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  • 301.
    E., Okwelume Gozie
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Kingsley, Ezeude Anayo
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    BLIND SOURCE SEPARATION USING FREQUENCY DOMAIN INDEPENDENT COMPONENT ANALYSIS2007Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    Our thesis work focuses on Frequency-domain Blind Source Separation (BSS) in which the received mixed signals are converted into the frequency domain and Independent Component Analysis (ICA) is applied to instantaneous mixtures at each frequency bin. Computational complexity is also reduced by using this method. We also investigate the famous problem associated with Frequency-Domain Blind Source Separation using ICA referred to as the Permutation and Scaling ambiguities, using methods proposed by some researchers. This is our main target in this project; to solve the permutation and scaling ambiguities in real time applications

  • 302. Ekelin, Annelie
    Från löfte till handling: lägesrapport om e-demokrati i förvandling2007Other (Other academic)
    Abstract [en]

    Rapporten ger en överblick över senaste årens utveckling av e-demokrati. Rapporten lyfter fram satsningar inom området, initierade av skilda aktörer från olika utgångspunkter i samhället. Rapporten behandlar följande fågor: Vad avses med e-demokrati? I vilka former och i vilken omfattning tillämpas e-demokrati? Vilka länder har kommit långt inom området och i vilken form? Vilket är nuläget när det gäller e-demokrati i Sverige på kommunal- landsting- och statlig/myndighetsnivå? Vilket är nuläget när det gäller e-demokrati ur ett internationellt perspektiv? Vilken är nuvarande regerings syn på e-demokrati och vilka planer finns på departementsnivå?

  • 303. Ekelin, Annelie
    Situating eParticipation2007In: Understanding eParticipation: Contemporary PhD eParticipation Research in Europe / [ed] Hedström, Anders ;; Rose, Karin ;; Grönlund, Jeremy ;; , Örebro: Örebro: Örebro University, Department of Business, Economics, Statistics and Informatics , 2007, p. 71-84Chapter in book (Other academic)
    Abstract [en]

    eParticipation is gaining more and more attention in public discourse.The purpose of this chapter is to describe and discuss how reproduction of certain user-values and power relations becomes technologically embedded during a process of customisation of a consultation tool, intended for online participation.The analysis and the discussion in this chapter is based on ethnographic participatory observations and interviews within a R&D project. The aim of the project was to broaden the scope of participation concerning spatial planning in a Swedish municipality. A prototype of the tool was also tested by a group of citizens. The findings of the study are discussed and analysed with the help of concepts derived from situated and relational theories. The overall objective is thus to develop methods for how to handle local processes of setting the stage for eParticipation.

  • 304. Ekelin, Annelie
    The Work to Make eParticipation Work2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    eParticipation is a new research domain focusing the development of ICT-supported participation in processes of government and governance. These processes may concern involvement of practitioners, citizens and politicians in electronic public administration, service delivery, policy-making and decision-making. The overall objective of this thesis is to discuss how eParticipation is enacted and shaped, in and by practice, and thus contribute to development of practice-based conceptualisation as well as development within the differing practices of eParticipation. The study is based on interpretive case studies as well as theoretical perspectives assisting the analysis of the research field as multiple and co-related processes and relations of change and learning. The empirical data has been gathered during participation in several research and development projects, conducted within a local municipality in Southeast Sweden. Several of the projects were also part of national and international collaboration. The methodological approach comprises ethnographic studies, including interviews, participatory observations and document analysis. The approach of ethnomethodology was also inspirational for the close examining of how various actors organised their participation or non-participation in the various settings of preparing for or conducting eParticipation. The theoretical basis is multi-disciplinary, drawing on perspectives from technological and social theories, such as political science, ANT and feminist theories along with IS (information systems) research. The concept of symbolic eParticipation is coined in order to explore how the preconceived ideas of managing participation seem to be constricting and limiting local and situated development. At the same time, symbolic eParticipation is inspiring development of local interpretations and participatory work. The mutual shaping of these activities leads to the formulation of the notion malleability of organisations and citizenship. The findings indicate that activities of for instance customisation of software or evaluation of consultation tools contribute in creating socio-technical mechanisms, of which they are themselves a part. Those mechanisms embed power relations, and thus become a delegated function of opening up or closing for participation. An example of such socio-technical mechanisms is the notion of “active citizenship”, which is given higher legitimate status if it is conducted mainly as an electronically mediated activity. The term “symbolic active citizenship” is suggested as a concept which describes the legitimate active citizenship. The process of becoming active is thoroughly addressed in this thesis, including variations such as pro-activity and active passivity. These are also mediated by processes of learning in communities of practice. Active participants alternate between being active and actively passive in the processes which are supposed to constitute, form and sustain activities of eParticipation. This fluidity of citizenship has implications for future design of technology and for how to perceive participation in these activities. The interplay of symbolic eParticipation and organisational and civic malle¬ability described in this thesis, underscores the significance of providing space for negotiations of situating eParticipation.

  • 305.
    Ekelin, Annelie
    Blekinge Institute of Technology, School of Computing.
    To Be or Not to Be Active: Exploring Practices of eParticipation2006In: Electronic Government, Berlin: Springer Berlin / Heidelberg , 2006, p. 107-118Chapter in book (Other academic)
    Abstract [en]

    This chapter discusses the interplay of participation and non-participation within institutional and public practices of electronically mediated policy-making in the local public sector. The aim is to contribute to practice-based development of situated theoretical conceptualisation in the research domain. Applying a dialectical analysis, including also examples and processes of dissociation detected in ethnographic studies of actual use and design of these technologies, suggests a re-specification of the conceptual basis of eParticipation.

  • 306. Ekelin, Annelie
    Uncovering the Janus face of eParticipation: A Delayed Introduction2008Conference paper (Refereed)
    Abstract [en]

    At the same time as eParticipation is culturally pictured as a rich area for exploration, reviving great expectations of possibilities to broaden and deepen the scope and results of democratic decision-making, it must also be acknowledged as having a double function. It is also a way to initiate sociotechnical mechanisms applicable when controlling and steering mediated participation towards uniformity and normalisation, contributing to the formation of a symbolic eParticipation. This means that activities of eParticipation can function in both ways, either open up for participation or prevent participation to take place. This paper describes a local practice of tailoring of a tool for eParticipation and describes how the work practices in the municipality contribute to adjusting the development to what is considered legitimate. These choices are based on established work practices rather than innovative thinking.

  • 307. Ekelin, Annelie
    “Who makes an active citizen? Dialogue about re-configuration of roles”.2007Other (Other academic)
    Abstract [en]

    Dialogue about re-configuration of roles”. Invited speaker at the council of Europe’s symposium entitled ‘E-democracy: new opportunities for enhancing civic participation’, theme III ‘The return of the citizen : new forms of social networking’, 23-24th of April, Strasbourg

  • 308.
    Elahi, Haroon
    Blekinge Institute of Technology, School of Engineering, Department of Interaction and System Design.
    Cooperation and Integration:Do we need them in Ubiquitous Computing Design?2008Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    This thesis takes in to account mainly the cooperative design and human factors from ubiquitous computing design perspective. Areas such as role of cooperative design in ubiquitous computing perspective, the changing attributes of society and the associated issues, the changing shape of public service delivery and need for a change in methodology in ubiquitous computing projects have been discussed. The overall approach is taking advantage of Suchman’s idea of ‘design as an artful integration of different social as well as technical aspects'. The advantage of the technique has been taken by bringing together social and societal aspects, agenda of governments from IT perspective, human factors and purely designs methodology to frame up in which we need to re-assess ubiquitous computing design methodology. The thesis work comprises literature review, and a case study to pick up on the role of cooperative and participatory design. The probe was specifically in the context of ubiquitous computing design requirements and ubiquitous computing vision

  • 309. Eliasson, Charlott
    Quality of Experience and Quality of Service in the Context of an Internet-based Map Service2008Conference paper (Other academic)
    Abstract [en]

    Increasingly many work processes depend on Information and Communication Technology (ICT) services. These define the efficiency of how tasks are solved. The perceived usability of a service is heavily linked to the performance of the service, for instance the service responsiveness. Users do not like to wait; long response times (RTs) will interrupt their flow of thoughts and finally result in a loss of interest. Quality aspects, seen from the user’s point of view, have gained importance. While the rather traditional notion Quality of Service (QoS) is mostly related to technical quality parameters of the actual data transport, the more recently established notion of Quality of Experience (QoE) extends the notion of quality to include user perception and expectations. Obviously, QoE has strong subjective components and is also connected to the situation and context in which the user finds him- or herself. This work aims at finding quantitative relationships between QoE and QoS in order to provide application designers with means to adapt their application to available networks and the related conditions. We have particularly focused on a Geographical Information System (GIS) Map Service, with a web-based client-server application, used amongst others by professional users for tasks of urban planning. We have conducted user experiments to derive the relationship between user-perceived QoE, expressed qualitatively (through comments) and quantitatively (on the well-known scale from 1 = worst to 5 = best), and the response time, i.e. the time the user has to wait for the execution of a command. We have then established quantitative relationships between the response time and network problems such as losses and delays that have been generated in a controlled way using a traffic shaper between client and server.

  • 310. Eliasson, Charlott
    et al.
    Fiedler, Markus
    Dimensioning study for road user charging2008Conference paper (Refereed)
    Abstract [en]

    Road User Charging (RUC) solutions based on the concept of thin clients rely upon timely delivery of Heavy Goods Vehicles (HGV) positions towards a RUC provider, which then performs the map matching and the calculation of the road user charges. In order to avoid data loss and late delivery, a proper dimensioning of the system is required. For the Swedish case, we investigate the feasibility of legacy mobile and wireless systems (in particular GPRS, UMTS and WLAN) for both streaming and bulk transfer of positioning data, and we determine sensible combinations of sampling and reporting intervals in terms of efficient and economic reporting. We also highlight a couple of traps regarding the dimensioning, in particular of sending patterns that might cause overload at the server side of the system. It becomes obvious that mobile networks can well cope with the extra load caused by reporting HGVs, while bulk transfer in wireless hot-spots can be used as a complementary solution.

  • 311. Eliasson, Charlott
    et al.
    Zúquete, André
    An Electronic Voting System Supporting Vote Weights2006Conference paper (Refereed)
    Abstract [en]

    Purpose - This paper aims to provide a solution for allowing an arbitrary number of weights and weight values to be used in an electronic voting system. Design/methodology/approach - Robust Electronic Voting System (REVS) was chosen, a voting system designed to support internet voting processes, as the start point for studying the introduction of vote weights. Findings - The work resulted in an internet voting system supporting vote weights, based on REVS. Research limitations/implications - In the solution presented, there is still a problem regarding anonymity, for the case of a single voter with a particular weighted vote. This is a fundamental problem, since it also exists in paper-based elections. Practical implications - This version of REVS has the same properties as the original REVS, apart from the anonymity issue above. Apart from this the process of registering voters got more complicated, since now it includes an extra action for binding a weight. Originality/value - To the best of the authors' knowledge, this modified version of REVS is the first electronic voting system supporting vote weights. Another novelty of this work is the modulus sharing optimization used for the RSA key pairs of each entity.

  • 312.
    Elnourani, Mohamed
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    COGNITIVE RADIO AND GAME THEORY: OVERVIEW AND SIMULATION2008Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    This thesis aims to clearly describe the cognitive radio and its components and operations. Moreover, it aims on describing the expected outcome from the most common techniques that are proposed for use in cognitive radios. In addition, it describes the basic principles of game theory and some simple game models that can be used to analyze the efficiency of the optimization algorithms. Furthermore, it investigates the use of load balancing algorithm and genetic algorithm in optimizing the decision making operation in cognitive radios. Matlab software simulations were carried out and the results show the promising benefit of using those two algorithms along with game theory in optimizing the dynamic spectrum allocation process.

  • 313.
    Enany, Ahmed
    Blekinge Institute of Technology, School of Engineering, Department of Interaction and System Design.
    Achieving Security in Messaging and Personal Content in Symbian Phones2007Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    This thesis describes two proposed schemes that could be used to secure mobile messaging (SMS/MMS) as well as one scheme that could be used to secure mobile content. The security services we considered in securing the mobile messages are confidentiality, authentication, non-repudiation and integrity. We used Identity Based Cryptography in order to secure the mobile messaging and Blowfish algorithm to secure the mobile content. Due to some of the disadvantages imposed by the Identity Based Cryptography, we recommended using it along with the RSA algorithm. The proposed schemes were implemented in java and tested on an actual device, Nokia N70. In addition, we measured the time required by each of the algorithms we used to encrypt/decrypt a certain number of bytes. We found that the time taken by RSA and Blowfish algorithms will not be noticeable by the user. However, since the implementation of the Identity Based Cryptography we used was not meant to run on mobile devices, we encountered a noticeable delay whenever encrypting/decrypting the data using this algorithm. Securing the SMS messages will make it to be considered as one of the proposed means that could be used to conduct m-commerce. In addition, securing the MMS messages and the mobile content will increase the usability and the reliability of the mobile phones especially to the users on the move.

  • 314. Engelke, Ulrich
    Perceptual Quality Metric Design for Wireless Image and Video Communication2008Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The evolution of advanced radio transmission technologies for third generation mobile radio systems has paved the way for the delivery of mobile multimedia services. In particular, wireless image and video applications are among the most popular services offered on modern mobile devices to support communication beyond the traditional voice services. The large amount of data necessary to represent the visual content and the scarce bandwidth of the wireless channel impose new challenges for the network operator to deliver high quality image and video services. Link layer metrics have conventionally been used to monitor the received signal quality but were found to not accurately reflect the visual quality as it is perceived by the end-user. These metrics thus need to be replaced by suitable metrics that measure the overall impairments induced during image or video communication and accurately relate them to subjectively perceived quality. In this thesis, we focus on objective metrics that are able to quantify the end-to-end visual quality in wireless image and video communication. Such metrics may then be utilised to support the efficient use of link adaptation and resource management techniques and thus guarantee a certain quality of service to the user. The thesis is divided into four parts. The first part contributes an extensive survey and classification of contemporary image and video quality metrics that may be applicable in a communication context. The second part then discusses the development of the Normalised Hybrid Image Quality Metric (NHIQM) that we propose for prediction of visual quality degradations induced during wireless communication. The metric is based on a set of structural features, which are deployed to quantify artifacts that may occur in a wireless communication system and also are well aligned to characteristics of the human visual system (HVS). In the third part, three metric designs are discussed that utilise the same structural feature set as a basis for quality prediction. Incorporation of further HVS characteristics into the metric design will then improve even more the visual quality prediction performance. The design and validation of all proposed metrics is supported by subjective quality experiments that we conducted in two independent laboratories. Comparison to other state of the art visual quality metrics reveals the ability of the proposed metrics to accurately predict visual quality in a wireless communication system. The last part contributes an application of NHIQM for filter design. In particular, the filtering performance of a de-blocking de-ringing post filter for H.263 video sequences is analysed with regards to visual quality of the filtered sequence when applying appropriate filter parameter combinations.

  • 315. Engelke, Ulrich
    et al.
    Kusuma, Tubagus Maulana
    Zepernick, Hans-Jürgen
    Perceptual Quality Assessment of Wireless Video Applications2006Conference paper (Refereed)
    Abstract [en]

    The rapid evolution of wireless networks is driven by the growth of wireless packet data applications such as interactive mobile multimedia applications, wireless streaming services, and video-on-demand. The largely heterogeneous network structures, severe channel impairments, and complex traffic patterns make the wireless networks much more unpredictable compared to their wired counterparts. One of the major challenges with the roll-out of these services is therefore the design of wireless networks that fulfill the stringent quality of service requirements of wireless video applications. In this paper, the applicability of perceptual image quality metrics for real-time quality assessment of Motion JPEG2000 (MJ2) video streams over wireless channels is investigated. In particular, a reduced-reference hybrid image quality metric (HIQM) is identified as suitable for an extension to video applications. It outperforms other known metrics in terms of required overhead and prediction performance.

  • 316. Engelke, Ulrich
    et al.
    Kusuma, Tubagus Maulana
    Zepernick, Hans-Jürgen
    Caldera, Manora
    Reduced-reference metric design for objective perceptual quality assessment in wireless imaging2009In: Signal Processing-Image Communication, ISSN 0923-5965 , Vol. 24, no 7, p. 525-547Article in journal (Refereed)
    Abstract [en]

    The rapid growth of third and development of future generation mobile systems has led to an increase in the demand for image and video services. However, the hostile nature of the wireless channel makes the deployment of such services much more challenging, as in the case of a wireline system. In this context, the importance of taking care of user satisfaction with service provisioning as a whole has been recognized. The related user-oriented quality concepts cover end-to-end quality of service and subjective factors such as experiences with the service. To monitor quality and adapt system resources, performance indicators that represent service integrity have to be selected and related to objective measures that correlate well with the quality as perceived by humans. Such objective perceptual quality metrics can then be utilized to optimize quality perception associated with applications in technical systems. In this paper, we focus on the design of reduced-reference objective perceptual image quality metrics for use in wireless imaging. Specifically, the Normalized Hybrid Image Quality Metric (NHIQM) and a perceptual relevance weighted L_p-norm are designed. The main idea behind both feature-based metrics relates to the fact that the human visual system (HVS) is trained to extract structural information from the viewing area. Accordingly, NHIQM and L_p-norm are designed to account for different structural artifacts that have been observed in our distortion model of a wireless link. The extent by which individual artifacts are present in a given image is obtained by measuring related image features. The overall quality measure is then computed as a weighting sum of the features with the respective perceptual relevance weight obtained from subjective experiments. The proposed metrics differ mainly in the pooling of the features and amount of reduced-reference produced. While NHIQM performs the pooling at the transmitter of the system to produce a single value as reduced-reference, the L_p-norm requires all involved feature values from the transmitted and received image to perform the pooling on the feature differences at the receiver. In addition, non-linear mapping functions are developed that relate the metric values to predicted mean opinion scores (MOS) and account for saturations in the HVS. The evaluation of prediction performance of NHIQM and the L_p-norm reveals their excellent correlation with human perception in terms of accuracy, monotonicity, and consistency. This holds not only for the prediction performance on images taken for the training of the metrics but also for the generalization to unknown images. In addition, it is shown that the NHIQM approach and the perceptual relevance weighted L_p-norm outperform other prominent objective quality metrics in prediction performance.

  • 317. Engelke, Ulrich
    et al.
    Maeder, Anthony
    Zepernick, Hans-Jürgen
    On Confidence and Response Times of Human Observers in Subjective Image Quality Assessment2009Conference paper (Refereed)
    Abstract [en]

    Mean opinion scores obtained in subjective image quality experiments are widely accepted as measures of perceived visual quality. They have, however, a strong limitation regarding the reliability of the rated quality, since there is no explicit information as to whether the human observer experienced difficulties when judging image quality. We thus suggest that additional information about the observers confidence should be provided along with the actual quality measure. In this paper, we analyse two ways of obtaining this confidence measure; firstly as a confidence score given by the human observer and secondly as an indirect measure of the observers response time to provide the quality score. We reveal strong relationships of confidence scores and response times to the quality scores. We further propose a model to predict observer confidence based on the quality scores and response times.

  • 318. Engelke, Ulrich
    et al.
    Maeder, Anthony
    Zepernick, Hans-Jürgen
    The Effect of Spatial Distortion Distributions on Human Viewing Behaviour when Judging Image Quality2009Conference paper (Refereed)
    Abstract [en]

    In wireless communication, distortions are induced into an image through both lossy source coding and an error prone channel. The combination thereof causes complex distortion patterns in the visual content which vary strongly in their spatial distribution, some being uniformly spread and others being locally clustered. In the context of image quality, it is of interest to identify as to how the distribution of the distortions impact on the visual attention of human observers and thus on the perceived quality. For this reason, we conducted an experiment in which fifteen participants were asked to rate the quality of eighty distorted images and their corresponding reference images, while we recorded their gaze patterns using an eye tracker. The test images contained a wide range of artifact magnitudes, both locally and globally distributed, and were created using a wireless channel simulation model. We then correlate the visual gaze patterns of the human observers with local energy measures of the distortions in order to identify the effect of distortion distributions on the viewing behaviour of human observers when judging image quality. The outcomes serve to improve the prediction performance of objective image quality metrics that we previously proposed.

  • 319. Engelke, Ulrich
    et al.
    Maeder, Anthony
    Zepernick, Hans-Jürgen
    Visual Attention Modelling for Subjective Image Quality Databases2009Conference paper (Refereed)
    Abstract [en]

    The modelling of perceptual image quality metrics has experienced increased effort in recent years. In order to allow for model design, validation, and comparison, a number of subjective image quality databases has been made available to the research community. Most metrics that were designed using these databases assess the quality uniformly over the whole image, not taking into account stronger attention to salient regions of an image. In order to facilitate incorporation of visual attention (VA) into objective metric design we have conducted an eye tracking experiment. The experiment and its outcomes will be explained in detail in this paper. The actual gaze data recorded in the experiment is publicly available in order to facilitate and encourage VA modelling for image quality metrics.

  • 320. Engelke, Ulrich
    et al.
    Rossholm, Andreas
    Zepernick, Hans-Jürgen
    Lövström, Benny
    Quality Assessment of an Adaptive Filter for Artifact Reduction in Mobile Video Sequences2007Conference paper (Refereed)
    Abstract [en]

    In this paper, we examine an adaptive deblocking deringing filter for mobile video sequences in H.263 format. The considered filter has been designed with reference to the constraints of computational complexity and working memory of mobile terminals. The post filter suggested by the International Telecommunications Union (ITU) in Recommendation H.263 App. III is also included as a reference. Given that fidelity metrics such as the peak signal-to-noise ratio (PSNR) do not necessarily correlate well with video quality as experienced by the user, we consider in this paper objective quality metrics that can incorporate knowledge about the user's perception into the quality assessment. Guidelines for choosing filter parameters in relation to user-perceived video quality are obtained from the numerical results.

  • 321. Engelke, Ulrich
    et al.
    Vuong, Xuan Nguyen
    Zepernick, Hans-Jürgen
    Regional Attention to Structural Degradations for Perceptual Image Quality Metric Design2008Conference paper (Refereed)
    Abstract [en]

    In this paper, regional attention to structural degradations in images is analyzed to improve perceptual quality prediction performance of objective image quality metrics. Subjective experiments were conducted to identify regions-of-interest for a set of natural images. A region-selective metric design is then applied to four objective image quality metrics which were trained and validated with respect to quality prediction accuracy and generalization to unknown images. For this purpose, data is used from subjective quality experiments conducted at two independent laboratories. It is shown that the region-selective design is highly beneficial for the considered objective image quality metrics, in particular, prediction accuracy can be significantly increased.

  • 322. Engelke, Ulrich
    et al.
    Zepernick, Hans-Jürgen
    An Artificial Neural Network for Quality Assessment in Wireless Imaging Based on Extraction of Structural Information2007Conference paper (Refereed)
    Abstract [en]

    In digital transmission, images may undergo quality degradation due to lossy compression and error-prone channels. Efficient measurement tools are needed to quantify induced distortions and to predict their impact on perceived quality. In this paper, an artificial neural network (ANN) is proposed for perceptual image quality assessment. The quality prediction is based on structural image features such as blocking, blur, image activity, and intensity masking. Training and testing of the ANN is performed with reference to subjective experiments and the obtained mean opinion scores (MOS). It is shown that the proposed ANN is capable of predicting MOS over a wide range of image distortions. This applies to both cases, when reference information about the structure of the original image is available to the ANN but also in absence of this knowledge. The considered ANN would therefore be well suited for combination with link adaption techniques.

  • 323. Engelke, Ulrich
    et al.
    Zepernick, Hans-Jürgen
    Multiobjective Optimization of Multiple Scale Visual Quality Processing2008Conference paper (Refereed)
    Abstract [en]

    In this paper, multiobjective optimization is applied to determine the optimal feature weights for a multi-resolution image quality metric. The optimization is conducted with respect to two aims; maximization of quality prediction accuracy and generalisation ability to unknown images. A thresholding of the optimal weights is applied to further reduce computational complexity of the quality metric. A detailed discussion of the tradeoff between prediction performance and complexity with respect to the threshold is provided. The metric design and evaluation is supported using mean opinion scores from subjective quality experiments that we conducted in two independent laboratories. Comparison to other state of the art quality metrics reveals the ability of the proposed metric to accurately predict subjective image quality perception.

  • 324. Engelke, Ulrich
    et al.
    Zepernick, Hans-Jürgen
    Multi-resolution Structural Degradation Metrics for Perceptual Image Quality Assessment2007Conference paper (Refereed)
    Abstract [en]

    In this paper, a multi-resolution analysis is proposed for image quality assessment. Structural features are extracted from each level of a pyramid decomposition that accurately represents the multiple scales of processing in the human visual system. To obtain an overall quality measure the individual level metrics are accumulated over the considered pyramid levels. Two different metric design approaches are introduced and evaluated. It turns out that one of them outperforms our previous work on single-resolution image quality assessment.

  • 325.
    Engelke, Ulrich
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Zepernick, Hans-Jürgen
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    On Perceptual Quality Evaluation of Video Applications for Wireless Ad-hoc Networks2007Conference paper (Refereed)
  • 326. Engelke, Ulrich
    et al.
    Zepernick, Hans-Jürgen
    Optimal Region-of-Interest Based Visual Quality Assessment2009Conference paper (Refereed)
    Abstract [en]

    Visual content typically exhibits regions that particularly attract the viewer's attention, usually referred to as regions-of-interest (ROI). In the context of visual quality one may expect that distortions occurring in the ROI are perceived more annoyingly than distortions in the background (BG). This is especially true given that the human visual system is highly space variant in sampling visual signals. However, this phenomenon of visual attention is only seldom taken into account in visual quality metric design. In this paper, we thus provide a framework for incorporation of visual attention into the design of an objective quality metric by means of region-based segmentation of the image. To support the metric design we conducted subjective experiments to both quantify the subjective quality of a set of distorted images and also to identify ROI in a set of reference images. Multiobjective optimization is then applied to find the optimal weighting of the ROI and BG quality metrics. It is shown that the ROI based metric design allows to increase quality prediction performance of the considered metric and also of two other contemporary quality metrics.

  • 327. Engelke, Ulrich
    et al.
    Zepernick, Hans-Jürgen
    Pareto Optimal Weighting of Structural Impairments for Wireless Imaging Quality Assessment2008Conference paper (Refereed)
    Abstract [en]

    In this paper, we consider multiobjective optimization for obtaining the feature weights associated with structural image impairments and its application to wireless imaging quality assessment. The proposed framework supports optimization with respect to finding a trade-off between metric prediction accuracy and generalization to unknown images. Evaluation of optimal trade-off solutions for two representative scenarios reveal the benefits of the proposed approach. In particular, quality prediction accuracy of an objective image metric can be strongly increased and negligible features are identified that can be discarded to save computational complexity.

  • 328. Engelke, Ulrich
    et al.
    Zepernick, Hans-Jürgen
    Perceptual-based Quality Metrics for Image and Video Services: A Survey2007Conference paper (Refereed)
    Abstract [en]

    The accurate prediction of quality from an end-user perspective has received increased attention with the growing demand for compression and communication of digital image and video services over wired and wireless networks. The existing quality assessment methods and metrics have a vast reach from computational and memory efficient numerical methods to highly complex models incorporating aspects of the human visual system. It is hence crucial to classify these methods in order to find the favorable approach for an intended application. In this paper a survey and classification of contemporary image and video quality metrics is therefore presented along with the favorable quality assessment methodologies. Emphasis is given to those metrics that can be related to the quality as perceived by the end-user. As such, these perceptual-based image and video quality metrics may build a bridge between the assessment of quality as experienced by the end-user and the quality of service parameters that are usually deployed to quantify service integrity.

  • 329.
    Engelke, Ulrich
    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.
    Quality Evaluation in Wireless Imaging Using Feature-Based Objective Metrics2007Conference paper (Refereed)
    Abstract [en]

    This paper addresses the evaluation of image quality in the context of wireless systems using feature-based objective metrics. The considered metrics comprise of a weighted combination of feature values that are used to quantify the extend by which the related artifacts are present in a processed image. In view of imaging applications in mobile radio and wireless communication systems, reduced-reference objective quality metrics are investigated for quantifying user-perceived quality. The examined feature-based objective metrics provide options for controlling the processing complexity and implementation resources required for performing the quality evaluation. Furthermore, the metrics support the scaling of overhead needed for communicating the image features over the wireless link and the accuracy for predicting the image quality.

  • 330. Engelke, Ulrich
    et al.
    Zepernick, Hans-Jürgen
    Kusuma, Tubagus Maulana
    Perceptual Evaluation of Motion JPEG2000 Quality over Wireless Channels2006Conference paper (Refereed)
    Abstract [en]

    In this paper, we investigate the applicability of perceptual image quality metrics for quality assessment of Motion JPEG2000 (MJ2) video streams over wireless channels. A performance evaluation of MJ2 quality for different levels of source compression and channel coding settings is provided. This reveals insights into the characteristics and suitability of the considered perceptual quality metrics for wireless video quality assessment. In particular, a reduced-reference hybrid image quality metric (HIQM) is identified as the most favorable metric with respect to supporting real-time applications. The findings obtained from the considered scenarios may also guide the design of efficient physical layer functions for wireless video systems.

  • 331. Engelke, Ulrich
    et al.
    Zepernick, Hans-Jürgen
    Maeder, Anthony
    Visual Attention Modeling: Region-of-Interest Versus Fixation Patterns2009Conference paper (Refereed)
    Abstract [en]

    Visual attention (VA) is an integral property of the human visual system. The deployment of a VA model can be beneficial for many image and video applications, such as, compression, transmission, and quality assessment. However, the design of a VA model is highly dependent on the subjective VA data used as ground truth and the application that the model is intended for. In this paper, we discuss two ways of obtaining subjective VA data that can subsequently be used to develop VA models; selective regions-of-interest and visual fixation patterns. The feasibility of both methods will be discussed, in particular, with respect to visual quality assessment.

  • 332.
    Erdogan, Ferhat
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Implementation and Comparison of Motion Estimation Algorithms for Video Coding2005Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    In video coding, motion compensated prediction between the frames is a very efficient way for exploiting temporal correlation. Different motion estimation algorithms have been developed in order to provide efficient motion compensated prediction of scene motion between frames. In this thesis, full search, fast search, hierarchical search, sub pixel interpolation and mesh based motion estimation algorithms have been implemented. Comparisons are made both in the spatial and temporal domain, mainly in terms of Peak Signal to Noise Ratio (PSNR) and computational complexity. A video codec using lifting based wavelet transform is used for the comparisons in the temporal domain.

  • 333.
    Erdtman, Samuel
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Interaction and System Design.
    Fylling, Johan
    Blekinge Institute of Technology, School of Engineering, Department of Interaction and System Design.
    Pathfinding with Hard Constraints: Mobile Systems and Real Time Strategy Games Combined2008Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    There is an abundance of pathfinding solutions, but are any of those solutions suitable for usage in a real time strategy (RTS) game designed for mobile systems with limited processing and storage capabilities (such as the Nintendo DS, PSP, cellular phones, etc.)? The RTS domain puts great requirements on the pathfinding mechanics used in the game; in the form of de- mands on responsiveness and path optimality. Furthermore, the Nintendo DS, and its portable, distant relatives, bring hard con- straints on the processing- and memory resources available to said mechanics. This master thesis aims to find a pathfinding solution well suited to function within the above mentioned, narrow domain. From a broad selection of candidate solutions, a few promising subjects are treated to an investigative empirical study; with the goal of finding the best “fitting” solution, considering the domain. The empirical study shows that the triangle-based TRA* solution and the hierarchical-abstraction influenced Minimal Memory so- lution are both very promising candidates. Depending on how one exactly defines the domain, either one of the solutions could be considered the ‘best’ choice. Since the overall performance of TRA* showed a slight advantage, this solution was further inves- tigated by running an implementation on one of the intended domain platforms; the Nintendo DS. This paper is structured to serve as a guide, of sorts, to some very interesting, and diverse, pathfinding solutions. In the spirit of this effort, all of the more important aspects of these solu- tions, and the pathfinding domain as a whole, are thoroughly explained.

  • 334.
    Erharuyi, Edison
    Blekinge Institute of Technology, School of Engineering, Department of Systems and Software Engineering.
    Combining eXtreme Programming with ISO 9000:2000 to Improve Nigerian Software Development Processes2007Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    The aim of this research work is to study how eXtreme programming could be combined with ISO 9000:2000 standards to improve Nigerian software development processes. The combination of these models will enable organizations take advantage of models’ strengths and compensate for their weaknesses in enhancing continuous software process improvement and rapidly responding customer’s changing needs. This was achieved by adopting a model in balancing ISO and eXtreme programming in software projects. This allows organization to determine whether to choose a pure method (eXtreme programming or ISO) or mixed methods (eXtreme programming and ISO) that will be most successful in executing software projects. Also developed was another strategy in modifying eXtreme programming practices to reflect ISO 9001:2000 standard requirements.

  • 335. Eriksson, Jeanette
    Bridging the Gap between Development and Use: Support of Tailorability in Software Evolution2005Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The intention of tailorable systems is to make it possible for end users to evolve an application to better fit altered requirements and tasks, and to make the system more endurable. This thesis discusses tailorable systems in the context of a rapidly changing business environment. The objective was to determine what is necessary for a tailorable business system to continuously adapt to expanding requirements and thereby live up to the intention of the system. The thesis includes five different studies, of which one is a literature study. The other four studies were conducted in three projects; one technical project exploring the possibility to use Metaobject Protocol in tailorable systems, one project in an explorative environment concerned with physical interfaces and one project, that also embraced user participation and user evaluation, regarded the possibility for end users to manage system infrastructure. The projects began with field studies (including participant observations and interviews) and workshops with users and developers. In each project, based on the outcome, an end-user tailorable prototype was developed. The prototypes were used for evaluating possibilities and problems with tailorable systems. Taken together the evaluations revealed what was required to make a tailorable system work as intended in a rapidly changing business environment. It could be concluded that tailoring is a good way to evolve a system to meet altered needs, because people who already possess the required domain knowledge can make changes quickly. Tailoring is not however enough, because the tailoring capabilities are always limited, meaning that tailoring cannot support completely unanticipated changes. In such cases the tailoring capabilities must be extended. Since such changes are only concerned with the system itself, and not the business task, it is hard to motivate even skilled users to make these types of changes. Tailoring activities must therefore be coordinated with software evolution activities performed by professional developers. This allows the system to adapt continuously to a rapidly changing business environment and thereby live up to the intention of the system. The final conclusion is that there is a need for close collaboration between end users, tailors and developers to make tailorable information systems adaptable to rapid changes in the business environment as well as being endurable. The collaboration has to be supported in the structure of the system by providing support for the work of users, tailors and developers.

  • 336. Eriksson, Jeanette
    Supporting the Cooperative Design Process of End-User Tailoring2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In most business areas today, competition is hard and it is a matter of company survival to interpret and follow up changes within the business market. The margin between success and failure is small. Possessing suitable, sustainable information systems is an advantage when attempting to stay in the front line of the business area. In order to be and remain competitive, these information systems must be up-to-date, and adapt to changes in the business environment. Keeping business systems up-to-date in a business environment such as this one, the telecom business, that changes rapidly and continuously, is a huge challenge. One way to approach this challenge is through flexibility in systems. The power of flexibility is that it keeps the system usable and relevant and allows it to evolve. This thesis is concerned with end-user tailorable software. Tailorable software makes it possible for end users to evolve an application better to fit altered business requirements and tasks. In the view of tailorable software taken in this thesis, the users should be seen as co-designers, as they take over the design of the software when it is in use. In this work, it is important that the users are aware of the possibilities and limitations of the software. However, tailoring is not enough, because the tailoring capabilities are always limited, meaning that tailoring cannot support completely unanticipated changes. The tailoring capabilities must therefore be extended, and tailoring activities must be coordinated with software evolution activities performed by professional developers. This allows the system to adapt continuously to a rapidly changing business environment and thereby live up to the intention of the system. Studies so far have tended to look at evolution from either a user perspective or a system perspective, resulting in a gap between development and use. This thesis takes an overall stand and states that it is possible to benefit from both the user and system perspectives, through collaboration between users, tailors and developers. It is necessary for users and developers to collaborate closely in order to make tailorable information systems both durable and adaptable to rapid changes in the business environment. In this way, the development of useful, sustainable software, which adapts easily to changes in an evolving environment, can be achieved. This thesis also presents a set of tools to support collaboration on equal terms between users and developers, in the technical design process of evolving the tailorable software and extending the tailoring capabilities. The toolkit aims at building a common understanding of tailoring, supporting democratic agreements and a common understanding of what kind of tailoring to implement. It makes it possible for the users to take part in technical design decisions and have a better understanding of trade-offs and system boundaries. These are key factors for the successful future evolution of a tailorable system, as it is the users who are the designers of the software during its future use. All of the research is based on field studies including participatory observations, interviews and workshops with users and developers. These studies led to the creation of prototypes and tools that act as mediating artefacts when exploring the research questions. The contribution of the thesis is twofold. Firstly, the thesis elucidates the need for a cooperative design process to ensure that end-user tailorable software remains useful and sustainable. Secondly, the thesis suggests a toolkit with four different tools to support such a cooperative design process.

  • 337.
    Eriksson, Olle
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Systems and Software Engineering.
    Erlandsson, Emil
    Blekinge Institute of Technology, School of Engineering, Department of Systems and Software Engineering.
    Experiences from Simulating TSP Clusters in the Simics Full System Simulator2004Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    TSP (or Telecommunication Server Platform) is a scalable, high availability cluster operating system developed by Ericsson for use in the telecommunications industry. This thesis describes an attempt to simulate a TSP cluster in the full system simulator Simics, and talks about some of the possibilities offered by such a setup and full system simulation in general. This attempt to simulate TSP was unsuccessful in completely booting the cluster in Simics, but some of the experiences and problems encountered are described. A proposed development environment for working with TSP in Simics is also presented, along with scripts that were created during this thesis to alleviate the working process.

  • 338. Eriksén, Sara
    et al.
    Ekelin, Annelie
    Beyond the Buzz: Participatory, sustainable, convergent and high quality public e-services - developing methods and practices in India and Sweden2008Conference paper (Refereed)
    Abstract [en]

    Can buzzwords be methodically exploited to develop more self-reflective and participatory research methods and practices within the ICT area? Research policies as well as research funding agencies rely heavily on buzzwords, yet tend to grow uncomfortable when these are deliberately highlighted and concatenated in research applications. This paper presents a multi-disciplinary R&D project in which we are exploring emerging methods and practices of participatory design of public e-services in India and Sweden. Using buzzwords as boundary objects, comparing methods and practices, with specific e-government projects we are involved in as examples, we attempt to address blind angles inherent in different cultural and disciplinary perspectives.

  • 339.
    Eriksén, Sara
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Interaction and System Design.
    Eliasson, Charlott
    Fiedler, Markus
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Chevul, Stefan
    Blekinge Institute of Technology, School of Computing.
    Ekelin, Annelie
    Blekinge Institute of Technology, School of Engineering, Department of Interaction and System Design.
    Mapping service quality: measuring and comparing quality of experience and quality of service for Internet-based map services2007Conference paper (Refereed)
    Abstract [en]

    In this paper, we present an on-going research project in which we are focusing on examining how users of map-based services on-line experience the quality of these services when the traffic load is high, and how the users' experiences of acceptable or not acceptable quality can be related to measurable parameters which can be used to manage network traffic and improve technical solutions. The project is a multi- and interdisciplinary project in cooperation between researchers within human work science and informatics, and researchers within telecommunication systems. Additionally, there are two external partners in the project: a provider of Internet-based map services, and a municipality which uses this provider's map services regularly. One of the main methodological issues addressed in the project is how laboratory based, quantitative research methods from research on Quality of Service in the telecommunication systems area can be related to qualitative research methods focusing on workplace- or other live-world based use situations and Quality of Expereince as defined by users of the services. How can experiments and studies be designed, and results shared, such that both network traffic measuring and evaluation of user experiences retain their own paradigmatic validity and relevance, while fruitfully informing service design?

  • 340.
    Erlandsson, Fredrik
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Interaction and System Design.
    Evertsson, Daniel
    Blekinge Institute of Technology, School of Engineering, Department of Interaction and System Design.
    S-UDDI: using Web services, the Secure and Trustworthy way2005Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    SOA and especially Web services are a big evolving market these days. SOA typically uses Web services when interacting between different parts of applications. Methods to easily discover the Web services must exist. For this UDDI has been introduced. The current implementation of UDDI has a weak security model. We have developed an extension to this model, which interacts with the current solution to make it more secure. Our solution, S-UDDI, enable a way to find and publish Web services in a secure and trustworthy way.

  • 341.
    Erman, David
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    BitTorrent Traffic Measurements and Models2005Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Internet has experienced two major revolutions. The first was the emergence of the World Wide Web, which catapulted the Internet from being a scientific and academic network to becoming part of the societal infrastructure. The second revolution was the appearance of the Peer-to-Peer (P2P) applications, spear-headed by Napster. The popularity of P2P networking has lead to a dramatic increase of the volume and complexity of the traffic generated by P2P applications. P2P traffic has recently been shown to amount to almost 80% of the total traffic in a high speed IP backbone link. One of the major contributors to this massive volume of traffic is BitTorrent, a P2P replication system. Studies have shown that BitTorrent traffic more than doubled during the first quarter of 2004, and still amounts to 60% of all P2P traffic in 2005. This thesis reports on measurement, modelling and analysis of BitTorrent traffic collected at Blekinge Institute of Technology (BTH) as well as at a local ISP. An application layer measurement infrastructure for P2P measurements developed at BTH is presented. Furthermore, a dedicated fitness assessment method to avoid issues with large sample spaces is described. New results regarding BitTorrent session and message characteristics are reported and models for several important characteristics are provided. Results show that several BitTorrent metrics such as session durations and sizes exhibit heavy-tail behaviour. Additionally, previously reported results on peer reactivity to new content are corroborated.

  • 342. Erman, David
    On BitTorrent Media Distribution2008Doctoral thesis, comprehensive summary (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 have reactualised the research on multicast, with the consequence that many of the previous mechanisms and schemes are being re-evaluated. This thesis 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 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, as well as a detailed validation study of the BT simulator itself. Furthermore, we present a comprehensive set of BT models for several important traffic characteristics, at both session and message levels.

  • 343. 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.

  • 344.
    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.

  • 345. 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.

  • 346. 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.

  • 347. 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.

  • 348. 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.

  • 349. Erman, Maria
    et al.
    Mohammed, Abbas
    Rakus-Andersson, Elisabeth
    Fuzzy Logic Applications in Wireless Communications2009Conference paper (Refereed)
    Abstract [en]

    A survey of fuzzy logic applications and principles in wireless communications is presented, with the aim of highlighting successful usage of fuzzy logic techniques in applied telecommunications and signal processing. To the best of our knowledge, this is the first such study of its kind. This paper will focus firstly on discerning prevalent fuzzy logic or fuzzy-hybrid approaches in the areas of channel estimation, channel equalization and decoding, and secondly outlining what conditions and situations for which fuzzy logic techniques are most suited for these approaches. Furthermore, after insights gained from isolating fuzzy logic techniques applied to real problems, this paper proposes areas for further research targeted to practice-oriented researchers.

  • 350.
    Eskilsson, Eric
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Styrprogram till PIC-processorer för fjärrmanövrerad relämatris2008Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [en]

    Abstract The aims with this report are to document the upgrade and development of new software for the distance laboratory at Blekinge Tekniska Högskola. The work has been focused on implementing the identification number in a microcontroller, to read its data from a so called look-up table and to be able to control digital components through a serial bus (SPI). The look-up table is a list of data from which the software reads data for the different types of printed circuit boards in the hardware component of the distance laboratory is in focus. The results of the report are an implemented, upgraded version of the software and all three aims has been accomplished. Sammanfattning Syftet med detta arbete har varit att utveckla och uppgradera en ny mjukvara till distanslaboaratoriet på Blekinge Tekniska Högskola, genom att implementera adressen till en microcontroller, att läsa dess data från en så kallad look-up table, samt att kunna styra digitala komponenter med en seriell buss (SPI). Fokus i programmeringen har legat på look-up table, vilket är en datalista som mjukvaran läser funktionsdata från för de olika korttyperna i matrisen. Resultatet är en implementerad, uppgraderad version av mjukvaran och alla tre målen har gått att genomföra.

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