Doctor of Philosophy(PhD) / In this thesis, we propose and investigate promising approaches for interference mitigation in multiple input multiple output (MIMO) and code division multiple access (CDMA) systems. Future wireless communication systems will have to achieve high spectral efficiencies in order to meet increasing demands for huge data rates in emerging Internet and multimedia services. Multiuser detection and space diversity techniques are the main principles, which enable efficient use of the available spectrum. The main limitation for the applicability of the techniques in these practical systems is the high complexity of the optimal receiver structures. The research emphasis in this thesis is on the design of a low complexity interference suppression/cancellation algorithm. The most important result of our research is the novel design of interference cancellation receivers which are adaptive and iterative and which are of low computational complexity. We propose various adaptive iterative receivers, based on a joint adaptive iterative detection and decoding algorithm. The proposed receiver can effectively suppress and cancel co-channel interference from the adjacent antennas in the MIMO system with a low computation complexity. The proposed adaptive detector, based on the adaptive least mean square (LMS) algorithm, is investigated and compared with the non-adaptive iterative receiver. Since the LMS algorithm has a slow convergence speed, a partially filtered gradient LMS (PFGLMS) algorithm, which has a faster convergence speed, is proposed to improve the convergence speed of the system. The performance and computational complexity of this receiver are also considered. To further reduce the computational complexity, we apply a frequency domain adaptation technique into the adaptive iterative receivers. The system performance and complexity are investigated. It shows that the computational complexity of the frequency domain based receiver is significantly lower than that of the time domain based receiver with the same system performance. We also consider applications of MIMO techniques in CDMA systems, called MIMO-CDMA. In the MIMO-CDMA, the presence of the co-channel interference (CCI) from the adjacent antennas and multiple access interference (MAI) from other users significantly degrades the system performance. We propose an adaptive iterative receiver, which provides the capability to effectively suppress the interference and cancel the CCI from the adjacent antennas and the MAI from other users so as to improve the system performance. The proposed receiver structure is also based on a joint adaptive detection and decoding scheme. The adaptive detection scheme employs an adaptive normalized LMS algorithm operating in the time and frequency domain. We have investigated and compared their system performance and complexity. Moreover, the system performance is evaluated by using a semi-analytical approach and compared with the simulation results. The results show that there is an excellent agreement between the two approaches.

<p>This dissertation evaluates the artificial neural technique for evolving a smart antenna system. The AI techniques pose a challenging research in the field of communication. As such the antennas help to communicate with the digital processor to choose the desired signals and reject the others. It makes its own decision even to find the level of interferences and noises to be discarded by amplitude elimination process through the use of perceptron optimization algorithms like LMS (Least Mean Squares). This method helps to enhance the performance of signal processing efficiently. The design of hardware and software are quite complex. This is due to the fact, that the behaviour of the system is not fully understood being a real-time dependent system. This research work is carried only on software with certain simulated activity on beam-formation algorithm and as well, the system responses before and after using the adaptive algorithm. In this report, we try to concentrate to work on the method of adaptivity to make antenna adaptable to a virtual form of real-time environment. For, this reason a two-element antenna is used for simulation testing, as it is the most commonly used antenna for all purposes in communication. It is also tested on various scanning levels of rotation to determine the learning rate (a parameter that has no effect on the radiation output after using LMS) mean-square error rates and convergence analysis. For the purpose of above mentioned tests, three hypotheses are framed in relation to side-lobe reduction level above 5 decibels, the narrowing of the beam after adaptivity and finally the response of the main beam output for varying values of learning rate, respectivelty. The given research work, may comprehend good practical use of this LMS algorithm and also to indicate antenna patterns and the responses to adaptivity conditions through clarity in graphical format.</p><p>The method is influenced to reduce computational complexity and bring simplicity to the functionality of the antenna with more efficient and effective adaptivness. An effort to test theoretical concepts in practice is also been made in this thesis work. The results show that the antenna system can be made to evolve itself through the process of adaptation with simple behaviour by relying on artificial intelligence technique which ensures little supervision and human intereference. Eventually, it is understood that the reader should have possessed prior concepts, related to antennas, digital signal processing and its practical usage in artificially intelligent systems and as well the exceptions in it, since the work is explained in the direct level assuming so.</p>

Η ενσωμάτωση των τεχνολογιών πληροφορικής και επικοινωνιών (ΤΠΕ) στην εκπαιδευτική διαδικασία έχει γίνει πλέον πραγματικότητα. Οι Η/Υ και οι εφαρμογές τους χρησιμοποιούνται κατά κόρον στα σχολεία και κατ' επέκταση από τους μαθητές και τους καθηγητές. Σκοπός της διπλωματικής εργασίας είναι o σχεδιασμός και η υλοποίηση μιας εκπαιδευτικής πλατφόρμας που θα χρησιμοποιεί τις ΤΠΕ για την ανάπτυξη και οργάνωση του εκπαιδευτικού υλικού από τους ίδιους τους διδάσκοντες. Η σχεδίαση της εφαρμογής ακολουθεί τα πρότυπα για σχεδίαση Learning Management Systems (LMS) που έχουν καθοριστεί και έχουν δοκιμαστεί σε άλλα επιτυχημένα Project. Η πλατφόρμα αυτή δεν απαιτεί ιδιαίτερες γνώσεις για τη χρήση της και έτσι μπορεί να απευθυνθεί σε μεγάλη μερίδα της εκπαιδευτικής κοινότητας. Η εφαρμογή που θα υλοποιηθεί, θα παρέχει στον καθηγητή τα απαραίτητα εργαλεία για τη δημιουργία και καταχώρηση εκπαιδευτικού υλικού αλλά και για την οργάνωσή του σε μαθησιακές οντότητες για να μπορεί να γίνει κατανοητό από τον εκπαιδευόμενο. Η πλατφόρμα αυτή παρέχει εργαλεία διαχείρισης μαθημάτων και τμημάτων (βαθμολόγιο, ημερολόγιο κτλ) καθώς και εργαλεία στο μαθητή για παρουσίαση του εκπαιδευτικού υλικού με τέτοιο τρόπο που να διευκολύνεται η διαδικασία μάθησης και απόκτησης γνώσης. Αυτό επιτυγχάνεται μέσω αλληλεπιδραστικών παρουσιάσεων και διαδικασιών αυτοαξιολόγησης του εκπαιδευόμενου με τη βοήθεια ενός φιλικού γραφικού περιβάλλοντος εργασίας. Η εφαρμογή μπορεί να αξιοποιηθεί με τρείς διαφορετικούς τρόπους: α) ως standalone εφαρμογή β) σε ένα εκπαιδευτικό εργαστήριο με τη χρήση ενός κοινού εξυπηρετητή (server) που θα περιέχει το εκπαιδευτικό υλικό και 3) με σύνδεση μέσω του διαδικτύου στον κεντρικό εξυπηρετητή με μόνη προϋπόθεση την ύπαρξη ικανοποιητικής ταχύτητας μετάδοσης δεδομένων. Με τον τρόπο αυτό εξασφαλίζεται η όσο το δυνατόν ευκολότερη πρόσβαση στο εκπαιδευτικό υλικό. Επίσης, στην πλατφόρμα αυτή, χρησιμοποιούνται διεθνή πρότυπα καταχώρησης εκπαιδευτικών οντοτήτων με μεταδεδομένα (LOM, Dublin Core) για εύκολη αναζήτηση και χρήση των οντοτήτων και από άλλες εφαρμογές. Για τη δημιουργία της πλατφόρμας χρησιμοποιήθηκαν εργαλεία και τεχνολογίες που προσφέρουν σταθερότητα, μεταφερσιμότητα και διαλειτουργικότητα της εφαρμογής. Το πλεονέκτημα που έχει η διαθεματική πλατφόρμα εκπαίδευσης έναντι άλλων περιβαλλόντων εκπαίδευσης είναι ότι δεν περιορίζει το χρήστη της εφαρμογής (εκπαιδευτή ή εκπαιδευόμενο) ως προς το τι υλικό θα χρησιμοποιήσει, αρκεί ο Η/Υ που θα χρησιμοποιηθεί για την παρουσίαση του υλικού να έχει εγκατεστημένο το ανάλογο πρόγραμμα για το άνοιγμα του αρχείου. Με τον τρόπο αυτό δίνεται η δυνατότητα στον εκπαιδευτή να χρησιμοποιήσει ότι εργαλείο θεωρεί αυτός πιο εύκολο και εύχρηστο για τη δημιουργία εκπαιδευτικού υλικού. / The use of information-communication technology (ICT) in the educational system is a reality of our times. Most educational institutes use computers to increase the level of understanding of their students and to enhance the learning capabilities of their educators. The purpose of this thesis is the design and development of an educational platform that uses modern ICT methods to provide the necessary tools to the educators for the creation and cataloguing of the available educational material. These tools will also help the educator to catalog the appropriate material to educational entities so that it can be understandable by the trainees. The software solution that we previously proposed involves tools to handle classes and subjects. The purpose of these tools is to enhance the capabilities of the educator to perform his duties with the best probable way. Nevertheless, this platform provides tools for the student- trainee to maximize his educational experience and training. These tools involve presentation aids, educational context administration, self-examining tests e.t.c The use of this platform gives the opportunity to the user to interact with the educational material that was pre-designed by the tutor and is presented on a friendly user interface. The educational platform can be deployed with three different ways: a ) as a standalone application, b) on an educational laboratory with the use of a server computer that contains the educational material, c) with a connection through the internet to the main server. In this way we provide the most convenient way to access the educational material. In order to achieve best performance and easiest access to the educational material we use international prototypes of metadata information, like IEEE LOM and Dublin Core, so that we can interoperate with other systems. For the development of the platform, we used tools and technologies that provide stability and interoperability. The main advantage of our platform against other available platforms is that it does not constrain the user to use a particular application in order to develop or execute the educational material, as long as he has the appropriate software installed on his computer. With this way, the educator can use any type of software that he prefers to develop the particular material.

The Group Research department in Tait Electronics has a reconfigurable platform for MIMO research. In particular, the platform has an adaptive multivariate DFE with the LMS algorithm currently implemented. The LMS algorithm has been simulated and optimised for implementation on the FPGA. The main objective of the research is to investigate an alternative, the RLS algorithm by comparing its performance to the LMS algorithm. The RLS algorithm is known to be more complex than the LMS algorithm but offers the potential for improved performance due to its fast-converging nature. This thesis provides a performance investigation of these adaptive filter algorithms on the MIMO system for the purpose of real-time implementation on the Tait platform. In addition to performance investigation, stability analysis and a feasibility study is shown for the RLS algorithm on the FPGA. The research is industry based and is supported by FRST.

With an overview how Moodle plugin works, this paper aims to focus on those areas where open source software impact has on learning management system software which is distributed for free. One of the essential goal of this project is to develop plugin tool for Moodle, which aid users by providing less interaction time while adjusting date related tasks mainly with courses and assignments, which currently in the Moodle system is accomplished by a lot of steps. The project concentrated on two application functions, namely assignment_daterollover and course_daterollover. These two application plugin features in Moodle learning environment allows instructors to automatically update all date items in their course at the beginning of each semester. Date adjustments can easily be made to each assignments in a course through one centralized screen, rather than having to go into each individual learning activity. The two plugin tool options are one which will change the course start date by which all assignments can be simultaneously set forward by a specified number of days which is called course_daterollover and the other option is to adjust individual assignment items within a course which is called assignment_daterollover. Through the methods, the number of steps (clicks) has been counted and compared with the existing date adjustment method in Moodle for course and assignments, to evaluate and identity UI limitations Heuristic evaluation method is used. The plugin is implemented using block-plugin, because of its appearance to simply reside the content on the right or left side of each main course page, which also gives users the right to turn it on or off if they don't want to use it. In addition, the tool can be used as an option associated with the existing Moodle date adjustment system from the point of view of having a different design. The result is a user-friendly plugin tool interface for the stated two purposes which have less number of clicks than the Moodle date adjustment system for courses and assignments. The plugin tool can be used by anyone since it has been published on Github. As a conclusion, Moodle with its cost-effectiveness can serve a lot of users around the world.

New adaptive-filtering algorithms, also known as adaptation algorithms, are proposed. The new algorithms can be broadly classified into two categories, namely, steepest-descent and Newton-type adaptation algorithms. Several new methods have been used to bring about improvements regarding the speed of convergence, steady-state misalignment, robustness with respect to impulsive noise, re-adaptation capability, and computational load of the proposed algorithms. In chapters 2, 3, and 8, several adaptation algorithms are developed that belong to the steepest-descent family. The algorithms of chapters 2 and 3 use two error bounds with the aim of reducing the computational load, achieving robust performance with respect to impulsive noise, good tracking capability and significantly reduced steady-state misalignment. The error bounds can be either prespecified or estimated using an update formula that incorporates a modified variance estimator. Analyses pertaining to the steady-state mean-square error (MSE) of some of these algorithms are also presented. The algorithms in chapter 8 use a so-called \textit{iterative/shrinkage method} to obtain a variable step size by which improved convergence characteristics can be achieved compared to those in other state-of-the-art competing algorithms. Several adaptation algorithms that belong to the Newton family are developed in chapters 4-6 with the aim of achieving robust performance with respect to impulsive noise, reduced steady-state misalignment, and good tracking capability without compromising the initial speed of convergence. The algorithm in chapter 4 imposes a bound on the $L_1$ norm of the gain vector in the crosscorrelation update formula to achieve robust performance with respect to impulsive noise in stationary environments. In addition to that, a variable forgetting factor is also used to achieve good tracking performance for applications in nonstationary environments. The algorithm in chapter 5 is developed to achieve a reduced steady-state misalignment and improved convergence speed and a reduced computational load. The algorithm in chapter 6 is essentially an extension of the algorithm in chapter 5 designed to achieve robust performance with respect to impulsive noise and reduced computational load. Analyses concerning the asymptotic stability and steady-state MSE of these algorithms are also presented. An algorithm that minimizes Reny's entropy of the error signal is developed in chapter 7 with the aim of achieving faster convergence and reduced steady-state misalignment compared to those in other algorithms of this family. Simulation results are presented that demonstrate the superior convergence characteristics of the proposed algorithms with respect to state-of-the-art competing algorithms of the same family in network-echo cancelation, acoustic-echo cancelation, system-identification, interference-cancelation, time-series prediction, and time-series filtering applications. In addition, simulation results concerning system-identification applications are also used to verify the accuracy of the MSE analyses presented. / Graduate

Doctor of Philosophy(PhD) / In this thesis, we propose and investigate promising approaches for interference mitigation in multiple input multiple output (MIMO) and code division multiple access (CDMA) systems. Future wireless communication systems will have to achieve high spectral efficiencies in order to meet increasing demands for huge data rates in emerging Internet and multimedia services. Multiuser detection and space diversity techniques are the main principles, which enable efficient use of the available spectrum. The main limitation for the applicability of the techniques in these practical systems is the high complexity of the optimal receiver structures. The research emphasis in this thesis is on the design of a low complexity interference suppression/cancellation algorithm. The most important result of our research is the novel design of interference cancellation receivers which are adaptive and iterative and which are of low computational complexity. We propose various adaptive iterative receivers, based on a joint adaptive iterative detection and decoding algorithm. The proposed receiver can effectively suppress and cancel co-channel interference from the adjacent antennas in the MIMO system with a low computation complexity. The proposed adaptive detector, based on the adaptive least mean square (LMS) algorithm, is investigated and compared with the non-adaptive iterative receiver. Since the LMS algorithm has a slow convergence speed, a partially filtered gradient LMS (PFGLMS) algorithm, which has a faster convergence speed, is proposed to improve the convergence speed of the system. The performance and computational complexity of this receiver are also considered. To further reduce the computational complexity, we apply a frequency domain adaptation technique into the adaptive iterative receivers. The system performance and complexity are investigated. It shows that the computational complexity of the frequency domain based receiver is significantly lower than that of the time domain based receiver with the same system performance. We also consider applications of MIMO techniques in CDMA systems, called MIMO-CDMA. In the MIMO-CDMA, the presence of the co-channel interference (CCI) from the adjacent antennas and multiple access interference (MAI) from other users significantly degrades the system performance. We propose an adaptive iterative receiver, which provides the capability to effectively suppress the interference and cancel the CCI from the adjacent antennas and the MAI from other users so as to improve the system performance. The proposed receiver structure is also based on a joint adaptive detection and decoding scheme. The adaptive detection scheme employs an adaptive normalized LMS algorithm operating in the time and frequency domain. We have investigated and compared their system performance and complexity. Moreover, the system performance is evaluated by using a semi-analytical approach and compared with the simulation results. The results show that there is an excellent agreement between the two approaches.

The aim of this diploma thesis is to analyze issues that come with the development of Moodle LMS modules. The theoretical part is devoted to the research of Moodle 2.0 programming framework capabilities, followed by the methodology of creating modules based on this platform. The verification of methodology is provided in the practical part by the development of a specific module, along with the effective installation of Moodle 2.0 LMS and documentation, that describes its functionality, installation procedure, critical points and a test of portability between other versions of this system.

The purpose of this paper is to give the reader an insight into the graphical interface of a Learning Management system, the theme, how it functions and its importance. The main point is how the creation of new themes can be done, and two different approaches are examined and compared.The use of learning management systems have been growing rapidly over the past years. Modern learning, be it basic school, higher education or professional training, is almost always supported by some learning management system where both instructors and participators share learning material, assignments, discussion, among other things.The theme of a learning management system is of great importance and can have a substantial impact on the efficiency of the actual learning process. Themes might also differ in their purpose, thus depending on the target audience, creating a specific theme might be desirable.The work done in this paper examines the structure and function of themes in the web based Totara learning management system, and looks at two different approaches to creating new themes. These approaches involve creating something from scratch, and cloning an already existing theme.The conclusion drawn from the work done in this paper is that the most efficient way of creating a new theme, is through cloning an already existing theme. Only when time and experience is plentiful, and a full control over the theme structure is desirable, is creating a theme from scratch a viable option.

Submitted by Etelvina Domingos (etelvina.domingos@ufpe.br) on 2015-03-11T19:21:28Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) paulo_perris.pdf: 3226477 bytes, checksum: 8491a6532e86869e3aa3b014f9ca649e (MD5) / Approved for entry into archive by Daniella Sodre (daniella.sodre@ufpe.br) on 2015-03-13T13:12:49Z (GMT) No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) paulo_perris.pdf: 3226477 bytes, checksum: 8491a6532e86869e3aa3b014f9ca649e (MD5) / Made available in DSpace on 2015-03-13T13:12:49Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) paulo_perris.pdf: 3226477 bytes, checksum: 8491a6532e86869e3aa3b014f9ca649e (MD5) Previous issue date: 2013-03 / CAPES / Nos ambientes de aprendizado colaborativo apoiados por computador (do inglês Computer-Supported Colaborative Learning, ou apenas CSCL) a percepção que os usuários têm do ambiente e das suas atividades favorece o aprendizado dos grupos. Há hoje esforços de pesquisa e desenvolvimento para dar suporte às diversas interações, à colaboração e ao compartilhamento de informações entre membros de um grupo em ambientes LMS (Learning Management System), com o objetivo de melhorar a coordenação das atividades dos alunos pelo professor. A adaptação destes ambientes às necessidades particulares de novos contextos pode significar um aumento relevante no potencial de inserção de novas formas de interação. Por isso, a construção de ferramentas que possam tornar o fluxo das atividades (Workflow Educativo) perceptível ao ambiente, podem atender de maneira satisfatória a estas novas necessidades. Este trabalho apresenta o resultado da aplicação de percepção das atividades desenvolvidas por pequenos grupos no LMS Amadeus para melhorar a coordenação destas pelo professor, a qualquer momento. Apresenta também a possibilidade de utilização dos logs dos eventos como scripts para a resolução de atividades por outros discentes, corroborando com o aprendizado colaborativo. Para atingir o objetivo proposto, utilizamos a literatura de Interação Humano-computador, especificadamente o método de design de interação. O processo foi composto por quatro atividades básicas: (1) revisão da literatura, (2) analise de contexto (necessidade do usuário), (3) storyboard, prototipagem e avaliação heurística e (4) concepção e avaliação da usabilidade. Foi considerado no método o foco no usuário, a avaliação da eficácia e a prototipagem evolutiva. Foram ainda utilizadas as técnicas de observação e entrevista para a construção dos primeiros protótipos e futuros storyboards usados na avaliação da eficácia das soluções. A partir das especificações e prototipagem definidas, foi implementada a solução no ambiente de LMS Amadeus, seguindo todas as regras de layout padrão. Por último foi feito um teste de usabilidade com usuários que teve como meta avaliar a eficácia de uso da solução desenvolvida.