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  • 551.
    Hylander, Björn
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Håkansson, Johan
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Johansson, Martin
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Analys, design och implementering av Orbit ones dokumenthanteringssystem2005Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [sv]

    This report describes the development of a system for controlling documents. The report starts with a problem description which the company wants an intranet-based solution for. The report then continues to describe the development phase for the different parts of the system which results in a complete system. The company that wanted this system is called Orbit One and is located in Ronneby, Sweden. They have had a problem with old documents circulating in different versions and in different binders. Now thanks to their new system they can access their documents easy and on demand through their intranet.

  • 552. Håkansson, Lars
    et al.
    Claesson, Ingvar
    A Solution to Control Path Differences in The Feedback Filtered-x LMS Control of Boring Bar Vibration2004Conference paper (Refereed)
    Abstract [en]

    The internal turning operation is a common metal working operation that is usually associated with vibration problems. Boring bar vibration affect the result of the machining, in particular the surface finish. Furthermore, the tool life is correlated with the amount of vibration and the acoustic noise introduced. The noise level is sometimes almost unbearable. Generally, the motion of a boring bar is greatest in the cutting speed direction, and related to one of the bars two fundamental bending modes. A self tuning solution that has a high potential to further reduce the vibration problems in internal turning is the adaptive active control of boring bar vibration based on the feedback filtered-x LMS algorithm and boring bars with embedded actuators. The filtered-x LMS requires an estimate of the control path. To obtain a practical estimation of the control path, to avoid internal turning with severe vibration levels, usually requires that the control path is estimated off-line, i.e. the boring bar is not in contact with the workpiece. However, the control path usually differs between continuous cutting operations and when the boring bar is not in contact with the workpiece, and a phase difference of approximately 90 degrees generally occurs at the resonance frequency to be controlled. This phase difference constitutes a severe problem concerning the feedback filtered-x LMS control. By using a short FIR-filter control path estimate sufficient phase accuracy is obtained to enable robust adaptive control of bar vibration, which attenuates the vibration level with up to approximately 40 dB.

  • 553. Håkansson, Lars
    et al.
    Johansson, Sven
    Claesson, Ingvar
    Chapter 78 Machine Tool Noise, Vibration and Chatter Prediction and Control2005In: HANDBOOK OF NOISE AND VIBRATION CONTROL / [ed] Crocker, Malcolm J., New York: To be published by by John Wiley & Sons , 2005Chapter in book (Other academic)
    Abstract [en]

    A frequent problem in the manufacturing industry today is the vibrations or chatter induced by metal cutting, e.g. turning, milling and boring operations. Vibrations in boring operations or internal turning operations, for example,are inevitable and constitute a major problem for the manufacturing industry. Tool vibrations in metal cutting affect the result of machining, particularly the surface finish. Furthermore, tool life is correlated with the degree of vibration and acoustic noise introduced. Generally, tool vibrations are related to a low-order bending mode of, for example, the tool holder shank in external turning, the boring bar in internal turning, spindle-cutter assembly in milling, etc. Tool chatter or vibration problems in internal turning or milling may be reduced, for example, by using boring bars and milling adapters with passive tuned dampers. These are usually manually tuned to increase the dynamic stiffness of the boring bar or milling adapter at one of the eigenfrequencies of its low-order bending modes. Active control approaches for the attenuation of the bending motion of boring bars, tool holder shanks and spindle-cutter assembly in milling have been developed; such approaches involve both adaptive and time-invariant feedback control. In addition, prediction and control methods for controlling cutting data to maintain stable cutting, i.e. to avoid cutting data resulting in chatter, have been developed.

  • 554. Håkansson, Lars
    et al.
    Johansson, Sven
    Claesson, Ingvar
    Machine Tool Noise, Vibration and Chatter Prediction and Control2007In: HANDBOOK OF NOISE AND VIBRATION CONTROL / [ed] Crocker, Malcolm J., New York: John Wiley & Sons , 2007Chapter in book (Other academic)
  • 555.
    Håkansson, Mikael
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Renman, Jan
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Simulation and Analysis of Wireless Ad Hoc Routing Schemes2004Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    An Ad Hoc network is a wireless network without any stationary infrastructure of any kind. The nodes should be able to communicate with each other using wireless links, where a packet might traverse multiple links from the source to the destination. Every node in the network acts as a router, forwarding packet from one node to another. Since Ad Hoc networks are wireless and the nodes often battery driven, it is very important that the routing protocol in use can handle a large degree of node mobility and at the same time be very energy efficient. This is not an easy thing and a numerous routing protocols for wireless Ad Hoc networks have been proposed. Our goal was to simulate and make a literature study of three completely different routing protocols for wireless Ad Hoc networks: the Dynamic Source Routing protocol (DSR), the Topology Dissemination Based on Reverse-Path Forwarding protocol (TBRPF), and the Zone Routing Protocol (ZRP).

  • 556. Håård, F.
    et al.
    Johansson, Stefan J.
    Multi-Agent Tactics in Diplomacy2004Conference paper (Refereed)
  • 557.
    Håård, Fredrik
    Blekinge Institute of Technology, School of Engineering, Department of Interaction and System Design.
    Multi-Agent Diplomacy: Tactical Planning using Cooperative Distributed Problem Solving2004Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    While there is a broad theoretic foundation for creating artificial intelligence based solutions for two-player games, such as Chess, the multi-player domain is not as well explored and artificial intelligence solutions for multi-player games is often flawed. This report is an attempt to apply a multi-agent approach to a multi-player game, and use distributed problem solving to create viable plans in an environment of huge search spaces and multiple adversaries. An automated player (bot) for the game Diplomacy was created using distributed methodologies, and tested against other existing bots. The tests show that the bot developed can outperform opposition in score while being competetive in speed.

  • 558. Höst, Martin
    et al.
    Wohlin, Claes
    Thelin, Thomas
    Experimental Context Classification: Incentives and Experience of Subjects2005Conference paper (Refereed)
    Abstract [en]

    There is a need to identify factors that affect the result of empirical studies in software engineering research. It is still the case that seemingly identical replications of controlled experiments result in different conclusions due to the fact that all factors describing the experiment context are not clearly defined and hence controlled. In this article, a scheme for describing the participants of controlled experiments is proposed and evaluated. It consists of two main factors, the incentives for participants in the experiment and the experience of the participants. The scheme has been evaluated by classifying a set of previously conducted experiments from literature. It can be concluded that the scheme was easy to use and understand. It is also found that experiments that are classified in the same way to a large extent point at the same results, which indicates that the scheme addresses relevant factors.

  • 559.
    Ibragimov, Nail H.
    Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Science.
    Approximate transformation groups2008Book (Other academic)
    Abstract [en]

    These notes provide an easy to follow introduction to the topic and are based on my talks at various conferences, in particular on the plenary lecture at the International Workshop on ``Differential equations and chaos" (University of Witwatersrand, Johannesburg, South Africa, January 1996). The book is prepared for the new graduate course ``Approximate transformation groups" that will be given at Blekinge Institute of Technology during January-March, 2009.

  • 560.
    Ibragimov, Nail H.
    Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Science.
    Archives of ALGA: volume 92012Collection (editor) (Other academic)
    Abstract [en]

    Volume 9 contains articles of different authors.

  • 561.
    Ibragimov, Nail H.
    Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Science.
    Integration of second-order linear equations via linearization of Riccati's equations2007In: Archives of ALGA, ISSN 1652-4934, Vol. 4, p. 71-75Article in journal (Refereed)
    Abstract [en]

    The test for linearization of the Riccati equations by a change of the dependent variable, proved by the author in 1989, is utilized for integration of second-order linear equations by quadratures.

  • 562.
    Ibragimov, Nail H.
    Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Science.
    Selected works. Volume 42009Book (Other academic)
    Abstract [en]

    Volume IV contains papers written during 1996-2007. The main topics in this volume include Equivalence groups and invariants of differential equations, Extension of Eulers’ method of integration of hyperbolic equations to parabolic equations, Invariant and formal Lagrangians, Conservation laws.

  • 563.
    Ibragimov, Nail H.
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Science.
    Khamitova, Raisa
    Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Science.
    Computer Algebra Programs in Group Analysis and Education2006Conference paper (Refereed)
    Abstract [en]

    Lie group analysis provides a universal tool for tackling considerable numbers of differential equations even when other means of integration fail. In fact, group analysis is the only effective method for solving nonlinear differential equations analytically. However the philosophy of Lie groups in the theory of differential equations did not enjoy widespread acceptance in the past and the subject has been neglected in university programs. One of the main aims of ALGA is to improve the situation by developing courses based on group analysis. But the problem is that calculation of symmetries is a lengthy process and this can scare students. The calculation can be simplified by using computer algebra packages. We started to use one of them for teaching engineering students at BTH. This project was supported by STINT, Swedish Foundation for International Cooperation in Research and Higher Education.

  • 564.
    Ibragimov, Nail H.
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Science.
    Khamitova, Raisa
    Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Science.
    Thidé, Bo
    Adjoint systems and conservation laws for symmetrized electromagnetic equations with a dual Ohm´s law2006In: Archives of ALGA, ISSN 1652-4934, Vol. 3Article in journal (Refereed)
  • 565.
    Ibragimov, Nail H.
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Science.
    Khamitova, Raisa
    Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Science.
    Thidé, Bo
    Conservation laws for symmetrised electromagnetic equations with a dual Ohm's law2007Conference paper (Refereed)
    Abstract [en]

    In all areas of physics, conservation laws are essential since they allow us to draw conclusions of our physical system under study in an indirect but efficient way. Electrodynamics, in terms of the standard Maxwell electromagnetic equations for fields in vacuum, exhibit a rich set of symmetries to which conserved quantities are associated. We have derived conservation laws for Dirac's symmetric version of the Maxwell-Lorentz microscopic equations, allowing magnetic charges and magnetic currents, where the latter, just as electric currents, are assumed to be described by a linear relationship between the field and the current, i.e. an Ohm's law. We find that when we use the method of Ibragimov to construct the conservation laws, they will contain two new adjoint vector fields which fulfil Maxwell-like equations. In particular, we obtain conservation laws for the electromagnetic field which are nonlocal in time.

  • 566.
    Ibragimov, Nail H.
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Science.
    Khamitova, Raisa
    Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Science.
    Thidé, Bo
    Conservation laws for the Maxwell-Dirac equations with dual Ohm's law2007In: Journal of Mathematical Physics, ISSN 0022-2488, E-ISSN 1089-7658, Vol. 48, no 5Article in journal (Refereed)
    Abstract [en]

    Using a general theorem on conservation laws for arbitrary differential equations proved by Ibragimov [J. Math. Anal. Appl. 333, 311-320 (2007)], we have derived conservation laws for Dirac's symmetrized Maxwell-Lorentz equations under the assumption that both the electric and magnetic charges obey linear conductivity laws (dual Ohm's law). We find that this linear system allows for conservation laws which are nonlocal in time. (c) 2007 American Institute of Physics.

  • 567.
    Ibragimov, Nail H.
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Science.
    Thidé, Bo
    Then, H.
    Sjöholm, J.
    Palmer, K.
    Bergman, J.
    Carozzi, T.D.
    Istomin, YaN
    Khamitova, Raisa
    Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Science.
    Utilization of photon orbital angular momentum in the low-frequency radio domain2007In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 99, no 8Article in journal (Refereed)
    Abstract [en]

    We show numerically that vector antenna arrays can generate radio beams that exhibit spin and orbital angular momentum characteristics similar to those of helical Laguerre-Gauss laser beams in paraxial optics. For low frequencies (1 GHz), digital techniques can be used to coherently measure the instantaneous, local field vectors and to manipulate them in software. This enables new types of experiments that go beyond what is possible in optics. It allows information-rich radio astronomy and paves the way for novel wireless communication concepts.

  • 568.
    Ijaz, Muhammad
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    TRASMISSION CONTROL PROTOCOL (TCP) PERFORMANCE EVALUATION IN MANET2009Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Mobile Ad hoc network routing protocols have been divided in several different categories such as Reactive and Proactive Routing Protocol. The performances of these categories are evaluated in different scenario with TCP variants. We present a comprehensive TCP performance evaluation study to understand the nature of the TCP performance in different scenarios with variable amount of payload and number of nodes. The traffic consists of three different packet sizes i.e. 512, 1000, 1500 bytes each. Three different routing protocols (AODV, DSR and TORA) are to be evaluated with three different TCP variants (Tahoe, Reno and New Reno) in three different scenarios having 3, 5 and 8 nodes. The performances parameters on the basis of which routing protocols are to be graded are mainly throughput, congestion window and delay. Conclusions are drawn based on the simulation results and the comparisons between them have been elaborated.

  • 569.
    Ikram, Imran
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Traffic Engineering with MPLS and QOS2009Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    In the modern era there exist applications that require very high resources and generate a tremendous amount of traffic so they require considerable amount of bandwidth and QOS to operate and perform correctly. MPLS is a new and a fast technology that offers much remuneration both in terms of providing trouble-free and efficient security together with the high speed of switching. MPLS not only guarantees quality of service of IP networks but in addition to provides scope for traffic engineering it offers many enhanced features of IP networks as it does not replace IP routing, but works along with existing and future routing technologies to provide high-speed data forwarding between label-switched routers (LSRs) together with QOS. Many network carriers are facing the problem of how to accommodate such ever-growing demands for bandwidth. And the static nature of current routing algorithms, such as OSPF or IS-IS, the situation is going even worse since the traffic is concentrated on the "least cost" paths which causes the congestion for some links while leaving other links lightly loaded. Therefore, MPLS traffic engineering is proposed and by taking advantage of MPLS, traffic engineering can route the packets through explicit paths to optimize network resource utilization and traffic performance. MPLS provides a robust quality of service control feature in the internet. MPLS class of service feature can work in accordance with other quality of service architectures for IP networks.

  • 570. Ilie, Dragos
    On Unicast QoS Routing in Overlay Networks2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In the last few years the Internet has witnessed a tremendous growth in the area of multimedia services. For example YouTube, used for videosharing [1] and Skype, used for Internet telephony [2], enjoy a huge popularity, counting their users in millions. Traditional media services, such as telephony, radio and TV, once upon a time using dedicated networks are now deployed over the Internet at an accelerating pace. The triple play and quadruple play business models, which consist of combined broadband access, (fixed and mobile) telephony and TV over a common access medium, are evidence for this development. Multimedia services often have strict requirements on quality of service (QoS) metrics such as available bandwidth, packet delay, delay jitter and packet loss rate. Existing QoS architectures (e. g. , IntServ and DiffServ) are typically used within the service provider network, but have not seen a wide Internet deployment. Consequently, Internet applications are still forced to rely on the Internet Protocol (IP)’s best-effort service. Furthermore, wide availability of computing resources at the edge of the network has lead to the appearance of services implemented in overlay networks. The overlay networks are typically spawned between end-nodes that share resources with each other in a peer-to-peer (P2P) fashion. Since these services are not relying on dedicated resources provided by a third-party, they can be deployed with little effort and low cost. On the other hand, they require mechanisms for handling resource fluctuations when nodes join and leave the overlay. This dissertation addresses the problem of unicast QoS routing implemented in overlay networks. More precisely, we are investigating methods for providing a QoS-aware service on top of IP’s best-effort service, with minimal changes to existing Internet infrastructure. A framework named Overlay Routing Protocol (ORP) was developed for this purpose. The framework is used for handling QoS path discovery and path restoration. ORP’s performance was evaluated through a comprehensive simulation study. The study showed that QoS paths can be established and maintained as long as one is willing to accept a protocol overhead of maximum 1.5% of the network capacity. We studied the Gnutella P2P network as an example of overlay network. An 11-days long Gnutella link-layer packet trace collected at Blekinge Institute of Technology (BTH) was systematically decoded and analyzed. Analysis results include various traffic characteristics and statistical models. The emphasis for the characteristics has been on accuracy and detail, while for the traffic models the emphasis has been on analytical tractability and ease of simulation. To the author’s best knowledge this is the first work on Gnutella that presents statistics down to message level. The models for Gnutella’s session arrival rate and session duration were further used to generate churn within the ORP simulations. Finally, another important contribution is the evaluation of GNU Linear Programming Toolkit (GLPK)’s performance in solving linear optimization problems for flow allocation with the simplex method and the interior point method, respectively. Based on the results of the evaluation, the simplex method was selected to be integrated with ORP’s path restoration capability.

  • 571. Ilie, Dragos
    Optimization Algorithms with Applications to Unicast QoS Routing in Overlay Networks2007Report (Other academic)
    Abstract [en]

    The research report is focused on optimization algorithms with application to quality of service (QoS) routing. A brief theoretical background is provided for mathematical tools in relation to optimization theory. The rest of the report provides a survey of different types of optimization algorithms: several numerical methods, a heuristics and a metaheuristic. In particular, we discuss basic descent methods, gradient-based methods, particle swarm optimization (PSO) and a constrained-path selection algorithm called Self-Adaptive Multiple Constraints Routing Algorithm (SAMCRA).

  • 572. Ilie, Dragos
    et al.
    Erman, David
    Peer-to-peer Traffic Measurements2007Report (Other academic)
    Abstract [en]

    The global Internet has emerged to become an integral part of everyday life. Internet is now as fundamental a part of the infrastructure as is the telephone system or the road network. Peer-to-Peer (P2P) is the logical antithesis of the Client-Server (CS) paradigm that has been the ostensible predominant paradigm for IP-based networks since their inception. Current research indicates that P2P applications are responsible for a substantial part of the Internet traffic. New P2P services are developed and released at a high pace. The number of users embracing new P2P technology is also increasing fast. It is therefore important to understand the impact of the new P2P services on the existing Internet infrastructure and on legacy applications. This report describes a measurement infrastructure geared towards P2P network traffic collection and analysis, and presents measurement results for two P2P applications: Gnutella and BitTorrent.

  • 573. Ilie, Dragos
    et al.
    Erman, David
    Popescu, Adrian
    Nilsson, Arne A.
    Measurement and Analysis of Gnutella Signaling Traffic2004Conference paper (Refereed)
    Abstract [en]

    The paper reports on in-depth measurements and analysis of Gnutella signaling traffic collected at the Blekinge Institute of Technology (BIT), Karlskrona, Sweden. The measurements are based on a week-long packet trace collected with help of the well-known tcpdump application. Furthermore, a novel approach has been used to measure and analyze Gnutella signaling traffic. Associated with this, a dedicated tcptrace module has been developed and used to decode the packet trace, down to individual Gnutella messages. The measurement infrastructure consists of a Gnutella node running in ultrapeer mode and protocol decoding software. Detailed traffic characteristics have been collected and analyzed, such as session durations and interarrival times, and Gnutella message sizes and duration. Preliminary results show a high degree of variability of the Gnutella signaling traffic, which is mostly created by the QUERY messages. Furthermore, the Gnutella session interarrival times are observed to resemble the exponential distribution.

  • 574. Ilie, Dragos
    et al.
    Erman, David
    Popescu, Adrian
    Nilsson, Arne A.
    Traffic Measurements of P2P Systems2004Conference paper (Refereed)
    Abstract [en]

    The paper reports on a measurement infrastructure developed at the Blekinge Institute of Technology (BIT) with the purpose to do traffic measurements and analysis on Peer-to-Peer (P2P) traffic. The measurement methodology is based on using application logging as well as link-layer packet capture. This offers the possibility to measure application layer information with link-layer accuracy. Details are reported on this methodology, together with description of the BIT measurement infrastructure. The paper also reports on traffic measurements done on BitTorrent and Gnutella protocols from an end-client perspective, together with some measurement results of salient protocol characteristics. Preliminary results show a high degree of variability of the BitTorrent and Gnutella traffic, where in the case of Gnutella a large contribution is given by the signaling traffic.

  • 575. Ilie, Dragos
    et al.
    Popescu, Adrian
    Statistical Models for Gnutella Signaling Traffic2007In: Computer Networks, ISSN 1389-1286, E-ISSN 1872-7069, Vol. 51, no 17, p. 4816-4835Article in journal (Refereed)
    Abstract [en]

    The paper is focused on signaling traffic between Gnutella peers that implement the latest Gnutella protocol specifications (v0.6). In particular, we provide analytically tractable statistical models at session level, message level and IP datagram level for traffic crossing a Gnutella ultrapeer at Blekinge Institute of Technology (BTH) in Karlskrona, Sweden. To the best of our knowledge this is the first work that provides Gnutella v0.6 statistical models at this level of detail. These models can be implemented straightforward in network simulators such as ns2 and OmNet++. The results show that incoming requests to open a session follow a Poisson distribution. Incoming Gnutella messages across all established sessions can be described by a compound Poisson distribution. Mixture distribution models for message transfer rates include a heavy-tailed component.

  • 576.
    Imam, Hasani Syed Hassan
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Implementation and Evaluation of P.880 Methodology2009Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Continuous Evaluation of Time Varying Speech Quality (CETVSQ) is a method of subjective assessment of transmitted speech quality for long speech sequences containing quality fluctuations in time. This method is modeled for continuous evaluation of long speech sequences based on two subjective tasks. First task is to assess the speech quality during the listening and second task is to assess the overall speech quality after listening to the speech sequences. The development of continuous evaluation of time varying speech quality was motivated by fact that speech quality degradations are often not constant and varies in time. In modern IP telephony and wireless networks, speech quality varies due to specific impairments such as packet loss, echo, handover in networks etc. Many other standard methods already exist, which are being used for subjective assessment of short speech sequences. These methods such as ITU-T Rec. P.800 are well suited for only time constant speech quality. In this thesis work, it was required to implement CETVSQ methodology, so that it could be possible to assess long speech sequences. An analog hardware slider is used for the continuous assessment of speech qualities, as well as for overall quality judgments. Instantaneous and overall quality judgments are being saved into Excel file. The results stored in the Excel file are analyzed by applying different statistical measures. In evaluation part of the thesis work, subjects’ scores are analyzed by applying statistical methods to identify several factors that have originated in the CETVSQ methodology. A subjective test had already been conducted according to P.800 ACR method. The long speech sequences were divided into 8 seconds short sequences and then assessed using P.800 ACR method. In this study, the long speech sequences are assessed using CETVSQ methodology and comparison is conducted between P.800 ACR and CETVSQ results. It has been revealed that if long speech sequences are divided into short segments and evaluated using P.800 ACR, then P.800 ACR results will be different from the results obtained from CETVSQ methodology. The necessity of CETVSQ methodology is proved by this study.

  • 577. Imran, Kashif
    et al.
    Mellia, Marco
    Meo, Michela
    Measurements of multicast television over IP2007Conference paper (Refereed)
    Abstract [en]

    In this paper, we present measurement results collected from real traces on the network FastWeb, an ISP provider that is the main broadband telecommunication company in Italy. The network relies on a fully IP architecture and delivers to the user services such as data, VoIP and IP television over a single broadband connection. Our measurements, that are based on a passive measurement technique, focus on IP TeleVision (IPTV) multicast, that consists of 83 digital TV channels encoded using different MPEG-2 encoders. The results show that, depending on the encoder and based on the bitrate, flows can be classified as being: CBR, 2-VBR (i.e., two typical bitrate values) and VBR. Measurement of the packet loss, jitter and inter-packet gap show that, independently from the class, packet generation process of the flows can have various degrees of burstiness. Despite the packet level burstiness, average jitter is limited to few milliseconds and no packet loss was ever observed, showing that the quality of IPTV offered by FastWeb is excellent.

  • 578.
    Iqbal, Muhammad Imran
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Aibinu, Abiodun Musa
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Gubbal, Nagendra Srinivas
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Khan, Asim
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    AUTOMATIC DIAGNOSIS OF DIABETIC RETINOPATHY USING FUNDUS IMAGES2006Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    This thesis applies the process and knowledge of digital signal processing and image processing to diagnose diabetic retinopathy from images of retina. The Pre-Processing stage equalizes the uneven illumination associated with fundus images and also removes noise present in the image. Segmentation stage clusters the image into two distinct classes while the Disease Classifier stage was used to distinguish between candidate lesions and other information. Method of diagnosis of red spots, bleeding and detection of vein-artery crossover points were also developed in this work using the colour information, shape, size, object length to breadth ration as contained in the digital fundus image in the detection of this disease. In addition to diagnosis of Diabetic Retinopathy (DR), two graphical user interfaces (GUI’s) were also developed during this work, this first is for collection of lesion data information and was used by the ophthalmologist in marking images for database while the second GUI is for automatic diagnosing and displaying the diagnosis result in a more friendly user interface and is as shown in chapter three of this report. The algorithm was tested with a separate set of 25 fundus images. From this, the Receiver Operating Characteristics (ROC) was determined for red spot disease and bleeding, while cross over points were only detected leaving further classification as part of future work needed to complete this global project. Sensitivity (classify abnormal fundus images as abnormal) and specificity (classify normal fundus image as normal) was calculated for the algorithm is given as 98% and 61%.

  • 579. Iqbal, Muhammad Imran
    et al.
    Aibinu, A.M.
    Nilsson, Mikael
    Tijani, I. B.
    Salami, M.J.E.
    Detection of Vascular Intersection in Retina Fundus Image Using Modified Cross Point Number and Neural Network Technique2008Conference paper (Refereed)
    Abstract [en]

    Vascular intersection can be used as one of the symptoms for monitoring and diagnosis of diabetic retinopathy from fundus images. In this work we apply the knowledge of digital image processing, fuzzy logic and neural network technique to detect bifurcation and vein-artery cross-over points in fundus images. The acquired images undergo preprocessing stage for illumination equalization and noise removal. Segmentation stage clusters the image into two distinct classes by the use of fuzzy c-means technique, neural network technique and modified cross-point number (MCN) methods were employed for the detection of bifurcation and cross-over points. MCN uses a 5x5 window with 16 neighboring pixels for efficient detection of bifurcation and cross over points in fundus images. Result obtained from applying this hybrid method on both real and simulated vascular points shows that this method perform better than the existing simple cross-point number (SCN) method, thus an improvement to the vascular point detection and a good tool in the monitoring and diagnosis of diabetic retinopathy. ©2008 IEEE.

  • 580. Iqbal, Muhammad Imran
    et al.
    Zepernick, Hans-Jürgen
    Engelke, Ulrich
    Error Sensitivity Analysis for Wireless JPEG2000 Using Perceptual Quality Metrics2008Conference paper (Refereed)
    Abstract [en]

    Quality assessment of mobile and wireless multimedia services including image and video applications has gained increased attention in recent years as a means of facilitating efficient radio resource management. In particular, approaches that utilize perceptual-based metrics are becoming more dominant, as conventional fidelity metrics such as the peak signal-to-noise ratio (PSNR) may not correlate well with quality as perceived by the human observer. In this paper, we focus on the error sensitivity analysis for images given in the wireless JPEG2000 (JPWL) format using perceptual quality metrics. Specifically, the perceptual quality improvements obtained by progressively decoding an increasing number of image packets are examined. It is shown that the considered perceptual quality metrics exploiting structural image features may accompany or replace the PSNR-based error sensitivity description (ESD) marker segment in the wireless JPEG2000 standard. This addition will increase the effectiveness of the ESD marker segment as it facilitates the communication of reduced-reference information about the image quality from the transmitter to the receiver. In addition, the proposed approach can be used to guide the design of preferential error control coding schemes, link adaptation techniques, and selective retransmission of packets with respect to their contribution to overall quality as perceived by humans.

  • 581.
    Iqbal, Naveed
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Cheema, Fahad-Mumtaz
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    QoS_of_VoIP_in_Wireless_Networks2009Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    In this thesis we have focused in the wireless environment and how to run voice application over it. Conducive environment that makes it possible for the voice services to run in wireless is necessary. As we know this well that wireless is a contemporary technology due to it low cost and its effectiveness, and one major advantage of it is the mobility that is one fell free to move anywhere but have the access to the resource. So this makes wireless networks of great value, we in this thesis have focused on wireless LAN’s. In second part of the thesis we have shed some light on the VoIP showing how it works in the wireless environment. Analysis phase is relatively more important phase then the previous section which shows issues or hindrances in carrying voice over wireless environment. This analysis shows that these issues still prevails and should be addresses and the corresponding results are also discussed and by looking at those results we have derived a summery out of it. Next chapter we firstly tried to explain why we have chosen specific protocols and then showing some graphical representation measurements that are to address the problem based on the work done. We tried to evaluate EDCF and DCF as these play important role in handling real time applications like voice. After that we proposed a scheme through which these effects can be minimized and to enhance the method is necessary to avoid the issues still in effect.

  • 582.
    Iqbal, Syed Amjad
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Ahmad, Muhammad
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Performance Evoluation of vertical handover between UMTS and WLAN2009Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Our Master’s thesis is about Vertical handovers in Heterogeneous networks. Due to lot of benefits provided by both the third generation Mobile phone networks and WLANs, it is desirable to integrate both of these networks. While studies specifying generic integration architectures are abundant, little or no studies are dedicated for applications performance over such heterogeneous networks. The purpose of this thesis is to evaluate the performance of integrated UMTS and WLAN network by using two types of standard integrated models proposed by 3GPP(Third Generation Partnership Project) which are open coupling and loose coupling together with network layer mobility management scheme such as Mobile IP. The performance evaluation is carried out for the application i-e FTP, HTTP. We used OPNET 14.5 modular as a simulation tool. We have created a large matrix of performance figures for different network configurations under these two are applications considered. We build the two different scenarios one for loose coupling scheme and other one for open coupling scheme and calculate the different application’s traffic our concluded results shows that page response time is smaller for loose coupling scheme as compare to open coupling scheme although difference is not so much wide, page response time increases with the passage of time because number of users increases as the time passes. Same is In case for FTP, download response time for FTP is smaller in case of loose coupling scheme. We have also calculated the WLAN performance parameters (delay and throughput) and UMTS downlink traffic sent and received. We have discussed in detail architecture and functionalities of UMTS and WLAN, mobile IP, standard interworked UMTS and WLAN models proposed by 3GPP.

  • 583. Isaksson, Lennart
    Improved Performance of Bluetooth with Focus on Ad-Hoc Applications2004Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The number of devices making use of Bluetooth cable-replacement technology has rapidly increased in numbers thanks to the amount of implementations in cellular telephones, Personal Digital Assistants (PDAs), etc. Instead of the point-to-point technique used today the wireless community demands more sophisticated solutions to transmit information between two devices, e.g. using a chat program within an ad-hoc network. However, Bluetooth provides neither a routing protocol, nor is the slave/slave bridge, which is an important enabler for point-to-multipoint communication in so-called scatternets, implemented in hardware. Another issue relates to the time-to-connect which determines the usability of Bluetooth in scenarios where the units move around. In order to build research on these topics on trustworthy ground, we first address the validation of a Bluetooth simulation model, implementing the Frequency Hopping Spread Spectrum (FHSS) technique of Bluetooth version 1.1 in a correct way. A potential source of problems in reference simulation models has been identified and corrections are described. Next, an improvement is presented for the pseudo random hop sequence regarding the distribution of frequencies used in the Adapted Channel Hopping (ACH) scheme for Bluetooth version 1.2. Further, the impact of the random backoff boundary, which determines the duration of the inquiry procedure and thus of the time-to-connect, is studied by simulation. Obviously, the settings of this parameter contained in the specification leads to suboptimal behaviour. In this thesis, a lower random backoff boundary parameter is suggested, which yields much faster time-to-connect. Finally, the Modified Reverse Path Forwarding (MRPF) routing algorithm for Bluetooth is proposed. This algorithm reduces the amount of connections needed to transmit Asynchronous Connection Less (ACL) data packets as compared to the standard RPF, at the cost of additional overhead. Altogether, especially with the proposed improvements of Bluetooth performance, this technology can be considered to be well suited for nomadic scenarios.

  • 584. Isaksson, Lennart
    Seamless Communications2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The evolution of today’s wireless technologies and small hand-held devices has enabled the handling of the trade-off between mobility and performance. Things have, however, become more complex. Users demand high performance when using small and resource-efficient devices. Users also demand high-performance connectivity anywhere and anytime without having to care about transitions between different access networks. As of today, the absence of Mobile IP (MIP) support in most networks implies the need for a reconnection of the service as soon as the access network changes. That is why a new seamless communication concept is required. In the thesis, a new seamless communication concept is proposed. The goal is to be Always Best Connected (ABC) even if the conditions change. Initially, a network link has to be selected and a connection has to be established. The service used should be maintained as long as the conditions are fulfilled. First, a set of Generic Services (GSs), each related to a specific communication task, is defined. Furthermore, a deep performance investigation of some of the wireless technologies available is summarized and used. Based on the combination of a GS and a wireless technology selected criteria are used. The data extracted from our measurements have the option of later being fed into statistical algorithms. The translation of the extracted information through the statistical methods could be non-linear and for that reason the Fuzzy Set Theory (FST) is used. The FST provides us with the tool needed for the next step, the decision aiming at ABC. To be able to handle the large amount of data, the Multi-Criteria Decision Making (MCDM) is used. This decision model requires a linguistic 9-point scale which suits the FST tool perfectly. A judgment between different criteria can then be made. Moreover, the thesis describes a couple of important issues regarding the Internet protocol address problem. Each problem is discussed and solutions are presented in the context of having seamless communication without today’s constraints. The result is a seamless communication concept that is more flexible than other solutions. Both the FST and the MCDM tools have been successfully implemented into a running prototype.

  • 585. Isaksson, Lennart
    et al.
    Chevul, Stefan
    Fiedler, Markus
    Karlsson, Johan
    Lindberg, Peter
    Application-Perceived Throughput Process in Wireless Systems2005Conference paper (Refereed)
    Abstract [en]

    Motivated by the central role and the importance of network throughput for the performance of networked applications and thus for user experience, this paper investigates the process of user-perceived throughput. This throughput is measured on rather small time scales and interpreted with aid of summary statistics, histograms and autocorrelation coefficients. The results including GPRS, UMTS and WLAN measurements reveal a clear influence of the network, seen from variations of application-perceived throughput on the one-second time scale, which has to be considered when choosing the right kind of network for a specific task. The different statistical metrics considered will later be used in our research to maintain the QoS of the service decided by the user. While theoretical throughputs are yielded as expected in UMTS, both GPRS and WLAN do not reach the promised throughput values.

  • 586. Isaksson, Lennart
    et al.
    Fiedler, Markus
    Improved Time to Connect for Bluetooth2005Conference paper (Refereed)
    Abstract [en]

    Bluetooth has from its beginning used Frequency Hopping (FH) from version 1.0A to the current version 1.2. The so-called selection box uses a complex scheme to calculate the next correct frequency in time. This makes transmissions between Bluetooth devices both robust and secure. Several attempts have been carried out to improve the time to connect, due to the relatively high time to connect given by the Bluetooth specification. Many have not fully understood the FH for Bluetooth and have therefore suggested sub-optimized solutions to improve the time to connect. In this paper, a presentation of the problem that causes the poor time to connect performance is given. This knowledge is needed for an improvement of the time to connect for Bluetooth. To accomplish a reduction of the time to connect by a factor of 100, three main parameters have to be changed: First, the A-train and B-train should be switched directly after each other. Second, the phase should be switched faster, which is based on the clock. Finally, a reduction of the random backoff parameter needs to be considered. These changes, together with other parameters, like time out values, have to be changed/reduced accordingly. Together with these changed parameters a simulation of the time to connect for Bluetooth is presented.

  • 587. Isaksson, Lennart
    et al.
    Fiedler, Markus
    On-Demand Ad Hoc Routing with Modified Reverse Path Forwarding for Bluetooth2004Conference paper (Refereed)
    Abstract [en]

    In an ad hoc network connection establishment is done to secure a path for routing packets from source to destination. This path is then maintained to secure further transmissions. In the case of Wireless Personal Area Networks (WPAN) which are more flexible, this is not usable. This is especially the case for Bluetooth. Some constraints in Bluetooth demands a more flexible on-demand ad hoc network compared to other types of ad hoc network protocols. Initially we found that creating a scatternet is not practically possible using Bluetooth version 1.1. The slave/slave bridge is not implemented into the hardware to create a scatternet. In this paper, we present a modified version of the Reverse Path Forwarding (RPF) algorithm to make it suitable for Bluetooth routing. With an on-demand ad hoc network solution together with the modified RPF algorithm we present a suitable solution for Bluetooth packets to be routed in a flexible ad hoc network. To be able to test the modified RPF and the on-demand ad hoc network, a test platform has also been developed.

  • 588. Isaksson, Lennart
    et al.
    Fiedler, Markus
    Optimization of the Random Backoff Boundary of the Bluetooth FHSS Technique2005Conference paper (Refereed)
    Abstract [en]

    The goal of an ad hoc network is to create a wireless connection when needed between nodes. Regarding Bluetooth (IEEE 802.15.1) the so-called state machine based on the selection box is responsible for the Frequency Hopping (FH). In this state machine a particular sub-state (random backoff) is heavily involved in the time-to-connect between two devices.

  • 589. Isaksson, Lennart
    et al.
    Fiedler, Markus
    Seamless Connectivity in WLAN and Cellular Networks with Multi Criteria Decision Making2007Conference paper (Refereed)
    Abstract [en]

    The evolution of today's wireless and mobile technologies and personalized hand-held devices has increased the challenge to handle the trade-off between mobility, performance and cost. The user simply needs to be Always Best Connected (ABC). To make this happen, different types of criteria reflecting relevant characteristics of wireless and mobile access networks such as WLAN, UMTS and GPRS have to be established and judged. In this paper the criteria are divided into three main groups, performance, cost and accessibility. The criteria are fed into a Multi Criteria Decision Making (MCDM) tool which is able to deliver a ranking of network links in order to become ABC. Finally, a case study with two different Generic Services (GS) illustrates the decision making process and its outcomes in different situations.

  • 590. Isaksson, Lennart
    et al.
    Fiedler, Markus
    Nilsson, Arne A.
    Validation of Simulations of Bluetooth's Frequency Hopping Spread Spectrum Technique2004Conference paper (Refereed)
    Abstract [en]

    The need for performance studies avoiding expensive hardware installations and the lack of analytical models motivates the need of trustworthy simulation models for the cable-replacement technology Bluetooth. In this paper we show a detailed description of the Bluetooth technique and validation of different simulation models used today. To do this, a two-step approach for validation and credibility is necessary. First, a comprehensive empirical measurement was performed to establish a "status quo" of the behavior of today's Bluetooth technology. Second, a validation between empirical and simulation model is conducted to ensure the comparability. To accomplish these objectives we developed and validated a simulation model with frequency hopping algorithms and the whole state machine including collision detection. The results in form of histograms of different Bluetooth-specific durations indicate problems in case of already established simulation programs. So, finally, some changes and suggestions how to correct these defects are given.

  • 591. Isaksson, Lennart
    et al.
    Fiedler, Markus
    Rakus-Andersson, Elisabeth
    A Fuzzy Set Theory Based Method to Discover Transmissions in Wireless Personal Area Networks2006Conference paper (Refereed)
    Abstract [en]

    The complexity within a Wireless Personal Area Network (WPAN) increases. Several technologies have to share the same radio spectrum. In this paper we take a look at the 2.4 GHz Industrial Scientific and Medical (ISM)-band. This paper discusses a method of selecting the best wireless channel within Wireless Local Area Network (WLAN) when several technologies could be used in the same WPAN range of the needed access point. The issue is to keep away from already occupied channels. The method is divided into four steps: the passive probing of the power level detecting IEEE 802.15.4 (ZigBee) channels using a new and affordable hardware, the transformation of the probed data to a linguistic level using Fuzzy Set Theory (FST), the classification of the data, and finally the sorting and selection of channels based on whose power levels.

  • 592. Isaksson, Lennart
    et al.
    Johnson, Henric
    Fiedler, Markus
    Toward Seamless Integration of Wireless LAN and Cellular Networks2005Report (Other academic)
    Abstract [en]

    Networked applications, no matter whether connected in a wired or wireless way, rely upon the ability of timely data delivery. The achievable throughput is a quality measure for the very task of a communication system, which is to transport data in time. This is of particular importance for nowadays trendy streaming applications such as digital TV, Internet Protocol (IP)-telephony, and gaming. Especially the higher throughput offered by 3G mobile systems (and beyond) as compared to earlier generations of mobile communications seems to pave the way for streaming applications into mobile environments. In this report a method is described that makes a decision between different communication technologies depending on different criteria and expectations stated by the end-user and perceived within the network itself. The Multi-Criteria Decision Making (MCDM) method together with the Analytic Hierarchy Process (AHP) method is used to achieve the concept of Always Best Connected (ABC). Two different groups of criteria are used: benefits and costs. Within the benefit group three metrics are used: Initial Delay (ID), Link Capacity (LC) and Direction Loss (DL) which are analyzed and used before a decision is made. These three metrics are weighted against each other. Finally a case study is presented, using the AHP together with the weighted metrics.

  • 593.
    Islam, Ibrahim Bin Nurul
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Performance Analysis of Wireless Ad hoc Networks in Different Network Situations from Routing Point of View2008Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    The research describes the performance of the three routing protocols (AODV,DSR,TORA)in different network situations, specially varying the size of the networks. AODV shows a considerable better performance over the others for any number of nodes. TORA and DSR show moderate performance for minimum number of nodes, where in the case of large networks, DSR shows some performance rather than TORA. OPNET Modeler 10.5 is used to model the network and to simulate the protocols. The thesis will show a future performance improvement for more routing protocols using OPNET Modelers or other Network Simulators.

  • 594.
    Islam, Mohammad Saiful
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Alam, Mohammad Tawhidul
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    WiMAX: An analysis of the existing technology and compare with the cellular networks.2009Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Broadband access technology has significant influences in the telecommunication industry. Worldwide interoperability for microwave access (WiMAX) is a broadband wireless technology which brings broadband experience to a wireless context. There are two different types of broadband wireless services. One is fixed wireless broadband which is similar to the traditional fixed line broadband access technology like DSL or cable modem but using wireless as a medium of transmission. Another type is broadband wireless known as mobile broadband which has additional functionality of portability, mobility and nomadicity. The IEEE 802.16 family WiMAX is designed to accommodate both fixed and mobile broadband application. WiMAX promises to solve the last mile problem which refers to the expense and time needed to connect individual homes and offices to trunk route for communications. WiMAX also offer higher peak data rates and greater flexibility than 3G networks and Wi-Fi. This thesis is provides the analysis of the broadband wireless access (BWA) technology with a focus on WiMAX and compare it with the other wireless technology like Wireless Fidelity (Wi-Fi) and third-generation (3G).

  • 595.
    Islam, Mohammad Taufiqul
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Hoque, Azimul
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Study of Reliable Multicast for IPTV Service2008Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Internet Protocol Television (IPTV) is a service on the Internet where digital TV signal data is delivered to the participants using the Internet Protocol (IP). IPTV promises to provide many TV channels with lower price for operators, lower price for consumers and it is also distributed more efficiently than using the nowadays prevalent coaxial cable distribution. As it is assumed that broadband connection of households will grow at a brisk pace, IPTV will play more and more important role in the incoming years in our lives. The plenty of TV channels requires large bandwidth for high clear TV programs in IPTV service which is a contradictory issue to the limitation of user access line bandwidth and aggregation network bandwidth. Multicast as a mature one-to-many packet data delivery technology, the use of multicast for IPTV service is considered necessary to resolve such contradiction. But which multicast or what level multicast will be best suited for this emerging technology is still a burning question. In this thesis we identify the appropriate multicast solution for IPTV. To accomplish our goal, we have done literature survey in gathering information to analyse different AL multicast protocol and IP multicast protocols. We have tried to find out different problems related to this protocol to deployment. Finally we have identified the best suited solution to carry multicast traffic for IPTV service.

  • 596.
    Ivarsson, Samuel
    Blekinge Institute of Technology, School of Engineering, Department of Systems and Software Engineering.
    Mobile payment with customer controlled connection: Can it be constructed to be safe enough?2008Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    The mobile commerce has given birth to many mobile payment systems and this thesis covers the security of a theoretical system where the communication is handled by the customer. There are many technologies that can be used when implementing such a system, each with different strengths and weaknesses. The system designed in this project was constructed for micropayments in vending machines that has no connection to the vendor except for the connection supplied by the customer. The design was then used for analyzing the threats against the designed system and comparing it to an identical system where the connection is supplied by the seller in order to find out the effects on security when changing the communication channel. The comparison shows that even though the designed system is more vulnerable, it is not a major difference and with low value payments, the mobile payment system can depend on the connection supplied by the user. The main advantages to security with this method is the protection against Denial of Service attacks and the protection against mass identity thefts as authentication is no longer done on the machine.

  • 597.
    Ivo, Akum Nji
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Comparative Analysis of Performance Routing Metrics for Multi-radio Wireless Mesh Networks2008Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Traditional Ad Hoc network wireless communication in the past years have contributed tremendously to the dawn of wireless mesh networks (WMNs) which have so far been able to provide a significant improvement in capacity and scalability. Routing metrics which form the basic element for the routing protocol in this innovative communication technology is a call for concern as they must take into consideration the wireless medium network characteristics in order to provide a optimum appreciable QoS performance. In the past many single-radio routing metrics have been proposed for Ad Hoc networks which are not compatible with the multi-radio routing scenario demanded by WMNs. In our work, we provide a comparative analysis of most recently proposed multi-radio routing metrics for WMNs. We begin by providing an overview of the features of a wireless mesh network thereby presenting a better understanding of some of the research challenges of WMNs. Also, since single-radio routing forms the basis of multi-radio routing, we in this regard provide a review of some single-radio routing metrics. In our comparative analysis, an overview of routing protocols for WMNs is provided enabling an understanding of the demands to be included in a routing metric to ensure efficient routing in WMNs since different routing protocols may impose different demands; we then identify the requirements of multi-radio routing metrics from which we base our comparative analysis.

  • 598. Jacobsson, Andreas
    Exploring Privacy Risks in Information Networks2004Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Exploring privacy risks in information networks is analysing the dangers and hazards that are related to personal information about users of a network. It is about investigating the dynamics and complexities of a setting where humans are served by technology in order to exploit the network for their own good. In the information network, malicious activities are motivated by commercial factors in that the attacks to privacy are happening, not in the name of national security, but in the name of the free market together with technological advancements. Based on the assumption of Machiavellian Intelligence, we have modelled our analyses by way of concepts such as Arms Race, Tragedy of the Commons, and the Red Queen effect. In a number of experiments on spam, adware, and spyware, we have found that they match the characteristics of privacy-invasive software, i.e., software that ignores users’ right to decide what, how and when information about themselves is disseminated by others. Spam messages and adware programs suggest a hazard in that they exploit the lives of millions and millions of users with unsolicited commercial and/or political content. Although, in reality spam and adware are rather benign forms of a privacy risks, since they, e.g., do not collect and/or transmit user data to third parties. Spyware programs are more serious forms of privacy risks. These programs are usually bundled with, e.g., file-sharing tools that allow a spyware to secretly infiltrate computers in order to collect and distribute, e.g., personal information and data about the computer to profit-driven third parties on the Internet. In return, adware and spam displaying customised advertisements and offers may be distributed to vast amounts of users. Spyware programs also have the capability of retrieving malicious code, which can make the spyware act like a virus when the file-sharing tools are distributed in-between the users of a network. In conclusion, spam, spyware and virulent programs invade user privacy. However, our experiments also indicate that privacy-invasive software inflicts the security, stability and capacity of computerised systems and networks. Furthermore, we propose a description of the risk environment in information networks, where network contaminants (such as spam, spyware and virulent programs) are put in a context (information ecosystem) and dynamically modelled by their characteristics both individually and as a group. We show that network contamination may be a serious threat to the future prosperity of an information ecosystem. It is therefore strongly recommended to network owners and designers to respect the privacy rights of individuals. Privacy risks have the potential to overthrow the positive aspects of belonging to an information network. In a sound information network the flow of personal information is balanced with the advantages of belonging to the network. With an understanding of the privacy risk environment, there is a good starting-point for recognising and preventing intrusions into matters of a personal nature. In reflect, mitigating privacy risks contributes to a secure and efficient use of information networks.

  • 599. Jacobsson, Andreas
    Privacy and security in Internet-based information systems2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In an increasingly networked world, where new technologies and applications are rapidly introduced into homes and offices of users, complexity is rising. As a consequence, threats and dangers related to Internet usage are more eminent than ever before. A central assumption is that if human activity is to evolve and grow in the environment constituted by the Internet, a sound control of personal information, and a reasonable level of protection from malicious and deceitful behaviors is necessary. The research presented in this thesis is organized around two concepts, privacy and security. Privacy can loosely be described as “the right to be let alone” and security as “the protection from harm”. The setting in which these concepts are studied is Internet-based information systems, which are the global information systems that use the Internet as the communication infrastructure, and which involve information, hardware, software, and human actors. Since Internet-based information systems are characterized by, e.g., openness, dynamicity, anonymity, connectivity, and hostility, managing privacy and security is a cumbersome and challenging task. In the study of privacy, a number of empirical studies are conducted, in which we explore the nature and extent of software-based privacy invasions in Internet-based information systems. Three examples of privacy-invasive activities that are specifically examined are spam (unsolicited bulk e-mail), adware (software that displays commercial content), and spyware (software that spies on users). The main contributions are the analyses of such privacy-invasions and their consequences, and the specification of a new category of software, which is referred to as privacy-invasive software (software that ignores users’ right to be let alone). In the study of security, it has been investigated how interorganizational and interoperable business collaboration using Internet-based information systems can be achieved in the context of virtual enterprises. Virtual enterprises are a major trend in enterprise interoperability, making it possible to configure cooperative settings in which different companies temporarily share their resources toward a common goal. To realize this vision, we introduce Plug and Play Business, which is an integrated framework of information and communication technologies intended to support secure formation and operation of virtual enterprises. A formal analysis of Plug and Play Business, and the crucial tasks involved in the management of virtual enterprises is carried out together with a discussion of how to improve security and promote trust. A community of virtual enterprises, a gatekeeper facility, and a set of security measures including norms and norm-enhancing mechanisms are identified for this purpose. To support the users of Plug and Play Business, intelligent software agents are suggested as means to automate some of the tasks necessary for operating a virtual enterprise. The study of security is concluded by an assessment of the available technologies in support of realizing of Plug and Play Business software.

  • 600. Jacobsson, Andreas
    Towards Plug and Play Business Software2007In: Interoperability for Enterprise Software Applications / [ed] H., Panetto; N., Boudjlida, London, U.K.: ISTE, Ltd. , 2007Chapter in book (Other academic)
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