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  • 101.
    Brunström, Anna
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Kearns, P
    Global Predicate Detection Based on Transport Layer Vector Time1997Konferensbidrag (Refereegranskat)
  • 102.
    Brunström, Anna
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Kearns, Phil
    Transport Layer versus Application Layer Vector Time1997Rapport (Refereegranskat)
    Abstract [en]

    Vector time has emerged as a useful technique for solving problems in distributed systems. Although vector time is likely to be maintained by supporting code positioned in kernel space or in message-passing middleware, vector time is traditionally viewed as if it were defined at the application layer.

    In this paper we consider vector time as perceived at the transport layer. We establish existing relationships between transport layer and application layer vector time. Transport layer vector time provides a more up-to-date view of the current system state. Furthermore, transport layer vector time preserves any interprocess causal relationships captured by application layer vector time. We illustrate how the more up-to-date view of the transport layer can improve both the accuracy and the efficiency for algorithms on which concurrency has an adverse effect. Some general guidelines for when transport layer vector time may be appropriate are provided. The possibility of updating vector time for acknowledgment messages is also considered. A new

    distributed termination detection algorithm based on this feature is presented

  • 103.
    Brunström, Anna
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Lindskog, Stefan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Proceedings of the 2nd International Workshop on Security and Communication Networks (IWSCN 2010)2010Bok (Refereegranskat)
    Abstract [en]

    This publication contains the Proceedings of the 2nd International Workshop on Security and Communication Networks (IWSCN 2010) that will be held on May 2628, 2010 in Karlstad, Sweden. IWSCN 2010 brings together researchers, developers, practitioners, and users interested in the area of security and communication networks. The workshop focuses on how to design, build, and evaluate future networks that are secure, reliable, and provide high and predictable performance. The aim of the workshop is to serve as a forum for presenting current and future work, as well as to exchange research ideas in these fields.Papers containing research contributions focusing on aspects of security and communication networks were solicited for submission to IWSCN 2010. A total of 40 papers were received, representing authors from 20 different countries and 5 different continents. Each paper was reviewed by at least three members of the technical program committee. After a thorough review process, 13 papers were selected for presentation at the workshop, giving an acceptance rate of 32.5%. In addition to the technical papers, two keynote presentations on The Changing Performance Goals in Internet Video Streaming and Dependable Protocols for Wireless Sensor Networks will be provided by Carsten Griwodz from the Simula Research Laboratory AS in Norway and Levente Buttyán from Budapest University of Technology and Economics in Hungary, respectively. Furthermore, a tutorial on Penetration Testing from an Attacker Perspective will be given by Vesa Virta from the National Defence Radio Establishment in Sweden.IWSCN 2010 is organized by the Department of Computer Science at Karlstad University and is supported by the Euro-NF and Newcom++ EU Networks of Excellence, and IEEE Sweden Section. The workshop is sponsored by Compare Karlstad Foundation, Coromatic, and TeliaSonera, and we thank them for their support. We also gratefully thank all authors, members of the program committee, and the local organizing committee for contributing to the scientific quality of the workshop

  • 104.
    Brunström, Anna
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Lindskog, Stefan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Garcia, Johan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    NEWCOM DR6.6: Second report on common frameworks/models matching Department 62006Rapport (Refereegranskat)
    Abstract [en]

    Work within Department 6 of NEWCOM is organized into the areas transport protocols, architectures and cross-layer aspects, and modelling. In this deliverable we provide a second report on the frameworks/models used to support research integration within the Department. The integration approach and the defined models/frameworks are described for each one of the three areas of the department. The deliverable also includes an updated report on tools, software libraries and traces that can be shared between the partners

  • 105.
    Brunström, Anna
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Lindskog, Stefan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Garcia, Johan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    NEWCOM DR6.7: Proceedings of the Newcom Department 6 Second Technical Workshop2006Rapport (Refereegranskat)
    Abstract [en]

    The Third Newcom Department 6 Technical Workshop was organized in Catania, Italy, on February 2, 2006. The workshop program contained 4 presentations and contained reports on ongoing integrated research activities as well as presentation intended to initiate additional joint research within the department. All of the three areas of the department, transport protocols, architectures and cross-layer

    aspects, and modelling were represented with presentations. This deliverable contains the presentation material from the workshop. The included presentations are:



    - P2P-based Video transmission in wireless networks

    - Transport Layer Handover using SCTP

    - WIPEMU 4G System Emulation and Sample Results

    - Wireless Networks Emulation



    Where available the presentation notes are also included with the presentations

  • 106.
    Brunström, Anna
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Lindskog, Stefan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Garcia, Johan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    NEWCOM DR6.9: Proceedings of the Newcom Department 6 Fourth Technical Workshop2006Rapport (Refereegranskat)
    Abstract [en]

    The Fourth Newcom Department 6 Technical Workshop was organized in Toulouse, France, on September 13-14, 2006. The workshop program contained 6 presentations and contained reports on ongoing integrated research activities as well as presentation intended to initiate additional joint research activities between the partners. All of the three areas of the department, transport protocols, architectures and cross-layer aspects, and modelling were represented with presentations. This deliverable contains the presentation material from the workshop. The included presentations are:



    - P2P Video Transmission over Heterogeneous Wired/Wireless Networks: A Starting Point for Integrated Research

    - DCCP Overview and First Experiments

    - Estimation of the SCTP Failover Time

    - Improving End to End Goodput of Ad Hoc Networks with SCTP Multihoming

    - A Taxonomy and Survey of SCTP Research

    - Integrating KAUnet and SWINE



    Where available the presentation notes are also included with the presentations

  • 107.
    Brunström, Anna
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Ottosson, T.
    The Introduction of Soft Information in IP-Based Wireless Networks2001Konferensbidrag (Refereegranskat)
    Abstract [en]

    The underlying physical link is transparent in most IP-based networks. Contrary to this commonly accepted

    design rule, we propose that the applications should be made aware of the channel conditions. This is especially

    fruitful for wireless links where the performance is many orders of magnitudes lower than in fixed networks.

    Instead of wasting resources to make the wireless link behave as a fixed link, the application could take care of

    the adaptation to the channel condition. The presented solution assumes that soft information consisting of a

    reliability measure of the received bits is produced in the physical layer. This soft information is then propagated

    to the application. The application may use this information to distinguish between errors caused by fading and network congestion. Another possible use for soft information is to make the applications adapt the source and channel codes to the current channel condition and thus maximize performance.

  • 108.
    Brunström, Anna
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Simha, R
    Dynamic versus Static Load Balancing in a Pipeline Computation1997Ingår i: International Journal of Modeling and Simulation. Vol. 17, No 4, 1997, pp317-327Artikel i tidskrift (Refereegranskat)
  • 109. Bubenko jr, Janis
    et al.
    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.
    Lindskog, Stefan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Nilsson, Anders G.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för informatik och projektledning.
    Promote IT 2004: Proceedings of the Fourth Conference for the Promotion of research in IT at New Universities and University Colleges in Sweden, 5-7 May, Karlstad University, The Knowledge Foundation, Part 1 and Part 22004Bok (Refereegranskat)
    Abstract [sv]

    The Knowledge Foundation of Sweden and Karlstad University are proud to announce the fourth annual conference for promoting research and advanced education in topics of IT at Sweden's new universities and university colleges. The conference takes place at Karlstad University in Sweden, May 5-7, 2004.



    The conference is in the Foundation's programme for promoting research and advanced education in topics of IT at Sweden's new universities and university colleges. Almost 200 MSEK (about 22 MEUR) has been allocated, for a period of five years, in order to increase the number of IT-teachers with a PhD. degree at Sweden's new universities and university colleges.



    Since the start of the programme in year 2000, almost one hundred persons are actively pursuing their graduate studies and research at these new universities and colleges. These are the persons that now present their progress at this conference

  • 110.
    Budzisz, Lukasz
    et al.
    Signal Theory and Communication Dept., Universitat Politechnìca de Catalunya.
    Ferrus, Ramon
    Signal Theory and Communication Dept., Universitat Politechnìca de Catalunya.
    Grinnemo, Karl-Johan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    An Analytical Estimation of the Failover Time in SCTP Multihoming Scenarios2007Ingår i: IEEE Wireless Communications and Networking Conference, IEEE , 2007, s. 3929-3934Konferensbidrag (Refereegranskat)
    Abstract [en]

    The motivation behind this paper is a need to have a more accurate estimation of the failover time in SCTP. The traditional one, commonly used in the literature, is based on the sum of the consecutive retransmission timeouts. This is not always appropriate, especially when using the SCTP multihoming feature as a basis for achieving transport layer mobility in wireless networking scenarios, where the transition time between available paths becomes a key aspect for the optimisation. Two new factors are introduced into the proposed estimation formula to reflect the influence of the network parameters and the behaviour of the most common protocol implementations. For the proposed model, we perform a best-worst case analysis, and then illustrate it with an example of a detailed estimation. Finally, we perform simulations comparing our proposal with the traditional estimation in a typical transport layer mobility scenario including long thin networks.

  • 111.
    Budzisz, Lukasz
    et al.
    Department of Signal Theory and Communications (TSC), Universitat Politecnica de Catalunya.
    Ferrús, Ramon
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Grinnemo, Karl-Johan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Fracchia, Roberta
    Motorola Labs – Paris, France.
    Galante, Giulio
    Istituto Superiore Mario Boella.
    Casadewall, Ferran
    Department of Signal Theory and Communications (TSC), Universitat Politecnica de Catalunya.
    Towards transport-layer mobility: Evolution of SCTP multihoming2008Ingår i: Computer Communications, ISSN 0140-3664, E-ISSN 1873-703X, Vol. 31, nr 5, s. 980-998Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recently, growing availability of emerging wireless technologies has pushed the demand to integrate different wireless-network technologies such as: wireless local-area networks, cellular networks, and personal and short-range networks. The inter-working of heterogeneous radio access networks poses many technical challenges, with mobility management being one of the most important. In this paper we survey the existing proposals and show that transport-layer mobility is a viable candidate for implementing seamless handover in heterogeneous wireless access networks. Since the mobile Stream Control Transmission Protocol (mSCTP) is at the core of most relevant transport-layer mobility schemes being currently studied, we identify the key scenarios where the protocol can effectively leverage the multihoming feature to enhance handover support. Moreover, to provide the reader with a complete overview of the mSCTP's application area, we also survey the situations where the use of mSCTP-based schemes is not possible or has some limitations. Then, in one of the identified key scenarios, we investigate several challenging open issues related to path management and path-transition optimization by considering bandwidth-estimation schemes and link-layer support. Finally, we consider introducing concurrent multipath transfer (CMT) into mSCTP-based mobility schemes, as a future research direction.

  • 112. Burnett, Robert
    et al.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Nilsson, Anders G.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för informatik och projektledning.
    Perspectives on Multimedia: Communication, Media and Information Technology2003Bok (Refereegranskat)
    Abstract [en]

    The uses of multimedia are rapidly increasing. Its power to present information in ways not previously possible and its integration of resources, allow for the creation of rich learning environments. The book "Perspectives on Multimedia: Communication, Media and Information Technology" provides a critical examination of the latest multimedia developments and approaches, such as Interface Technology and QoS architectures.



    Topics covered include:

    - The key concepts intrinsic to digital forms of multimedia: integration, interactivity, hypermedia, immersion, narrativity, and hybridity.

    - The development of Informatiuon Technology (IT) usage in society and in the business community.

    - How modern IT enables private companies and public organisations to support business operations, create new business opportunities, and to promote more proactive service management.

    - Multimedia from a computer science perspective and how computer science provides the technical foundation for the computer software and hardware that drives the information usage.



    Gives a broad range of perspectives on key issues for interactive multimedia in organsiations and industry today. This book will be of interest to practioners involved in multimedia development in an organisation, management consultants gviving professional advice on digital solutions and inforamtion technology matters to their customer organisations and academics focusing on business and technical aspects of multimedia frameworks

  • 113. Camenisch, Jan
    et al.
    Fischer-Hübner, SimoneKarlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.Murayama, YukoPortmann, ArmandRieder, Carlos
    Future Challenges in Security and Privacy for Academia and Industry: Proceedings of the 26th IFIP TC 11 International Information Security Conference, SEC 2011, Lucerne/Switzerland, June 20112011Proceedings (redaktörskap) (Refereegranskat)
  • 114. Camenisch, Jan
    et al.
    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.
    Rannenberg, Kai
    Privacy and Identity Management for Life2011Bok (Refereegranskat)
  • 115. Camenisch, Jan
    et al.
    Shelat, Abhi
    Sommer, Dieter
    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.
    Hansen, Marit
    Krasemann, Henry
    Lacoste, Gerard
    Leenes, Ronald
    Tseng, Jimmy
    Privacy and Identity Management for Everyone2005Konferensbidrag (Refereegranskat)
  • 116.
    Castro C, Marcel
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Prasad, Durga M
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Avallone, Stefano
    Peer-to-Peer Selection and Channel Assignment for Wireless Mesh Networks2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    Wireless mesh networks are an emerging paradigm for future broadband wireless access networks, with manyapplication areas ranging from content distribution over community networking and providing backhaul networking for sensor devices. In wireless mesh networks, clients connect to wireless routers which are equipped with one or more wireless cards and relay the packets over the wireless links towards internetgateways or the destination. Peer-to-Peer applications are an important class of applications which contributes nowadays to the majority of internet traffic. Therefore, it is important to provide high capacity in the mesh network to support them. However, the capacity of wireless mesh networks depends on many factors such as network topology and size, traffic volume and pattern, interfaces per node and channel assignment scheme used, modulation schemes, routing approaches, etc. In this paper, we develop an analytical framework which allows to estimate theachievable capacity of a wireless mesh network when peer-to-peer applications download many flows simultaneously. The model is based on the collision domain concept and incorporates various channel assignment, replication and peer selection strategies. We investigate the achievable capacity for various scenarios and study the impact of different parameters such as the number of channels or radios used

  • 117.
    Castro, Marcel C.
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Dely, Peter
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Vaidya, Nitin H.
    QoS-Aware Channel Scheduling for Multi-Radio/Multi-Channel Wireless Mesh Networks2009Ingår i: Proceedings of the Fourth ACM International Workshop on Wireless Network Testbeds, Experimental evaluation and Characterization (WiNTECH 09), New York: ACM , 2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    In non-static multi-radio/multi-channel wireless mesh networks architectures such as Net-X, mesh nodes need to switch channels in order to communicate with different neighbors. Present channel schedulers do not consider the requirements of real time traffic such as voice over IP. Thus the resulting quality is low. We propose a novel channel scheduler for the Net-X platform that takes into account packet priorities. We evaluate the algorithm on the KAUMesh testbed. Our algorithm outperforms the standard round-robin scheduler both in terms of average delay and jitter.

  • 118.
    Castro, Marcel
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Villanueva, Eva
    Ruiz, Iraide
    Sargento, Susana
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Performance Evaluation of Structured P2P over Wireless Multi-hop Networks2008Ingår i: SENSORCOMM '08 Proceedings of the 2008 Second International Conference on Sensor Technologies and Applications, IEEE conference proceedings, 2008, s. 796-801Konferensbidrag (Refereegranskat)
    Abstract [en]

    Internet connected wireless multi-hop networks are an interesting alternative for providing broadband wireless access. In order for the network to be transparent, the same services need to be available as in standard infrastructure wireless deployments. However, there is a significant challenge in providing services such as authentication, name resolution, VoIP over multi-hop mesh networks as dedicated servers implementing those services might be not available. Therefore, deploying overlay networks in the mesh to decentralize those services and move towards a Peer-to-Peer paradigm is an interesting approach. However, the multi-hop nature of wireless mesh networks and the restrictions in resource availability might cause problems when deploying overlay networks on top of such environments. In this paper, we investigate the overhead and trade-offs when deploying a structured overlay solution such as the Bamboo DHT over wireless multi-hop mesh networks. We provide various simulation results characterizing the overhead of management and control traffic and give recommendations for performance improvement.

  • 119.
    Cavalcanti de Castro, Marcel
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Enabling Multimedia Services over Wireless Multi-Hop Networks2009Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    With the constant development of wireless technologies, the usageof wireless devices tends to increase even more in the future.Wireless multi-hop networks (WMNs) have emerged as a keytechnology to numerous potential scenarios, ranging from disasterrecovery to wireless broadband internet access. The distributedarchitecture of WMNs enables nodes to cooperatively relay othernode's packets. Because of their advantages over other wirelessnetworks, WMNs are undergoing rapid progress and inspiringnumerous applications. However, many technical issues still existin this field. In this thesis we investigate how Voice over IP(VoIP) and peer-to-peer (P2P) application are influenced bywireless multi-hop network characteristics and how to optimizethem in order to provide scalable communication.We first consider the deployment of VoIP service in wirelessmulti-hop networks, by using the Session Initiation Protocol (SIP)architecture. Our investigation shows that the centralized SIParchitecture imposes several challenges when deployed in thedecentralized wireless multi-hop environment. We find that VoIPquality metrics are severely degraded as the traffic and number ofmultiple hops to the gateway increase. In the context ofscalability, we further propose four alternative approaches whichavoid current limitations.In the second part of this thesis we tackle the network capacityproblem while providing scalable VoIP service over wirelessmulti-hop networks. The performance evaluation shows the influenceof intra and inter-flow interference in channel utilization, whichdirect impacts the VoIP capacity. In order to avoid the small VoIPpacket overhead, we propose a new adaptive hop-by-hop packetaggregation scheme based on wireless link characteristics. Ourperformance evaluation shows that the proposed scheme can increasethe VoIP capacity by a two-fold gain.The study of peer-to-peer applicability over wireless multi-hopnetworks is another important contribution. A resource lookupapplication is realized through structured P2P overlay. We showthat due to several reasons, such as characteristics of wirelesslinks, multi-hop forwarding operation, and structured P2Pmanagement traffic aggressiveness the performance of traditionalP2P applications is rather low in wireless multi-hop environments.Therefore, we suggested that a trade-off between the P2P lookupefficiency and the P2P management traffic overhead can be achievedwhile maintaining the overlay network consistency in wirelessmulti-hop networks.

  • 120.
    Cavalcanti de Castro, Marcel
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Enhancing P2P Systems over Wireless Mesh Networks2011Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    Due to its ability to deliver scalable and fault-tolerant solutions, applications based on the peer-to-peer (P2P) paradigm are used by millions of users on the internet. Recently, wireless mesh networks (WMNs) have attracted a lot of interest from both academia and industry, because of their potential to provide flexible and alternative broadband wireless internet connectivity. However, due to various reasons such as unstable wireless link characteristics and multi-hop forwarding operation, the performance of current P2P systems is rather low in WMNs.

    This dissertation studies the technological challenges involved while deploying P2P systems over WMNs. We study the benefits of location-awareness and resource replication to the P2P overlay while targeting efficient resource lookup in WMNs. We further propose a cross-layer information exchange between the P2P overlay and the WMN in order to reduce resource lookup delay by augmenting the overlay routing table with physical neighborhood and resource lookup history information.

    Aiming to achieve throughput maximization and fairness in P2P systems, we model the peer selection problem as a mathematical optimization problem by using a set of mixed integer linear equations. A study of the model reveals the relationship between peer selection, resource replication and channel assignment on the performance of P2P systems over WMNs. We extend the model by formulating the P2P download problem as chunk scheduling problem. As a novelty, we introduce constraints to model the capacity limitations of the network due to the given routing and channel assignment strategy. Based on the analysis of the model, we propose a new peer selection algorithm which incorporates network load information and multi-path routing capability.

    By conducting testbed experiments, we evaluate the achievable throughput in multi-channel multi-radio WMNs. We show that the adjacent channel interference (ACI) problem in multi-radio systems can be mitigated, making better use of the available spectrum. Important lessons learned are also outlined in order to design practical channel and channel bandwidth assignment algorithms in multi-channel multi-radio WMNs.

  • 121.
    Cavalcanti de Castro, Marcel
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Biglia, Paola
    Inchingolo, Irene
    Bogucka, Hanna
    Zalonis, Andreas
    NEWCOM++ DI3.1 Report on first year researchers exchange and joint publications2009Övrigt (Övrig (populärvetenskap, debatt, mm))
    Abstract

    The report is dedicated to the description of the actions that have taken place during the first year of

    NEWCOM++ within WPI.3 Valorization of human capital.

    This WP is inserted in the integration activities of NEWCOM++; the integration among partners gives

    the opportunity to researchers to meet and exchange their talents. This positive trend gives a benefit to

    the network as a whole and it is a chance for researchers to improve their knowledge and values.

    Therefore, in order to have some indicators on the degree of integration among the partners, data on

    joint papers, researchers exchange and grants, are presented.

    A final paragraph is dedicated to gender issue, as the importance of this topic involves NEWCOM++

    life too.

    As a result, 38 scientific exchanges of a short term and long-term durations have been taken place, 47

    joint papers have been published, 2 mobility grants for projects implementation have been given by

    the NEWCOM++ Mobility Panel, as well as one grant for the PhD student to participate in the ICT

    Mobile Summit 2008

  • 122.
    Cavalcanti de Castro, Marcel
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Dely, Peter
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Karlsson, Jonas
    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.
    Capacity Increase for Voice over IP Traffic through Packet Aggregation in Wireless Multihop Mesh Networks2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    Recently, Voice over IP (VoIP) has become an important service for the future internet. However, for ubiquitous wireless VoIP services, greater coverage will be necessary as promised by the advent of e.g. 802.11 WLAN based wireless meshed networks. Unfortunately, the transmission of small (voice) packets imposes high overhead which leads to low capacity for VoIP over 802.11 based multihop meshed networks. In this work, we present a novel packet aggregation mechanism that significantly enhances capacity of VoIP in wireless meshed networks while still maintaining satisfactory voice quality. Extensive experiments using network simulation ns-2 confirm that our packet aggregation algorithm can lead to a significantly increase in the number of supported concurrent VoIP flows over a variety of different hop numbers while reducing the MAC layer contention

  • 123.
    Cavalcanti de Castro, Marcel
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Galluccio, L
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Palazzo, S
    Rametta, C
    On the comparison between performance of DHT-based protocols for opportunistic networks2010Ingår i: Proceedings of Future Network and MobileSummit 2010, IIMC , 2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    Opportunistic networks represent a new frontier for networking research as due to node mobility the network might become disconnected. Such intermittent connectivity imposes challenges to protocol design, especially when information access might require the availability of updated information about resources shared by mobile nodes. An opportunistic network can be seen as a peer-to-peer network where resources should be located in a distributed way. Numerous solutions for P2P resource management have been proposed in the last years. Among the different approaches being considered, Distributed Hash Table (DHT) based schemes offer the advantages of a distributed approach which can be tuned to network scalability. In this paper we consider two well known P2P DHT-based solutions for wireless networks denoted as Bamboo and Georoy, and compare their performance in a multihop wireless scenario. We evaluate scalability and key lookup behavior for different network sizes. The results allow us to gain insights into protocol behavior which allows to select for a given network configuration the appropriate scheme.

  • 124.
    Cavalcanti de Castro, Marcel
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Gallucio, Laura
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Rametta, Corrado
    Opportunistic P2P Communications in Delay Tolerant Rural Scenarios2011Ingår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. Januari, artikel-id 892038Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Opportunistic networking represents a promising paradigm for support of communications, specifically in infrastructure-less scenarios such as remote areas communications. In principle in opportunistic environments, we would like to make available all the applications thought for traditional wired and wireless networks like file sharing and content distribution. In this paper we present a delay tolerant scenario for file sharing applications in rural areas where an opportunistic approach is exploited. In order to support communications, we compare two peer-to-peer (P2P) schemes initially conceived for wireless networks and prove their applicability and usefulness to a DTN scenario where replication of resources can be used to improve the lookup performance and the network can be occasionally connected by mean of a data mule. Simulation results show the suitability of the schemes and allow to derive interesting design guidelines on the convenience and applicability of such approaches

  • 125.
    Cavalcanti de Castro, Marcel
    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.
    Challenges of SIP in Internet Connected MANETs2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    Mobile Ad Hoc networking has been considered as one of the most important technologies to support future Ubiquitous and Pervasive Computing Scenarios and internet connected MANETs will be an integral part of future wireless networks. For providing multimedia services and Voice over IP in such environment, support for Session Initiation Protocol (SIP) is essential. A MANET is a decentralized collection of autonomous nodes but a SIP infrastructure requires centralized proxies and registrar servers. In this paper, we study the implications of using standard SIP architecture in internet connected MANETs. We analyze performance limitations of SIP service scalability when centralized proxies/registrars located in the access network are used by MANET nodes. We also present and compare an alternative approach to provide SIP services in internet connected MANETs in order to minimize the impact of such performance limitations

  • 126.
    Cavalcanti de Castro, Marcel
    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 the Interaction Between Peer Selection, Routing and Channel Assignment2011Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
  • 127.
    Cavalcanti de Castro, Marcel
    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.
    Optimizing SIP service provisioning in internet connected MANETs (Invited Paper)2006Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    Recently, Mobile Ad-hoc Networks (MANETs) have gained a lot of attraction because they are flexible, self-configurable and fast to deploy. Systems beyond 4G are likely to consist of a combination of heterogeneous wireless technologies and naturally might comprise MANETs as one component. In order to provide multimedia services such as Voice over IP in such environment, support for Session Initiation Protocol (SIP) is essential. A MANET is a decentralized collection of autonomous nodes but a SIP infrastructure requires centralized proxies and registrar servers. In this paper, we first study the implications of using standard SIP architecture in internet connected MANETs. We analyze limitations of SIP service scalability when centralized proxies/registrars located in the Access Network are used by MANET nodes. Finally, we present alternative approaches to provide SIP services in such environment to avoid such limitations

  • 128.
    Cavalcanti de Castro, Marcel
    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.
    SIP based Service Provisioning for hybrid MANETs2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    Traditional Voice over IP (VoIP) systems is based on client/server architecture, which is not applicable to Mobile Ad Hoc Networks (MANETs), which are a decentralized collection of autonomous nodes. However, internet connectivity for MANETs becomes important as internet connected MANETs can serve as hot spot extension in 4G scenarios. Here, MANET nodes can reach any wired node thus potentially registering with SIP proxies in the fixed network becomes a viable solution. In order to study the implications of using VoIP systems in internet connected MANETs we present in this paper simulation result of SIP service scalability when centralized proxies/registrars located in the Access Network are used by MANET nodes. Alternative approaches to provide SIP services in such environment are also discussed to improve performance

  • 129.
    Cavalcanti de Castro, Marcel
    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.
    SIP in hybrid MANETs - A gateway based approach2006Konferensbidrag (Refereegranskat)
    Abstract [en]

    Mobile Ad Hoc networking has been considered as one of the most important technologies to support future Ubiquitous and Pervasive Computing Scenarios and internet connected MANETs will be an integral part of future wireless networks. For providing multimedia services and Voice over IP in such environment, support for Session Initiation Protocol (SIP) is essential. A MANET is a decentralized collection of autonomous nodes but a SIP infrastructure requires centralized proxies and registrar servers. In this paper, we study the implications of using standard SIP architecture in internet connected MANETs. We analyze performance limitations of SIP service scalability when centralized proxies/registrars located in the Access Network are used by MANET nodes. We also present and compare an alternative approach to provide SIP services in internet connected MANETs in order to minimize the impact of such performance limitations

  • 130.
    Cavalcanti de Castro, Marcel
    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.
    Avallone, Stefano
    Uni Napoli.
    BestPeer: A Load-aware Multi-path Peer Selection for Wireless Mesh Networks2012Ingår i: 2012 IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks (WoWMoM), IEEE Press, 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we study the interactions between peer selection, routing and channel assignment while deploying Peer-to-Peer (P2P) systems over multi-channel multi-radio Wireless Mesh Networks (WMNs). In particular we propose Bestpeer, a novel peer selection algorithm for WMNs which incorporates a cross-layer path load metric and integrates multi-path load balancing capability throughout the P2P download process in order to achieve faster resource disseminations. By comparing Bestpeer with BitTorrent through extensive simulations, we show that we can reduce the time to disseminate a resource by up to 40 %. The key mechanism used by Bestpeer to increase performance in WMNs is the effective exploitation of cross-layer information made available from the routing and channel assignment during the peer selection process in order to balance the load along high capacity paths

  • 131.
    Cavalcanti de Castro, Marcel
    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.
    Avallone, Stefano
    Measuring the Impact of ACI in Cognitive Multi-Radio Mesh Networks2010Konferensbidrag (Refereegranskat)
    Abstract

    In this paper we address the impact of ACI on dynamic spectrum allocation in multi-radio systems. In particular, we present the benefits of dynamic spectrum allocation by adapting channel bandwidth and distance in order to mitigate ACI in multi-radio mesh networks. Based on our measurement campaign in an indoor mesh testbed, which we extended in order to use adaptive channel width, we evaluate the performance in terms of network throughput. We show that by using channel bandwidth adaptation and antenna separation, the impact of ACI can be significantly reduced. The performed experiments give important insights into ACI in multi-radio cognitive systems which help to develop e.g. better channel assignment algorithms or capacity estimation methods

  • 132.
    Cavalcanti de Castro, Marcel
    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.
    Castro, Marcel C
    Chiasserini, Carla-Fabiana
    Casetti, Claudio
    Korpeoglu, Ibrahim
    Peer-to-Peer Overlay in Mobile Ad-hoc Networks2009Ingår i: Handbook of Peer-to-Peer Networking / [ed] X. Shen, H. Yu and J. Buford and M. Akon, New York: Springer , 2009Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract

    Wireless multi-hop networks such as mobile ad-hoc (MANET) or wireless

    mesh networks (WMN) have attracted big research efforts during the last years

    as they have huge potential in several areas such as military communications, fast

    infrastructure replacement during emergency operations, extension of hotspots or

    as an alternative communication system. Due to various reasons, such as characteristics

    of wireless links, multi-hop forwarding operation, and mobility of nodes,

    performance of traditional peer-to-peer applications is rather low in such networks.

    In this book chapter, we provide a comprehensive and in-depth survey on recent research

    on various approaches to provide peer-to-peer services in wireless multi-hop

    networks. The causes and problems for low performance of traditional approaches

    are discussed. Various representative alternative approaches to couple interactions

    between the peer-to-peer overlay and the network layer are examined and compared.

    Some open questions are discussed to stimulate further research in this area

  • 133.
    Cavalcanti de Castro, Marcel
    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.
    Kliot, Gabriel
    Friedman, Roy
    Kummer, Raphäel
    Kropf, Peter
    Felber, Pascal
    Minimizing DHT Routing Stretch in MANETs2009Konferensbidrag (Refereegranskat)
  • 134.
    Chow, Lawrence
    et al.
    Stanford University.
    Collins, Bradley
    Stanford University.
    Bambos, Nick
    Stanford University.
    Peylo, Christoph
    Telekom Innovation Laboratories.
    Einsiedler, Hans
    Telekom Innovation Laboratories.
    Bayer, Nico
    Telekom Innovation Laboratories.
    Dely, Peter
    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.
    Playout-Buffer Aware Hand-Off Control for Wireless Video Streaming2012Ingår i: 2012 IEEE Global Communications Conference (GLOBECOM 2012): Proceedings of a meeting held 3-7 December 2012, Anaheim, California, USA, IEEE conference proceedings, 2012, s. 5237-5242Konferensbidrag (Refereegranskat)
    Abstract [en]

    Wireless hand-off control typically considers only connectivity strength from the mobile terminal to alternative access points. In wireless video streaming, however, where video freezing must be avoided at the mobile terminal, the playout buffer level should also be considered by hand-off control. In this paper, we first develop a model capturing hand-off dynamics under video streaming, and design a new playout buffer aware hand-off control. It aims to avert a video freeze for as long as possible, maximizing the expected time until freezing. We compute the optimal control in the general case of multiple access points and multiple connectivity strength states per channel. The optimal hand-off control is then computationally probed in specific relevant cases. It is demonstrated that there is a certain playout buffer threshold level - a buffer tipping point - above which a hand-off should be attempted. Of course, this tipping point depends on the access point to mobile channel statistics

  • 135. Christoforidis, Christos
    et al.
    Ivarsson, Niklas
    Johansson, Henrik
    Nilsson, Jonas
    Grinnemo, Karl-Johan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    SCTPTrace: An Extension of TCPTrace for SCTP2016Rapport (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    When it comes to analyzing TCP data and extracting the information in such a way that it becomes viewable, there are a couple of tools that can be used. One of them is TCPTrace. TCPTrace is used to analyze special dump files created from programs such as tcpdump, snoop and WinDump. TCPTrace became published for a broader public in the late 1996 by Shawn Ostermann. Since then functionalities, changes and fixes have been implemented for example the extension to create graphs and trace UDP packets. From the dump files a trace will be done, and depending on the input from the user, TCPTrace can present this information in a number of ways such as plain text, trace files and graphs, depending on the amount of information the user is looking for. The extensive information traced will be viewed and divided for each connection found. For each connection, information such as retransmits, throughput, round trip times, bytes and packets sent and received etc. can be presented.

    This project came to be, since there has been a desire to see a tool for SCTP that provides the same functionalities as TCPTrace. The project, called SCTPTrace, aimed to implement as much of the previous TCP functionalities as possible for the SCTP protocol. 

  • 136.
    Claes, Barthelson
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    PaddelAppen2015Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Mobila lösningar blir allt vanligare och appar kan utvecklas för att hjälpa mobilanvändare

    med det mesta. Att utveckla appar är populärt och kan göras i en mängd olika språk och

    utvecklingsmiljöer, och projektet har haft som mål att både utveckla en användbar app

    och utvärdera en sådan utvecklingsmiljö.

    PaddelAppen som utvecklats i projektet fyller ett tomrum genom att vara en resurs för

    paddelintresserade. Samtidigt har utvecklingsarbetet resulterat i en utvärdering av utveck-lingsmiljön Xamarin, som använts tillsammans med Visual Studio för att plattformsobe-roende utveckla appen för både Android och Windows Phone.

  • 137. Conchon, Emmanuel
    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.
    Pérennou, Tanguy
    Diaz, Michel
    Improved IP-level Emulation for Mobile and Wireless Systems2007Ingår i: Proceedings IEEE Wireless Communications and Networking Conference (WCNC07), IEEE Communications Society, 2007, s. 3592-3597Konferensbidrag (Refereegranskat)
  • 138.
    Conchon, Emmanuel
    et al.
    Université de Toulouse.
    Pérennou, Tanguy
    Université de Toulouse.
    Garcia, Johan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Diaz, Michel
    W-NINE: A Two-stage Emulation Platform for Mobile and Wireless Systems2010Ingår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2010, s. 1-20Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    More and more applications and protocols are now running on wireless networks. Testing         the implementation of such applications and protocols is a real challenge as the position of the mobile terminals and environmental effects strongly affect the overall performance. Network emulation is often perceived as a good trade-off between experiments on operational wireless networks and discrete-event simulations on Opnet or ns-2. However, ensuring repeatability and realism in network emulation while taking into account mobility in a wireless environment is very difficult. This paper proposes a network emulation platform, called W-NINE, based on off-line computations preceding online pattern-based traffic shaping. The underlying concepts of repeatability, dynamicity, accuracy, and realism are defined in the emulation context. Two different simple case studies illustrate the validity of our approach with respect to these concepts.

  • 139.
    Dahlén, Magnus
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Windows 8-surfplatta: gränssnitt till ordersystem2012Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
  • 140.
    Danielsson, Anton
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Kling, Niklas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Presentation av projektstatus samt design av automatiska tester2012Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Denna rapport beskriver det arbete vi gjorde hos Ninetech i Karlstad. Målet med vårtarbete var att skapa en applikation som hämtar information rörande resultat av automatiskabyggen i pågående projekt. Sammanställningen av olika projekt skulle visas löpande. Vårtarbete kan beskrivas som två delar, en praktisk och en teoretisk del. Den praktiska delenbestod av att skapa en applikation som visar status på de olika projekt som Ninetech förtillfället arbetar med. Denna applikation är tänkt att köras dagligen på en skärm synlig förpersonalen. Skärmen är också tänkt att visa gästande kunder statusen på deras projekt.Applikationen visar bl.a. information om tester som körs på de olika projekten.I den teoretiska delen skapades ett dokument som Ninetech kan använda för att introducerasin personal till att arbeta med automatiska tester.

  • 141. de Leeuw, Elisabeth
    et al.
    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.
    Tseng, Jimmy
    Borking, John
    Proceedings of the First IFIP WG 11.6 Working Conference on Policies & Research in Identity Management (IDMAN07)2008Bok (Refereegranskat)
  • 142. Debbah, Merouane
    et al.
    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.
    Guillaud, Maxime
    Intermediate report about wireless secrecy metrics and preliminary algorithms: NEWCOM++ DR.A.12008Rapport (Refereegranskat)
    Abstract [en]

    This deliverable provides a first overview of the state of the art on wireless security metrics and algorithms,

    which are particularly very important with respect to the intrinsic vulnerability of the wireless

    medium. The first part deals with building practical physical layer information-theoretic secure schemes.

    Indeed, Shannon formalized the concepts of capacity (as a transmission efficiency measure) and equivocation

    (as a measure of secrecy). While the concept of capacity has been extended to fading channels

    with the introduction of concepts like the outage capacity or the ergodic capacity, similar paths are yet to

    be developed concerning equivocation. In the second part, we present a taxonomy of threats for wireless

    networks, and particularly for wireless sensor networks, in terms of the affected protocol layers. Besides,

    an overview to attack tree and attack graph techniques as formal means for describing and measuring

    vulnerabilities and thus also for assessing also the security level of wireless sensor networks is provided.

    Finally, an overview to suitable security concepts for wireless networks is given

  • 143.
    Dely, Peter
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Architectures and Algorithms for Future Wireless Local Area Networks2012Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    Future Wireless Local Area Networks (WLANs) with high carrier frequencies and wide channels need a dense deployment of Access Points (APs) to provide good performance. In densely deployed WLANs associations of stations and handovers need to be managed more intelligently than today.

    This dissertation studies when and how a station should perform a handover and to which AP from a theoretical and a practical perspective. We formulate and solve optimization problems that allow to compute the optimal AP for each station in normal WLANs and WLANs connected via a wireless mesh backhaul. Moreover, we propose to use software defined networks and the OpenFlow protocol to optimize station associations, handovers and traffic rates. Furthermore, we develop new mechanisms to estimate the quality  of a link  between a station and an AP. Those mechanisms allow optimization algorithms to make better decisions about when to initiate a handover. Since handovers in today’s WLANs are slow and may disturb real-time applications such as video streaming, a faster procedure is developed in this thesis.

    Evaluation results from wireless testbeds and network simulations show that our architectures and algorithms significantly increase the performance of WLANs, while they are backward compatible at the same time.

  • 144.
    Dely, Peter
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Cross-Layer Optimization of Voice over IP in Wireless Mesh Networks2010Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Wireless Mesh Networks (WMNs) have emerged as a promising network technology, which combines the benefits of cellular networks and Wireless Local Area Networks (WLANs). In a WMN mesh routers wirelessly relay traffic on behalf of other mesh routers or clients and thereby provide coverage areas comparable to cellular networks, while having the low complexity and low costs of WLANs. As Voice over IP (VoIP) is a very important Internet service, it is critical for the success of WMNs to support high quality VoIP. However, currentWMNs are not adapted well for VoIP. The capacity and scalability of single-radio WMNs is low, especially for small packet transmissions of VoIP calls, because the MAC and PHY layer overhead for small packets is high. The scalability of multiradio/multi-channel WMNs is usually higher, since fewer nodes contend for a channel. However channel scheduling might be required, which can lead to excessive delay and jitter and result in poor VoIP quality. In this thesis we investigate how to deliver high quality VoIP in single radio and multi-radio networks by using cross-layer optimization. For single radio WMNs, we consider the use of IP packet aggregation and IEEE 802.11e transmission opportunities. We conclude that IP packet aggregation greatly improves the capacity and thereby the scalability of WMNs. We show that the key for providing good quality is to artificially delay packets prior to aggregation. We propose a distributed cross-layer optimization system, which, based on Fuzzy Logic Inference, derives an aggregation delay that enhances the capacity and quality. For multi-radio/multi-channel WMNs, we demonstrate the importance of qualityof- service-aware channel scheduling. We develop a quality-of-serviceaware channel scheduler that compared to a basic round-robin scheme significantly reduces jitter and in that way increases VoIP quality. Our analysis shows that there is a trade-off between the jitter of high priority VoIP traffic and the throughput of background TCP traffic. The proposed optimizations significantly increase the capacity of singleradio and multi-radio WMNs. This allows network operators to serve more users with an existing mesh infrastructure or provide better service delivery to existing users.

  • 145.
    Dely, Peter
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Towards an Architecture for OpenFlow and Wireless Mesh Networks2011Konferensbidrag (Refereegranskat)
  • 146.
    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.
    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.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Moldsvor, Arild
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för fysik och elektroteknik.
    Soukhakian, Sina
    Practical Considerations for Channel Assignment in Wireless Mesh Networks2010Ingår i: GLOBECOM Workshops (GC Wkshps), 2010 IEEE, IEEE , 2010, s. 763-767Konferensbidrag (Refereegranskat)
    Abstract [en]

    Abstract--- In multi-radio wireless mesh networks (WMNs) several radios can operate within one node simultaneously on different channels. Due to frequency selective fading and varying output powers of WLAN cards the received signal strength on channels in the U-NII band can differ by several dB. Furthermore, power leakage from neighboring channels in the frequency spectrum can cause adjacent channel interference (ACI). Using a IEEE 802.11a testbed, we experimentally evaluate the achievable throughput of a multi-radio mesh network in a string topology under the impact of ACI and channel heterogeneity. Our results show that for low PHY rates the channel separation is a good indicator for throughput. However, for high PHY rates the propagation properties of a specific channel also need to be considered. Based on the results we provide recommendations for designing channel assignment algorithms for IEEE 802.11-based WMNs

  • 147.
    Dely, Peter
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    D’Andreagiovanni, Fabio
    Konrad-Zuse-Zentrum für Informationstechnik Berlin (ZIB), 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.
    Fair Optimization of Mesh-Connected WLAN Hotspots2015Ingår i: Wireless Communications & Mobile Computing, ISSN 1530-8669, E-ISSN 1530-8677, Vol. 15, nr 5, s. 924-946Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In Wireless mesh networks mesh access points (MAPs) forward traffic wirelessly towards users or Internet gateways. A user device usually connects to the MAP with the strongest signal, as such MAP should guarantee the best quality of service. However, this connection policy may lead to: (i) unfairness towards users that are distant from gateways; (ii) uneven distribution of users to MAPs; and (iii) inefficient use of network paths. We present a new model and solution approach to the problem of assigning users to MAPs and routing the data within the mesh network with the objective of providing max–min fair throughput. The problem is formulated as a mixed-integer linear programming problem (MILP). Because of the inherent complexity of the problem, real size instances cannot be solved to optimality within the time limits for online optimization. Therefore, we propose an original heuristic solution algorithm for the resulting MILP. Both numerical comparisons and network simulations demonstrate the effectiveness of the proposed heuristic. For random networks, the heuristic achieves 98% of the optimal solution. Network simulations show that in medium-sized networks, the number of users with at least 1Mbit/s minimum end-to-end rate increases by 550% when compared with the classical signal-strength based association.

  • 148.
    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.
    Adaptive Aggregierung von VoIP Paketen in Wireless Mesh Networks2008Konferensbidrag (Refereegranskat)
  • 149.
    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 Networks2011Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
  • 150.
    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 Testbed2009Övrigt (Övrig (populärvetenskap, 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

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