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  • 251.
    Dely, Peter
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Architecture and Algorithms for User Association and Routing in Wireless Mesh Networks2011Konferansepaper (Annet (populærvitenskap, debatt, mm))
  • 252.
    Dely, Peter
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    KAUMesh Demo: A MultiRadio MultiChannel Mesh Testbed2009Annet (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    In this demo, we will present KAUMesh, an experimental Wireless Broadband Mesh Network based on 802.11a/b/g WLAN devices that has been deployed at the Karlstad University Campus. KAUMesh comprises currently 20 mesh nodes, which are permanently installed to cover large areas inside the new House 21. Standard 802.11b/g based clients can be used to connect to the mesh as they would to any given normal WLAN access point. KAUMesh features multiple gateways that connect the mesh network towards the internet. By deploying multiple radio cards in mesh nodes, KAUMesh is able to fully exploit available spectrum in the mesh backbone. One radio card interface is used for transparent client access, using typically 802.11b/g mode. The mesh backhaul connectivity is established using multiple radio interfaces per mesh node. The interfaces involved in the backhaul use a hybrid channel assignment mechanism, which rebalances channel usage according to user demand. As the hybrid channel assignment involves channel switching, a novel scheduling approach for making the channel switching QoS aware has been developed. KAUMesh also supports 802.11e standard on the mesh interface to provide service differentiation on the mesh backhaul

  • 253.
    Dely, Peter
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    On Packet Aggregation for VoIP in Wireless Meshed Networks2007Konferansepaper (Fagfellevurdert)
  • 254.
    Dely, Peter
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Bayer, Nico
    Telekom Innovation Laboratories.
    Einsiedler, Hans
    Telekom Innovation Laboratories.
    Method and System for Centralized Control of User Associations in Wireless Mesh Networks2012Patent (Annet (populærvitenskap, debatt, mm))
  • 255.
    Dely, Peter
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Bayer, Nico
    Telekom Innovation Laboratories.
    Einsiedler, Hans
    Telekom Innovation Laboratories.
    Peylo, Christoph
    Telekom Innovation Laboratories.
    Optimization of WLAN associations considering handover costs2012Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 255Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In Wireless Local Area Network (WLAN) hotspots the coverage areas of Access Points (APs) often overlap considerably. Current state of the art optimization models find the optimal AP for each user station by balancing the load across the network. Recent studies have shown that in typical commercial WLAN hotspots the median connection duration is short. In such dynamic network settings the mentioned optimization models might cause many handovers between APs to accommodate for user arrivals or mobility. We introduce a new mixed integer linear optimization problem that allows to optimize handovers but takes into account the costs of handovers such as signaling and communication interruption. Using our model and extensive numeric simulations we show that disregarding the handover costs leads to low performance. Based on this insight we design a new optimization scheme that uses estimates of future station arrivals and mobility patterns. We show that our scheme outperforms current optimization mechanisms and is robust against estimation errors

  • 256.
    Dely, Peter
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Bayer, Nico
    Telekom Innovation Laboratories.
    Einsiedler, Hans
    Telekom Innovation Laboratories.
    Peylo, Christoph
    Telekom Innovation Laboratories.
    Chow, Lawrence
    Stanford University.
    Collins, Bradley
    Stanford University.
    Bambos, Nicholas
    Stanford University.
    Daniel, Mellado
    Miguel, Sanchez
    A Software Defined Networking Approach for Handover Management with Real-Time Video in WLANs2012Konferansepaper (Fagfellevurdert)
  • 257.
    Dely, Peter
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Bayer, Nico
    Telekom Innovation Laboratories.
    Einsiedler, Hans
    Telekom Innovation Laboratories.
    Sivchenko, Dmitry
    Method and system for deriving an aggregation delay for packet aggregation in a wireless network2011Patent (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    System and method for deriving an aggregation delay for a packet aggregation in a wireless network comprising a controller for deriving an optimal aggregation delay at a network node depending on information relating to the channel quality related parameters at the network node in the wireless network.

  • 258.
    Dely, Peter
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Bayer, Nico
    Einsiedler, Hans-Joachim
    Sivchenko, Dmitry
    FUZPAG: A Fuzzy-Controlled Packet Aggregation Scheme for Wireless Mesh Networks2010Inngår i: Proceedings of the International Conference on Fuzzy Systems and Knowledge Discovery (FSKD'10), IEEE , 2010, s. 778-782Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Wireless mesh networks (WMNs) are wireless multi-hop backhaul networks in which mesh routers relay traffic on behalf of clients or other routers. Due to large MAC layer overhead, applications such as Voice over IP, which send many small packets, show poor performance in WMNs. Packet aggregation increases the capacity of IEEE 802.11-based WMNs by aggregating small packets into larger ones and thereby reducing overhead. In order to have enough packets to aggregate, packets need to be delayed and buffered. Current aggregation mechanisms use fixed buffer delays or do not take into account the delay characteristics of the saturated IEEE 802.11 MAC layer. In this work, we present FUZPAG, a novel packet aggregation architecture for IEEE 802.11-based wireless mesh networks. It uses fuzzy control to determine the optimum aggregation buffer delay under the current channel utilization. By cooperation among neighboring nodes FUZPAG distributes the buffer delay in a fair way. We implemented and evaluated the system in a wireless mesh testbed. For different network topologies we show that FUZPAG outperforms standard aggregation in terms of end-to-end latency under a wide range of traffic patterns.

  • 259.
    Dely, Peter
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Bayer, Nico
    Sivchenko, Dmitry
    An Experimental Comparison of Burst Packet Transmission Schemes in IEEE 802.11-based Wireless Mesh Networks2010Inngår i: Proceedings of IEEE Global Telecommunications Conference (GLOBECOM) 2010, IEEE , 2010, s. 1-5Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Wireless mesh networks (WMNs) are wireless multihop networks comprised of mesh routers, which relay traffic on behalf of clients and other nodes. Using the standard IEEE 802.11 distributed coordination function (DCF) as MAC layer, a node needs to contend for the medium each time it wants to transmit a packet. This creates high overhead in particular for small packets and leads to poor performance for real-time applications such as Voice over IP (VoIP) or online gaming. Burst packet transmission can increase the efficiency. For example, with the Transmission Opportunity limit (TXOPlimit) in IEEE 802.11e, a station may transfer several packets without contending for the channel in between. Similarly, IP packet aggregation combines several IP packets together and sends them as one MAC Service Data Unit. Originally, both schemes have been developed for singlehop networks only. Thus the impact on WMNs is unclear if the packets need to contend over multiple hops. In this paper, we use measurements from a 9-node WMN testbed to compare TXOPs and IP packet aggregation for VoIP in terms of fairness, network capacity and quality of user experience. We show that for low networks loads, both TXOPs and IP packet aggregation increase the VoIP quality compared to IEEE 802.11 DCF. However, in highly loaded networks IP packet aggregation outperforms the other schemes.

  • 260.
    Dely, Peter
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Cavalcanti de Castro, Marcel
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Paolo Delia, Francesco
    Avallone, Stefano
    OLSR and Net-X as a Framework for Channel Assignment Experiments: Poster Presentation2009Inngår i: Proceedings of the 4th ACM international workshop on Experimental evaluation and characterization WiNTECH 09, NewYork: ACM , 2009Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We present a software framework for channel assingment and routing experiments in multi-channel/multi-radio wireless mesh networks.Based on a plug-in architecture we develop a traffic demand-aware channel assignment algorithm. The evaluation in KAUMesh - an experimental multi-radio mesh network - shows around 30% throughput improvement with respect to a traffic un-aware channel assignment scheme

  • 261.
    Dely, Peter
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Chow, Lawrence
    USA.
    Bambos, Nicholas
    USA.
    Bayer, Nico
    Germany.
    Einsiedler, Hans
    Germany.
    Peylo, Christoph
    Germany.
    Mellado, Daniel
    Spain.
    Sanchez, Miguel
    Spain.
    A software-defined networking approach for handover management with real-time video in WLANs2013Inngår i: Journal of Modern Transportation, ISSN 2095-087X, E-ISSN 2196-0577, Vol. 21, nr 1, s. 58-65Artikkel i tidsskrift (Fagfellevurdert)
  • 262.
    Dely, Peter
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Einsiedler, Hans
    Telekom Innovation Laboratories.
    Bayer, Nico
    Telekom Innovation Laboratories.
    Peylo, Christoph
    Telekom Innovation Laboratories.
    Software Defined Networking for the Management and Operation of WLANs2013Annet (Annet (populærvitenskap, debatt, mm))
  • 263.
    Dely, Peter
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Sivchenko, Dmitry
    Theoretical and Experimental Analysis of the Channel Busy Fraction in IEEE 802.112010Inngår i: Proceedings of Future Network & Mobile Summit 2010, IEEE , 2010, s. 1-9Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Optimizing the operation of IEEE 802.11 networks requires to estimate the load of the wireless channel. The channel busy fraction, which is the fraction of time in which the wireless channel is sensed busy due to successful or unsuccessful transmissions, can be used as such indicator. It can be obtained from e.g. the IEEE 802.11k channel load report or hardware-specific interfaces. Previously, the channel busy fraction has been used as a metric for different purposes such as routing and admission control. However, a thorough evaluation of the relationship between the busy fraction and other important characteristics such as the collision probability and throughput is missing. In this paper, we present an analytical model to study the channel busy fraction in non-saturated IEEE 802.11 networks. We validate the model with measurements in a testbed. The predictions from the model match measurements well. Furthermore, we demonstrate how to apply the model to estimate the available link bandwidth. Using measurements obtained from a testbed operated at 6 Mbit/s, we show that the channel busy fraction allows an accurate prediction of the available bandwidth with an error smaller than 70 Kbit/s.

  • 264.
    Dely, Peter
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Staehle, Barbara
    Staehle, Dirk
    Pries, Rastin
    Hirth,, Matthias
    Measuring One-Way Delay in Wireless Mesh Networks: An Experimental Investigation2009Inngår i: Proceedings of the 4th ACM workshop on Performance monitoring and measurement of heterogeneous wireless and wired networks, New York: ACM , 2009Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Wireless Mesh networks are multi-hop networks mostly based on IEEE 802.11 technology and are considered as a viable alternative for providing broadband wireless Internet access. As a consequence, they require support for Quality of Service or advanced mechanisms for selecting Internet gateways. One important requiredinformation is the one-way delay between different nodes. In this paper, we have developed, implemented, and evaluated an one-way delay estimation technique for wireless mesh networks which is based on estimating intra node queuing and inter node forwarding delay. An IP-header option field is used to accumulate the per hop delay estimate to provide an end-to-end estimate. We also outline problems with the implementation and compare results with real one-way delays obtained from a 14 node mesh testbed.We show how estimation accuracy depends on network load and provide insights into further improvements

  • 265.
    Dely, Peter
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Vestin, Jonathan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    CloudMAC - Using OpenFlow to Process 802.11 MAC Frames in the Cloud2013Inngår i: PIK - Praxis der Informationsverarbeitung und Kommunikation, ISSN 0930-5157, Vol. 36, nr 1, s. 53-Artikkel i tidsskrift (Fagfellevurdert)
  • 266.
    Dely, Peter
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Vestin, Jonathan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Bayer, Nico
    Telekom Innovation Laboratories.
    Einsiedler, Hans
    Telekom Innovation Laboratories.
    Peylo, Christoph
    Telekom Innovation Laboratories.
    CloudMAC: An OpenFlow based Architecture for 802.11 MAC Layer Processing in the Cloud2012Inngår i: 2012 IEEE Globecom Workshops (GC Wkshps 2012): Proceedings of a meeting held 3-7 December 2012, Anaheim, California, USA, IEEE conference proceedings, 2012, s. 186-191Konferansepaper (Fagfellevurdert)
  • 267. Deng, Ming
    et al.
    Fritsch, Lothar
    Johann Wolfgang Goethe-University, Frankfurt, Germany.
    Kursawe, Klaus
    Personal rights management: Taming camera-phones for individual privacy enforcement2006Inngår i: Privacy Enhancing Technologies, Springer, 2006, s. 172-189Konferansepaper (Fagfellevurdert)
    Abstract [en]

    With ubiquitous use of digital camera devices, especially in mobile phones, privacy is no longer threatened by governments and companies only. The new technology creates a new threat by ordinary people, who could take and distribute pictures of an individual with no risk and little cost in any situation in public or private spaces. Fast distribution via web based photo albums, online communities and web pages expose an individual's private life to the public. Social and legal measures are increasingly taken to deal with this problem, but they are hard to enforce in practice. In this paper, we proposed a model for privacy infrastructures aiming for the distribution channel such that as soon as the picture is publicly available, the exposed individual has a chance to find it and take proper action in the first place. The implementation issues of the proposed protocol are discussed. Digital rights management techniques are applied in our proposed infrastructure, and data identification techniques such as digital watermarking and robust perceptual hashing are proposed to enhance the distributed content identification.

  • 268.
    Deng, Shuiguang
    et al.
    Zhejiang University, Hangzhou, China.
    Huang, Longtao
    Chinese Academy of Sciences, Beijing, China.
    Taheri, Javid
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Yin, Jianwei
    Zhejiang University, Hangzhou, China.
    Zhou, MengChu
    Macau University of Science and Technology, Macau, China.
    Zomaya, Albert
    The University of Sydney, Sydney, Australia.
    Mobility-Aware Service Composition in Mobile Communities2016Inngår i: IEEE Transactions on Systems, Man & Cybernetics. Systems, ISSN 2168-2216, E-ISSN 1349-2543, IEEE Transactions on Systems, Man, and Cybernetics: Systems, ISSN 2168-2216, Vol. 47, nr 3, s. 555-568Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    he advances in mobile technologies enable mobile devices to perform tasks that are traditionally run by personal computers as well as provide services to the others. Mobile users can form a service sharing community within an area by using their mobile devices. This paper highlights several challenges involved in building such service compositions in mobile communities when both service requesters and providers are mobile. To deal with them, we first propose a mobile service provisioning architecture named a mobile service sharing community and then propose a service composition approach by utilizing the Krill-Herd algorithm. To evaluate the effectiveness and efficiency of our approach, we build a simulation tool. The experimental results demonstrate that our approach can obtain superior solutions as compared with current standard composition methods in mobile environments. It can yield near-optimal solutions and has a nearly linear complexity with respect to a problem size.

  • 269.
    Deng, Shuiguang
    et al.
    Zhejiang University, Hangzhou, China.
    Huang, Longtao
    Zhejiang University, Hangzhou, China.
    Taheri, Javid
    The University of Sydney, Australia.
    Zomaya, Albert
    The University of Sydney, Sydney, Australia.
    Computation Offloading for Service Workflow in Mobile Cloud Computing2015Inngår i: IEEE Transactions on Parallel and Distributed Systems, ISSN 1045-9219, E-ISSN 1558-2183, Vol. 26, nr 12, s. 3317-3329Artikkel i tidsskrift (Fagfellevurdert)
  • 270.
    Di Felice, Marco
    et al.
    Department of Computer Science, University of Bologna, Italy.
    Chowdhury, Kaushik
    Department of Electrical and Computer Engineering, Northeastern University, Boston, USA.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Bononi, Luciano
    Department of Computer Science, University of Bologna, Italy.
    Adaptive Sensing Scheduling and Spectrum Selection in Cognitive Wireless Mesh Networks2011Inngår i: Proceedings of 20th International Conference on Computer Communications and Networks (ICCCN), IEEE conference proceedings, 2011, s. 1-6Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Cognitive Radio (CR) technology constitutes a promising approach to increase the capacity of Wireless Mesh Networks (WMNs). Using this technology, Mesh Routers (MRs) and the attached Mesh Clients (MCs) are allowed to opportunistically transmit on the licensed band, but under the constraint not to interfere with the Primary Users (PUs) of the spectrum. Thus, the effective deployment of CR- WMNs require that each MR must be able to: sense the current spectrum, select an available PU-free channel and perform the spectrum handoff to a new channel in case of PU arrival on the current one. How to coordinate these actions in the optimal way which maximizes the performance of the CR-WMNs while minimizing the interference to the PUs constitutes an open research issue in CR systems. In this paper, we propose an adaptive spectrum scheduling and allocation scheme which allows a MR to identify the best schedule of (i) when to sense the current channel, (ii) when to transmit, (iii) when to perform a spectrum handoff. Due the large number of parameters involved, we propose Reinforcement Learning (RL) techniques to allow a MR to learn by itself the optimal balance between spectrum sensing-exploitation- exploration actions based on network feedbacks coming from the MCs. We perform extensive simulations which confirm the adaptivity and efficiency of our approach in terms of increased throughput when compared with non-learning based schemes for CR-WMNs.

  • 271.
    Di Felice, Marco
    et al.
    Department of Computer Science, University of Bologna, Italy.
    Chowdhury, Kaushik Roy
    Department of Electrical and Computer Engineering, Northeastern University, Boston, USA.
    Kim, Wooseong
    Department of Computer Science, University of California, Los Angeles, USA.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Bononi, Luciano
    Department of Computer Science, University of Bologna, Italy.
    End-to-end Protocols for Cognitive Radio Ad Hoc Networks: An Evaluation Study2010Inngår i: Performance evaluation (Print), ISSN 0166-5316, E-ISSN 1872-745X, Vol. 68, nr 9, s. 859-875Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cognitive radio ad hoc networks (CRAHNs) constitute a viable solution to solve the current problems of inefficiency in the spectrum allocation, and to deploy highly reconfigurable and self-organizing wireless networks. Cognitive radio (CR) devices are envisaged to utilize the spectrum in an opportunistic way by dynamically accessing different licensed portions of the spectrum. To this aim, most of the recent research has mainly focused on devising spectrum sensing and sharing algorithms at the link layer, so that CR devices can operate without interfering with the transmissions of other licensed users, also called primary users (PUs). However, it is also important to consider the impact of such schemes on the higher layers of the protocol stack, in order to provide efficient end-to-end data delivery. At present, routing and transport layer protocols constitute an important yet not deeply investigated area of research over CRAHNs. This paper provides three main contributions on the modeling and performance evaluation of end-to-end protocols (e.g. routing and transport layer protocols) for CRAHNs. First, we describe NS2-CRAHN, an extension of the NS-2 simulator, which is designed to support realistic simulation of CRAHNs. NS2-CRAHN contains an accurate yet flexible modeling of the activities of PUs and of the cognitive cycle implemented by each CR user. Second, we analyze the impact of CRAHNs characteristics over the route formation process, by considering different routing metrics and route discovery algorithms. Finally, we study TCP performance over CRAHNs, by considering the impact of three factors on different TCP variants: (i) spectrum sensing cycle, (ii) interference from PUs and (iii) channel heterogeneity. Simulation results highlight the differences of CRAHNs with traditional ad hoc networks and provide useful directions for the design of novel end-to-end protocols for CRAHNs.

  • 272.
    Do, Truong-Xuan
    et al.
    School of Electronics Engineering, Soongsil University, South Korea.
    Nguyen, Van-Giang
    School of Electronics Engineering Soongsil UniversityDongjak-gu, SeoulKorea.
    Kim, Younghan
    School of Electronics Engineering, Soongsil University, South Korea.
    SDN-based Mobile Packet Core for Multicast and Broadcast Services2018Inngår i: Wireless networks, ISSN 1022-0038, E-ISSN 1572-8196, Vol. 24, nr 5, s. 1715-1729Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The current mobile packet core network is evolving to cope with the pressure of the mobile traffic explosion and the advent of new services. Software-defined networking (SDN) is currently being adopted as one of the promising drivers for redesigning the mobile packet core network toward a 5G network. SDN-based mobile packet core approaches are expected to deliver features, such as fast service deployment, flexibility, and capital expenditure and operational expenditure reduction within future 5G networks. However, current SDN-based mobile packet core approaches only focus on providing unicast services without considering multicast and broadcast services. In this article, we propose an efficient SDN-based mobile packet core network architecture for supporting multicast and broadcast services. The proposed architecture takes advantage of the SDN paradigm and enables multicast and broadcast service deployment. In addition, a new SDN-based multicast subscription procedure is introduced to reduce network bandwidth resources. By numerical analysis, our scheme improves the current multicast and broadcast solution in terms of signaling cost.

  • 273.
    Dobrijevic, Ognjen
    et al.
    University of Zagreb, Croatia.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Skorin-Kapov, Lea
    University of Zagreb, Croatia.
    Matijasevic, Maja
    University of Zagreb, Croatia.
    QoE-Driven Path Optimization Model for Multimedia Services2014Inngår i: Wired/Wireless Internet Communications : 12th International Conference, WIWIK14, Paris, FRANCE, May 26-28, 2014 Proceedings, Springer, 2014, Vol. 8458, s. 134-147Konferansepaper (Fagfellevurdert)
    Abstract [en]

    When delivering multimedia services over Internet, different media types are impacted by resource limitations in a different way. While an interactive audio service calls for low-latency communication, video streams should be routed over network paths with sufficient capacity. However, in current networks flows towards the same destination follow the same path, which may lead to a suboptimal resource utilization that effectively penalizes end-users' quality of experience (QoE). This paper proposes Q-POINT, a QoE-driven path optimization model to fairly maximize aggregated end-user QoE for competing clients' service flows by calculating the best path for each flow, subject to resource constraints. We formulate the problem as a mixed integer linear program integrating QoE models for audio, video and data transfer. Such an approach can be leveraged within the software-defined networking paradigm, which provides a control plane to orchestrate path set-up. We evaluate our model and illustrate its benefits over shortest path selection.

  • 274.
    Doganay, Kivanc
    et al.
    SICS Swedish ICT AB, Sweden; Mälardalen University, Sweden..
    Eldh, Sigrid
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013). Ericsson AB, Sweden.
    Afzal, Wasif
    Mälardalen University, Sweden.
    Bohlin, Markus
    SICS Swedish ICT AB, Sweden; Mälardalen University, Sweden.
    Search-Based Testing for Embedded Telecom Software with Complex Input Structures2014Inngår i: Testing Software and Systems (Ictss 2014) / [ed] Merayo, MG & DeOca, EM, Springer, 2014, s. 205-210Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, we discuss the application of search-based software testing techniques for unit level testing of a real-world telecommunication middleware at Ericsson. Our current implementation analyzes the existing test cases to handle non-trivial variables such as uninitialized pointers, and to discover any setup code that needs to run before the actual test case, such as setting global system parameters. Hill climbing (HC) and (1+1) evolutionary algorithm (EA) metaheuristic search algorithms are used to generate input data for branch coverage. We compare HC, (1+1) EA, and random search with respect to effectiveness, measured as branch coverage, and efficiency, measured as number of executions needed. Difficulties arising from the specialized execution environment and the adaptations for handling these problems are also discussed.

  • 275.
    Doolin, Kevin
    et al.
    Waterford Institute of Technology, Ireland.
    Pashalidis, Andreas
    NEC Europe Ltd., Heidelberg, Germany.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Mota, Telma
    PT Inovação S.A., Portugal.
    Context-Aware Multimedia Services in a Pervasive Environment: The Daidalos Approach2008Inngår i: Proceedings of the 2008 Ambi-Sys workshop on Software Organisation and MonIToring of Ambient Systems, ICST , 2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    There is a clear trend towards making multimedia applications context-aware so as to customize them by taking into account any collection of information which may be relevant, such as e.g. user location. However, current multimedia services are dominated by IMS, which is seen as a service platform that uses the SIP protocol to access all services that the internet can provide. In this paper, we describe the Daidalos approach on making IMS based multi-media services context-aware. We also demonstrate, how generic sensor networks can be integrated into the context management system of our platform thus enabling sensor network detected events to influence behavior of context-aware multimedia applications

  • 276.
    Dorronsoro, Bernabé
    et al.
    Univ Lille, Lille, France.
    Nesmachnow, Sergio
    Univ Republica, Montevideo, Uruguay.
    Taheri, Javid
    The University of Sydney, Australia.
    Zomaya, Albert
    The University of Sydney, Sydney, Australia.
    Talbi, El-Ghazali
    Univ Lille, Lille, France.
    Bouvry, Pascal
    Univ Luxembourg, Luxembourg, Luxembourg.
    A hierarchical approach for energy-efficient scheduling of large workloads in multicore distributed systems2014Inngår i: Sustainable Computing: Informatics and Systems, ISSN 2210-5379, E-ISSN 2210-5387, Vol. 4, nr 4, s. 252-261Artikkel i tidsskrift (Fagfellevurdert)
  • 277.
    Ehlert, Sven
    et al.
    Fraunhofer Institute FOKUS.
    Zhang, Ge
    Fraunhofer Institute FOKUS.
    Geneiatakis, Dimitris
    University of the Aegean, Greece.
    Kambourakis, Georgios
    University of the Aegean, Greece.
    Dagiuklas, Tasos
    TEI of Mesolonghi, Greece.
    Markl, Jiri
    Nextsoft, Prague, Czech Republic.
    Sisalem, Dorgham
    Tekelec, Berlin, Germany.
    Two Layer Denial of Service Prevention on SIP VoIP Infrastructures2008Inngår i: Computer Communications, ISSN 0140-3664, E-ISSN 1873-703X, Vol. 31, nr 10, s. 2443-2456Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The emergence of Voice over IP (VoIP) has offered numerous advantages for end users and providers alike, but simultaneously has introduced security threats, vulnerabilities and attacks not previously encountered in networks with a closed architecture like the Public Switch Telephone Network (PSTN). In this paper we propose a two layer architecture to prevent Denial of Service attacks on VoIP systems based on the Session Initiation Protocol (SIP). The architecture is designed to handle different types of attacks, including request flooding, malformed message sending, and attacks on the underlying DNS system. The effectiveness of the prevention mechanisms have been tested both in the laboratory and on a real live VoIP provider network

  • 278. Eklind, Dennis
    et al.
    Yalda, Zeena
    Flexible Time Reporting with An iPhone Application2010Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
  • 279.
    Eklund, Johan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Evaluation of Emulab as Experimental Platform by comparing TCP and SCTP2004Annet (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    To be able to evaluate new protocols it is important to have access to good experimental environments. Several experiments are needed to verify different aspects of protocol performance as well as robustness under various network conditions. Emulab is a new public experimental platform which is available for remote users. The ambition is that Emulab should offer the user the possibility to perform both simulation and emulation of a network. In addition, Emulab offers access to an experimental live network. This thesis presents a study where a series of tests are performed on the Emulab platform and also gives an introduction to SCTP. The first objective of the thesis is to obtain practical experience and to evaluate the usability of Emulab and the second objective is to compare the throughput between the transport protocols TCP and SCTP. The experiences from using Emulab are very positive. The results show that Emulab is a reliable and robust platform with high availability. The throughput comparison did not reveal significant differences between SCTP and TCP under moderate traffic load. Further tests and analyses are necessary to obtain a clear view of the situation in a heavily loaded network

  • 280.
    Eklund, Johan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013). Karlstad University.
    Latency Reduction for Soft Real-Time Traffic using SCTP Multihoming2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    More and more so-called soft real-time traffic is being sent over IP-based networks. The bursty, data-limited traffic pattern as well as the latency requirements from this traffic present challenges to the traditional communication techniques, designed for bulk traffic without considering latency.

    To meet the requirements from soft real-time traffic, in particular from telephony signaling, the Stream Control Transmission Protocol (SCTP) was designed. Its support for connectivity to multiple networks, i.e., multihoming, provides robustness and opens up for concurrent multipath transfer (CMT) over multiple paths. Since SCTP is a general transport protocol, it also enables for handover of media sessions between heterogeneous networks. Migrating an ongoing session to a new network, as well as CMT with minimal latency, requires tuning of several protocol parameters and mechanisms.

    This thesis addresses latency reduction for soft real-time traffic using SCTP multihoming from three perspectives. The first focus is on latency for signaling traffic in case of path failure, where a path switch, a failover, occurs. We regard quick failure detection as well as rapid startup on the failover target path. The results indicate that by careful parameter tuning, the failover time may be significantly reduced. The second focus in the thesis is on latency for signaling traffic using CMT. To this end, we address sender-side scheduling. We evaluate some existing schedulers, and design a dynamic stream-aware scheduler. The results indicate that the dynamic stream-aware scheduler may provide significantly improved latency in unbalanced networks. Finally, we target multihomed SCTP to provide for handover of a media session between heterogeneous wireless networks in a mobile scenario. We implement a handover scheme and our investigation shows that SCTP could provide for seamless handover of a media session at walking speed.

  • 281.
    Eklund, Johan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    On Switchover Performance in Multihomed SCTP2010Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The emergence of real-time applications, like Voice over IP and video conferencing, in IP networks implies a challenge to the underlying infrastructure. Several real-time applications have requirements on timeliness as well as on reliability and are accompanied by signaling applications to set up, tear down and control the media sessions. Since neither of the traditional transport protocols responsible for end-to-end transfer of messages was found suitable for signaling traffic, the Stream Control Transmission Protocol (SCTP) was standardized. The focus for the protocol was initially on telephony signaling applications, but it was later widened to serve as a general purpose transport protocol. One major new feature to enhance robustness in SCTP is multihoming, which enables for more than one path within the same association.

    In this thesis we evaluate some of the mechanisms affecting transmission performance in case of a switchover between paths in a multihomed SCTP session. The major part of the evaluation concerns a failure situation, where the current path is broken. In case of failure, the endpoint does not get an explicit notification, but has to react upon missing acknowledgements. The challenge is to distinguish path failure from temporary congestion to decide  when to switch to an alternate path. A too fast switchover may be spurious, which could reduce transmission performance, while a too late switchover also results in reduced transmission performance. This implies a tradeoff which involves several protocol as well as network parameters and we elaborate among these to give a coherent view of the parameters and their interaction. Further, we present a recommendation on how to tune the parameters to meet  telephony signaling requirements, still without violating fairness to other traffic.

    We also consider another angle of switchover performance, the startup on the alternate path. Since the available capacity is usually unknown to the sender, the transmission on a new path is started at a low rate and then increased as acknowledgements of successful transmissions return. In case of switchover in the middle of a media session the startup phase after a switchover could cause problems to the application. In multihomed SCTP the availability of the alternate path makes it feasible for the end-host to estimate the available capacity on the alternate path prior to the switchover. Thus, it would be possible to implement a more efficient startup scheme. In this thesis we combine different switchover scenarios with relevant traffic. For these combinations, we analytically evaluate and quantify the potential performance gain from utilizing an ideal startup mechanism as compared to the traditional startup procedure.

  • 282.
    Eklund, Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Impact of SACK delay and link delay on Failover performance in SCTP2006Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The Stream Control Transmission Protocol (SCTP) was developed

    to support the transfer of telephony signaling over

    IP networks. One of the ambitions when designing SCTP

    was to offer a robust transfer of traffic between hosts. For

    this reason SCTP was designed to support multihoming,

    which gives the possibility to set up several paths between

    the same hosts in the same session. If the primary path between

    a source machine and a destination machine breaks

    down, the traffic may still be sent to the destination by utilizing

    one of the alternate paths. The failover that occurs

    when changing path is to be transparent to the application.

    Consequently, the time between occurrence of a break on

    the primary path until the traffic is run smoothly on one of

    the alternate paths is important. This paper presents experimental

    results concerning SCTP failover performance. The

    focus in this paper is to evaluate the impact of the SACK

    delay and link delay on the failover time as well as on the

    maximum transfer time for a single message, which complements

    earlier studies in this area. The results show a

    significant performance impact of the SACK delay as well

    as of the link delay. This suggests that the SACK delay

    is an important parameter to tune to enhance application

    transparency in failure situations

  • 283.
    Eklund, Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Performance of Network Redundancy Mechanisms in SCTP2005Rapport (Fagfellevurdert)
    Abstract [en]

    One of the ambitions when designing the Stream Control Transmission Protocol was to offer a robust transfer of traffic between hosts. For this reason SCTP was designed to support multihoming, which presumes the possibility to set up several paths between the same hosts in the same session. If the primary path between a source machine and a destination machine breaks down, the traffic may still be sent to the destination, by utilizing one of the alternate paths. The failover that occurs when changing path is to be transparent to the application.



    This paper describes the results from an experiment concerning SCTP failover performance, which means the time between occurrence of a break on the primary path until the traffic is run smoothly on the alternate path. The experiment is performed mainly to verify the Linux Kernel implementation of SCTP (LK-SCTP) and is run on the Emulab platform. The results will serve as a basis for further experiments.



    The experiment is performed in a network without concurrent traffic and in conclusion the results from the experiment correspond well to the values found in other studies and they are close to the theoretical best values. As expected the parameter Path.Max.Retrans has a great impact on the failover time. One observation is that the failover time and the max transfer time for a message are dependent upon the status in the network when the break of the primary path occurs.

  • 284.
    Eklund, Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Grinnemo, Karl-Johan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Cheimonidis, Georgios
    Ismailov, Yuri
    Delay Penalty during SCTP Handover2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The rapidly growing interest in untethered Internet connections such as WLAN and 3G/4G mobile connections,calls for intelligent session management, not least in terms of handovers. As part of an effort to develop a SCTP-based session management framework, we are studying ways of improving the SCTP handover delay forreal-time traffic by optimizing the startup delay on the handover-target path. We have developed a theoretical model that predicts the transfer times of SCTP messages during the startup on a new path. This paper validates our model. It shows that the model can be used to predict message transfer times in variable bitrate flows. The paper further employs our model to study the startup delay penalty during handover for the spectrum of network conditions considered relevant for real-time traffic over mobile connections.

  • 285.
    Eklund, Johan
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Grinnemo, Karl-Johan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Cheimonidis, Georgios
    Ismailov, Yuri
    Impact of Slow Start on SCTP Handover Performance2011Inngår i: Proceedings of 20th International Conference on Computer Communications and Networks: ICCCN2011, IEEE conference proceedings, 2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The rapidly growing interest in untethered Internet connections, especially in terms of WLAN and 3G/4G mobile connections, calls for intelligent session management: a mobile device should be able to provide a reasonable end-user experience despite location changes, disconnection periods and, not least, handovers. As part of an effort to develop a SCTP-based session management framework that meets these criteria, we are studying ways of improving the SCTP handover delay for real-time traffic; especially the startup delay on the connection between a mobile device and the target access point. To obtain an appreciation of the theoretically feasible gains of optimizing the startup delay on the handover-target path, we have developed a model that predicts the transfer times of SCTP messages during slow start. This paper experimentally validates our model and demonstrates that it could be used to predict the message transfer times in a variable bitrate flow by approximating the variable flow with a constant dito. It also employs our model to obtain an appreciation of the startup delay penalties incured by slow start during handovers in typical mobile, real-time traffic scenarios.

  • 286.
    Eldh, Sigrid
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Andersson, Kenneth
    Ermedahl, Andreas
    Wiklund, Kristian
    Towards a Test Automation Improvement Model (TAIM)2014Inngår i: Proceedings - IEEE 7th International Conference on Software Testing, Verification and Validation Workshops, ICSTW 2014, s. 337-342Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In agile software development, industries are becoming more dependent on automated test suites. Thus, the test code quality is an important factor for the overall system quality and maintainability. We propose a Test Automation Improvement Model (TAIM) defining ten key areas and one general area. Each area should be based on measurements, to fill the gap of existing assessments models. The main contribution of this paper is to provide the outline of TAIM and present our intermediate results and some initial metrics to support our model. Our initial target has been the key area targeting implementation and structure of test code. We have used common static measurements to compare the test code and the source code of a unit test automation suite being part of a large complex telecom subsystem. Our intermediate results show that it is possible to outline such an improvement model and our metrics approach seems promising. However, to get a generic useful model to aid test automation evolution and provide for comparable measurements, many problems still remain to be solved. TAIM can as such be viewed as a framework to guide the research on metrics for test automation artifacts. 

  • 287.
    Eldh, Sigrid
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Punnekkat, Sasikumar
    Mälardalens Högskola.
    Synergizing industrial needs and academic research for better software education2012Inngår i: Software Engineering Education based on Real-World Experiences (EduRex), 2012 First International Workshop, IEEE Press, 2012, s. 33-36Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The ubiquity of software is making every industry increasingly dependent on it for achieving their core products' functionality. The complexity in a telecommunication network requires not only thorough understanding of telecommunication per se, but software becomes equally interesting. This is the case with many industries, which rely more and more on software as their key enabler. Industry definitely needs a large number of software engineers with potential to be productive from day one. They are feeling impatient at the academic community for not being pragmatic. At the same time Academic community faces many challenges, which often make them thread a traditional path thus ignoring the industrial needs. We present some of these challenges from both the industrial and academic perspectives. We also present how we established a Master level advanced course on software verification and validation through mutual support and collaboration which became highly successful.

  • 288.
    Eldh, Sigrid
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT.
    Sundmark, Daniel
    Swedish Institute of Computer Science, Västerås.
    Robustness Testing of Mobile Telecommunication Systems: A Case Study on Industrial Practice and Challenges2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Robustness relates to the capability of a system to handle internal and external negative situations and disturbances. Robustness testing is the act of subjecting the system under test to such disturbances in a controlled manner. The objective of this study is to understand how robustness is considered in the development and testing of large-scale telecom systems, to identify the main challenges related to robustness and robustness testing, and to identify potential improvements to the current situation. We performed an exploratory case study of a telecom industry. Data was collected through interviews, study of documentation, and participant observation. Our result is a number of challenges related to robustness testing. The key challenge identified relates to understanding how robustness test can be broken down from a system-level to a low-level perspective. Our conclusion is that the area of robustness test is challenging for large complex systems, where the understanding of how to provoke complex failures and derive a root cause, as well as defining the correct level of robust design in software is not sufficiently explored.

  • 289.
    Elsholz, Jan-Patrick
    et al.
    Institute of Distributed Systems, Ulm University, Germany.
    Schmidt, Holger
    Institute of Distributed Systems, Ulm University, Germany.
    Schober, Sven
    Institute of Distributed Systems, Ulm University, Germany.
    Hauck, Franz J
    Institute of Distributed Systems, Ulm University, Germany.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Instant-X: Towards a Generic API for Multimedia Middleware2009Inngår i: Proceedings of IEEE International Conference on Internet Multimedia Systems Architecture and Applications, IEEE Press, 2009Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The globalisation of our society leads to an increasing need for spontaneous communication. However, the development of such applications is a tedious and error-prone process. This results from the fact that in general only basic functionality is available in terms of protocol implementations and encoders/decoders. This leads to inflexible proprietary software systems implementing unavailable functionality on their own. In this work we introduce Instant-X, a novel component-based middleware platform for multimedia applications. Unlike related work, Instant-X provides a generic programming model with an API for essential tasks of multimedia applications with respect to signalling and data transmission. This API abstracts from concrete component implementations and thus allows replacing specific protocol implementations without changing the application code. Furthermore, Instant-X supports dynamic deployment, i.e., unavailable components can be automatically loaded at runtime. To show the feasibility of our approach we evaluated our Instant-X prototype regarding code complexity and performance.

  • 290. Endeshaw, T.
    et al.
    Garcia, Johan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Jakobsson, Andreas
    Fast Classification of Indecent Video by Low Complexity Repetitive Motion Detection2008Konferansepaper (Fagfellevurdert)
  • 291.
    Engman, Anton
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Olsson, Anders
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Utveckling av testmiljö för kommunikation inom hälso- och sjukvården med stöd för standarden FHIR2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    För att svenska vårdsystem skall kunna kommunicera med varandra har Inera som ägs av Sveriges Kommuner och Landsting (SKL) utformat en standard för hur vårdinformation skall struktureras. Denna standard kallas Regelverk för interoperabilitet inom vård och omsorg – tekniska anvisningar (RIVTA) och består av en uppsättning regler, så kallade tjänstekontrakt. Problemet med RIVTA är att det inte sträcker sig utanför Sveriges gränser. Därför är regioner (f.d. landsting) och kommuner intresserade av en ny internationell standard som kallas Fast Healthcare Interoperability Resources (FHIR). Studiens uppdragsgivare Nordic Medtest, är ett företag som testar och kvalitetssäkrar mjukvara inom svensk vård och omsorg. Nordic Medtest vill därför ligga i framkant gällande FHIR och skapa en miljö där deras kunder kan testa sina system.

     

    Målet med denna studie är att översätta en delmängd av information i två tjänstekontrakt för RIVTA, som tillhandahållits av uppdragsgivaren på Nordic Medtest tjänstekontrakten getObservations och getActivities till motsvarande standarden för FHIR.

    Tillsammans med detta skall en testmiljö för dessa två översatta tjänstekontrakt tas fram. En användare skall kunna efterfråga de två översatta kontrakten via ett gränssnitt där de sedan presenteras på skärmen för användaren. I samband med översättningen av tjänstekontrakten och utvecklingen av testmiljön ska en teststrategi tas fram vars mål är att säkerställa en korrekt översättning och en kvalitetssäkrad testmiljö.

  • 292.
    Eriksson, Johannes
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013).
    Andrejenko, Erik
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013).
    Närvaroappen: Närvarohantering direkt i din mobil2016Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Att dokumentera närvaro är något som är nödvändigt i många olika områden som t.ex. idrott, skola och arbete, men det kan även behövas vid spontana tillfällen där det inte sällan används papper och penna för ändamålet. Denna rapport behandlar skapandet av Närvaroappen, en Android-applikation som utvecklats med syftet att underlätta hantering av närvaro genom ett enkelt och tydligt användargränssnitt, och med möjlighet till att strukturera upp olika scenarion där närvaro behöver dokumenteras. För att mer bekvämt kunna arbeta med skapad data och föra eventuell statistik finns även generösa delningsmöjligheter via både molntjänster och mail. Projektet har resulterat i en fungerande applikation för dokumentering av närvaro. Applikationen har även visats upp samt testats av ett fåtal personer inom relevanta yrkesområden och erhållit positiv kritik.

  • 293. Escudero-Pascual, A.
    et al.
    Holleboom, Thijs Jan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Fischer Hübner, Simone
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Privacy for location data in mobile networks, a summary2003Konferansepaper (Fagfellevurdert)
    Abstract [en]

    EU Directive 2002/58/EC has introduced, by means of Art. 9, special protection for location data other than traffic data. In this paper, we argue that also location data within traffic data can contain sensitive information about the relative positioning and co-located displacements of mobile nodes and thus also

    requires special protection.



    Brief discussions are given to how mobility is supported in IP networks, to the level of privacy protection for location data that was introduced in the new European Union data protection directive, and to means of protecting privacy by technology. The concept of \textit{co-located displacements in

    MobileIP} is introduced and we show how the home agent will be able to determine whether or not a set of mobile nodes move in a co-located fashion.



    Finally we present how, also for location information within traffic data, privacy-enhancing technologies can be used to provide the level of privacy protection that is required by Art. 9 of the EU Directive 2002/58/EC for location data other than traffic data.

  • 294. Faigl, Zoltán
    et al.
    Fazekas, Péter
    Lindskog, Stefan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Analytical Analysis of the Performance Overheads of IPsec in Mobile IPv6 Scenarios2008Inngår i: Advances in Mobile and Wireless Communications: Views of the 16th IST Mobile and Wireless Communication Summit / [ed] István Frigyes, Janos Bito, and Péter Bakki, Berlin/Heidelberg, Germany: Springer-Verlag , 2008Kapittel i bok, del av antologi (Fagfellevurdert)
  • 295. Faigl, Zoltán
    et al.
    Fazekas, Péter
    Lindskog, Stefan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Performance Analysis of IPsec in MIPv6 Scenarios2007Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper describes an analysis of the performance overheads caused by the processing and space requirements of IPsec when protecting Mobile IPv6 (MIPv6) signaling. Signaling between the Mobile Nodes and the Home Agent (HA) in a large-scale reference scenario is considered. The analysis is based on queuing theory and focuses on the overall utilization of the HA by the MIPv6 signaling processes as well as the total mean response time for a mobility process in the network. The results can assist network designers in finding the most appropriate security configuration for their specific network and mobility scenario

  • 296. Faigl, Zoltán
    et al.
    Lindskog, Stefan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Experimental Evaluation of the Performance Costs of Different IKEv2 Authentication Methods2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents an experimental evaluation of the costs of different IKEv2 authentication methods. The studied methods are pre-shared keys (PSK), extensible authentication protocol (EAP) using MD5 and TLS, which are typically referred to as EAP-MD5 and EAP-TLS, respectively. For the EAP-based methods RADIUS is used as AAA server. Different lengths of certification chains are studied in the EAP-TLS case. The paper first presents a brief overview of the considered authentication methods. Then, an experimental comparison of the costs for computations and messages transfers associated with the authentication methods are provided. The measurement results illustrate the practical costs involved for IKEv2 authentication, and show the performance implications of using different authentication methods. EAP-TLS is several times more demanding than both PSK and EAP-MD5. When EAP-TLS is used, the length of certificate chains also has a notable impact on performance

  • 297. Faigl, Zoltán
    et al.
    Lindskog, Stefan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    IKEv2 Performance when Protecting Mobile IPv6 Signaling2007Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper describes an analysis of the performance overheads caused by the processing and space requirements of the IKEv2 protocol using Diameter and EAP-TLS authentication when protecting Mobile IPv6 signaling. IKEv2 negotiation between mobile nodes, the home agent, and the AAA server in a large-scale reference scenario is considered. The analysis is based on queuing theory and focuses on the overall utilization of the home agent and the AAA server by the IKEv2 reauthentication processes as well as the total mean response time for such a process in the network

  • 298. Faigl, Zoltán
    et al.
    Lindskog, Stefan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Tóth, Katalin
    Providing Tunable Security in IEEE 802.11i Enabled Networks2006Rapport (Fagfellevurdert)
    Abstract [en]

    The basic idea of QoS is to provide mechanisms that can offer different service levels, which are expressed through well-defined parameters that are specified at run-time on the basis of need. Bit rate, throughput, delay, jitter, and packet loss rate are all examples of common QoS parameters suggested for packet networks. These parameters are all aimed to express (and guarantee) a certain service level with respect to reliability and/or performance. In this report, we investigate how security can be treated as yet another QoS parameter through the use of tunable security services. The main idea with this work is to let users specify a trade-off between security and performance through the choice of available security configuration(s). The performance metric used is latency. The concept is illustrated using the IEEE 802.11i wireless local area networking standard.

  • 299.
    Fazio, Maria
    et al.
    Univ Messina, Comp Sci, Messina, Italy.
    Ranjan, Rajiv
    Newcastle University.
    Girolami, Michele
    Italian Natl Council Res, Rome, Italy.
    Taheri, Javid
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Dustdar, Schahram
    TU Wien, Computer Science.
    Villari, Massimo
    Univ Messina, Comp Sci, Messina, Italy.
    A Note on the Convergence of IoT, Edge, and Cloud Computing in Smart Cities2018Inngår i: IEEE Cloud Computing, ISSN 2325-6095, Vol. 5, nr 5, s. 22-24Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of the special issue is to cover all aspects of design and implementation, as well as deployment and evaluation of solutions aimed at the osmotic convergence of IoT, edge, and cloud computing, with specific reference to the smart cities application scenario.

  • 300. Feiten, B.
    et al.
    Wolf, I.
    Guenkova-Luy, T.
    Schorr, A.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    New mode for rfc3640: AAC-BSAC with MPEG-21 gBSD: draft-feiten-avt-bsacmode-for-rfc3640-00.txt, Feb2005Annet (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    This draft proposes a mode for RFC 3640 to support an MPEG-4 AAC-BSAC audio codec format with an optional attached bitstream description. The bitstream description employs the MPEG-21 generalized Bitstream Syntax Description Language (gBSDL). The description is attached as auxiliary header and can be used to support adaptation

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