these four, we have implemented the store application and the order management application.

     

    Our hope is that users will find the system easy to use and graphically appealing.

  • 400.
    Johnsson, John
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Pontus, Ljungdahl
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    PRIMConverter2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
567891011 351 - 400 of 909
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