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  • 151. Arvidsson, Åke
    Strategies for Dynamic Network Management1993Conference paper (Refereed)
    Abstract [en]

    We study management of transport networks based on virtual paths, i.e. rearrangable end-to-end transport network \highways". Among its main advantages are found cost savings, network op- eration simplification and enhanced network management capabilities. Virtual paths networks are readily implemented in any network using the synchronous digital hierarchy and/or the asyn- chronous transfer mode. Algorithms for virtual path designs are reviewed and found to have a few shortcomings. A new algorithm is therefore proposed and it is found to compare favourably with the algorithm providing the most similar features. Applying the proposed algorithm to a large number of networks, we discuss operational con- siderations associated with reconfigurable networks and investigate simple traffic estimation pro- cedures and their performance in this context. Finally, the choice of reconfiguration parameters such as updating frequency, and the impact of network design time are examined.

  • 152. Arvidsson, Åke
    Traffic Management in ATM Networks: A Proposal for Imperfect Traffic Information1995Conference paper (Refereed)
    Abstract [en]

    Traffic in ATM networks can be described by numerous parameters. On a per session basis, one may use peak rate, average rate, sustainable rate, average burst duration, average silence duration, and others. In a longer time scale, parameters like the average and peakedness of connection request arrivals, the average and variance of session holding times, and so on are proposed. Theoretically, users should provide the former parameters and network operators the latter. In reality, however, few users can be expected to provide all sorts of statistical information about their traffic in advance, and operators do not have enough experience to prepare traffic forecasts for new services and applications. Moreover, even if the information could be provided, the lack of simple yet valid traffic models for ATM networks means that it is far from clear how it should be used. Realising that ATM networks, which are already being built, at least for the next few years will have to operate under these uncertain conditions, we focus on robust and forgiving strategies for traffic management. The idea is to use only little information about offered traffics and then dynamically control resource allocations, so as to provide acceptable quality of service combined with high utilisation. We give some draft proposals in this direction and point at some open research issues.

  • 153. Arvidsson, Åke
    et al.
    Berry, Les
    Harris, Richard
    Performance Comparison of Bursty Traffic Models1991Conference paper (Refereed)
    Abstract [en]

    Models of bursty arrival processes are reviewed and compared with re- spect to their in uence on the performance of a single server system. Considerable variations are found between different models fitted to the same traffic, though some models exhibit similar behaviour. Comparing the ability of the models to reproduce the performance of an explicitly given parcel they all tend to fail.

  • 154. Arvidsson, Åke
    et al.
    Harris, Richard
    Analysis of the Accuracy of Bursty Traffic Models1993Conference paper (Refereed)
    Abstract [en]

    Traffic models are an essential component of performance analyses of telecommunication networks. This paper investigates the modeling of bursty traffic streams in both single source and multiple source environments. Using a ranking scheme it is shown that, for the single server case, the switched Poisson process models performed the best and that for the multiple source case, models based on the switched Poisson process, or its discrete version (switched Bernoulli) together with the threshold model may give the closest match to the performance of the “real data“. The results also seem to suggest that for traffic for which there is no known, ideal model, a traffic-oriented fitting method performs better than a model oriented one. This study has concentrated on a particular set of “real data” and it has not tried to consider the many different types of bursty traffic, since, at the time of commencing this study, there was little real data available

  • 155. Arvidsson, Åke
    et al.
    Harris, Richard
    Performance Comparison of Models of Individual and Merged Bursty Traffics1991Conference paper (Refereed)
  • 156. Arvidsson, Åke
    et al.
    Harris, Richard
    Performance Comparison of Models of Individual and Merged Bursty Traffics1992Conference paper (Refereed)
  • 157. Arvidsson, Åke
    et al.
    Hederstierna, Anders
    Hellmer, Stefan
    Forecasting Cellular Mobile Traffic: An Econometric Approach2006Conference paper (Refereed)
    Abstract [en]

    We consider the problem of explaining and forecasting the volume of cellular mobile traffic in a long-term perspective. To this end, we create a model of a market with both economic and non-economic variables, viz. the state of the economy, the current price level and the penetration effect on the market in question. We measure these variables by using publicly available data and by applying income theories and by combining theories of demand and technology diffusion. Applying the model to three markets, viz. China, Italy and Sweden, we show that it performs very well in explaining and predicting the volume of cellular mobile traffic. Noting the qualitative differences between these markets, we conclude that the model has some universality in that the results are comparable for all of them

  • 158. Arvidsson, Åke
    et al.
    Holender, Wlodek
    Karlsson, Torgny
    Reduction of Routing Complexity in Telecommunication Networks by a Novel Decomposition Method1996Conference paper (Refereed)
    Abstract [en]

    Routing problems are often encountered when designing and managing telecommuni- cation networks. Today, routing problems are affected by the growing sizes of networks, which increase the complexity, and by introduction of new services and technologies, which rise the demands. Rather than resorting to entirely heuristic algorithms and/or large data bases with off-line precomputed routing information for various situations, we propose a a new decomposition method whereby any routing algorithm is speeded up considerably, thus permitting the deployment of well founded routing algorithms even for real time purposes. In our paper, we present this new method in formal terms, and apply it to a real routing problem. Finally, investigating the performance of our fast implementation by comparing it to the optimal, non-accelerated solution, we find that considerable time savings can be made at a limited cost in terms of non-optimality of the final solution. It is also emphasised that in real-time applications with non-constant traffics, this nominal degradation might be more than compensated for by the prompt delivery.

  • 159. Arvidsson, Åke
    et al.
    Lind, Christer
    On the Validity of Some Markovian Models in ATM Traffic Modelling1995Conference paper (Refereed)
    Abstract [en]

    Markov modulated models are often used to model traffic in a network. How well the processes really capture the essentials of real traffic is less known. We review some of these models and apply a number of associated fitting methods to an Ethernet traffic in different timescales. The fitted models are then used as input to a buffer where buffer occupancies are used as a measure of the goodness of the models. Also, the ability of a fitting method to correctly model the traffic when applied to traffic generated from a model that the fitting method was intended for is examined.

  • 160. Arvidsson, Åke
    et al.
    Lind, Christer
    Using markovian Models to Replicate Real ATM Traffics1996In: ATM Networks: Performance Modelling an Analysis / [ed] Kouvatsos, Demetres, London: Chapman & Hall , 1996, p. 39-54Chapter in book (Other academic)
  • 161. Arvidsson, Åke
    et al.
    Pettersson, Stefan
    Angelin, Lars
    Congestion Control in Intelligent Networks for Real Time Performance and Profit Optimisation1996Conference paper (Refereed)
    Abstract [en]

    Current developments in technologies and markets stress the importance of exible and robust performance optimisation and congestion control. In intelligent networks, congestion control has traditionally taken a purely technical view and focused on pro- tecting individual nodes from harmful overloads. We take a profit oriented, network wide view and develop a congestion control mechanism to ensure real time performance under profit maximisation. Numerical studies in a simulator show that the proposed mechanism is robust and, in particular in overloaded states, provides a substantial improvement in comparison to conventional load control mechanisms.

  • 162. Arvidsson, Åke
    et al.
    Pettersson, Stefan
    Angelin, Lars
    Profit Optimal Congestion Control in Intelligent Networks1997In: 15th International Teletraffic Congress on Teletraffic Contributions for the Information / [ed] Ramaswami, V.; Wirth, P.E., WASHINGTON, DC: ELSEVIER SCIENCE PUBL B V , 1997, p. 911-920Chapter in book (Refereed)
    Abstract [en]

    Current developments in technologies and markets stress the importance of exible and robust performance optimisation and congestion control. In intelligent networks, conges- tion control has traditionally taken a mainly technical view and focused on protecting individual nodes from harmful overloads. We take a profit oriented, network wide view and develop a congestion control mechanism to ensure profit maximisation under real time performance. Numerical studies in a simulator show that the proposed mechanism is robust and, in particular in overloaded states, provides a substantial improvement in comparison to conventional load control mechanisms.

  • 163.
    Asghar, Gulfam
    et al.
    Blekinge Institute of Technology, School of Computing.
    Azmi, Qanit Jawed
    Blekinge Institute of Technology, School of Computing.
    Security Issues of SIP2010Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Voice over IP (VoIP) services based on Session Initiation Protocol (SIP) has gained much attention as compared to other protocols like H.323 or MGCP over the last decade. SIP is the most favorite signaling protocol for the current and future IP telephony services, and it‘s also becoming the real competitor for traditional telephony services. However, the open architecture of SIP results the provided services vulnerable to different types of security threats which are similar in nature to those currently existing on the Internet. For this reason, there is an obvious need to provide some kind of security mechanisms to SIP based VOIP implementations. In this research, we will discuss the security threats to SIP and will highlight the related open issues. Although there are many threats to SIP security but we will focus mainly on the session hijacking and DoS attacks. We will demonstrate these types of attacks by introducing a model/practical test environment. We will also analyze the effect and performance of some the proposed solutions that is the use of Network Address Translation (NAT), IPSec, Virtual Private Networks (VPNs) and Firewalls (IDS/IPS) with the help of a test scenario.

  • 164.
    Ashraf, Hafiz Farhan
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Electrical Engineering.
    Khan, Shakeel
    Analysis of Pakistan's Electric Power Sector2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Pakistan is among some countries which has a lot of potential to produce electricity. The country is geographically very rich in terms of various renewable resources which are low costing to produce electricity and at the same time more environment friendly. But still from last 15 years Pakistan has a series of crises in power sector and there is a shortfall because electricity demand is growing day by day and the resources to produce electricity are not used efficiently.

    This study covers how the country is producing electricity from different available resources, furthermore to address how to reduce shortfall using renewable resources. The main parameters covered by this study are electricity production and its consumption, and installed capacity from different power sources.

    Currently there are 81 different Power plants with installed capacity 24857 MW of electricity and some more power generating projects are in consideration in future to increase electricity production in the country.  Production units are shown in terms of bar charts which compares installed capacity of all power plants. Annual production data of different power plants and their generation history is also shown and explained in tables.

    Furthermore in our study, reasons of existing shortfall are explained and renewable resources like wind, hydel and solar potential of the country is specified, which will help to reduce existing shortfall. At the end, it is concluded that renewable resources importance is realizing in the country with time, as their contribution towards electricity generation is increasing, and are more beneficial, sustainable, economical and long lasting.

  • 165.
    Askwall, Niklas
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Utvärderingsmetod Säkerhetskultur: Ett första steg i en valideringsprocess2013Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [sv]

    Företag investerar idag väldigt mycket pengar på att säkra sina fysiska och logiska tillgångar med hjälp av tekniska skyddsmekanismer. Dock är all säkerhet på något sätt beroende av den enskilde individens omdöme och kunskap. Hur går det avgöra att organisationen kan lita på individens omdöme och kunskap? Hur går det avgöra om en organisation har en god kultur kring säkerhet? Genom att utvärdera säkerhetskulturen kan organisationer få ett utökat underlag i riskhanteringsarbetet samt en bättre förmåga att hantera det som hotar verksamhetens tillgångar. Den forskning som finns idag på området säkerhetskultur är både oense kring vad som utgör god säkerhetskultur men framför allt hur kulturen ska utvärderas. Denna forskningsansats är således ett försök att ta fram en intuitiv utvärderingsmetod som organisationer kan använda för att utvärdera sin säkerhetskultur. Utvärderingsmetoden liknar en gap-analys där en organisations önskade kultur fastställs och datainsamling sker genom en enkätundersökning. Dataunderlaget sammanställs och används för att skapa ett index för den rådande kulturen i jämförelse med den önskade kulturen. I detta inledande försök testas undersökningens reliabilitet genom Cronbach's alpha och validiteten testas genom en form av konfirmatorisk faktoranalys. Resultatet visar hur ett index som representerar en organisations säkerhetskultur skapas. Det går att påvisa god reliabilitet på utvärderingsmetoden och författaren finner goda argument för nyttan av en sådan metod i det proaktiva säkerhetsarbetet. Dock har omständigheter gjort det mycket svårt att påvisa god validitet i denna inledande undersökning.

  • 166.
    Asl, Babak Ghafary
    Blekinge Institute of Technology, School of Engineering.
    A Computer Aided Detection System for Cerebral Microbleeds in Brain MRI2012Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    Advances in MR technology have improved the potential for visualization of small lesions in brain images. This has resulted in the opportunity to detect cerebral microbleeds (CMBs), small hemorrhages in the brain that are known to be associated with risk of ischemic stroke and intracerebral bleeding. Currently, no computerized method is available for fully- or semi-automated detection of CMBs. In this paper, we propose a CAD system for the detection of CMBs to speed up visual analysis in population-based studies. Our method consists of three steps: (i) skull-stripping (ii) initial candidate selection (iii) reduction of false-positives using a two layer classi cation and (iv) determining the anatomical location of CMBs. The training and test sets consist of 156 subjects (448 CMBs) and 81 subjects (183 CMBs), respectively. The geometrical, intensity-based and local image descriptor features were used in the classi cation steps. The training and test sets consist of 156 subjects (448 CMBs) and 81 subjects (183 CMBs), respectively. The sensitivity for CMB detection was 90% with, on average, 4 false-positives per subject.

  • 167.
    Asteborg, Marcus
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Svanberg, Niklas
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Implementation Considerations for Active Noise Control in Ventilation Systems2006Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [en]

    The most common method to attenuate noise in ventilation systems today is passive silencers. For these to efficiently attenuate frequencies below 400 Hz such silencers need to be large and a more neat solution to attenuate low frequencies is to use active noise control (ANC). The usage of ANC in ventilation systems is well known and there are several commercial products available. ANC is not, however, used on a wide basis due to its often high price and poor performance. Since the price is an important factor in ANC systems the expensive laboratory filters and the amplifier that is currently used in the experimental setup at Blekinge Institute of Technology (BTH) need to be replaced with cheaper ones, but without too much performance loss. For easier implementation in ventilation systems the placement of the reference microphone is important, the shorter distance from the anti-noise loud speaker the easier the ANC system is to implement. But if the distance is so small that the ANC system is no longer causal the performance will be decreased and if the reference microphone is close enough to pick up acoustic feedback from the anti-noise loud speaker the performance will also be decreased. In this thesis the expensive laboratory filters will be exchanged to cheaper alternatives, power and total harmonic distortion (THD) measurements will be done on the amplifier that is driving the loud speaker and the reference microphones position will be investigated with measurements on the group delay of the system and the acoustic feedback between the loud speaker and the reference microphone.

  • 168.
    Ataeian, Seyed Mohsen
    et al.
    Blekinge Institute of Technology, School of Computing.
    Darbandi, Mehrnaz Jaberi
    Blekinge Institute of Technology, School of Computing.
    Analysis of Quality of Experience by applying Fuzzy logic: A study on response time2011Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    To be successful in today's competitive market, service providers should look at user's satisfaction as a critical key. In order to gain a better understanding of customers' expectations, a proper evaluations which considers intrinsic characteristics of perceived quality of service is needed. Due to the subjective nature of quality, the vagueness of human judgment and the uncertainty about the degree of users' linguistic satisfaction, fuzziness is associated with quality of experience. Considering the capability of Fuzzy logic in dealing with imprecision and qualitative knowledge, it would be wise to apply it as a powerful mathematical tool for analyzing the quality of experience (QoE). This thesis proposes a fuzzy procedure to evaluate the quality of experience. In our proposed methodology, we provide a fuzzy relationship between QoE and Quality of Service (QoS) parameters. To identify this fuzzy relationship a new term called Fuzzi ed Opinion Score (FOS) representing a fuzzy quality scale is introduced. A fuzzy data mining method is applied to construct the required number of fuzzy sets. Then, the appropriate membership functions describing fuzzy sets are modeled and compared with each other. The proposed methodology will assist service providers for better decision-making and resource management.

  • 169.
    Atchukatla, Mahammad suhail
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Algorithms for efficient VM placement in data centers: Cloud Based Design and Performance Analysis2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Content: Recent trends show that cloud computing adoption is continuously increasing in every organization. So, demand for the cloud datacenters tremendously increases over a period, resulting in significantly increased resource utilization of the datacenters. In this thesis work, research was carried out on optimizing the energy consumption by using packing of the virtual machines in the datacenter. The CloudSim simulator was used for evaluating bin-packing algorithms and for practical implementation OpenStack cloud computing environment was chosen as the platform for this research.

     

    Objectives:  In this research, our objectives are as follows

    • Perform simulation of algorithms in CloudSim simulator.
    • Estimate and compare the energy consumption of different packing algorithms.
    • Design an OpenStack testbed to implement the Bin packing algorithm.

     

    Methods:

    We use CloudSim simulator to estimate the energy consumption of the First fit, the First fit decreasing, Best fit and Enhanced best-fit algorithms. Design a heuristic model for implementation in the OpenStack environment for optimizing the energy consumption for the physical machines. Server consolidation and live migration are used for the algorithms design in the OpenStack implementation. Our research also extended to the Nova scheduler functionality in an OpenStack environment.

     

    Results:

    Most of the case the enhanced best-fit algorithm gives the better results. The results are obtained from the default OpenStack VM placement algorithm as well as from the heuristic algorithm developed in this simulation work. The comparison of results indicates that the total energy consumption of the data center is reduced without affecting potential service level agreements.

     

    Conclusions:

    The research tells that energy consumption of the physical machines can be optimized without compromising the offered service quality. A Python wrapper was developed to implement this model in the OpenStack environment and minimize the energy consumption of the Physical machine by shutdown the unused physical machines. The results indicate that CPU Utilization does not vary much when live migration of the virtual machine is performed.

  • 170.
    Atla, Prashant
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Power Profiling of different Heterogeneous Computers2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Context: In the present world, there is an increase in the usage of com- munication services. The growth in the usage and services relying on the communication network has brought in the increase in energy consumption for all the resources involved like computers and other networking compo- nent. Energy consumption has become an other efficient metric, so there is a need of efficient networking services in various fields which can be obtained by using the efficient networking components like computers. For that pur- pose we have to know about the energy usage behavior of that component. Similarly as there is a growth in use of large data-centers there is a huge requirement of computation resources. So for an efficient use of these re- sources we need the measurement of each component of the system and its contribution towards the total power consumption of the system. This can be achieved by power profiling of different heterogeneous computers for es- timating and optimizing the usage of the resources.

    Objectives: In this study, we investigate the power profiles of different heterogeneous computers, under each system component level by using a predefined workload. The total power consumption of each system compo- nent is measured and evaluated using the open energy monitor(OEM). Methods: In oder to perform the power profile an experimental test bed is implemented. Experiments with different workload on each component are conducted on all the computers. The power for all the system under test is measured by using the OEM which is connected to each system under test(SUT).

    Results: From the results obtained, the Power profiles of different SUT’s are tabulated and analyzed. The power profiles are done in component level under different workload scenarios for four different heterogeneous comput- ers. From the results and analysis it can be stated that there is a variation in power consumed by each component of a computer based on its con- figuration. From the results we evaluate the property of super positioning principle. 

  • 171.
    Atuyota-Ejughemre, Kesiena
    Blekinge Institute of Technology, School of Management.
    Promoting Mobile Financial Transactions: A Case Study Zain Sierra Leone2009Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    Title – Promoting Mobile Financial Transactions: A Case study of Zain Sierra Leone Author – Kesiena Atuyota-Ejughemre Supervisor - Anders Hederstierna Department: School of Management, Blekinge Institute of Technology Course: Master’s thesis in business administration, 15 credits (ECTS). Background and Problem Discussion: There are challenges associated with overly cash based societies. The use of mobile financial systems could address some of these challenges. Understanding the factors that influence people’s willingness to use mobile systems for financial transactions could be significant in developing strategies to transition from traditional payment systems to mobile financial transaction systems. Purpose – The purpose of this is to assess contribution of customer trust and perception of customer focus to the willingness of GSM subscribers to use the mobile system for financial transactions and how the understanding derived from these factors can be used to develop strategies to promote a transition from cashed based society to mobile financial transactions. Method- Quantitative and deductive approach was used. 300 GSM respondents who were selected with a multistage sampling method in three locations were surveyed. Interviewers were used to get data on perceived customer focus level, customer trust and willingness to engage in mobile financial transactions. Theory – Theory section looks at the concepts relating to customer trust and customer perception of customer focus and pertinent subconstructs applicable to the engagement in mobile financial transactions. Analysis – I have used correlational analysis to verify the level of association between customer trust, customer focus perception, socio demographic factors and the willingness to engage in mobile financial transactions. In order to verify the influence of income, a non parametric test was done. Conclusions – The analysis of the data results showed that there is a strong positive association between the willingness to use mobile for financial transactions. Also, the analysis revealed a positive correlation between the perception of customer focus by subscribers and the willingness to engage in mobile financial transactions. There was no significant influence by demographic factors such as age and gender on the willingness to engage in mobile financial transactions. A 3 phased implementation strategy was proposed for the deployment of a mobile financial transaction system.

  • 172.
    Augustsson, Jens
    Blekinge Institute of Technology, Department of Signal Processing.
    Full duplex Konferenstelefon1997Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [sv]

    Denna rapport analyserar ekosläckning för en full duplex högtalartelefon. Systemet bygger på en LMS-algoritm som har implementerats på en TMS320C3 1 signalprocessor. Arbetet har gått ut på att undertrycka ekon genom utnyttja så mycket som möjligt av processoms kapacitet. Möjligheterna för att två eller fler personer skall kunna tala med varandra på att ledigt sätt genom en högtalartelefon påverkas mycket av de ekon som finns i systemet. Högtalartelefonens mikrofon fångar upp ljudet ifrån sin egen högtalare och skickar detta ljud tillbaka genom telefonnätet. Utan någon form av ekokontroll uppstår ett irriterande eko av sin egen röst i telefonen. Ju längre fardröjning som telefonnätet tillför, ju mer irriterande blir ekot. Konventionella högtalartelefoner använder röstaktivering av mikrofonen för att bli av med ekot. Detta medför att de samtalande partertema inte både kan höra och prata med varandra samtidigt. Detta kallas i kommunikationssammanhang Halv-Duplex. Denna onaturliga form av samtal medför att bägge börjar tala samtidigt och att de avbryter varandra. 1 mitt arbete tittar jag närmare på metoder för ekokontroll med mål att bägge parterna skall både kunna tala med och höra varandra simultant, sk. Full-Duplex, utan rundgång. Teorierna kring adaptiv ekosläckning har varit kända sedan Iänge men det är inte förrän på senare tid som det finns processorer som klarar av beräkningarna’ i realtid. TMS320C3 1 ‘an har inte riktigt den önskvärda beräkningskapaciteten för realtidsberäkning av langa adaptiva FIR-filter. En filterlängd på 300 filter koefficienter uppnåddes. För att nå upp till denna längd användes en metod med adaptering bara på halva bandbredden, 1500 Hz. Den andra halvan av bandbredden, 1500 - 3500 Hz, i ett telefonnät lämnades ofiltrerad. Ett stort bekymmer visade sig vara att finna en lamplig metod för att besluta när adaptering får ske. En enkel sk. taldetektor implementerades för detta endamål.

  • 173. A.V., Fidalgo
    et al.
    G.R., Alves
    M.A., Marques
    M.C, Viegas
    M.C, Costa-Lobo
    U., Henandez-Jayo
    J., Garcia-Zúbia
    Ingvar, Gustavsson
    Blekinge Institute of Technology, School of Engineering, Department of Electrical Engineering.
    Adapting remote labs to learning scenarios: Case studies using VISIR and remotElectLab2014In: Revista Iberoamericana de Tecnologias del Aprendizaje, ISSN 1932-8540, Vol. 9, no 1, p. 33-39Article in journal (Refereed)
    Abstract [en]

    Remote laboratories are an emergent technological and pedagogical tool at all education levels, and their widespread use is an important part of their own improvement and evolution. This paper describes several issues encountered on laboratorial classes, on higher education courses, when using remote laboratories based on PXI systems, either using the VISIR system or an alternate in-house solution. Three main issues are presented and explained, all reported by teachers, that gave support to students' use of remote laboratories. The first issue deals with the need to allow students to select the actual place where an ammeter is to be inserted on electric circuits, even incorrectly, therefore emulating real-world difficulties. The second one deals with problems with timing when several measurements are required at short intervals, as in the discharge cycle of a capacitor. In addition, the last issue deals with the use of a multimeter in dc mode when reading ac values, a use that collides with the lab settings. All scenarios are presented and discussed, including the solution found for each case. The conclusion derived from the described work is that the remote laboratories area is an expanding field, where practical use leads to improvement and evolution of the available solutions, requiring a strict cooperation and information-sharing between all actors, i.e., developers, teachers, and students.

  • 174.
    Avdic, Adnan
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science.
    Ekholm, Albin
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science.
    Anomaly Detection in an e-Transaction System using Data Driven Machine Learning Models: An unsupervised learning approach in time-series data2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Background: Detecting anomalies in time-series data is a task that can be done with the help of data driven machine learning models. This thesis will investigate if, and how well, different machine learning models, with an unsupervised approach,can detect anomalies in the e-Transaction system Ericsson Wallet Platform. The anomalies in our domain context is delays on the system.

    Objectives: The objectives of this thesis work is to compare four different machine learning models ,in order to find the most relevant model. The best performing models are decided by the evaluation metric F1-score. An intersection of the best models are also being evaluated in order to decrease the number of False positives in order to make the model more precise.

    Methods: Investigating a relevant time-series data sample with 10-minutes interval data points from the Ericsson Wallet Platform was used. A number of steps were taken such as, handling data, pre-processing, normalization, training and evaluation.Two relevant features was trained separately as one-dimensional data sets. The two features that are relevant when finding delays in the system which was used in this thesis is the Mean wait (ms) and the feature Mean * N were the N is equal to the Number of calls to the system. The evaluation metrics that was used are True positives, True Negatives, False positives, False Negatives, Accuracy, Precision, Recall, F1-score and Jaccard index. The Jaccard index is a metric which will reveal how similar each algorithm are at their detection. Since the detection are binary, it’s classifying the each data point in the time-series data.

    Results: The results reveals the two best performing models regards to the F1-score.The intersection evaluation reveals if and how well a combination of the two best performing models can reduce the number of False positives.

    Conclusions: The conclusion to this work is that some algorithms perform better than others. It is a proof of concept that such classification algorithms can separate normal from non-normal behavior in the domain of the Ericsson Wallet Platform.

  • 175.
    Avinash, Avinash
    et al.
    Blekinge Institute of Technology, School of Engineering.
    Alampally, Shravan Kumar
    Blekinge Institute of Technology, School of Engineering.
    Verification of Crane Control Algorithm2013Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    In the present world the heavy machine applications have grown more sophisticated. Crane is designed in such a way to perform the tasks that are hard for human beings, in order to make the work faster and easier. In this area of crane utilization, forwarder movement is the key in performing most of the tasks. Forwarder movement plays an important role in tasks such as collecting logs from the ground and moving them from one place to another. These types of cranes find a wide range of utilization in forestry applications. In order to perform these tasks movement of the forwarder has to be according. Depending on the loads to carry the size of the forwarder also varies. Partial automation of the crane movement in the form of forwarder movement is the area of interest. Aim of the thesis is to concentrate on automation of crane link, to be more specific, the prismatic link. This can be achieved through the verification of the mechanism and similarity of the two algorithms in the Matlab system and in the DASA system.

  • 176.
    Awais, Muhammad
    Blekinge Institute of Technology, School of Engineering.
    Multichannel Wiener Filtering for Speech Enhancement in Modulation Domain2011Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Normally speech signals are contaminated with noise and interference that reduces the intelligibility of speech during communication. In order to make speech signals e ective and useful, they need to be enhanced from the noisy speech signal. In speech processing eld many speech enhancement techniques are developed and are providing very good results. Multichannel microphone array is also one of the techniques used for speech enhancement, that provides better results than the single channel speech enhancement. Moreover, Wiener filtering is the most commonly used technique for multichannel microphone array for speech enhancement. The main focus of this thesis is to implement multichannel microphone array using Wiener filtering in the modulation domain system and also in the time domain system to enhance the speech. Both are implemented successfully and validated e ectively by considering diff erent parameters, i,e; Signal to Noise Ratio (SNR), Signal to Noise Ratio Improvement (SNRI) and Mean Opinion Score (MOS). Both the systems are tested with one female and one male speech distorted with diff erent types of noise at -5dB,0dB,5dB,10dB,15dB and 20dB SNR. The values are calculated for the diff erent number of subbands, as the main focus is on modulation domain system. It provided efficient results in terms of SNRI and MOS score.

  • 177.
    Awan, Zafar Iqbal
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Azim, Abdul
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Network Emulation, Pattern Based Traffic Shaping and KauNET Evaluation2008Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Quality of Service is major factor for a successful business in modern and future network services. A minimum level of services is assured indulging quality of Experience for modern real time communication introducing user satisfaction with perceived service quality. Traffic engineering can be applied to provide better services to maintain or enhance user satisfaction through reactive and preventive traffic control mechanisms. Preventive traffic control can be more effective to manage the network resources through admission control, scheduling, policing and traffic shaping mechanisms maintaining a minimum level before it get worse and affect user perception. Accuracy, dynamicity, uniformity and reproducibility are objectives of vast research in network traffic. Real time tests, simulation and network emulation are applied to test uniformity, accuracy, reproducibility and dynamicity. Network Emulation is performed over experimental network to test real time application, protocol and traffic parameters. DummyNet is a network emulator and traffic shaper which allows nondeterministic placement of packet losses, delays and bandwidth changes. KauNet shaper is a network emulator which creates traffic patterns and applies these patterns for exact deterministic placement of bit-errors, packet losses, delay changes and bandwidth changes. An evaluation of KauNet with different patterns for packet losses, delay changes and bandwidth changes on emulated environment is part of this work. The main motivation for this work is to check the possibility to delay and drop the packets of a transfer/session in the same way as it has happened before (during the observation period). This goal is achieved to some extent using KauNet but some issues with pattern repetitions are still needed to be solved to get better results. The idea of history and trace-based traffic shaping using KauNet is given to make this possibility a reality.

  • 178.
    AWONIYI, OLUWASEYI
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    STRATOSHPHERIC CHANNEL MODELLING2007Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    High Altitude Platform Stations (HAPs) are communication facilities situated at an altitude of 17 to 30 km and at a specified, nominal, fixed point relative to the Earth. They are mostly solar-powered, unmanned, and remotely-operated. These platforms have the capability of carrying multipurpose communications relay payload, which could be in the form of full base station or, in some cases, a simple transponder as is being used in satellite communication systems. HAPs, when fully deployed will have the capability of providing services and applications ranging from broadband wireless access, navigation and positioning systems, remote-sensing and weather observation/monitoring systems, future generation mobile telephony etc. HAPs are also known to be low cost when it comes to its implementation and are expected to be the next big provider of infrastructure for wireless communications. There have been a lot of ongoing and exciting research works into various aspects of this emergent technology. As radio Engineers, the need to predict the channel quality and analyze the performance evaluation of such stratospheric propagation has generated quite a few models. Although some of the models under consideration are from the existing terrestrial and satellite communications which in some way, have some relationships with this new technology. This thesis work provides some insight into this new aspect of wireless communications in terms of the need for a new system, its benefits, challenges services provided and applications supported. Existing models already researched and developed for HAPS are reviewed; one of them was picked and deeply looked into as regards the propagation and channel efficiency. The analysis of the choice model is presented using one of the performance test for channel models, the bit error rate (BER).

  • 179.
    Axelsson, Arvid
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Light Field Coding Using Panoramic Projection2014Student thesis
    Abstract [en]

    A new generation of 3d displays provides depth perception without the need for glasses and allows the viewer to see content from many different directions. Providing video for these displays requires capturing the scene by several cameras at different viewpoints, the data from which together forms light field video. To encode such video with existing video coding requires a large amount of data and it increases quickly with a higher number of views, which this application needs. One such coding is the multiview extension of High Efficiency Video Coding (mv-hevc), which encodes a number of similar video streams as different layers. A new coding scheme for light field video, called Panoramic Light Field (plf), is implemented and evaluated in this thesis. The main idea behind the coding is to project all points in a scene that are visible from any of the viewpoints to a single, global view, similar to how texture mapping maps a texture onto a 3d model in computer graphics. Whereas objects ordinarily shift position in the frame as the camera position changes, this is not the case when using this projection. A visible point in space is projected to the same image pixel regardless of viewpoint, resulting in large similarities between images from different viewpoints. The similarity between the layers in light field video helps to achieve more efficient compression when the projection is combined with existing multiview coding. In order to evaluate the scheme, 3d content was created and software was developed to encode it using plf. Video using this coding is compared to existing technology: a straightforward encoding of the views using mvhevc. The results show that the plf coding performs better on the sample content at lower quality levels, while it is worse at higher bitrate due to quality loss from the projection procedure. It is concluded that plf is a promising technology and suggestions are given for future research that may improve its performance further.

  • 180.
    Ayichiluhm, Theodros
    et al.
    Blekinge Institute of Technology, School of Computing.
    Mohan, Vivek
    Blekinge Institute of Technology, School of Computing.
    IPv6 Monitoring and Flow Detection2013Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    IPv6 Privacy extensions, implemented in major operating systems, hide user’s identity by using a temporary and a randomly generated IPv6 addresses rather than using the former, EUI-64 format where the MAC address is part of the IPv6 address. This solution for privacy has created a problem for network administrators to back-trace an IPv6 address to a specific MAC address, since the temporary IP address used once by the node is removed from the interface after a period of time. An IPv6 Ethernet test bed is setup to investigate IPv6 implementation dynamics in Windows 7 and Ubuntu10.04 operating systems. The testbed is extended to investigate the effects of temporary IPv6 addresses due to IPv6 privacy extensions on the on-going sessions of different applications including ping, File Transfer Protocol (FTP) and video streaming (HTTP and RTP). On the basis of the knowledge obtained from investigations about dynamics of IPv6 privacy extensions, this work proposes Internet Protocol version 6 Host Tracking (IPv6HoT), a web based IPv6 to MAC mapping solution. IPv6HoT uses Simple Network Management Protocol (SNMP) to forward IPv6 Neighbor table from routers to Network Management Stations (NMS). This thesis work provides guidelines for configuring IPv6 privacy extensions in Ubuntu10.04 and Windows 7; the difference of implementation between these two operating systems is also presented in this work. The results show that temporary IPv6 addressing has a definite effect on the on-going sessions of video streaming and FTP applications. Applications running as server on Temporary IPv6 address encountered more frequent on-going session interruptions than applications running as a server over public IPv6 address. When temporary IPv6 addresses were configured to host FTP and video streaming applications, their on-going sessions were permanently interrupted. It is also observed that LFTP, a client FTP application, resumes an interrupted session.

  • 181.
    Ayub, Hasan
    et al.
    Blekinge Institute of Technology, School of Engineering.
    Awan, Shoaib Shafiq
    Blekinge Institute of Technology, School of Engineering.
    QoS and Integrating issues of Real Time Traffic within Wireless Environment2009Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Wireless technology in simple words is a technique that enables more than one user to share resources without having wiring. In comparison with wired local area network in which twisted pair cables, adapters and coaxial cables are used to connect multiple devices. Wireless technology has enabled us to send and receive data through radio and infrared waves and a single access point in WLAN can easily accommodate many users in the same domain. In this era of technology we want everything to be simplified to the maximum and in regards to wireless technology we want to have voice over IP instead of analog phones this is what we call real time traffic. In this Thesis report we have studied the WLAN technology in detail with special emphasis on QoS issues and tried to suggest the possibilities on how to integrate real time traffic on WLAN. Through simulation we will try to find improvements in this field. Our main focus will be on CSMA/CA protocol of 802.11 and 802.11e standards, and different MAC schemes that are used to accommodate different types of traffic, special emphasis is given on DCF and EDCA. Through simulation we will show the results that how these fields can affect the QoS of WLAN, these schemes enables more user capacity which means that we can increase the traffic and make wireless LAN more adaptive. The simulation that we will do in this Thesis will be totally correlated with our research but it will not be practically implemented.

  • 182.
    Ayyagari, Nitin Reddy
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Databases For Mediation Systems: Design and Data scaling approach2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Context: There is continuous growth in data generation due to wide usage of modern communication systems. Systems have to be designed which can handle the processing of these data volumes efficiently. Mediation systems are meant to serve this purpose. Databases form an integral part of the mediation systems. Suitability of the databases for such systems is the principle theme of this work.

    Objectives: The objective of this thesis is to identify the key requirements for databases that can be used as part of Mediation systems, gain a thorough understanding of various features, the data models commonly used in databases and to benchmark their performance.

    Methods: Previous work that has been carried out on various databases is studied as a part of literature review. Test bed is set up as a part of experiment and performance metrics such as throughput and total time taken were measured through a Java based client. Thorough analysis has been carried out by varying various parameters like data volumes, number of threads in the client etc.

    Results: Cassandra has a very good write performance for event and batch operations. Cassandra has a slightly better read performance when compared to MySQL Cluster but this differentiation withers out in case of fewer number of threads in the client.

    Conclusions: On evaluation of MySQL Cluster and Cassandra we conclude that they have several features that are suitable for mediation systems. On the other hand, Cassandra does not guarantee ACID transactions while MySQL Cluster has good support. There is need for further evaluation on new generation databases which are not mature enough as of now.

  • 183.
    Azam, Adnan
    et al.
    Blekinge Institute of Technology, School of Engineering.
    Siddique, Taimoor
    Blekinge Institute of Technology, School of Engineering.
    Spectrum Optimization in Cognitive Radio Networks using Genetic Algorithms2010Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    The rapid revolution in wireless communication in past years has increased the demand of radio spectrum to fulfill quality of service (QoS) requirements of wireless applications, leading to spectrum overcrowding. To solve the spectrum overcrowding problem, cognitive radio (CR) has emerged as a leading technology because it can intelligently sense an unused spectrum without creating any harm to authorized users. Once the spectrum is sensed, to fulfill QoS requirement of the application and to utilize the radio resources more efficiently, an intelligent decision to allocate an optimum spectrum is a prime requirement. In this thesis work a spectrum allocation procedure is proposed. Genetic Algorithms (GA) an evolutionary computational technique is used which works on Darwin theory of evolution. It defines the radio in the form of chromosomes and genes. The procedure is modeled using Matlab, and the application’s QoS requirements are given as input to the GA procedure, which results in an optimum solution after several evolution

  • 184.
    Azam, Muhammad
    Blekinge Institute of Technology, School of Engineering.
    Methods for Recovery of Missing Speech Packets2011Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    In packetized voice communication, speech packets are sometimes lost due to data transmission problems, e.g., signal fading, or interfering users and noise. For the recovery of missing speech packets, different methods are proposed. This thesis analyzes some recovery methods, and four variants of a waveform substitution method used during the objective analysis. This method is based on slow varying speech parameter estimates. These parameters include the short time energy (STE) and the zero crossing (ZC) measure. This technique is implemented in two different ways based on the slow varying parameters. These parameters are stored in the previous packet. If a speech packet is lost, it is recovered by the information stored in the previous packets. Both implementations differ only in the use of the zero crossing information. The short time energy estimation is the same in both implementations. A slight modification is made in these two implementations where the estimated speech parameters are stored in the previous and in future packets in order to recover two consecutive packets. This modification is applied only if the speech signal is already saved at the transmitter because it requires the future packets to store the information of previous packets, i.e., a non-causal solution. However, a causal solution is obtained if the signal is allowed to be delayed by one packet. The speech quality of the reconstructed speech signal is analyzed and compared between the four implementations. The implementation of these methods has been validated by subjectively observing the recovered speech packets, and by considering the improvement of the objective measures mean opinion score (MOS), mean square error (MSE) and signal-to-noise ratio (SNR). The recovery of samples within the packets is also discussed. The recovery of samples within a packet is done by the Fast Fourier Transform (FFT) block code method. The FFT block code method is implemented by an iterative algorithm. This method is validated by subjective observations and improvements in objective measures mean square error (MSE) and signal to noise ratio (SNR). The VAD is also used for the waveform substitution method and in the introduction of channel noise. After subjective observations and objective measures, it is concluded that modified method A provides better performance for the recovery of speech packets and the FFT block code method has been validated for recovering the samples within a packet.

  • 185. Aziz, Hussein Muzahim
    et al.
    Fiedler, Markus
    Grahn, Håkan
    Lundberg, Lars
    Streaming Video as Space – Divided Sub-Frames over Wireless Networks2010Conference paper (Refereed)
    Abstract [en]

    Real time video streaming suffers from lost, delayed, and corrupted frames due to the transmission over error prone channels. As an effect of that, the user may notice a frozen picture in their screen. In this work, we propose a technique to eliminate the frozen video and provide a satisfactory quality to the mobile viewer by splitting the video frames into sub- frames. The multiple descriptions coding (MDC) is used to generate multiple bitstreams based on frame splitting and transmitted over multichannels. We evaluate our approach by using mean opinion score (MOS) measurements. MOS is used to evaluate our scenarios where the users observe three levels of frame losses for real time video streaming. The results show that our technique significantly improves the video smoothness on the mobile device in the presence of frame losses during the transmission.

  • 186.
    Aziz, Md. Tariq
    et al.
    Blekinge Institute of Technology, School of Computing.
    Islam, Mohammad Saiful
    Blekinge Institute of Technology, School of Computing.
    Performance Evaluation of Real–Time Applications over DiffServ/MPLS in IPv4/IPv6 Networks2011Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Over the last years, we have witnessed a rapid deployment of real-time applications on the Internet as well as many research works about Quality of Service (QoS) in particularly IPv4 (Internet Protocol version 4). The inevitable exhaustion of the remaining IPv4 address pool has become progressively evident. As the evolution of Internet Protocol (IP) continues, the deployment of IPv6 QoS is underway. Today, there is limited experience in the deployment of QoS for IPv6 traffic in MPLS backbone networks in conjunction with DiffServ (Differentiated Services) support. DiffServ itself does not have the ability to control the traffic which has been taken for end-to-end path while a number of links of the path are congested. In contrast, MPLS Traffic Engineering (TE) is accomplished to control the traffic and can set up end-to-end routing path before data has been forwarded. From the evolution of IPv4 QoS solutions, we know that the integration of DiffServ and MPLS TE satisfies the guaranteed QoS requirement for real-time applications. This thesis presents a QoS performance study of real-time applications such as voice and video conferencing over DiffServ with or without MPLS TE in IPv4/IPv6 networks using Optimized Network Engineering Tool (OPNET). This thesis also studies the interaction of Expedited Forwarding (EF), Assured Forwarding (AF) traffic aggregation, link congestion, as well as the effect of various performance metrics such as packet end-to-end delay, packet delay variation, queuing delay, throughput and packet loss. The effectiveness of DiffServ and MPLS TE integration in IPv4/IPv6 network is illustrated and analyzed. The thesis shows that IPv6 experiences more delay and loss performance than their IPv4 counterparts.

  • 187.
    AZIZ, YASSAR
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Natural Sciences.
    ASLAM, MUHAMMAD NAEEM
    Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Natural Sciences.
    Traffic Engineering with Multi-Protocol Label Switching, Performance Comparison with IP networks2008Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Traffic Engineering (TE) is the stage which deals with geometric design planning and traffic operation of networks, network devices and relationship of routers for the transportation of data. TE is that feature of network engineering which concentrate on problems of performance optimization of operational networks. It involves techniques and application of knowledge to gain performance objectives, which includes movement of data through network, reliability, planning of network capacity and efficient use of network resources. This thesis addresses the problems of traffic engineering and suggests a solution by using the concept of Multi-Protocol Label Switching (MPLS). We have done simulation in Matlab environment to compare the performance of MPLS against the IP network in a simulated environment. MPLS is a modern technique for forwarding network data. It broadens routing according to path controlling and packet forwarding. In this thesis MPLS is computed on the basis of its performance, efficiency for sending data from source to destination. A MATLAB based simulation tool is developed to compare MPLS with IP network in a simulated environment. The results show the performance of MPLS network in comparison of IP network.

  • 188.
    Babaeeghazvini, Parinaz
    Blekinge Institute of Technology, School of Engineering.
    EEG enhancement for EEG source localization in brain-machine speller2013Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    A Brain-Computer Interface (BCI) is a system to communicate with external world through the brain activity. The brain activity is measured by Electro-Encephalography (EEG) and then processed by a BCI system. EEG source reconstruction could be a way to improve the accuracy of EEG classification in EEGbased brain–computer interface (BCI). In this thesis BCI methods were applied on derived sources which by their EEG enhancement it became possible to obtain a more accurate EEG detection and brought a new application to BCI technology that are recognition of writing letters imagery from brain waves. The BCI system enables people to write and type letters by their brain activity (EEG). To this end, first part of the thesis is dedicated to EEG source reconstruction techniques to select the most optimal EEG channels for task classification purposes. Due to this reason the changes in EEG signal power from rest state to motor imagery task was used, to find the location of an active single equivalent dipole. Implementing an inverse problem solution on the power changes by Multiple Sparse Priors (MSP) method generated a scalp map where its fitting showed the localization of EEG electrodes. Having the optimized locations the secondary objective was to choose the most optimal EEG features and rhythm for an efficient classification. This became possible by feature ranking, 1- Nearest Neighbor leave-one-out. The feature vectors were computed by applying the combined methods of multitaper method, Pwelch. The features were classified by several methods of Normal densities based quadratic classifier (qdc), k-nearest neighbor classifier (knn), Mixture of Gaussians classification and Train neural network classifier using back-propagation. Results show that the selected features and classifiers are able to recognize the imagination of writing alphabet with the high accuracy.

  • 189.
    Badampudi, Deepika
    Blekinge Institute of Technology, Faculty of Computing, Department of Software Engineering.
    Towards decision-making to choose among different component origins2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Context: The amount of software in solutions provided in various domains is continuously growing. These solutions are a mix of hardware and software solutions, often referred to as software-intensive systems. Companies seek to improve the software development process to avoid delays or cost overruns related to the software development.  

    Objective: The overall goal of this thesis is to improve the software development/building process to provide timely, high quality and cost efficient solutions. The objective is to select the origin of the components (in-house, outsource, components off-the-shelf (COTS) or open source software (OSS)) that facilitates the improvement. The system can be built of components from one origin or a combination of two or more (or even all) origins. Selecting a proper origin for a component is important to get the most out of a component and to optimize the development. 

    Method: It is necessary to investigate the component origins to make decisions to select among different origins. We conducted a case study to explore the existing challenges in software development.  The next step was to identify factors that influence the choice to select among different component origins through a systematic literature review using a snowballing (SB) strategy and a database (DB) search. Furthermore, a Bayesian synthesis process is proposed to integrate the evidence from literature into practice.  

    Results: The results of this thesis indicate that the context of software-intensive systems such as domain regulations hinder the software development improvement. In addition to in-house development, alternative component origins (outsourcing, COTS, and OSS) are being used for software development. Several factors such as time, cost and license implications influence the selection of component origins. Solutions have been proposed to support the decision-making. However, these solutions consider only a subset of factors identified in the literature.   

    Conclusions: Each component origin has some advantages and disadvantages. Depending on the scenario, one component origin is more suitable than the others. It is important to investigate the different scenarios and suitability of the component origins, which is recognized as future work of this thesis. In addition, the future work is aimed at providing models to support the decision-making process.

  • 190. Badoi, Cornelia-Ionela
    et al.
    Croitoru, Victor
    Popescu, Adrian
    IPSAG Cognitive Radio Routing Protocol: Models and Performance2011Conference paper (Refereed)
    Abstract [en]

    The paper is about performance evaluation of IP Spectrum Aware Geographic routing protocol (IPSAG). IPSAG is an opportunistic cognitive routing protocol which determines a source-destination route in a hop by hop manner, based on both global and local information. Simulation results are reported for a particular case of IPSAG, where the cognitive radio (CR) nodes are uniformly distributed inside the cognitive radio network (CRN), and a two-dimensional random walk model is used to model the mobility of CR nodes. The results show that the IPSAG protocol is performing well in the case of a highly mobile CRN and that the source-destination path is successfully found in the majority of the cases, especially when the network is highly populated.

  • 191.
    Bafana, Ramzi
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Applied Signal Processing.
    Zulfiqar, Zain
    Blekinge Institute of Technology, Faculty of Engineering, Department of Applied Signal Processing.
    Solar Energy2014Student thesis
    Abstract [en]

    This thesis is about Photovoltaic (PV) cells and its stresses in various directions by calculating the power generated using solar cells under different conditions to improve its efficiency. Our research studies found that using multi-junction cells with larger substrates can increase the efficiency to some extent which in practice is limited to 43 percent. The experiment was conducted using ten solar cells each with an area of 20.9〖cm〗 ^2, where each cell gives 0.5 V and 0.4 A and a 1.25 Ω resistor was used. The cells were connected in series. Once, the PV cells were fixed horizontally and the other time tested in tilted position under same outdoor condition. The purpose of testing PV cells was to investigate the efficiency under above mentioned conditions. The data collected from the readings was used in calculation, and we have obtained from the calculations that horizontally fixed cells gave 4.8 percent efficiency whereas tilted cells gave 6.6 percent efficiency. Hence, the ratio showed that fixed cells produced 37.5 percent more power compared to horizontally fixed cells. Our other experiment consisted of testing PV cells under different temperature conditions that was done using a freezer and an oven for temperature variation and a tungsten bulb was used as a light source. The purpose of performing this experiment was to investigate how the efficiency of PV cells is affected under extreme conditions. Part of our thesis was also including studies and analysis of produced energy by the solar panel installed on the roof of “BTH” building in Karlskrona, Sweden. The data consisted of energy produced from February up to August 2014. The investigation also included finding the highest produced energy during these months. We have found that the highest energy was generated on the 1st of July which was 12.86 kWh. Furthermore, we went deep into investigation of the 1st of July to know exactly which hour of that day the highest energy was produced. The data showed that the highest produced energy was at 12:19 and 13:19 which was 2.03 kWh.

  • 192.
    Bahrieh, Sara
    Blekinge Institute of Technology, School of Engineering.
    Sensor Central / Automotive Systems2013Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [en]

    How to display objects which were detected from different devices in one coordinate system? Nowadays most vehicles are equipped with front and back sensors to help the driver in driving process. Companies who provide this technology need to have an application which enables them for easy data fusion from these sensors and recording the process. Besides sensor’s design, programming of them is an important aspect. BASELABS Connect has the solution in a user friendly way. Creating Sensor Central component for BASELABS Connect is the main goal of this thesis. Sensor Central from BASELABS Connect requires six variables of sensor’s position for each sensor to demonstrate the objects from all sensors to one unique coordinate system. In this thesis, it was intended to create such a component which was mounted between all the sensors and the charting component to convert the objects location from different sensor’s position to one coordinate system and to be usable from other vehicles too.

  • 193.
    BAIG, CLEMENT RANJITH ANTHIKKAD & IRFAN AHMED
    Blekinge Institute of Technology, School of Engineering.
    PERFORMANCE ENHANCEMENT OF OFDM IN PAPR REDUCTION USING NEW COMPANDING TRANSFORM AND ADAPTIVE AC EXTENSION ALGORITHM FOR NEXT GENERATION NETWORKSPERFORMANCE ENHANCEMENT OF OFDM IN PAPR REDUCTION USING NEW COMPANDING TRANSFORM AND ADAPTIVE AC EXTENSION ALGORITHM FOR NEXT GENERATION NETWORKS2013Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    This paper presents a new hybrid PAPR reduction technique for the OFDM signal, which combines a multiple symbol representations method with a signal clipping method. The clipping method is a nonlinear PAPR reduction scheme, where the amplitude of the signal is limited to a given threshold. Considering the fact that the signal must be interpolated before A/D conversion, a variety of clipping methods has been proposed. Some methods suggest the clipping before interpolation, having the disadvantage of the peaks re-growth. Other methods contributed that the clipping after interpolation, having the disadvantage of out-of-band power production. In order to overcome this problem different filtering techniques have been proposed. Filtering can also cause peak re-growth, but less than the clipping before interpolation. Another clipping technique supposes that only subcarriers having the highest phase difference between the original signal and its clipped variant will be changed. This is the case of the partial clipping method. To further reduce the PAPR, the dynamic of the clipped signal can be compressed. Linear methods like partial transmit sequence or selective mapping has been proposed for the reduction of PAPR as well. Another PAPR reduction method is the tone reservation. It uses tones on which no data is sent to reduce the transmitted signal peaks. Derivatives of this method with lower computation complexity and improved performance have been proposed: One-Tone One-Peak and one by-one iteration. A similar PAPR reduction method is the multiple symbol representations, where alternative signalling points are used to represent one symbol. The simulation results highlight the advantages of the proposed PAPR reduction method.

  • 194.
    Baig, Mirza Hamid
    et al.
    Blekinge Institute of Technology, School of Computing.
    Kiani, Hassan Shahzad
    Blekinge Institute of Technology, School of Computing.
    Performance Evaluation of MANET using MPLS2010Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Mobile Ad Hoc Network (MANET) is special kind of wireless network which does not have any fixed structure. They are paired for specific purpose within some concise time period. As the concept of “Micro Products” with a feature of “Mobility” has gain popularity, the MANET has benefited the mankind in many ways and in number of situations such as Natural Disaster, War Zone, and Medical Camp in far-flung Earthquake hit areas etc. In every situation mobile nodes organized themselves on temporary bases in network topology. Autonomous nodes having wireless infrastructure are interconnected to form an autonomous network and easily establish a connection from one place to another. These mobile nodes act either as routers or as a host. These nodes have routing capabilities for multi hop paths through which these are interconnected. The mobility of nodes needs efficient routing for MANET. So therewith, Multi Protocol Label Switching (MPLS) enhances routing with respect to path and packet forwarding. In our thesis we try to analyze the various effects of MPLS on MANET protocols when integrated with MPLS. Simulations were carried out using OPNET modeler 14.5 for analyzing the MPLS effects on the metrics like route discovery time, packet end-to-end delay and throughput. Moreover case study is also included to present a conceptual model for integrating MPLS with MANET protocols.

  • 195.
    Bajagain, Krishna Mani
    Blekinge Institute of Technology, Faculty of Engineering, Department of Applied Signal Processing.
    Experiment with Moving Target Focusing using GB-SAR2014Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Ground Based Synthetic Aperture Radar (GB-SAR) refers to SAR system which is mounted on ground linear track. It works on same principle as conventional SAR. Nowadays GB-SAR plays prominent role in the studies of many natural phenomenon as well as in studying some artificial infrastructure or terrain. It is a cost effective solution for the target scenes where it needed continuous monitoring. In this thesis GB-SAR system is experimented to detect moving targets. It should be emphasized that detection of moving target using GB-SAR is very new idea in the research field. As in conventional SAR, defocusing and/or displacement errors for moving target occur during image formation process in GB-SAR too. To detect the moving target, we need to test different Normalized Relative Speed (NRS) until the best focusing of moving target is reached. The research has been carried out in the following way. Firstly several simulations were tested on MATLAB with ideal condition. Secondly real experiments with moving targets were implemented based on the simulation results to collect real SAR data. Finally the data retrieved in the experiments was processed for moving target detection. The experiment was conducted at the Radio Communication Laboratory of Blekinge Institute of Technology. The radar is developed with a vector network analyzer (ENA 5071C), a double ridge guide horn antenna, a corner reflector, low loss high frequency cables and a antenna positioner. The movement of the radar is determined by a linear track. The developed GB-SAR system is configured as an ultra wideband–ultra wide beam (UWB) system. The operating frequency range is set to 1.5 - 2.5 GHz and the length of aperture is about 4 m. The radar measurement is taken place at 17 positions. The Global Back Projection (GBP) algorithm is used for UWB SAR data processing including image formation and moving target detection.

  • 196.
    Bajwa, Ahmer Ali
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Awan, Junaid Anwar
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Performance study of IEEE 802.16d (Fixed WiMAX) Physical layer with Adaptive Antenna System2008Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    In this thesis work, WiMAX (IEEE 802.16d) PHY layer with underlying OFDM technology and an optional feature called Adaptive Antenna System has been considered. The SUI-3 channel model (Rician fading) is used for creating fading phenomena. An Adaptive Antenna System has been deployed at the receiver module to reduce the fading effects caused by SUI-3 channel model. Adaptive Antenna Systems (AAS) uses different beamforming techniques to focus the wireless beam between the base station and the subscriber station. In this thesis, the transmitter (SS) and receiver (BS) are fixed and AAS installed at the receiver is used to direct the main beam towards the desired LOS signal and nulls to the multipath signals. Pre-FFT beamformer based on Least Mean Square (LMS) algorithm is used. Different aspects of the complete system model were investigated such as adaptive modulation, angle of arrival of the incoming signals and number of array elements. It has been demonstrated through MATLAB simulations that the performance of the system significantly improves by AAS, where beamforming is implemented in the direction of desired user. The performance of the system further increases by increasing the number of antennas at receiver.

  • 197.
    Bakhtyar, Shoaib
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Designing Electronic Waybill Solutions for Road Freight Transport2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In freight transportation, a waybill is an important document that contains essential information about a consignment. The focus of this thesis is on a multi-purpose electronic waybill (e-Waybill) service, which can provide the functions of a paper waybill, and which is capable of storing, at least, the information present in a paper waybill. In addition, the service can be used to support other existing Intelligent Transportation System (ITS) services by utilizing on synergies with the existing services. Additionally, information entities from the e-Waybill service are investigated for the purpose of knowledge-building concerning freight flows.

    A systematic review on state-of-the-art of the e-Waybill service reveals several limitations, such as limited focus on supporting ITS services. Five different conceptual e-Waybill solutions (that can be seen as abstract system designs for implementing the e-Waybill service) are proposed. The solutions are investigated for functional and technical requirements (non-functional requirements), which can potentially impose constraints on a potential system for implementing the e-Waybill service. Further, the service is investigated for information and functional synergies with other ITS services. For information synergy analysis, the required input information entities for different ITS services are identified; and if at least one information entity can be provided by an e-Waybill at the right location we regard it to be a synergy. Additionally, a service design method has been proposed for supporting the process of designing new ITS services, which primarily utilizes on functional synergies between the e-Waybill and different existing ITS services. The suggested method is applied for designing a new ITS service, i.e., the Liability Intelligent Transport System (LITS) service. The purpose of the LITS service isto support the process of identifying when and where a consignment has been damaged and who was responsible when the damage occurred. Furthermore, information entities from e-Waybills are utilized for building improved knowledge concerning freight flows. A freight and route estimation method has been proposed for building improved knowledge, e.g., in national road administrations, on the movement of trucks and freight.

    The results from this thesis can be used to support the choice of practical e-Waybill service implementation, which has the possibility to provide high synergy with ITS services. This may lead to a higher utilization of ITS services and more sustainable transport, e.g., in terms of reduced congestion and emissions. Furthermore, the implemented e-Waybill service can be an enabler for collecting consignment and traffic data and converting the data into useful traffic information. In particular, the service can lead to increasing amounts of digitally stored data about consignments, which can lead to improved knowledge on the movement of freight and trucks. The knowledge may be helpful when making decisions concerning road taxes, fees, and infrastructure investments.

  • 198.
    Bakhtyar, Shoaib
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Henesey, Lawrence
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Electronic Waybill Solutions: A Systemtic ReviewIn: Journal of Special Topics in Information Technology and Management, ISSN 1385-951X, E-ISSN 1573-7667Article in journal (Other academic)
    Abstract [en]

    A critical component in freight transportation is the waybill, which is a transport document that has essential information about a consignment. Actors within the supply chain handle not only the freight but also vast amounts of information,which are often unclear due to various errors. An electronic waybill (e-Waybill) solution is an electronic replacement of the paper waybill in a better way, e.g., by ensuring error free storage and flow of information. In this paper, a systematic review using the snowball method is conducted to investigate the state-of-the-art of e-Waybill solutions. After performing three iterations of the snowball process,we identified eleven studies for further evaluation and analysis due to their strong relevancy. The studies are mapped in relation to each other and a classification of the e-Waybill solutions is constructed. Most of the studies identified from our review support the benefits of electronic documents including e-Waybills. Typically, most research papers reviewed support EDI (Electronic Documents Interchange) for implementing e-Waybills. However, limitations exist due to high costs that make it less affordable for small organizations. Recent studies point to alternative technologies that we have listed in this paper. Additionally in this paper, we present from our research that most studies focus on the administrative benefits, but few studies investigate the potential of e-Waybill information for achieving services, such as estimated time of arrival and real-time tracking and tracing.

  • 199. Balakrishna, L.
    et al.
    Kumar, P.V.A.
    Prakash, Chetana
    Gangashetty, Suraykanath
    Speech enhancement using ICA with Bessel features2011Conference paper (Refereed)
    Abstract [en]

    The Independent Component Analysis with Reference (ICA R) also called as constrained ICA (cICA) extracts only the desired source signals from the mixture of source signals by incorporating some prior information into the separation process. To overcome the problem of designing the reference signal when there is no prior information about the desired signal in the cICA, an improved method is proposed to use a different speech signal generated by the same physical source. The cICA is extended to use Bessel coefficients of the observed signals and the reference signal for processing as they converge faster than the other transformations. Since the Bessel functions provide the desired properties, efficient in representing speech signals, less memory storage they have been exploited in speech processing [1]. The results demonstrate the efficiency of the proposed method.

  • 200.
    Balakrishnan, Radhakrishnan
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Applied Signal Processing.
    Kesavan, Shijith Kunneth
    Blekinge Institute of Technology, Faculty of Engineering, Department of Applied Signal Processing.
    CAD TOOLS FOR HYBRID INTEGRATION2015Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    In this thesis, we present a graphical computer-aided design (CAD) environment for the design, analysis and layout of printed electronic batteries in the first phase and the parasitic extraction of the connecting wires in the second phase. The primary motivation of our work is that this prototyping software tool so far does not exist. Our tool has been integrated within the existing CAD tool which allows quick prototyping and simplifies the interface between the system designer and the device manufacturer. This tools supports the schematic and layout entry, rule checking and netlist generation. The first phase of the device synthesis modelling is based on Enfucell printed batteries, by which using the CAD tool, the shape of the battery is optimized and designed to fit the product and is able to simulate the performance during the optimization, whereas the second phase is the parasitic extraction using an extracting tool named fasthenry, which is integrated to our CAD tool to extract unwanted resistance and inductance within the shared wires between the battery and other devices. We believe that the availability of this tool is useful to the CAD community for novel ideas in the circuit design for flexible hybrid electronics.

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