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  • 51.
    Mehmood, Faisal
    et al.
    Blekinge Institute of Technology, School of Engineering.
    Ejaz, Muneeb
    Blekinge Institute of Technology, School of Engineering.
    Performance Analysis of 3-hop using DAF and DF over 2-hop Relaying Protocols2013Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    In wireless Communication, the need of radio spectrum increases nowadays. But in the system we are losing approximately 82-86% of spectrum most of the time due to the absence of Primary User (PU). To overcome this issue Cognitive Radio (CR) is an admirable approach. The concept of cooperative communication needs to be considering because high data rate is the demand for wireless services. Cooperative diversity in the network realized by 3-hop Decode, Amplify and Forward (DAF) and Decode and Forward (DF) and in 2-hop DF and Amplify and Forward (AF) Protocols implemented in cognitive radio communication network using Orthogonal Space Time Block Coding (OSTBC). The communication between end points is accomplished by using Multiple Input and Multiple Output (MIMO) antenna arrangement. During the Propagation, Alamouti Space Time Block Coding is used to accomplish spatial diversity and the encoded data is transmitted through Rayleigh fading channel. CR decodes the transmitted signal using Maximum Likelihood (ML) decoding method. Afterward signal broadcast toward the destination. To check the energy level of signal, energy detection technique applies at the Cognitive Controller (CC). Finally, CC will take ultimate decision for the presence of primary user if the energy level of signal is greater than predefined threshold level, it means PU is present otherwise it is absent. The main objective of this thesis is to analyze the performance of 3-hop and 2-hop communication network using relays. The performance is compared on the bases of two parameters i.e. Bit Error Rate (BER) and Probability of Detection (PD). The results are processed and validated by MATLAB simulation.

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  • 52.
    Mohamed, Amer
    Blekinge Institute of Technology, School of Engineering, Department of Mechanical Engineering.
    Load Calculation and Simulation of an Asphalt Roller2005Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    Free body diagrams of an Asphalt Roller were designed for several load cases and used for an optimisation study. Assumptions for the load calculations for each load case were carried out in MATLAB®. The Roller was built in I-DEAS® and the results were compared with the theoretical results

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  • 53.
    Mopidevi, Vydik
    Blekinge Institute of Technology, School of Engineering.
    Video Quality Evaluation using NR metric with Detection of Frame Dips and Drops2013Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Wireless technology has become the most interesting field in the area of communications and networking. Video transmission plays a major role in this area. Data transmission via wireless communications is a major task, especially to send the data without loss of packets. The digital video decoder produces dropped or repeated frames from the encoded video due to packet loss. Brief frame drops of one frame duration are referred as dips. This research work investigates how to identify these frame dips and drops and also to measure the quality of the video which contain frame dips and frame drops. A dynamic threshold estimator is implemented to identify these frame dips. The qualitative analysis of a video is performed using a No Reference metric. In this metric the quality assessment can be achieved by identification of frame dips and drops and calculating Modified Fraction of Dropped Frames. Dips and abrupt temporal variation occurring at the end of frame freezing event of a video fluidity impairment caused by frame dropping will be taken into account using this metric. The parameters which are generated from Structural Similarity Index Metric (SSIM) analysis are efficient enough to compare the video quality and estimate the metric performance objectively. Our proposed metric has predicted the SSIM with a Pearson correlation coefficient of 0.99 in test1, 0.92 in test2 and 0.99 in test3. Therefore in terms of prediction accuracy the proposed metric has a good correlation with the deployed metric and obtained robustness to our approach.

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  • 54. Mustafa, Wail
    et al.
    Yu, Jhang Shih
    Rakus-Andersson, Elisabeth
    Mohammed, Abbas
    Kulesza, Wlodek
    Fuzzy-based Opportunistic Power Control Strategy in Cognitive Radio Networks2010Conference paper (Refereed)
    Abstract [en]

    This paper considers the spectrum sharing network consisting of a pair of primary users (PUs) and a pair of cognitive users (CRs) in a fading channel. The pair of PUs establishes a wireless link as the PU link. The pair of CRs establishes a wireless link as the CR link. The PU link and CR link utilize spectrum simultaneously with different priorities. The PU link has a higher priority to utilize spectrum with respect to the CR link. When the PU link utilizes spectrum, a desired quality of service (QoS) is given to be assured and the CR utilizes spectrum with an opportunistic power scale under this constraint, assuring the desired QoS on the PU link. To compute an optimal opportunistic power scale for the CR link, a fuzzy-based opportunistic power control strategy is proposed based on the Mamdani fuzzy control model using two input variables: the PU’s SNR and PU’s interference channel gain. By the proposed fuzzy-based power control strategy, the desired QoS could be assured on the PU link and the bit error rate (BER) is also reduced compared with the spectrum sharing network without power control strategy.

  • 55.
    Naman, Saleem Muhammad
    Blekinge Institute of Technology, School of Engineering.
    Eigen Fuzzy Sets of Fuzzy Relation with Applications2010Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Eigen fuzzy sets of fuzzy relation can be used for the estimation of highest and lowest levels of involved variables when applying max-min composition on fuzzy relations. By the greatest eigen fuzzy sets (set which can be greater anymore) maximum membership degrees of any fuzzy set can be found, with the help of least eigen fuzzy set (set which can be less anymore) minimum membership degrees of any fuzzy sets can be found as well.The lowest and highest level, impact or e ffect of anything can be found by applying eigen fuzzy set theory. The implicational aspect of this research study is medical and customer satisfaction level measurement. By applying methods of eigen fuzzy set theory the e ffectiveness of medical cure and customer satisfaction can be found with high precision.

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  • 56.
    Nilsson, Emilio
    et al.
    Blekinge Institute of Technology, School of Management.
    Kacprzak, Oscar
    Blekinge Institute of Technology, School of Management.
    Lågkonjunktur, En studie i vilka skillnader som finns för variationen i antal anställda inom IT- respektive industribranschen2009Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [sv]

    Sammanfattning Titel: Lågkonjunktur – En studie i vilka skillnader som finns för variationen i antal anställda inom IT- respektive industribranschen Författare: Emilio Nilsson, Oscar Kacprzak Handledare: Emil Numminen Institution: Blekinge Tekniska Högskola Kurs: Kandidatarbete i Företagsekonomi Syfte: Syftet med uppsatsen är att undersöka och analysera för hur företagets ekonomiska data för den relativt unga IT-sektorn förklarar antal anställda gentemot hur företagets ekonomiska data förklarar nyckeltalet för en äldre mer erfaren bransch som industrisektorn. Metod: Vi har samlat ihop kvartalsrapporter från 1999 års första kvartal till 2009 års första kvartal för totalt 10 stycken företag som vi bedömt lämpliga för studien, 5 företag från IT-branschen samt 5 företag från industribranschen. Vi har därefter fört regressionsanalyser med antal anställda som Y-variabel och totala intäkter, aktienivå, rörelsekostnader samt rörelseresultat som X-variabler för att finna korrelationen däremellan. Slutsats: De framkomna resultaten från regressionsanalyserna pekar på att det finns skillnader branscherna emellan. Dessa var mest påtagliga i variablerna totala intäkter och rörelsekostnader. För båda variablerna hade industriföretagen större korrelation med Y-variabeln än vad IT-företagen hade. Korrelationen mellan antal anställda och rörelseresultatet kunde vi inte urskilja några tendenser branscherna emellan. Aktienivån hade en något större korrelation i variationen av antalet anställda för industriföretagen än för IT-företagen, där korrelationen var låg rakt igenom. Abstract Title: Recession - A study of the differences that exist for the variation in the number of employees in the IT and industrial sector Author: Emilio Nilsson, Oscar Kacprzak Supervisor: Emil Numminen Institution: Blekinge Institute of Technology Course: Bachelor thesis in Economics Purpose: The aim of the paper is to examine and analyze how a company's financial data for the relatively young IT sector explains the number of employees compared to how the financial data explains it for an older more experienced branch like the industry sector. Method: We have collected quarterly reports from the first quarter of 1999 to the first quarter of 2009 for a total of 10 different companies that we determined appropriate for the study, 5 companies from the IT sector and 5 companies from the industrial sector. We have subsequently conducted a regression analysis with number of employees as the Y-variable and total income, stock level, operating expenses and operating income as the X-variables to find the correlation between them. Conclusion: The results of the regression analysis indicate that there are differences between the industries. These were most visible in the variables of total income and operating expenses. For both variables, the industrial companies’ had a greater correlation with the Y-variable than IT companies had. In the correlation between the number of employees and operating profit, we could not find any differences between the sectors. Stock levels had a slightly higher correlation in the variance of the number of employees for manufacturing companies than for the IT companies, where the correlation was low right through.

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  • 57.
    Nilsson, Mikael
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    First Order Hidden Markov Model: Theory and Implementation Issues2005Report (Refereed)
    Abstract [en]

    This report explains the theory of Hidden Markov Models (HMMs). The emphasis is on the theory aspects in conjunction with the implementation issues that are encountered in a floating point processor. The main theory and implementation issues are based on the use of a Gaussian Mixture Model (GMM) as the state density in the HMM, and a Continuous Density Hidden Markov Model (CDHMM) is assumed. Suggestions and advice related to the implementation are given for a typical pattern recognition task.

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  • 58.
    Olayanju, Iyeyinka Damilola
    et al.
    Blekinge Institute of Technology, School of Engineering.
    Ojelabi, Olabode Paul
    Blekinge Institute of Technology, School of Engineering.
    Using Multilateration and Extended Kalman Filter for Localization of RFID Passive Tag in NLOS2010Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    The use of ubiquitous network has made real time tracking of objects, animals and human beings easy through the use of radio frequency identification system (RFID). Localization techniques in RFID rely on accurate estimation of the read range between the reader and the tags. The tags consist of a small chip and a printed antenna which receives from and transmits information to the reader. The range information about the distance between the tag and the reader is obtained from the received signal strength indication (RSSI). Accuracy of the read range using RSSI can be very complicated especially in complicated propagation environment due to the nature and features of the environment. There are different kinds of localisation systems and they are Global Positioning System (GPS) which can be used for accurate outdoor localization; while technologies like artificial vision, ultrasonic signals, infrared and radio frequency signals can be employed for indoor localization. This project focuses on the location estimation in RFID Non Line-of-Sight (NLOS) environment using Real Time Localization System (RTLS) with passive tags, in carrying out passengers and baggage tracking at the airport. Indoor location radio sensing suffers from reflection, refraction and diffractions due to the nature of the environment. This unfavourable phenomenon called multipath leads to delay in the arrival of signal and the strength of signal received by receiving antenna within the propagation channel which in turns affects the RSSI, yielding inaccurate location estimation. RTLS based on time difference of arrival and error compensation technique and extended Kalman filter technique were employed in a NLOS environment to determine the location of tag. The better method for location estimation in a NLOS between the Kalman filtering and extended Kalman filtering is investigated. According to simulation results, the extended Kalman filtering technique is more suitable to be applied to RTLS.

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  • 59.
    Pesämaa, Ossi
    et al.
    Blekinge Institute of Technology, School of Management.
    Shoham, Aviv
    Wincent, Joakim
    Ruvio, Ayalla
    How a learning orientation affects drivers of innovativeness and performance in service delivery2013In: Journal of engineering and technology management, ISSN 0923-4748, E-ISSN 1879-1719, Vol. 30, no 2, p. 169-187Article in journal (Refereed)
    Abstract [en]

    Relying on organizational innovativeness for long-term growth and profitability can be difficult, time consuming, and expensive. In the context of service delivery of 395 strategic business units (SBU) in Israel's healthcare industry, this paper examines the role of a learning-orientation as a moderator in an integrative model of organizational innovativeness. We find moderation of the impacts of risk-taking, creativity, competitor benchmarking orientation, and environmental opportunities on innovativeness. Moreover, we find the influence on performance pronounced for high learning-oriented SBUs. The paper shows that learning orientation should be considered for understanding effective innovativeness work for competitive service delivery.

  • 60.
    Quoreshi, Shahiduzzaman
    Blekinge Institute of Technology, Faculty of Engineering, Department of Industrial Economics.
    A long-memory integer-valued time series model, INARFIMA, for financial application2014In: Quantitative Finance, ISSN 1469-7688, Vol. 14, no 12, p. 2225-2235Article in journal (Refereed)
    Abstract [en]

    A model to account for the long-memory property in a count data framework is proposed and applied to high-frequency stock transactions data. By combining features of the INARMA and ARFIMA models, an Integer-valued Auto Regressive Fractionally Integrated Moving Average (INARFIMA) model is proposed. The unconditional and conditional first- and second-order moments are given. The CLS, FGLS and GMM estimators are discussed. In its empirical application to two stock series for AstraZeneca and Ericsson B, we find that both series have a fractional integration property.

  • 61.
    Quoreshi, Shahiduzzaman
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Industrial Economics. Blekinge Tekniska Högskola.
    Mamode Khan, Naushad
    University of Mauritius, MUS.
    Uddin, Reaz
    Blekinge Institute of Technology, Faculty of Engineering, Department of Industrial Economics.
    A Review of INMA Integer-valued Model Class, Application and Further Development2019In: FILOMATArticle in journal (Refereed)
    Abstract [en]

    In this paper, we review INMA time series of integer-valued model class, and discuss its further development. These models have been developed for analyzing high frequency financial count data. A vivid description of high frequency data in the context of market micro structure is given. The most distinguishing feature that makes the INMA model class different from its continuous variable MA counterpart is that multiplication of variables with real valued parameters no longer remains a viable operation when the result is to be integer-valued. In the estimation of these models, no underlying distributions are assumed. Hence, the discussion of estimations are limited to CL, FGLS and GMM. A further development of estimation procedures for these models have also been reviewed. We suggest that the models could be estimated with Quasi Maximum Likelihood and propose in addition a Generalized Method of Moment of Quasi Maximum Likelihood. We have also discussed how INMA model class can be extended with different underlying distributions for innovations.

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  • 62.
    Quoreshi, Shahiduzzaman
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Industrial Economics. Blekinge Tekniska Högskola.
    Uddin, Reaz
    Blekinge Institute of Technology, Faculty of Engineering, Department of Industrial Economics.
    Mamode Khan, Naushad
    University of Mauritius, MUS.
    Quasi-Maximum Likelihood Estimation for Long Memory Stock Transaction Data—Under Conditional Heteroskedasticity Framework2019In: Journal of Risk and Financial Management, Vol. 12, no 2, article id 74Article in journal (Refereed)
    Abstract [en]

    This paper introduces Quasi-Maximum Likelihood Estimation for Long Memory Stock Transaction Data of unknown underlying distribution. The moments with conditional heteroscedasticity have been discussed. In a Monte Carlo experiment, it was found that the QML estimator performs as well as CLS and FGLS in terms of eliminating serial correlations, but the estimator can be sensitive to start value. Hence, two-stage QML has been suggested. In empirical estimation on two stock transaction data for Ericsson and AstraZeneca, the 2SQML turns out relatively more efficient than CLS and FGLS. The empirical results suggest that both of the series have long memory properties that imply that the impact of macroeconomic news or rumors in one point of time has a persistence impact on future transactions.

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  • 63. Rakus-Andersson, Elisabeth
    Continuous Fuzzy Sets as Probabilities of Continuous Fuzzy Events2010Conference paper (Refereed)
    Abstract [en]

    In the first part of this study we explore continuous fuzzy numbers in the interval- and the alpha-cut forms to detect their similar nature. The conversion from one form to the other is a question of using the appropriate apparatus, which we also provide. Since the fuzzy numbers can reproduce fuzzy events we then will make a trial of extending the concept of fuzzy probability, defined by R. Yager for discrete fuzzy events, on continuous fuzzy events. In order to fulfill the task we utilize conclusions made about fuzzy numbers to propose an initial conception of approximating the Gauss curve by a particularly designed function originated from the pi-class functions. Due to the procedure of the approximation, characterized by an irrelevant cumulative error, we expand fuzzy probabilities of continuous fuzzy events in the form of continuous fuzzy sets. Furthermore, we assume that this sort of probability holds some conditions formulated for probabilities of discrete fuzzy events.

  • 64. Rakus-Andersson, Elisabeth
    Factor Analysis with Qualitative Factors and Yager’s Probability in the Lattice of Verbal Fuzzy Numbers2005In: Issues in Soft Computing Theory and Applications / [ed] P., Grzegorzewski; M., Krawczak; S., Zadrozny, Warsaw: EXIT - the Publishing House of Polish Academy of Sciences , 2005, p. 241-260Chapter in book (Other academic)
    Abstract [en]

    The classical crisp version of Factor Analysis seldom is used in the case of qualitative factors, which often are presented by codes. It is rather difficult to divide codes in level groups without possessing appropriate criteria. To omit this obstacle, we thus propose a fuzzy application of Factor Analysis, which gives a possibility to investigate the strength of an influence of qualitative factors on a tested qualitative variable. When making a new approach to the analysis of factors, we introduce a space of verbal fuzzy numbers that first are expressed as descriptions coming from a natural language and then designed in L-R form. Since the definition of newly created verbal fuzzy numbers deviates from the general conception of fuzzy numbers, we also will check effects of other operations performed on verbal numbers, which are different from the arithmetic based on the extension principle. The verbal fuzzy numbers represent both the qualitative variable and the qualitative factors in all computations that follow the Factor Analysis algorithm. For the first time we also formulate the Yager probability of an event expanded as the verbal fuzzy number.

  • 65. Rakus-Andersson, Elisabeth
    The fuzzy development and adaptation of statistical and numerical methods to applications to technical and medical models with imprecise data2002Other (Other academic)
    Abstract [en]

    All the solutions to the problems sketched below will be created on the basis of Fuzzy Set Theory. Fuzzy Set Theory is applied instead of the classical set theory when data involved in the problem to solve is imprecise, verbally described or cannot be measured exactly. The models, which are the contents of the project should contain some proposed solutions to such problems as: 1) the approximation of the mean value and the standard deviation for some imprecise data, 2) a probability distribution filled with fuzzy probability sets (Yager’s probabilities) that replace the probability values from the normal distribution, 3) the application of the last distribution to statistical tests with imprecise data, 4) the development of Factor Analysis for qualitative variables and factors provided that the data is collected by means of a questionnaire, 5) the interpolation of a set of points with imprecise coordinates by a fuzzy function.

  • 66. Rakus-Andersson, Elisabeth
    The verbal space of fuzzy numbers in the fuzzy development and adaptation of statistical and numerical methods2003Other (Other academic)
    Abstract [en]

    This project is a continuation of the last one from 2002 with the supplement, which introduces the space of verbally defined fuzzy numbers in the L-R form. The space has its total order, and the numbers in it have borders from the interval [0, 1]. This gives a possibility of testing the fuzzy norms as the operations on fuzzy numbers from the space. The models discussed earlier can now be solved again by using this new technique.

  • 67.
    Rakus-Andersson, Elisabeth
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Frey, Janusz
    Örebro University Hospital, Department of Urology.
    Similarity coefficients of normal distributions in selecting the optimal treatments2016In: Proccedings of the International e-HEALTH Conference 2016. Part of Proceedings of the Multi-Conference of Computer Science and Information Systems 2016 / [ed] Mario Macedo, IADIS Press, 2016, p. 115-122, article id 13Conference paper (Refereed)
    Abstract [en]

    In the current research, we aim to define a new form of the similarity coefficient to compare the resemblance grade of two Gaussian density functions. We aim to assess the method utility on a theoretical model. The density functions are stated for a biological marker “survival length”, observed in three groups of patients, suffering from a hypothetical disease. The first group consists of patients who are not treated, whereas we recommend 2 possible treatment methods for the second and the third group, respectively. All the “survival length” assumptions of the model (mean values and standard deviations) are made to exclude the equivocal conclusion, regarding a selection of the better treatment. At the first stage, we apply the measure of similarity to populations: survival among untreated patients contra survival among patients after Treatment 1. Another similarity coefficient estimates a relation between populations: survival among untreated patients versus survival among patients after Treatment 2. The lower value of the coefficient points out the more effective treatment. In order to simplify calculations, proposed in the definition of a similarity coefficient, we approximate the Gaussian curve by a specially designed polynomial, known as the p-function.

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  • 68.
    Rakus-Andersson, Elisabeth
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Science.
    Jogréus, Claes
    Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Science.
    The Choquet and Sugeno Integrals as Measures of Total Effectiveness of Medicines2007Conference paper (Refereed)
    Abstract [en]

    The concepts of the Choquet and Sugeno integrals, based on a fuzzy measure, can be adopted as useful tools in estimation of the total effectiveness of a drug when appreciating its positive influence on a collection of symptoms typical of a considered diagnosis. The expected effectiveness of the medicine is evaluated by a physician as a verbal expression for each distinct symptom. By converting the words at first to fuzzy sets and then numbers we can regard the effectiveness structures as measures in the Choquet and Sugeno problem formu-lations. After comparing the quantities of total effectiveness among medicines, expressed as the values of the Choquet or Sugeno integrals, we accomplish the selection of the most efficacious drug.

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  • 69.
    Rao, Peddi Srinivas
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Applied Signal Processing.
    Sreelatha, Vallabhaneni
    Blekinge Institute of Technology, Faculty of Engineering, Department of Applied Signal Processing.
    Implementation and Evaluation of Spectral Subtraction with Minimum Statistics using WOLA and FFT Modulated Filter Banks2014Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    In communication system environment speech signal is corrupted due to presence of additive acoustic noise, so with this distortion the effective communication is degraded in terms of the quality and intelligibility of speech. Now present research is going how effectively acoustic noise can be eliminated without affecting the original speech quality, this tends to be our challenging in this current research thesis work. Here this work proposes multi-tiered detection method that is based on time-frequency analysis (i.e. filter banks concept) of the noisy speech signals, by using standard speech enhancement method based on the proven spectral subtraction, for single channel speech data and for a wide range of noise types at various noise levels. There were various variants have been introduced to standard spectral subtraction proposed by S.F.Boll. In this thesis we designed and implemented a novel approach of Spectral Subtraction based on Minimum Statistics [MinSSS]. This means that the power spectrum of the non-stationary noise signal is estimated by finding the minimum values of a smoothed power spectrum of the noisy speech signal and thus circumvents the speech activity detection problem. This approach is also capable of dealing with non-stationary noise signals. In order to analyze the system in time frequency domain, we have implemented two different filter bank approaches such as Weighted OverLap Added (WOLA) and Fast Fourier Transform Modulated (FFTMod). The proposed systems were implemented and evaluated offline using simulation tool Matlab and then validated their performances based on the objective quality measures such as Signal to Noise Ratio Improvement (SNRI) and Perceptual Evaluation Speech Quality (PESQ) measure. The systems were tested with a pure speech combination of male and female sampled at 8 kHz, these signals were corrupted with various kinds of noises at different noise power levels. The MinSSS algorithm implemented using FFTMod filter bank approach outperforms when compared the WOLA filter bank approach.

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  • 70.
    Rehman, Atti Ur
    et al.
    Blekinge Institute of Technology, School of Engineering.
    Asif, Muhammad
    Blekinge Institute of Technology, School of Engineering.
    Spectrum Sensing Techniques for 2-hop Cooperative Cognitive Radio Networks: Comparative Analysis2012Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Spectrum sensing is an important aspect of cognitive radio systems. In order to efficiently utilize the spectrum, the role of spectrum sensing is essential in cognitive radio networks. The transmitter detection based techniques: energy detection, cyclostationary feature detection, and matched filter detection, is most commonly used for the spectrum sensing. The Energy detection technique is implemented in the 2-hop cooperative cognitive radio network in which Orthogonal Space Time Block Coding (OSTBC) is applied with the Decode and Forward (DF) protocol at the cognitive relays. The Energy detection technique is simplest and gives good results at the higher Signal to Noise Ratio (SNR) values. However, at the low SNR values its performance degrades. Moreover, each transmitter detection technique has a SNR threshold, below which it fails to work robustly. This thesis aims to find the most reliable and accurate spectrum sensing technique in the 2-hop cooperative cognitive radio network. Using Matlab simulations, a comparative analysis of three transmitter detection techniques has been made in terms of higher probability of detection. In order to remove the shortcomings faced by all the three techniques, the Fuzzy-combined logic sensing approach is also implemented and compared with transmitter detection techniques.

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  • 71.
    R-Smith, Nawfal Al-Zubaidi
    et al.
    Blekinge Institute of Technology, School of Engineering.
    Humood, Khaled
    Blekinge Institute of Technology, School of Engineering.
    An Effecient Scheme in IEEE 802.22 WRAN for Real Time and Non Real Time Traffic Delay2013Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Cognitive radio network has emerged as a prevailing technique and an exciting and promising technology which has the potential of dealing with the inflexible prerequisites and the inadequacy of the radio spectrum usage. In cognitive radios, in-band sensing is fundamental for the protection of the licensed spectrum users, enabling secondary users to vacate channels immediately upon detection of primary users. This channel sensing scheme directly affects the quality-of-service of cognitive radio user and licensed user especially with the undesirable delay induced into the system. In this thesis, a combination of different delay reduction schemes from different papers has been introduced, the first paper [47] argues about performing fine sensing for non-real time traffic, while real time traffic continues transmission in the channel. The second paper [46] argues about performing fine sensing after multiple alarms that have been triggered. Both schemes have combined with applying data rate reservation as well in order to reduce as much as possible this crucial factor of delay for IEEE 802.22 wireless regional area network and to improve the channel utilization. Data rate reservation for real time users has been applied in order to reduce the queuing delay for real time services [47]. The average packet delay for the proposed scheme combination has been analyzed, with both numerical and simulation results. The results show that the scheme combination considerably reduces the average packet delay for both real time and non-real time services and hence satisfies the performance of IEEE 802.22 wireless regional networks. Index terms–Channel sensing, Cognitive radio, energy and feature detection, IEEE 802.22, quiet period.

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  • 72.
    sajiduet84@gmail.com, Sajid Mahmood /
    et al.
    Blekinge Institute of Technology, School of Engineering.
    mujeeb.abdullah@gmail.com, Mujeeb Abdullah /
    Blekinge Institute of Technology, School of Engineering.
    Priority Queuing Based Spectrum sensing Methodology in Cognitive Radio Network2011Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Radio spectrum is becoming scarce resource due to increase in the usage of wireless communication devices. However studies have revealed that most of the allotted spectrum is not used effectively. Given the demand for more bandwidth and the amount of underutilized spectrum, DSA (Dynamic Spectrum Access) networks employing cognitive radios are a solution that can revolutionize the telecommunications industry, significantly changing the way we use spectrum resources, and design wireless systems and services. Cognitive radio has improve the spectral efficiency of licensed radio frequency bands by accessing unused part of the band opportunistically without interfering with a license primary user PU. In this thesis we investigate the effects on the quality of service (QoS) performance of spectrum management techniques for the connection-based channel usage behavior for Secondary user (SU). This study also consider other factors such as spectrum sensing time, spectrum handoff and generally distributed service time and channel contention for different SUs. The preemptive resume priority M/G/1 queuing theory is used to characterize the above mentioned effects. The proposed structure of the model can integrate various system parameters such spectrum sensing, spectrum decision, spectrum sharing and spectrum handoff.

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  • 73. Schenkman, Bo
    Notes on Attitudes to Statistics among Swedish Psychology and Education Science Students: The Effects of Self-perception and Anxiety2010Conference paper (Other academic)
    Abstract [en]

    A number of studies have pointed out the resistance to statistics courses and the anxiety it induces among social science students. The attitudes to statistics among psychology and education science students in a new university in Sweden were studied. Seven students were from a higher level course eight were from a course at a second year level. The students were asked voluntarily to respond to a questionnaire. The higher level students were given the questionnaire both before and after the course and they were also interviewed for about one hour each. Although all students experienced anxiety about statistics, some of them had become more positive to statistics after the course. This shows that feelings of interest and anxiety can exist at the same time. The anxiety might often be a result of low self perception of one’s own mathematical abilities. This self-perception must be made more positive. Teaching statistics at the same time to both distance and campus students is not to be recommended. The students expressed a wish for a more continuous teaching of statistics, repetitions, more practical examples and practice in using statistical packages.

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  • 74.
    Shahzad, Hamid
    et al.
    Blekinge Institute of Technology, School of Engineering.
    Botchu, Jaishankar
    Blekinge Institute of Technology, School of Engineering.
    Applying OSTBC in Cooperative Cognitive Radio Networks2010Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    In this report, we introduce cooperative spectrum sensing using orthogonal space time block coding (OSTBC) in order to achieve cooperative diversity in the cognitive radios (CRs) network. Transmit diversity or gain is achieved by introducing more than one antenna on the transmitter and receiver side, but in small electronic mobile devices it looks impractical. The signals received from the primary users (PUs) are amplified by the cognitive relays and further forwarded to the cognitive controller where decisions are made on the basis of the information collected from each cognitive relay. The cooperative relaying protocol used here in cognitive relays is based on an amplifying-forward (AF) scheme. Alamouti scheme in OSTBC has been proposed to achieve better detection performance in CR network. The energy detector performance is analyzed over an independent Rayleigh fading channel. In CR network the secondary user (SU) shares PU's frequency band if it fi nds PU is not in its vicinity. The SU starts using the licensed band and leaves the band as soon as it finds the PU is present or going to use the same band. The detection of the spectrum holes by CRs has to be more agile and intelligent. The main objective of the CRs network is to use the free holes without causing any interference to the PUs. The energy detection technique is simple and outperforms other sensing techniques in cooperative cognitive radio networks. The energy detector collects information from different users, compares it with a certain prede fined threshold () value and then makes a fi nal decision. Detection and false alarm probabilities are derived and manipulated using OSTBC on PU and SU through AF protocol in cooperative communication. The performance of the system is analyzed with single and multiple relays and with and without direct path between the PUs and SUs. Maximum ratio (MRC) and selection combining (SC) schemes are used in energy detector and the results are compared with and without direct link between PU and SU. The analysis is performed by placing the relay close to the PUs. Our results are processed and validated by computer simulation.

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  • 75. Shoham, Aviv
    et al.
    Pesämaa, Ossi
    Blekinge Institute of Technology, School of Management.
    Gadget Loving: A Test of an Integrative Model2013In: Psychology & Marketing, ISSN 0742-6046, E-ISSN 1520-6793, Vol. 30, no 3, p. 29-40Article in journal (Refereed)
    Abstract [en]

    Following the seminal work of Bruner and Kumar (2007) on gadget loving, this paper views gadget loving as the attachment individuals have toward advanced electronic items and how such an attachment relates to actual use (i.e., actual gadgets ownership). It extends existing research in two important ways. First, it provides a retest of the reliability and validity of the gadget-loving scale in two new countries (Israel and Sweden), thus adding to the generalizability of the scale across cultures. Second, it develops and tests an integrative model that includes gadget loving as a central construct as well as several antecedents and consequences proposed as important topics for future research in the extant literature. The results show that inherent novelty seeking, technological innovativeness, and technical curiosity predict the gadget-loving trait, which in turn affects technological opinion leadership and gadget ownership. These findings have theoretical and practical implications.

  • 76.
    Siddique, Muhammad
    Blekinge Institute of Technology, School of Engineering.
    Fuzzy decision making using max-min and MMR methods2009Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Fuzzy logic is based on the theory of fuzzy sets, where an object’s membership of a set is gradual rather than just member or not a member. Fuzzy logic uses the whole interval of real numbers between zero (False) and one (True) to develop a logic as a basis for rules of inference. Particularly the fuzzified version of the modus ponens rule of inference enables computers to make decisions using fuzzy reasoning rather than exact. We study decision making problem under uncertainty. we analyze Max-Min method and Minimization of regret method originally developed by Savage and further developed by Yager. We generalize The MMR method by creating the parameterized family of minimum regret methods by using the ordered weighted averaging OWA operators.

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  • 77.
    Silase, Geletu Biruk
    Blekinge Institute of Technology, School of Engineering.
    Modeling the Behavior of an Electronically Switchable Directional Antenna for Wireless Sensor Networks2011Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Reducing power consumption is among the top concerns in Wireless Sensor Networks, as the lifetime of a Wireless Sensor Network depends on its power consumption. Directional antennas help achieve this goal contrary to the commonly used omnidirectional antennas that radiate electromagnetic power equally in all directions, by concentrating the radiated electromagnetic power only in particular directions. This enables increased communication range at no additional energy cost and reduces contention on the wireless medium. The SPIDA (SICS Parasitic Interference Directional Antenna) prototype is one of the few real-world prototypes of electronically switchable directional antennas for Wireless Sensor Networks. However, building several prototypes of SPIDA and conducting real-world experiments using them may be expensive and impractical. Modeling SPIDA based on real-world experiments avoids the expenses incurred by enabling simulation of large networks equipped with SPIDA. Such a model would then allow researchers to develop new algorithms and protocols that take advantage of the provided directional communication on existing Wireless Sensor Network simulators. In this thesis, a model of SPIDA for Wireless Sensor Networks is built based on thoroughly designed real-world experiments. The thesis builds a probabilistic model that accounts for variations in measurements, imperfections in the prototype construction, and fluctuations in experimental settings that affect the values of the measured metrics. The model can be integrated into existing Wireless Sensor Network simulators to foster the research of new algorithms and protocols that take advantage of directional communication. The model returns the values of signal strength and packet reception rate from a node equipped with SPIDA at a certain point in space given the two-dimensional distance coordinates of the point and the configuration of SPIDA as inputs.

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  • 78.
    Taghavianfar, Mohsen
    Blekinge Institute of Technology, School of Engineering.
    An Investigation on Network Entropy-Gossiping Protocol and Anti-entropy Evaluation2013Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    This thesis is concerned with studying the behavior of a gossiping protocol in the specific sense meant by Ericsson; in the following pages I’ll introduce a Markov process which models the spread of information in such systems. The results will be verified by means of a discreet-event simulation.

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  • 79.
    Tahseen, Muhammad Mustafa
    et al.
    Blekinge Institute of Technology, School of Engineering.
    Khan, MatiUllah
    Blekinge Institute of Technology, School of Engineering.
    Ullah, Farhan
    Blekinge Institute of Technology, School of Engineering.
    Analysis of OSTBC in Cooperative Cognitive Radio Networks using 2-hop DF Relaying Protocol2011Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    To achieve cooperative diversity in cognitive radio network, Decode and Forward (DF) protocol is implemented at Cognitive Radios (CRs) using Orthogonal Space Time Block Coding (OSTBC). The 2-hop communication between source and destination is completed with the help of Cognitive Relays (CRs) using Multiple Input Multiple Output (MIMO) technology within the network. To achieve spatial diversity and good code rate Alamouti 2×2 STBC is used for transmission. CR is using the decoding (Decode and Forward (DF)) strategy and without amplifying ability before forwarding data towards destination provide better performance. The main objective of this thesis is to detect Primary User (PU) spectrum availability or non-availability for the use of Secondary Users (SU). The Alamouti STBC encoded data is broadcasted to wireless Rayleigh faded channel through transmitter having two transmitting antennas. The CRs are preferred to place close with PU to detect transmitted signal and because of having decoding capability CRs decode the collected data using Maximum Likelihood (ML) decoding technique then re-encode the decoded data for further transmission towards receiver. The energy of PU signal received at relays is calculated using energy detector used at cognitive controller having authority to make final decision about presence or absence of PU signal within the spectrum by comparing calculated energy of PU received signal with a predefined value. If the calculated signal energy is less than threshold value it is pretended as the absence of PU and in the other case spectrum is assumed as occupied by PU. Decoding PU signal at relays before forwarding towards destination provide better performance in terms of detection probability and decreasing probability of false alarming as the Signal to Noise (SNR) increases. The proposed cooperative spectrum sensing using DF protocol at cognitive relays with Alamouti STBC is implemented and results are validated by MATLAB simulation.

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  • 80. Torkar, Richard
    et al.
    Awan, Nasir Majeed
    Alvi, Adnan Khadem
    Afzal, Wasif
    Predicting Software Test Effort in Iterative Development Using a Dynamic Bayesian Network2010Conference paper (Refereed)
    Abstract [en]

    Projects following iterative software development methodologies must still be managed in a way as to maximize quality and minimize costs. However, there are indications that predicting test effort in iterative development is challenging and currently there seem to be no models for test effort prediction. This paper introduces and validates a dynamic Bayesian network for predicting test effort in iterative software devel- opment. The proposed model is validated by the use of data from two industrial projects. The accuracy of the results has been verified through different prediction accuracy measurements and statistical tests. The results from the validation confirm that the model has the ability to predict test effort in iterative projects accurately.

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  • 81. Wohlin, Claes
    A New Index for the Citation Curve of Researchers2009In: Scientometrics, ISSN 0138-9130 , Vol. 81, no 2, p. 521-533Article in journal (Refereed)
    Abstract [en]

    Internet has made it possible to move towards researcher and article impact instead of solely focusing on journal impact. To support citation measurement, several indexes have been proposed, including the h–index. The h–index provides a point estimate. To address this, a new index is proposed that takes the citation curve of a researcher into account. This article introduces the index, illustrates its use and compares it to rankings based on the h–index as well as rankings based on publications. It is concluded that the new index provides an added value, since it balances citations and publications through the citation curve.

  • 82.
    Yao, Yong
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Popescu, Alexandru
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Popescu, Adrian
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    On prioritised opportunistic spectrum access in cognitive radio cellular networks2015In: European transactions on telecommunications, ISSN 1124-318X, E-ISSN 2161-3915, Vol. 27, no 2, p. 294-310Article in journal (Refereed)
    Abstract [en]

    Cognitive radio (CR) networks allow secondary users (SUs) to opportunistically access licensed spectrum, thus providing efficient use of radio resources. Different studies carried out on CR networks have focused on the procedure of spectrum handoff of SUs such as the data transmission in a communication that can be carried out in different channels. In this paper, we consider cellular networks enhanced with facilities for CR communication where a user with a call in progress moves across neighbouring cells, that is, the so-called inter-cell handoff. Our model assumes that the cell gives priority to inter-cell handoff calls over the calls originating within it. A finite queue is used in every cell for SUs, and a fixed number of buffer slots are reserved for the inter-handoff SU calls. With these considerations, we study the transmission performance of SUs by using Markov chains-based modelling approach. The numerical analysis is validated by simulation experiments. We also suggest a fuzzy logic-based hybrid decision-making algorithm to select the best solution for inter-handoff prioritisation. The goal is to optimise the transmission performance of SUs by leveraging their requirements on service completion throughput and waiting time in each cell. Copyright © 2014 John Wiley & Sons, Ltd.

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