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  • 51. Erman, David
    Replication Strategies for Streaming Media2007Report (Other academic)
    Abstract [en]

    Large-scale, real-time multimedia distribution over the Internet has been the subject of research for a substantial amount of time. A large number of mechanisms, policies, methods and schemes have been proposed for media coding, scheduling and distribution. Internet Protocol (IP) multicast was expected to be the primary transport mechanism for this, though it was never deployed to the expected extent. Recent developments in overlay networks has reactualized the research on multicast, with the consequence that many of the previous mechanisms and schemes are being re-evaluated. This report provides a brief overview of several important techniques for media broadcasting and stream merging, as well as a discussion of traditional IP multicast and overlay multicast. Additionally, we present a proposal for a new distribution system, based on the broadcast and stream merging algorithms in the BitTorrent distribution and replication system.

  • 52.
    Erman, David
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Ilie, Dragos
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Popescu, Adrian
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    BitTorrent Session Characteristics and Models2005Conference paper (Refereed)
    Abstract [en]

    The paper reports on a modeling and evaluation study of session characteristics of BitTorrent traffic. BitTorrent is a second generation Peer-to-Peer (P2P) application recently developed as an alternative to the classical client-server model to reduce the load burden on content servers and networks. Results are reported on measuring, modeling and analysis of application layer traces collected at the Blekinge Institute of Technology (BIT) and a local ISP. For doing this, a dedicated measurement infrastructure has been developed at BIT to collect P2P traffic. A dedicated modeling methodology has been put forth as well. New results are reported on session characteristics of BitTorrent, and it is observed that session interarrivals can be accurately modeled by the hyper-exponential distribution while session durations and sizes can be reasonably well modeled by the lognormal distribution.

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

    BitTorrent is a second generation Peer-to-Peer application that has been recently developed as an alternative to the classical client-server model to reduce the load burden on content servers and networks. The protocol relies on the use of swarming techniques for distributing content. No search functionality is built into the protocol, and the signaling is geared only towards an efficient dissemination of data. The paper reports on measurement and analysis of BitTorrent traffic collected at the Blekinge Institute of Technology (BIT), Karlskrona, Sweden. We measure and analyze data from local BitTorrent client sessions at BIT. The characteristics of the signaling traffic exchanged among the participating peers in a BitTorrent distribution swarm are investigated. A dedicated approach based on combining instrumentation at the application layer with flow identification and extraction at the transport layer is used for traffic measurements.

  • 54. Erman, David
    et al.
    Popescu, Adrian
    BitTorrent Request Message Models2005Conference paper (Refereed)
    Abstract [en]

    BitTorrent, a replicating Peer-to-Peer (P2P) file sharing system, has become extremely popular over the last years. According to Cachelogic, the BitTorrent traffic volume has increased from 26% to 52% of the total P2P traffic volume during the first half of 2004. This paper reports on new results obtained on modelling and analysis of BitTorrent traffic collected at Blekinge Institute of Technology (BTH) as well as a local Internet Service Provider (ISP). In particular, we report on new request models for a BitTorrent peer during downloading.

  • 55. Erman, David
    et al.
    Saavedra, Daniel
    González, José Á. Sánchez
    Popescu, Adrian
    Validating BitTorrent Models2008In: Telecommunications Systems, ISSN 1018-4864, E-ISSN 1572-9451, Vol. 39, no 2, p. 103-116Article in journal (Refereed)
    Abstract [en]

    BitTorrent (bt), a Peer-to-Peer (p2p) distribution system, is a major bandwidth consumer in the current Internet. This paper reports on a measurement study of bt traffic intended to identify potential traffic invariants. To this end, we employ high-accuracy packet capture hardware together with specialized parsing software. Important characteristics regarding bt sessions and messages as well as general system characteristics are reported. The results indicate that characteristics such as session inter-arrival times are corroborated to be exponentially distributed, while other characteristics are shown to differ from previously reported results. These differences are attributed to changes in the core bt algorithms. Further, it is observed that long- and heavy-tailed distributions can be used to model several characteristics. The log-normal, Pareto and mixtures of these distributions are used to model session sizes and durations, while the Weibull distribution has been observed to model message inter-arrival and inter-departure times for bandwidth-limited clients.

  • 56. Erman, David
    et al.
    Vogeleer, Karel de
    Popescu, Adrian
    On Piece Selection for Streaming BitTorrent2008Conference paper (Refereed)
    Abstract [en]

    Video-on-Demand (VoD) has been hailed as a "killer app" of the Internet for a long time, but it has yet to really make a major breakthrough, due to various technical and political reasons. The recent influx of community-driven video distribution has reactualized the research into efficient distribution methods for streaming video. In this paper, we propose a number of modifications and extensions to the BitTorrent (BT) distribution and replication system to make it suitable for use in providing a streaming video delivery service, and implement parts of these in a simulator. Also, we report on a simulation study of the implemented extensions to the BT system.

  • 57.
    Feroze, Zeeshan
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Ahmed, Bilal
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    3G Cellular Network2009Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    In our thesis we discussed CDMA2000 and UMTS channels, QoS issues and Routing loops in 3G. We also discussed Handover and Mobility effects in 3G.

  • 58. Fiedler, Markus
    Internet performance issues for safety-critical applications2004Conference paper (Refereed)
    Abstract [en]

    Networked safety-critical applications have to rely upon a certain Quality of Service (QoS). Internet, however, might not be that reliable in that respect. Thus, quality feedback towards the application is a crucial aspect. This contribution reviews typical origins of QoS problems and discusses possibilities how to monitor them. It also presents a lightweight monitoring solution for bandwidth problems which can be used for quality feedback towards the application.

  • 59. Fiedler, Markus
    Traffic Measurement, Characterization and Modeling2005In: Analysis and Design of Advanced Multiservice Networks Supporting Mobility, Multimedia, and Internetworking. COST Action 279 Final Report / [ed] Brazio, J.; Tran-Gia, P.; Akar, N.; Beben, A.; Burakowski, W.; Fiedler, Markus; Karasan, E.; Menth, M.; Olivier, P.; Tutschku, K., Springer , 2005, p. 97-125Chapter in book (Refereed)
    Abstract [en]

    N/A

  • 60. Fiedler, Markus
    et al.
    Blouin, Francois
    Arlos, Patrik
    18th ITC Specialist Seminar on Quality of Experience2008Report (Other academic)
    Abstract [en]

    The notion and topic of Quality of Experience (QoE) keeps attracting the attention of manufacturers, operators and researchers. It links user perception and expectations on one side and technical Quality of Service (QoS) parameters, management, pricing schemes etc. on the other side. Such links are needed in order to balance user satisfaction and economic aspects of service provisioning. However, the notion of QoE as such is not without controversy. Technicians, used to a world of objective and clearly definable parameters, tend to fear the subjective, somehow fuzzy parts associated with end user perception. Vice versa, customer relationship and marketing departments might find themselves uncomfortable with technical parameters which might not reflect the user perception in some tense situations. Nevertheless, appearance and utility of a networked service depend on the underlying technical solutions and their performance. Thus, we face the challenge of bringing it all together, which essentially describes the spirit of the 18th ITC Specialists Seminar on Quality of Experience (ITC-SS 18). ITC Specialist Seminars have a very good reputation in gathering experts and their high-quality contributions around a performance-oriented topic of mutual interest. ITC-SS 18 is intended as a meeting place between experts, researchers, practitioners, vendors and customers. It is devoted to presentations and discussions of QoE concepts, analysis, management approaches etc., both from industry and academia. While many conferences are dominated by academia, one third of the submissions to ITC-SS 18 originated from industry. The contributions have been peer-reviewed by at least three independent reviewers and finally, we selected 18 papers to be presented. Additionally, two keynote speeches reflect one industrial and one academic approach to QoE analysis and implementation. For the ITC, the leading conference for performance modeling and analysis of communication networks & systems, ITC-SS 18 opens a window towards the end user. ITC-SS 18 takes place in Karlskrona on May 29—30, 2008. It is organized by the Dept. of Telecommunication Systems (ATS) within the School of Engineering (TEK) at Blekinge Institute of Technology (BTH) in cooperation with the International Advisory Council (IAC) of ITC.

  • 61. Fiedler, Markus
    et al.
    Chevul, Stefan
    Isaksson, Lennart
    Lindberg, Peter
    Karlsson, Johan
    Communication requirements of generic services for Intelligent Transport Systems2004Other (Other academic)
    Abstract [en]

    In order to meet their users’ expectations and to be of efficient help for people using or maintaining Intelligent Transport Systems (ITS), related services need efficient support from the underlying communication systems, which in turn requires profound knowledge of those needs. This paper presents an approach to gather services into generic groups and a framework to classify their needs in terms of availability, performance, security and cost in a generic manner. These needs are consequently seen from the user’s perspective, but formulated in a way such that the matching towards technical parameters as e.g. throughput offered by a communication network can be performed. Upon comparing needs with offers, the feasibility of a certain communication technology for a certain type of service can be determined, which in turn helps to choose the right kind of connectivity in order to yield the desired degree of availability, performance, security and cost. This work is carried out within the VINNOVA-sponsored project PIITSA (Personal Information for Intelligent Transport Systems through Seamless communications and Autonomous decisions) conducted by Aerotech Telub, Blekinge Tekniska Högskola, Statens Provningsanstalt Borås and Vägverket, respectively.

  • 62. Fiedler, Markus
    et al.
    Chevul, Stefan
    Isaksson, Lennart
    Lindberg, Peter
    Karlsson, Johan
    Generic communication requirements of its-related mobile services as basis for seamless communications.2005Conference paper (Refereed)
    Abstract [en]

    In order to meet user expectations and to be of efficient help for people using or implementing Intelligent Transport Systems and Services (ITS), mobile ITS-related services need efficient support from the underlying communication systems, which in turn requires profound knowledge of those needs. As a first step towards an optimal automatic choice of communication technologies in order to provide for seamless communications, this paper groups services into generic groups and presents a framework to classify their needs in terms of availability, performance, security and cost in a generic manner. These needs are consequently seen from the user’s perspective, but formulated in a way such that they can be matched towards known network parameters. Upon comparing needs with offers, the feasibility of a certain communication technology for a certain type of service can be determined both proactively and reactively, which helps to automatically select the right kind of connectivity in order to yield the desired degree of availability, performance, security and cost. We motivate for instance the need for determining and monitoring applicationperceived speeds, a multi-level security models and the one-stop service concept. We also provide an example on how these needs can be matched to offers by different networks.

  • 63. Fiedler, Markus
    et al.
    Chevul, Stefan
    Isaksson, Lennart
    Tutschku, Kurt
    Binzenhöfer, Andreas
    The Throughput Utility Function: Assessing network impact on mobile services2005Conference paper (Refereed)
    Abstract [en]

    Based on the need for distributed end-to-end quality management for next-generation mobile Internet services, this paper presents a ready-to-deploy quality assessment concept for the impact of the network on the performance of mobile services. We consider the throughput utility function (TUF) as a special case of the network utility function (NUF). These functions combine the observed network utility at the inlet and the outlet of a mobile network. NUF and TUF capture the damping effect of the network onto user-perceived quality from an end-to-end perspective. As opposed to sometimes hard-to-evaluate QoS parameters such as delay and loss, the NUF is highly intuitive due to its mapping to a simple value between 0 and 100 %, which reflects user perception. We demonstrate the capabilities of the proposed TUF by measurements of application-perceived throughput conducted in a mobile, i.e. GPRS and UMTS network.

  • 64. Fiedler, Markus
    et al.
    Eliasson, Charlott
    Ciszkowski, Tomasz
    Mazurczyk, Wojciech
    Kotulski, Zbigniew
    Parameterisation of a reputation system for VoIP in P2P networks for improved communication quality and security2008Conference paper (Other academic)
    Abstract [en]

    In this paper, we propose how to parameterize and maintain a reputation system that, based on the current network conditions, supports the selection of the optimal end-to-end communication path for VoIP communication in a P2P context. Each node’s reputation is formed based on three factors: (1) performance reputation (own experience from passive measures of the network conditions); (2) security reputation; and (3) information reputation consisting of recommendations from other nodes. Reputation data is periodically updated from continuous monitoring of path quality and security and also from information exchange between the nodes. When network conditions deteriorate, the reputation system enables switching, if possible, to another available path for furthercommunication. The proposed reputation system is a component of the SecMon system, which is intended especially for VoIP service over P2P networks. SecMon features lightweight QoS parameter monitoring, authentication and data integrity services. The exchange of monitoring information represents a low-bandwidth consumption solution that is transparent to the users and possesses a self-organizing capability. The above-mentioned exchange features are accomplished by utilizing two information hiding techniques: digital audio watermarking and network steganography. These techniques are used to create covert channels that serve as transport channels for lightweight QoS measurement results. Moreover, in this paper, we present results of the simulations that were performed to investigate how the proposed reputation system is performing for a simple twopath case scenario. Additionally, we show how different network conditions like delays and packet losses affect the proposed reputation system and how they are modeled with utility functions. Results of the simulations also illustrate the approaches to thresholds that trigger path changes.

  • 65. Fiedler, Markus
    et al.
    Isaksson, Lennart
    Chevul, Stefan
    Karlsson, Johan
    Lindberg, Peter
    Measurements and analysis of application-perceived throughput via mobile links2005Conference paper (Refereed)
    Abstract [en]

    Application-perceived throughput plays a major role for the performance of networked applications and thus for user experience. Especially in mobile environments, throughput is limited, which is a challenge for applications and users. On this background, this tutorial paper investigates the process of user-perceived throughput in GPRS and UMTS systems seen over rather small averaging intervals. It discusses the corresponding active measurements mimicking the needs of streaming applications and analyzes results with aid of summary statistics, histograms and autocorrelation coefficients. These results reveal a clear influence of the network, seen from variations and autocorrelation of application-perceived throughput mostly on the one-second time scale. Such an influence has to be considered when choosing the right kind of network for a specific task. To that aim, the investigated metrics will serve as input to a multi-criteria decision process to determine the proper network for a specific service. The results indicate that, applications have to cope with considerably large jitter when trying to use the nominal throughputs. In GPRS, the promised average throughputs are not even reached in downlink direction; instead, a quite large amount of packet loss occurs. With aid of causality arguments for an equivalent bottleneck, bounds for the extra delay of the first packet sent via mobile links can in fact be derived from throughput measurements.

  • 66. Fiedler, Markus
    et al.
    Persson, Mårten
    Bertilsson, Tobias
    Situationsberoende spontan mobil informationstjänst för resenärer2005Other (Other academic)
    Abstract [en]

    Detta bidrag kommer att beskriva en tjänst (applikation) som försörjer resenärer med aktuell och relevant reseinformation under resans gång. Tjänsten är tilltänkt som demonstration för sömlös kommunikation inom det VINNOVA-sponsrade projektet PIITSA = Personal Information for Intelligent Transport Systems through Seamless communications and Autonomous decisions. Tjänsten kommer att kombinera Public Streaming with Personal Interactive Services för att ge resenären spontan information om aktuella trafikstörningar på dennes resa samt alternativa reseförslag. Den är tilltänkt att kunna köras via sömlös kommunikation. Tjänsten designas av magisterstudenter vid BTH inom kursen ETD013 Mobila Tjänster – vilkens verksamket kommer att belyses kort – samt efterföljande magisterarbete. Mobila tjänster, informationstjänst, situationsberoende tjänst, tjänstearkitektur, sömlös kommunikation

  • 67.
    Fiedler, Markus
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Zepernick, Hans-Jürgen
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Lundberg, Lars
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Arlos, Patrik
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Pettersson, Mats
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    QoE-based Cross-Layer Design of Mobile Video Systems: Challenges and Concepts2009Conference paper (Refereed)
    Abstract [en]

    This conceptual paper focuses on revealing challenges and offering concepts associated with the incorporation of the Quality of Experience (QoE) paradigm into the design of mobile video systems. The corresponding design framework combines application, middleware and networking layer in a unique cross-layer approach, in which all layers shall jointly analyse the quality of the video and its delivery in face of volatile conditions. Particular ingredients of the framework are efficient video processing, advanced realtime scheduling, and reduced-reference metrics on application and network layer.

  • 68.
    Gagbla, George Kofi
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Applying Keystroke Dynamics for Personal Authentication2005Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    With the establishment of the information society, security had become the greatest concern for Institutions transacting business over the Internet. Home banking and on-line brokerage applications currently, use basic software-only security functions for the internet such as server authentications and Secure Sockets layer. Higher levels of protections are being achieved with Smart card based authentication schemes and transaction protocols. Password based security identifies users based on what they know – the password or PIN, which can be guessed, hacked, found or stolen. Smart Cards, tokens and badges identify users based on what they have which can also be lost, loaned or stolen. The objective of the thesis was to design and implement a biometric authentication scheme by means of keystroke dynamics to secure web applications. The scheme illustrates the effect of the template size and the number of biometric features used to improve performance of FAR, FRR and EER. The enrolment process is devoid of spurious outliers that may introduce significant variations to template data. Due to the dependence of the system on the user’s psychological characteristics, the adaptation module introduces dynamism into the template features per changes in the legitimate user’s login template variants. At the quest of attaining a zero bias in statistical variants, an off-line simulator tool was designed to regenerate impostor and genuine data set obtained from live users and set as input to the system. The report includes an architectural description of the system, conceptual models and analysis of field data of over 200 samples.

  • 69. Gustafsson, Kristian
    et al.
    Fiedler, Markus
    E-Government: services, needs and user satisfaction2004Other (Other academic)
    Abstract [en]

    Within the e-government process, needs are identified and people try to come up with ideas for the public sector that will increase the effectiveness as well as lead to cost savings. Consequently, many new electronic services are being developed. As a result, Quality of Service (QoS) becomes an even more critical issue in the domain of electronic services. This paper starts by a general discussion of e-government and its services in general. Thereafter it explains different QoS factors that have been identified within the field of electronic services. The identification has been carried out by studying several researchers’ work and by experience from e-government projects. The result shows that service design, security aspects, network performance issues, as well as the users’ perspective, such as user requirements, are all factors of the QoS model. A new electronic service that does not take these factors into consideration might fail and therefore be rejected by its intended users.

  • 70.
    Hariharan, Mahesh
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    P2P Networking and Technology Enablers in Business Applications2006Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    The usage of Peer to Peer Networks over the Internet has been growing by exponentially. Apartbfrom the hype surrounding P2P, it has remarkable ramifications on the way the Internet could be used. This is an area which is not explored as well as we would want to. This thesis examines the architectural differences in P2P networks and generic application domains where the principles of P2P are exploited. The usage of P2P in different business verticals and technology enablers that go along with it are presented. The focus is on several case studies each addressing a different use case. The common thread running through all of these use cases is the ability to resolve a business issue. Finally the focus is on how P2P networks might probably change the way the Internet behaves in the near future.

  • 71. Hong, Seung-Sun
    et al.
    Wong, Fiona
    Wu, Felix
    Lilja, Bjorn
    Jansson, Tony Y.
    Johnson, Henric
    Nilsson, Arne A.
    TCPtransform: Property-Oriented TCP Traffic Transformation2005Conference paper (Refereed)
    Abstract [en]

    A TCPdump file captures not only packets but also various "properties" related to the live TCP sessions on the Internet. It is still an open problem to identify all the possible properties, if ever possible, and more importantly, which properties really matter for the consumers of this particular TCPdump file and how they are related to each other. However, it is quite clear that existing traffic replay tools, for the purpose of system evaluation, such as TCPreplay destroyed at least some of critical properties such as "ghost acknowledgment" (while the origin packet has never been delivered), which is a critical issue in conducting experimental evaluations for intrusion detection systems. In this paper, we present a software tool to transform an existing TCPdump file into another traffic file with different "properties". For instance, if the original traffic is being captured in a laboratory environment, the new file might "appear" to be captured in between US and Sweden. The transformation we have done here is "heuristically consistent" as there might be some hidden properties still being destroyed in the transformation process. One interesting application of our tool is to build long-term profiles to detect anomalous TCP attacks without really running the target application over the Internet. While, in this paper, we only focus on property-oriented traffic transformation, we have built and evaluated an interactive version of this tool, called TCPopera, to evaluate commercial intrusion prevention systems.

  • 72. Hossfeld, Tobias
    et al.
    Binzenhöfer, Andreas
    Fiedler, Markus
    Tutschku, Kurt
    Measurement and Analysis of Skype VoIP Traffic in 3G UMTS Systems2006Conference paper (Refereed)
    Abstract [en]

    Voice-over-IP (VoIP) telephony becomes more and more popular in the wired Internet because of easy-to-use applications with high sound quality like Skype. UMTS operators promise to offer large data rates which should also make VoIP possible in a mobile environment. However, the success of those application strongly depends on the user perceived voice quality. In this paper, we therefore analyze the achievable and the actual quality of IP-based telephony calls using Skype. This is done performing measurements in both a real UMTS network and a test environment. The latter is used to emulate rate control mechanisms and changing system conditions of UMTS networks. The results show whether Skype over UMTS is able to keep pace with existing mobile telephony systems and how it reacts to different network characteristics. The investigated performance measures comprise the Perceptual Evaluation of Speech Quality (PESQ) to evaluate the voice quality, the packet loss, the inter-packet delay, and the throughput to capture networkbased factors. In this context, the concept of the Network Utility Function (NUF) is applied to describe the impact of the network on the voice quality as perceived by the end-user.

  • 73. Hossfeld, Tobias
    et al.
    Hock, David
    Tran-Gia, Phuoc
    Tutschku, Kurt
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Fiedler, Markus
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Testing the IQX Hypothesis for Exponential Interdependency between QoS and QoE of Voice Codecs iLBC and G.7112008Conference paper (Refereed)
    Abstract [en]

    Given the growing importance of quantitative relationships between user-perceived Quality of Experience (QoE) and network Quality of Service (QoS), this paper investigates the IQX hypothesis for two voice codecs, iLBC and G.711. This hypothesis expresses QoE as an exponential function of QoS degradation. The experiments are carried out in a controlled environment using the softphone SJPhone, the network emulator NIST Net, and a tool calculating the PESQ (Perceptual Evaluation of Speech Quality) from sent and received audio files. The IQX hypothesis is confirmed exactly for disturbances perceived on applications level, packet loss and packet reordering, which clearly correlate to the main sensitivities of the used softphone to packet-level disturbances such as loss, jitter and reordering. So, besides of providing a unified relationship between QoE and QoS, the IQX also proved to be capable of identifying the QoS parameters of relevance for QoE degradations. The study also points out interesting tracks for future work in terms of QoS degradations and related QoE evaluations.

  • 74.
    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.

  • 75.
    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).

  • 76.
    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.

  • 77.
    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.

  • 78. 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.

  • 79. 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).

  • 80. 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.

  • 81. 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.

  • 82. 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.

  • 83. 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.

  • 84.
    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.

  • 85. 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.

  • 86.
    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.

  • 87.
    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.

  • 88. 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.

  • 89. 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.

  • 90. 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.

  • 91. 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.

  • 92. 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.

  • 93. 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.

  • 94. 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.

  • 95. 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.

  • 96.
    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.

  • 97.
    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).

  • 98.
    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.

  • 99.
    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.

  • 100.
    Jadoon, Adeel
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Evaluation of UICC-based IMS authentication schemes2009Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    This thesis study involves evaluation of UICC based IMS authentication schemes. The schemes included in this study are IMS AKA, E-IMS AKA, One-Pass GPRS IMS authentication and Early IMS security. These schemes are evaluated on the basis of security, user friendliness and simplicity. Based on the analysis it is concluded that the IMS AKA which is the standardized authentication mechanism for IMS and embedded in ISIM is the most suitable authentication scheme for IMS, regardless of access network. However, the Early IMS authentication scheme is used only for GSM/GPRS network.

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