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  • 101.
    Bayer, Nico
    et al.
    Deutsche Telekom/T-Systems, Darmstadt, Germany.
    Cavalcanti de Castro, Marcel
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Dely, Peter
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Koucheryavy, Yevgeni
    Tampere University of Technolo, Finland.
    Mitoraj, Piotr
    Tampere University of Technology, Finland.
    Staehle, Dirk
    University of Würzburg, Germany.
    VoIP service performance optimization in pre-IEEE 802.11s Wireless Mesh Networks2008In: Proceedings of the IEEE International Conference on Circuits andSystems for Communications (ICCSC) 2008, IEEE conference proceedings, 2008, p. 75-79Conference paper (Refereed)
    Abstract [en]

    802.11-based wireless mesh networks are seen as a means for providing last mile connections to next generation networks. Due to the low deployment cost and the mature technology used, they are scalable, easy to implement and robust. With an increasing coverage of wireless networks, VoIP becomes a cheaper alternative for traditional and cellular telephony. In this paper, we carry out a feasibility study of VoIP in a dual radio mesh environment. Heading towards 802.11s, we present the design of a mesh testbed and methodology for performing the measurements. Additionally, we address the problem that small voice packets introduce a high overhead leading to a low voice capacity of 802.11 based mesh networks. In order to alleviate this problem and increase the voice capacity, a novel packet aggregation mechanism is presented and evaluated using the ns-2 simulator.

  • 102.
    Beckerle, Matthias
    et al.
    Technische Universität Darmstadt,, Germany.
    Martucci, Leonardo
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Formal Definitions for Usable Access Control Rule Sets: From Goals to Metrics2013In: Proceedings of the Ninth Symposium on Usable Privacy and Security, Association for Computing Machinery (ACM), 2013, p. 2:1-2:11Conference paper (Refereed)
    Abstract [en]

    Access control policies describe high level requirements for access control systems. Access control rule sets ideally trans-late these policies into a coherent and manageable collectionof Allow/Deny rules. Designing rule sets that reflect desired policies is a difficult and time-consuming task. The result is that rule sets are difficult to understand and manage. The goal of this paper is to provide means for obtaining usable access control rule sets, which we define as rule sets that (i) reflect the access control policy and (ii) are easy to understand and manage. In this paper, we formally define the challenges that users face when generating usable access control rule sets and provide formal tools to handle them more easily. We started our research with a pilot study in which specialists were interviewed. The objective was to list usability challenges regarding the management of access control rule sets and verify how those challenges were handled by specialists. The results of the pilot study were compared and combined with results from related work and refined into six novel, formally defined metrics that are used to measure the security and usability aspects of access control rule sets. We validated our findings with two user studies, which demonstrate that our metrics help users generate statistically significant better rule sets.

  • 103.
    Beckerle, Matthias
    et al.
    Technische Universitt Darmstadt Darmstadt, Germany.
    Martucci, Leonardo
    Ries, Sebastian
    Technische Universitt Darmstadt, Darmstadt, Germany.
    Interactive access rule learning: Generating adapted access rule sets2010In: ADAPTIVE 2010: The Second International Conference on Adaptive and Self-Adaptive Systems and Applications November 21-26, 2010 - Lisbon, Portugal / [ed] Ali Beklen, Jorge Ejarque, Wolfgang Gentzsch, Teemu Kanstren, Arne Koschel, Yong Woo Lee, Li Li & Michal Zemlicka, International Academy, Research and Industry Association (IARIA), 2010, p. 104-110Conference paper (Refereed)
    Abstract [en]

    This paper tackles the problem of usability and security in access control mechanisms. A theoretical solution for this problem is presented using the combination of automaticrule learning and user interaction. The result is the interactive rule learning approach. Interactive rule learning is designed to complete attribute-based access control to generate concise rule sets even by non-expert end-users. The resulting approach leads to adaptive access control rule sets that can be used for smart products.

  • 104.
    Beckerle, Matthias
    et al.
    Telecooperation Group (TK), Technische Universität Darmstadt.
    Martucci, Leonardo
    Telecooperation Group (TK), Technische Universität Darmstadt.
    Ries, Sebastian
    Telecooperation Group (TK), Technische Universität Darmstadt.
    Mühlhäuser, Max
    Telecooperation Group (TK), Technische Universität Darmstadt.
    Interactive Rule Learning for Access Control: Concepts and Design2011In: International Journal on Advances in Intelligent Systems, ISSN 1942-2679, E-ISSN 1942-2679, Vol. 4, no 3-4, p. 234-244Article in journal (Refereed)
    Abstract [en]

    Nowadays the majority of users are unable toproperly configure security mechanisms mostly because theyare not usable for them. To reach the goal of having usable security mechanisms, the best solution is to minimize the amount of user interactions and simplify configuration tasks. Automation is a proper solution for minimizing the amount of user interaction. Fully automated security systems are possible for most security objectives, with the exception ofthe access control policy generation. Fully automated accesscontrol policy generation is currently not possible because individual preferences must be taken into account and, thus, requires user interaction. To address this problem we proposea mechanism that assists users to generate proper accesscontrol rule sets that reflect their individual preferences. We name this mechanism Interactive Rule Learning for AccessControl (IRL). IRL is designed to generate concise rule setsfor Attribute-Based Access Control (ABAC). The resulting approach leads to adaptive access control rule sets that can be used for so called smart products. Therefore, we first describe the requirements and metrics for usable access control rulesets for smart products. Moreover, we present the design of asecurity component which implements, among other security functionalities, our proposed IRL on ABAC. This design is currently being implemented as part of the ICT 7th Framework Programme SmartProducts of the European Commission.

  • 105.
    Beckman, Claes
    et al.
    KTH, Center for Wireless Systems.
    Garcia, Johan
    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).
    On the Impact of Velocity on the Train-to-Earth MIMO Propagation Channel: Statistical Observations and Qualitative Analysis2017In: 2017 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting, IEEE, 2017, p. 1865-1866Conference paper (Refereed)
    Abstract [en]

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

  • 106.
    Bellalta, Boris
    et al.
    Department of Information and Communication Technologies, Universitat Pompeu Fabra, Barcelona 08018, Spain.
    Bononi, Luciano
    Department of Computer Science and Engineering, University of Bologna, 40127 Bologna, Italy.
    Bruno, Raffaele
    Institute for Informatics and Telematics (IIT), Italian National Research Council (CNR), Pisa 56124, Italy.
    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.
    Next generation IEEE 802.11 Wireless Local Area Networks: Current status, future directions and open challenges2016In: Computer Communications, ISSN 0140-3664, E-ISSN 1873-703X, Vol. 75, p. 1-25Article in journal (Refereed)
    Abstract [en]

    A new generation of Wireless Local Area Networks (WLANs) will make its appearance in the market in the forthcoming years based on the amendments to the IEEE 802.11 standards that have recently been approved or are under development. Examples of the most expected ones are IEEE 802.11aa (Robust Audio Video Transport Streaming), IEEE 802.11ac (Very-high throughput at < 6 GHz), IEEE 802.11af (TV White Spaces) and IEEE 802.11ah (Machine-to-Machine communications) specifications. The aim of this survey is to provide a comprehensive overview of these novel technical features and the related open technical challenges that will drive the future WLAN evolution. In contrast to other IEEE 802.11 surveys, this is a use case oriented study. Specifically, we first describe the three key scenarios in which next-generation WLANs will have to operate. We then review the most relevant amendments for each of these use cases focusing on the additional functionalities and the new technologies they include, such as multi-user MIMO techniques, groupcast communications, dynamic channel bonding, spectrum databases and channel sensing, enhanced power saving mechanisms and efficient small data transmissions. We also discuss the related work to highlight the key issues that must still be addressed. Finally, we review emerging trends that can influence the design of future WLANs, with special focus on software-defined MACs and the internet-working with cellular systems.

  • 107.
    Berglind, Raymond
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Larsson, Louise
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Mobile SIF-application: Cross-platform development of a Xamarin application utilizing data from a SharePoint intranet solution2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Xamarin, a cross-platform development framework, was used in this project for the development of a proof-of-concept mobile client application for an existing intranet solution. The intranet consists of Microsoft SharePoint components and is a pre-assembled product produced by the requestor of this project; Sogeti. To fetch the intranet’s data, a web API was implemented as an intermediary between the mobile application and the intranet. The Xamarin application targets three different mobile platforms including iOS, Android and Universal Windows Platform, and since Xamarin allows for shared logic between different operating systems, this approach was adopted to the greatest extent possible. However, during the development of the project several problems were encountered that prompted platform-specific implementations. For example, the user authentication process needed to be implemented in a platform-specific manner in the client application and some parts of the graphical user interface needed to be adapted to each individual platform as well. Even though the development of the applications was not completely finished, four out of seven of the original requirements set forth by Sogeti at the beginning of the project were achieved. These fulfilled requirements include, among other functionality, the implementation of displaying news articles and attention messages from a user’s specific intranet solution. Overall, the project was found to be successful, especially with regard to evaluating how well Xamarin and cross-platform development works with these kinds of mobile applications.

  • 108.
    Berglund, Simon
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Digital skyltning på Androidenheter: Ett Android integrationsprojekt2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Digital skyltning är en speciell form av skyltning där information, bilder, videoklipp eller liknande media visas på digitala skärmar. Skyltningen sker vanligtvis på LCD eller LED skärmar och placeras vanligtvis på antingen offentliga platser eller på arbetsplatser.

    Projektet går ut på att expandera en färdig digital-skyltningsmjukvara där koden huvudsakligen är skriven i HTML5 och JavaScript genom att göra den exekverbar och anpassad för operativsystemet Android.

    Resultatet av projektet gjorde mjukvaran anpassad samt exekverbar på Android. Verktyget Cordova användes för att göra webb-koden exekverbar på Android. Anpassningen gäller huvudsakligen att ge mjukvaran tillgång till Androidenhetens funktioner och resurser som exempelvis filsystemet och skärmdumps-funktionen.

  • 109. Bernhard, David
    et al.
    Kulyk, Oksana
    Volkamer, Melanie
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Security Proofs for Participation Privacy and Stronger Verifiability for Helios2016Report (Other academic)
  • 110.
    Bernhard, David
    et al.
    University of Bristol, UK.
    Oksana, Kulyk
    Technische Universität Darmstadt, Germany.
    Volkamer, Melanie
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013). Technische Universität Darmstadt, Germany.
    Security proofs for Participation privacy, receipt-freeness and ballot privacy for the helios voting scheme2017In: ARES '17 Proceedings of the 12th International Conference on Availability, Reliability and Security, New York: Association for Computing Machinery (ACM), 2017, article id UNSP 1Conference paper (Refereed)
    Abstract [en]

    The Helios voting scheme is well studied including formal proofs for verifiability and ballot privacy. However, depending on its version, the scheme provides either participation privacy (hiding who participated in the election) or verifiability against malicious bulletin board (preventing election manipulation by ballot stuffing), but not both at the same time. It also does not provide receipt-freeness, thus enabling vote buying by letting the voters construct receipts proving how they voted. Recently, an extension to Helios, further referred to as KTV-Helios, has been proposed that claims to provide these additional security properties. However, the authors of KTV-Helios did not prove their claims. Our contribution is to provide formal definitions for participation privacy and receipt-freeness that we applied to KTV-Helios. In order to evaluate the fulfillment of participation privacy and receipt-freeness, we furthermore applied the existing definition of ballot privacy, which was also used for evaluating the security of Helios, in order to show that ballot privacy also holds for KTV-Helios

  • 111.
    Berthold, Stefan
    Karlstad University, Faculty of Economic Sciences, Communication and IT.
    Linkability of communication contents: Keeping track of disclosed data using Formal Concept Analysis2006Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [en]

    A person who is communication about (the data subject) has to keep track of all of his revealed data in order to protect his right of informational self-determination. This is important when data is going to be processed in an automatic manner and, in particular, in case of automatic inquiries. A data subject should, therefore, be enabled to recognize useful decisions with respect to data disclosure, only by using data which is available to him.

    For the scope of this thesis, we assume that a data subject is able to protect his communication contents and the corresponding communication context against a third party by using end-to-end encryption and Mix cascades. The objective is to develop a model for analyzing the linkability of communication contents by using Formal Concept Analysis. In contrast to previous work, only the knowledge of a data subject is used for this analysis instead of a global view on the entire communication contents and context.

    As a first step, the relation between disclosed data is explored. It is shown how data can be grouped by types and data implications can be represented. As a second step, behavior, i. e. actions and reactions, of the data subject and his communication partners is included in this analysis in order to find critical data sets which can be used to identify the data subject.

    Typical examples are used to verify this analysis, followed by a conclusion about pros and cons of this method for anonymity and linkability measurement. Results can be used, later on, in order to develop a similarity measure for human-computer interfaces.

  • 112.
    Berthold, Stefan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    The Privacy Option Language: Specification & Implementation2013Report (Other academic)
    Abstract [en]

    The data protection laws in Europe require that data controllers provide privacy policies to inform individuals about the prospective processing of their personal data. The ever growing expressiveness of privacy policy languages allows to specify policies in a growing number of details. This and new options for policy negotiations transformed rather general privacy policies into specific privacy contracts between the data controller and the individual.

    In this report, we specify a privacy contract language and call it the Privacy Option Language. It is modelled after the analogy between financial option contracts and data disclosures which has been presented in previous work and led to the Privacy Option notion. The language specification provides privacy by design through its data minimisation provisions, i.e., all contracts are automatically reduced to their canonical form so that individual differences in the contract formulation are inherently normalised. The language specification is extensible in two ways. First, hooks are specified in the core language and can be used to connect sublanguages. The freedom to choose any suitable sublanguage allows to specify language details independent of the core language. Second, the Privacy Option Language itself can be used as a sublanguage within a more general-domain language. We give examples for both types of extensions. Additionally, we provide tools for evaluating semantics such as human-readable presentations of Privacy Options and contract management. The definitions of the semantics are kept simple and serve as templates for more practical ones.

    All functionality can be checked by interactive tests in a standard multi-purpose programming language interpreter, since the Privacy Option Language is specified as an embedded domain-specific language within Haskell. Hands-on examples are provided along with the language specification.

  • 113.
    Berthold, Stefan
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Towards a Formal Language for Privacy Options2011In: Privacy and Identity Management for Life / [ed] Simone Fischer-Hübner, Penny Duquenoy, Marit Hansen, Ronald Leenes & Ge Zhang, Springer, 2011, p. 27-40Conference paper (Refereed)
  • 114.
    Berthold, Stefan
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Towards Inter-temporal Privacy Metrics2011Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Informational privacy of individuals has significantly gained importance after information technology has become widely deployed. Data, once digitalised, can be copied and distributed at negligible costs. This has dramatic consequences for individuals that leave traces in form of personal data whenever they interact with information technology. The right of individuals for informational privacy, in particular to control the flow and use of their personal data, is easily undermined by those controlling the information technology.

    The objective of this thesis is the measurement of informational privacy with a particular focus on scenarios where an individual discloses personal data to a second party, the data controller, which uses this data for re-identifying the individual within a set of others, the population. Several instances of this scenario are discussed in the appended papers, most notably one which adds a time dimension to the scenario for modelling the effects of the time passed between data disclosure and usage. This extended scenario leads to a new framework for inter-temporal privacy metrics.

    The common dilemma of all privacy metrics is their dependence on the information available to the data controller. The same information may or may not be available to the individual and, as a consequence, the individual may be misguided in his decisions due to his limited access to the data controller’s information when using privacy metrics. The goal of this thesis is thus not only the specification of new privacy metrics, but also the contribution of ideas for mitigating this dilemma. However a solution will rather be a combination of technological, economical and legal means than a purely technical solution.

  • 115.
    Berthold, Stefan
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Böhme, Rainer
    Valuating Privacy with Option Pricing Theory2010In: Economics of Information Security and Privacy / [ed] Tyler Moore, David Pym, and Christos Ioannidis, New York: Springer , 2010, p. 187-193Chapter in book (Refereed)
    Abstract

    One of the key challenges in the information society is responsible handling of personal data. An often-cited reason why people fail to make rational decisions regarding their own informational privacy is the high uncertainty about future consequences of information disclosures today. This chapter builds an analogy to financial options and draws on principles of option pricing to account for this uncertainty in the valuation of privacy. For this purpose, the development of a data subject's personal attributes over time and the development of the attribute distribution in the population are modelled as two stochastic processes, which fit into the Binomial Option Pricing Model (BOPM). Possible applications of such valuation methods to guide decision support in future privacy-enhancing technologies (PETs) are sketched

  • 116.
    Berthold, Stefan
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Böhme, Rainer
    Berkley Business College, Oviedo, Spain.
    Valuating Privacy with Option Pricing Theory2010In: Economics of Information Security and Privacy / [ed] Tyler Moore, David Pym, Christos Ioannidis, London: Springer , 2010, p. 187-210Conference paper (Refereed)
  • 117.
    Berthold, Stefan
    et al.
    Technische Universität, Dresden.
    Böhme, Rainer
    Technische Universität, Dresden.
    Köpsell, Stefan
    Technische Universität, Dresden.
    Data Retention and Anonymity Services: Introducing a New Class of Realistic Adversary Models2009In: The Future of Identity in the Information Society, Springer , 2009, p. 92-106Conference paper (Refereed)
  • 118.
    Berthold, Stefan
    et al.
    Teknische Universistät, Dresden, Germany.
    Clauss, Sebastian
    Teknische Universistät, Dresden, Germany.
    Linkability Estimation Between Subjects and Message Contents Using Formal Concepts2007In: Proceedings of the 2007 ACM Workshop on Digital identity management (DIM), New York: ACM , 2007, p. 36-45Conference paper (Refereed)
  • 119.
    Berthold, Stefan
    et al.
    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.
    Clauß, Sebastian
    Linkability Estimation Between Subjects and Message Contents Using Formal Concepts2007Conference paper (Refereed)
    Abstract [en]

    In this paper, we examine how conclusions about linkability threats can be drawn by analyzing message contents and subject knowledge in arbitrary communication systems. At first, we define messages described by their contents as formal contexts. Then, we define subjects described by their knowledge as further formal contexts. Finally, we show that concept lattices, which are achieved by applying Formal Concept Analysis to the concatenation of these formal contexts, can be used in order to draw conclusions about correlations, and therefore linkability, between contents of messages and knowledge of subjects. The goal is to define formal specifications which can be utilized in privacy enhancing identity management systems in order to support users in the choice of data items which are to be disclosed to a communication partner

  • 120.
    Berthold, Stefan
    et al.
    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.
    Martucci, Leonardo
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Pulls, Tobias
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Crime and Punishment in the Cloud: Accountability, Transparency, and Privacy2013Conference paper (Refereed)
    Abstract [en]

    The goal of this work is to reason on the complexity of the relationship between three non-functional requirements in cloud comput-ing; privacy, accountability, and transparency. We provide insights on the complexity of this relationship from the perspectives of end-users, cloud service providers, and third parties, such as auditors. We shed light onthe real and perceived conflicts between privacy, transparency, and accountability, using a formal definition of transparency and an analysis on how well a privacy-preserving transparency-enhancing tool may assist in achieving accountability. Furthermore, we highlight the importance of the privacy impact assessment process for the realisation of both transparency and accountability.

  • 121.
    Bhamare, Deval
    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).
    Vestin, Jonathan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Khoshkholghi, Mohammad Ali
    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).
    IntOpt: In-Band Network Telemetry Optimization for NFV Service Chain Monitoring2019In: 2019 IEEE International Conference on Communications (ICC) Próceedings, 2019Conference paper (Refereed)
    Abstract [en]

    Managing and scaling virtual network function(VNF) service chains require the collection and analysis ofnetwork statistics and states in real time. Existing networkfunction virtualization (NFV) monitoring frameworks either donot have the capabilities to express the range of telemetryitems needed to perform management or do not scale tolarge traffic volumes and rates. We present IntOpt, a scalableand expressive telemetry system designed for flexible VNFservice chain network monitoring using active probing. IntOptallows to specify monitoring requirements for individual servicechain, which are mapped to telemetry item collection jobsthat fetch the required telemetry items from P4 (programmingprotocol-independent packet processors) programmable dataplaneelements. In our approach, the SDN controller creates theminimal number of monitoring flows to monitor the deployedservice chains as per their telemetry demands in the network.We propose a simulated annealing based random greedy metaheuristic(SARG) to minimize the overhead due to activeprobing and collection of telemetry items. Using P4-FPGA, webenchmark the overhead for telemetry collection and compareour simulated annealing based approach with a na¨ıve approachwhile optimally deploying telemetry collection probes. Ournumerical evaluation shows that the proposed approach canreduce the monitoring overhead by 39% and the total delays by57%. Such optimization may as well enable existing expressivemonitoring frameworks to scale for larger real-time networks.

  • 122.
    Blom, Martin
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Documentation Methods and Reusability: an Experimental Evaluation2004Conference paper (Refereed)
    Abstract [en]

    This document presents an experimental evaluation carried out during the summer of 2003 in an academic environment. The goal of the experiment was to compare how different methods of documenting semantic information affect software reuse. More specifically, we wanted to measure if there were any differences between the methods with regard to the time needed to implement changes to existing software. Four methods of documentation were used; executable contracts, non-executable contracts, Javadoc-style documentation and sequence diagrams. The experimental setup used was a factorial design with documentation method as the treatment, and with test persons and assignments as blocking variables. The results indicate that executable contracts demanded more time than the other three methods and that sequence diagrams and Javadoc demanded the least time. ANOVA-tests on the data indicates that there were statistically significant differences between the methods

  • 123.
    Blom, Martin
    Karlstad University, Faculty of Economic Sciences, Communication and IT.
    Empirical Evaluations of Semantic Aspects in Software Development2006Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    This thesis presents empirical research in the field of software development with a focus on handling semantic aspects. There is a general lack of empirical data in the field of software development. This makes it difficult for industry to choose an appropriate method for their particular needs. The lack of empirical data also makes it difficult to convey academic results to the industrial world.

    This thesis tries to remedy this problem by presenting a number of empirical evaluations that have been conducted to evaluate some common approaches in the field of semantics handling. The evaluations have produced some interesting results, but their main contribution is the addition to the body of knowledge on how to perform empirical evaluations in software development. The evaluations presented in this thesis include a between-groups controlled experiment, industrial case studies and a full factorial design controlled experiment. The factorial design seems like the most promising approach to use when the number of factors that need to be controlled is high and the number of available test subjects is low. A factorial design has the power to evaluate more than one factor at a time and hence to gauge the effects from different factors on the output.

    Another contribution of the thesis is the development of a method for handling semantic aspects in an industrial setting. A background investigation performed concludes that there seems to be a gap between what academia proposes and how industry handles semantics in the development process. The proposed method aims at bridging this gap. It is based on academic results but has reduced formalism to better suit industrial needs. The method is applicable in an industrial setting without interfering too much with the normal way of working, yet providing important benefits. This method is evaluated in the empirical studies along with other methods for handling semantics. In the area of semantic handling, further contributions of the thesis include a taxonomy for semantic handling methods as well as an improved understanding of the relation between semantic errors and the concept of contracts as a means of avoiding and handling these errors.

  • 124.
    Blom, Martin
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Experimental Evaluation of Semantic-based Programming2003Conference paper (Refereed)
    Abstract [en]

    This paper deals with semantic-based programming and presents two experiments, one executed and one planned where the aim is to see what benefits a semantic-based program development method would bring. The first experiment was designed to compare a contract-based programming method with a standard programming method based on exceptions. The purpose was to evaluate if using contracts would shorten development time, if contracts would improve work satisfaction and if contracts would increase the quality of the resulting software program. The experiment was performed in a project work course for computer science students who were to solve an assignment in groups of four. Half of the groups used the contract-based method and the other half used the exception-based method. The results indicate that there is a gain in the time spent on implementation of the assignment if the contract-based method is used, but no significant difference in total time consumption was found. The results also indicate that the work satisfaction was slightly higher in the groups using the contract-based method. The resulting program was analyzed for a range of quality metrics, but no significant differences were found. The main problems of this experiment were too few data points, diversity in competence and ethical considerations. These problems all contribute to the statistically weak results. The last part of this paper presents a planned experiment where the problems in the first experiment hopefully will be remedied. This part is the main new contribution of the paper and is thought of as a starting point for discussions and not as a finished product or paper. The first part of the paper has been published before in a longer version, but is included for background and reference

  • 125.
    Blom, Martin
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Handling of Semantic Aspects in Academia and Industry - A Taxonomy and Case Study2005Conference paper (Refereed)
    Abstract [en]

    Handling semantic aspects of a software system is one important issue in software development along with developing code and managing the organization and process. Code related issues has been thoroughly researched throughout the years as has process/organization related issues in more recent years. The semantic level inbetween has also had its share of contributions, but to a lesser extent than the two other levels. The paper presents some insight into how semantic issues are handled in both academia and industry. It presents a taxonomy based on literature studies of research papers for the academic part, and a case study that gives some insight into the work on semantic issues in industry

  • 126.
    Blom, Martin
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Is Scrum and XP suitable for CSE Development?2010Conference paper (Refereed)
    Abstract

    This article discusses the question if Scrum and XP is well suited for development of Computational Science and Engineering (CSE) software. The reason for choosing Scrum and XP is based on two facts. Firstly, CSE developers are not used to formal processes for software development and Scrum and XP are informal in nature, hence easier to adopt. Secondly CSE projects are often once-off and aimed at producing scientific results rather than commercial software, so the overhead of a process or methodology needs to be kept at a minimum. Scrum and XP are focused on producing software, thus keeping everything else, i.e. the overhead to a minimum, a fact that benefits CSE development. In this article, the characteristics of Scrum and XP in particular and agile development in general are evaluated against the needs of CSE developers. The results show that almost all the key points in both methodologies are well suited for CSE development and that agile development in general is a good match with CSE

  • 127.
    Blom, Martin
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Metodbeskrivning för pilotexperiment. ("Method Description for Pilot Experiment")1999Report (Other academic)
  • 128.
    Blom, Martin
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Semantic Aspects in Software Development2002Licentiate thesis, monograph (Other academic)
    Abstract [en]

    This thesis presents research on how to raise the quality of software by helping developers focus on semantic aspects during the development process. Our research has so far been concentrated on software design, impolementation, testing and maintenance, but we believe that the ideas are applicable to other phases as well. The need for methods that better support software developers when working with semantic aspects was initially found in some of our industrial surveys. In these, we tried to evaluate the documentation for real software artefacts and found that semantic aspects were not handled as well as other aspects. To remedy this, we have developed an industrially applicable method that helps the developer focus on issues related to semantics. The method has been tested in a controlled experiment in a university course to evaluate its effects on the development process and the resulting product. The initial experiences of using the method were positive and the results indicate that it is possible to introduce a focus on semantics without any large overhead and still profit from higher quality software. In summary, we believe that improving the semantic aspects will improve the quality of the development process and of the resulting software

  • 129.
    Blom, Martin
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Semantic Aspects in Software Development2002Report (Other academic)
  • 130.
    Blom, Martin
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Semantic Integrity in Programming Industry. (Master's Dissertation)1997Other (Other (popular science, discussion, etc.))
  • 131.
    Blom, Martin
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Brunström, Anna
    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.
    Nordby, Eivind J
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    A Software Engineering Course that Integrates Education and Research2000Conference paper (Refereed)
  • 132.
    Blom, Martin
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Nordby, Eivind J
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Brunström, Anna
    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.
    An Experimental Evaluation of Documentation Methods and Reusability2008Conference paper (Refereed)
    Abstract [en]

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

  • 133.
    Blom, Martin
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Nordby, Eivind J
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Brunström, Anna
    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.
    An Experimental Evaluation of Programming by Contract2002Conference paper (Refereed)
    Abstract [en]

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

  • 134.
    Blom, Martin
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Nordby, Eivind J
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Brunström, Anna
    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.
    Introducing Contract-Based Programming in Industry - A Case Study2005Conference paper (Refereed)
    Abstract [en]

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

  • 135.
    Blom, Martin
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Nordby, Eivind J
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Brunström, Anna
    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.
    Method Description for Semla - A Software Design Method with a Focus on Semantics2000Report (Refereed)
  • 136.
    Blom, Martin
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Nordby, Eivind J
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Brunström, Anna
    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.
    Systemarkitektur och -design2000In: Del av kapitel 3 i "Industriell Programvaruteknik. Forskningsresultat i kortform", NUTEK Förlag Nr: B 2000:01 (www.nutek.se), ([MS Word]) , 2000Chapter in book (Other academic)
  • 137.
    Blom, Martin
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Nordby, Eivind J
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Brunström, Anna
    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.
    Teaching Semantic Aspects of OO Programming2002Conference paper (Refereed)
  • 138.
    Blom, Martin
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Nordby, Eivind J
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Ross, Donald F
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Jonsson, E.
    Using Quality Criteria in Programming Industry: A Case Study1998Conference paper (Refereed)
  • 139.
    Blom, Martin
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Öfverberg, Johan
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Information Systems and Project Management.
    Combining Contract-Based Development and Test-Driven Development2009In: / [ed] Hamid R. Arabnia, Hassan Reza, CSREA Press , 2009Conference paper (Refereed)
    Abstract

    Contract-based Development and Test-Driven Development are two techniques for handling and avoiding software errors. They are generally not combined and we have studied the processes associated with the techniques to

    see how this combination could be done. We have found possible ways to move to and from both processes and some benefits for both ways. Moving from contracts to test cases is rather straight forward due to the completeness of the contracts, whereas moving from test cases to contracts demand some more work since the test cases are only examples of usage.

  • 140.
    Bondarenko, Olga
    et al.
    Simula Research laboratory.
    Rajiullah, Mohammad
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Griwodz, Carsten
    Simula Research laboratory.
    Calvet, Lilian
    Simula Research laboratory.
    Brunstrom, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Petlund, Andreas
    Simula Research laboratory.
    Elmokashfi, Ahmed
    Simula Research laboratory.
    A Method for Hierarchical Clustering of Internet Traffic and its Use in Detecting Application-Limited FlowsManuscript (preprint) (Other academic)
  • 141.
    Bood, Martin
    et al.
    Karlstad University.
    Fisk, Karl-Johan
    Karlstad University.
    Tjänsteorienterad Integration, ESB2007Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [en]

    If today’s software systems and their complex applications shall be able to integrate with each

    other, they have to communicate through services. This service oriented integration can be

    accomplished by using Service Oriented Architecture (SOA) where all components are

    loosely coupled and communicate in a standardized way. An important part when building an

    integrated solution is the Enterprise Service Bus (ESB). In this report we will explain the

    basics of SOA and take a more detailed look at the world of ESB. The concept of ESB is not

    well defined and hence means different things to different people. We are going to present an

    interpretation of the ESB and its benefits and disadvantages. To find out what the market

    thinks about ESB we have been talking to producers, consultants and customers.

  • 142.
    Borchert, Thomas
    Karlstad University, Faculty of Economic Sciences, Communication and IT.
    Code Profiling: Static Code Analysis2008Independent thesis Advanced level (degree of Master), 20 points / 30 hpStudent thesis
    Abstract [en]

    Capturing the quality of software and detecting sections for further scrutiny within are of high interest for industry as well as for education. Project managers request quality reports in order to evaluate the current status and to initiate appropriate improvement actions and teachers feel the need of detecting students which need extra attention and help in certain programming aspects. By means of software measurement software characteristics can be quantified and the produced measures analyzed to gain an understanding about the underlying software quality.

    In this study, the technique of code profiling (being the activity of creating a summary of distinctive characteristics of software code) was inspected, formulized and conducted by means of a sample group of 19 industry and 37 student programs. When software projects are analyzed by means of software measurements, a considerable amount of data is produced. The task is to organize the data and draw meaningful information from the measures produced, quickly and without high expenses.

    The results of this study indicated that code profiling can be a useful technique for quick program comparisons and continuous quality observations with several application scenarios in both industry and education.

  • 143. Borges, Fabio
    et al.
    Martucci, Leonardo
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    iKUP keeps users' privacy in the Smart Grid2014In: Communications and Network Security (CNS), 2014 IEEE Conference on, IEEE conference proceedings, 2014, p. 310-318Conference paper (Refereed)
    Abstract [en]

    Privacy-enhancing technologies for the Smart Grid usually address either the consolidation of users’ energy consumption or the verification of billing information. The goal of this paper is to introduce iKUP, a protocol that addresses both problems simultaneously. iKUP is an efficient privacy-enhancingprotocol based on DC-Nets and Elliptic Curve Cryptography as Commitment. It covers the entire cycle of power provisioning, consumption, billing, and verification. iKUP allows: (i) utility providers to obtain a consolidated energy consumption value that relates to the consumption of a user set, (ii) utility providers to verify the correctness of this consolidated value, and (iii) the verification of the correctness of the billing information by both utility providers and users. iKUP prevents utility providers from identifying individual contributions to the consolidated value and, therefore, protects the users’ privacy. The analytical performance evaluation of iKUP is validated through simulation using as input a real-world data set with over 157 million measurements collected from 6,345 smart meters. Our results show that iKUP has a worse performance than other protocols in aggregationand decryption, which are operations that happen only once per round of measurements and, thus, have a low impactin the total protocol performance. iKUP heavily outperformsother protocols in encryption, which is the most demanded cryptographic function, has the highest impact on the overall protocol performance, and it is executed in the smart meters.

  • 144. Borges, Fábio
    et al.
    Martucci, Leonardo
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Beato, Filipe
    Mühlhäuser, Max
    Secure and Privacy-Friendly Public Key Generation and Certification2014In: 2014 IEEE 13th International Conference on Trust, Security and Privacy in Computing and Communications, New York: IEEE Press, 2014, p. 114-121Conference paper (Refereed)
    Abstract [en]

    Digital societies increasingly rely on secure communication between parties. Certificate enrollment protocols are used by certificate authorities to issue public key certificates to clients. Key agreement protocols, such as Diffie-Hellman, are used to compute secret keys, using public keys as input, for establishing secure communication channels. Whenever the keys are generated by clients, the bootstrap process requires either (a) an out-of-band verification for certification of keys when those are generated by the clients themselves, or (b) a trusted server to generate both the public and secret parameters. This paper presents a novel constrained key agreement protocol, built upon a constrained Diffie-Hellman, which is used to generate a secure public-private key pair, and to set up a certification environment without disclosing the private keys. In this way, the servers can guarantee that the generated key parameters are safe, and the clients do not disclose any secret information to the servers.

  • 145.
    Borges, Fábio
    et al.
    Technische Universität Darmstad, Germany.
    Martucci, Leonardo
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Mühlhäuser, Max
    Technische Universität Darmstadt, Germany.
    Analysis of privacy-enhancing protocols based on anonymity networks2012In: Smart Grid Communications (SmartGridComm), 2012 IEEE Third International Conference on, IEEE, 2012, p. 378-383Conference paper (Refereed)
    Abstract [en]

    In this paper, we analyze privacy-enhancing protocols for Smart Grids that are based on anonymity networks. The underlying idea behind such protocols is attributing two distinct partial identities for each consumer. One is used to send real-time information about the power consumption, and the other for transmitting the billing information. Such protocols provide sender-anonymity for the real-time information, while consolidated data is sent for billing. In this work, the privacy properties of such protocols are analyzed, and their computational efficiencyis evaluated and compared using simulation to other solutionsbased on homomorphic encryption.

  • 146.
    Boru, Dejene
    et al.
    Create-Net, Italy.
    Kliazovich, Dzmitry
    University Luxembourg, Luxembourg.
    Granelli, Fabrizio
    DISI University Trento, Italy..
    Bouvry, Pascal
    University Luxembourg, Luxembourg.
    Zomaya, Albert Y.
    University Sydney, Australia.
    Energy-Efficient Data Replication in Cloud Computing Datacenters2013In: 2013 IEEE GLOBECOM WORKSHOPS (GC WKSHPS), IEEE , 2013, p. 446-451Conference paper (Refereed)
    Abstract [en]

    Cloud computing is an emerging paradigm that provides computing resources as a service over a network. Communication resources often become a bottleneck in service provisioning for many cloud applications. Therefore, data replication, which brings data (e.g., databases) closer to data consumers (e.g., cloud applications), is seen as a promising solution. It allows minimizing network delays and bandwidth usage. In this paper we study data replication in cloud computing data centers. Unlike other approaches available in the literature, we consider both energy efficiency and bandwidth consumption of the system, in addition to the improved Quality of Service (QoS) as a result of the reduced communication delays. The evaluation results obtained during extensive simulations help to unveil performance and energy efficiency tradeoffs and guide the design of future data replication solutions.

  • 147.
    Boru, Dejene
    et al.
    Create-Net, Italy.
    Kliazovich, Dzmitry
    University Luxembourg, Luxembourg.
    Granelli, Fabrizio
    University Trento, Italy.
    Bouvry, Pascal
    University Luxembourg, Luxembourg.
    Zomaya, Albert Y.
    University Sydney, Australia.
    Models for Efficient Data Replication in Cloud Computing Datacenters2015In: 2015 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC), Institute of Electrical and Electronics Engineers (IEEE), 2015, p. 6056-6061Conference paper (Refereed)
    Abstract [en]

    Cloud computing is a computing model where users access ICT services and resources without regard to where the services are hosted. Communication resources often become a bottleneck in service provisioning for many cloud applications. Therefore, data replication which brings data (e.g., databases) closer to data consumers (e.g., cloud applications) is seen as a promising solution. In this paper, we present models for energy consumption and bandwidth demand of database access in cloud computing datacenter. In addition, we propose an energy efficient replication strategy based on the proposed models, which results in improved Quality of Service (QoS) with reduced communication delays. The evaluation results obtained with extensive simulations help to unveil performance and energy efficiency tradeoffs and guide the design of future data replication solutions.

  • 148.
    Boström, Rikard
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT.
    Moilanen, Lars-Olof
    Karlstad University, Faculty of Economic Sciences, Communication and IT.
    Capacity profiling modeling for baseband applications2009Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Real-time systems are systems which must produce a result within a given time frame. A result given outside of this time frame is as useless as not delivering any result at all. It is therefore essential to verify that real-time systems fulfill their timing requirements. A model of the system can facilitate the verification process. This thesis investigates two possible methods for modeling a real-time system with respect to CPU-utilization and latency of the different components in the system. The two methods are evaluated and one method is chosen for implementation.The studied system is the decoder of a WCDMA system which utilizes a real-time operating called system OSEck. The methodology of analyzing the system and different ways of obtaining measurements to base the model upon will be described. The model was implemented using the simulation library VirtualTime, which contains a model of the previously mentioned operating system. Much work was spent acquiring input for the model, since the quality of the model depends largely on the quality of the analysis work. The model created contains two of the studied systems main components.This thesis identifies thorough system knowledge and efficient profiling methods as the key success factors when creating models of real-time systems.

  • 149.
    Bozakov, Zdravko
    et al.
    Dell EMC, Ireland.
    Mangiante, Simone
    Dell EMC, Ireland.
    Hernandez Benet, Cristian
    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). Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Santos, Ricardo
    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).
    Buckley, Donagh
    Dell EMC, Ireland.
    A NEAT framework for enhanced end-host integration in SDN environments2017In: 2017 IEEE Conference on Network Function Virtualization and Software Defined Networks (NFV-SDN), IEEE, 2017Conference paper (Refereed)
    Abstract [en]

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

  • 150.
    Brajdic, Agata
    et al.
    Fac. of EE & Comput., Univ. of Zagreb, Zagreb, Croatia .
    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.
    Matijasevic, Maja
    Quality of Experience based optimization of heterogeneous multimedia sessions in IMS2011In: Proceedings of Baltic Congress on Future Internet Communications, IEEE conference proceedings, 2011, p. 25-32Conference paper (Refereed)
    Abstract [en]

    For delivering multimedia services over (wireless) networks it is important that the mechanisms which negotiate and optimize content delivery under resource constraints take into account user perceived quality in order to improve user satisfaction. Within the scope of the IP Multimedia Subsystem (IMS) architecture a novel application server may be added which handles multi-user multi-flow Quality of Experience (QoE) negotiation and adaptation for heterogeneous user sessions. Based on a mathematical model, which takes into account the characteristics of audio, video and data sessions for QoE optimization, we develop several optimization algorithms to be used by the application server to maximize overall user defined QoE parameters for all ongoing multimedia sessions, subject to network resource constraints. Our results show that a greedy based approach provides a reasonable compromise in terms of run-time and sub-optimality for the overall QoE based resource allocations.

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