published_or_final_version / Language Studies / Master / Master of Arts

Στα πλαίσια αυτής της διπλωματικής εργασίας μελετήσαμε μεθόδους κωδικοποίησης με χρήση πινάκων ισοτιμίας μεγάλων διαστάσεων που έχουν χρησιμοποιηθεί και εφαρμοσθεί μέχρι τώρα σε προηγούμενες μελέτες. Επιλέξαμε τη σχεδίαση ενός αποκωδικοποιητή, που στηρίζεται στο WiMAX – 802.16e ΙΕΕΕ πρότυπο μετάδοσης και συγκεκριμένα με χρήση πομπού και δέκτη με περισσότερες από μία κεραίες. Παρουσιάζουμε, λοιπόν τη θεωρία που συσχετίζεται με το θέμα αυτό τόσο από την πλευρά της κωδικοποίησης όσο κι από την πλευρά της ασύρματης ΜΙΜΟ μετάδοσης και το πρότυπο WiMAX. Αναλύουμε κάθε τμήμα του συστήματός που προσομοιώνουμε και παραθέτουμε τα αποτελέσματα της προσομοίωσης. / -

Šiame darbe aptariama statinė ir dinaminė kodo analizė, jų privalumai ir trūkumai, analizės įrankių tipai bei jų paskirtis. Analizuojami „Gendarme“, „Cppcheck“ ir „FindBugs“ statinės kodo analizės įrankiai. Plačiau analizuojamas laisvai platinamas statinės kodo analizės įrankis „Gendarme“. Pateikiamos spragos, rastos esamose „Gendarme“ taisyklėse bei siūlomi jų patobulinimai, kurie turėtų padėti aptikti daugiau klaidų ir padidinti programų spartą, stabilumą, saugumą ir kodo skaitomumą. Taip pat pateikiamos naujos sukurtos taisyklės, kurios turėtų padėti aptikti daugiau perteklinio, nelogiško kodo, kurio kompiliatorius neaptinka. Naujos taisyklės turėtų padėti supaprastinti programos kodą ir taip pagerinti jo skaitomumą bei aptikti daugiau spragų, kuriomis pasinaudojus galima įtakoti programų veikimą. Atliktas eksperimentinis tyrimas, kurio metu buvo išanalizuotos programos su patobulintu ir nepatobulintu „Gendarme“ statinės kodo analizės įrankiu. Pateikiami eksperimento rezultatai ir išvados. / This paper discusses the static and dynamic code analysis, their advantages and disadvantages, types of analysis tools and their purpose. Analyzes the "Gendarme", "Cppcheck" and "FindBugs" static code analysis tools. Wider analyzes the freely distributed static source code analysis tool "Gendarme". Presented gaps which were found in existing "Gendarme" rules and the proposed modifications, which should help to detect more errors and improve program performance, stability, security and code readability. It also introduces new rules, which should help to detect more excessive, illogical code, which are not detected by the compiler. As well as simplify the code and thus to improve its readability and detect more vulnerabilities, which may be used to affect the functioning of applications. Experimental research was carried out in which some programs were analyzed with improved and not improved static code analysis tool "Gendarme". Experimental results and conclusions are presented.

In recent years, Component models have become common for desktop and server-side applications. But it has not obtained such importance in case of embedded real-time systems.  Therefore, there has been a lot of research undergoing for introducing such component models for embedded real-time systems.  This thesis work proposes an alternative approach for doing this, by the generation of proxies.   The idea is to provide an extension to an existing binary component and modify it to adapt to the targeted real-time operating system. Rather than modifying the existing component, a new component is generated, which is called as the proxy component.  This newly generated proxy component provides the same method implementation as the original component and also provides some additional services.  These services enable these components to meet the needs of targeted embedded real-time systems.  In order to achieve this, a Visual Studio 2008 add-in has been created. This add-in is capable of inspecting an existing Smart Device Component and visualizes the Classes, Interfaces and Methods in the original component in its UI.  In addition to this, the add-in also shows the available services to be included in the proxy component.  The UI of the add-in is designed in such a way that, the user is able to select the services, which should be included in the proxy component.  Based on the user’s selection, the add-in generates the proxy component with the additional services.

Wireless radio access technologies have been progressively evolving to meet the high data rate demands of consumers. The deployment and success of voice-based second generation networks were enabled through the use of the Global System for Mobile Communications (GSM) and the Interim Standard Code Division Multiple Access (lS-95 CDMA) networks. The rise of the high data rate third generation communication systems is realised by two potential wireless radio access networks, the Wideband Code Division Multiple Access (WCDMA) and the CDMA2000. These networks are based on the use of various types of codes to initiate, sustain and terminate the communication links. Moreover, different codes are used to separate the transmitting base stations. This dissertation focuses on base station identification aspects of the Frequency Division Duplex (FDD) WCDMA networks. Notwithstanding the ease of deployment of these networks, their asynchronous nature presents serious challenges to the designer of the receiver. One of the challenges is the identification of the base station identity by the receiver, a process called Cell Search. The receiver algorithms must therefore be robust to the hostile radio channel conditions, Doppler frequency shifts and the detrimental effects of carrier frequency offsets. The dissertation begins by discussing the structure and the generation of WCDMA base station data along with an examination of the effects of the carrier frequency offset. The various cell searching algorithms proposed in the literature are then discussed and a new algorithm that exploits the correlation length structure is proposed and the simulation results are presented. Another design challenge presented by WCDMA networks is the estimation of carrier frequency offset at the receiver. Carrier frequency offsets arise due to crystal oscillator inaccuracies at the receiver and their effect is realised when the voltage controlled oscillator at the receiver is not oscillating at the same carrier frequency as that of the transmitter. This leads to a decrease in the receiver acquisition performance. The carrier frequency offset has to be estimated and corrected before the decoding process can commence. There are different approaches in the literature to estimate and correct these offsets. The final part of the dissertation investigates the FFT based carrier frequency estimation techniques and presents a new method that reduces the estimation error. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2006.

A product turbo code (PTC) decoder application specific integrated circuit (ASIC) is designed in 0.18μm 1P6M CMOS with embedded SRAM. From simulation, an operating frequency of 73.1 MHz at typical conditions is obtained, yielding a throughput of 3.8 Mbps with 4 decoding iterations, while consuming 103.4 mW. The total area is 5.13 mm2. Assuming the ASIC would be used as a hard macro, the area could be reduced to 1.7 mm2. The ASIC was tested at 20 MHz under typical conditions, which resulted in a throughput of 1.0 Mbps at 1.8V supply while consuming 36.6 mW. By making a slight modification, this design can be easily scaled to support IEEE 802.16d WiMAX. Allow for this, and moving to a 45nm process an estimated throughput of 9.44 Mbps with 4 iterations can be obtained. Total macro area would be approximately 0.11 mm2.

A product turbo code (PTC) decoder application specific integrated circuit (ASIC) is designed in 0.18μm 1P6M CMOS with embedded SRAM. From simulation, an operating frequency of 73.1 MHz at typical conditions is obtained, yielding a throughput of 3.8 Mbps with 4 decoding iterations, while consuming 103.4 mW. The total area is 5.13 mm2. Assuming the ASIC would be used as a hard macro, the area could be reduced to 1.7 mm2. The ASIC was tested at 20 MHz under typical conditions, which resulted in a throughput of 1.0 Mbps at 1.8V supply while consuming 36.6 mW. By making a slight modification, this design can be easily scaled to support IEEE 802.16d WiMAX. Allow for this, and moving to a 45nm process an estimated throughput of 9.44 Mbps with 4 iterations can be obtained. Total macro area would be approximately 0.11 mm2.

The mammalian visual system has a remarkable capacity of processing a large amount of information within milliseconds under widely varying conditions into invariant representations. Recently a model of the primary visual system exploited the unique feature of dense local excitatory connectivity of the neo-cortex to match these criteria. The model rapidly generates invariant representations integrating the activity of spatially distributed modeled neurons into a so-called Temporal Population Code (TPC). In this thesis, we first investigate an issue that has persisted TPC since its introduction: to extend the concept to a biologically compatible readout stage. We propose a novel neural readout circuit based on wavelet transform that decodes the TPC over different frequency bands. We show that, in comparison with pure linear readouts used previously, the proposed system provides a robust, fast and highly compact representation of visual input. We then generalized this optimized encoding-decoding paradigm to deal with a number of robotics application in real-world tasks to investigate its robustness. Our results show that complex stimuli such as human faces, hand gestures and environmental cues can be reliably encoded by TPC which provides a powerful biologically plausible framework for real-time object recognition. In addition, our results suggest that the representation of sensory input can be built into a spatial-temporal code interpreted and parsed in series of wavelet like components by higher visual areas. / El sistema visual dels mamífers té una remarcable capacitat per processar informació en intervals de temps de mili-segons sota condicions molt variables i adquirir representacions invariants d'aquesta informació. Recentment un model del còrtex primari visual explota les característiques d'alta connectivitat excitatriu local del neocortex per modelar aquestes capacitats. El model integra ràpidament l'activitat repartida espaialment de les neurones i genera codificacions invariants que s'anomenen Temporal Population Codes (TPC). Aquí investiguem una qüestió que ha persistit des de la introducció del TPC: estudiar un procés biològicament possible capaç de fer la lectura d'aquestes codificacions. Nosaltres proposem un nou circuit neuronal de lectura basat en la Wavelet Transform que decodifica la senyal TPC en diferents intervals de freqüència. Monstrem que, comparat amb lectures purament lineals utilitzades previament, el sistema proposat proporciona una representació robusta, ràpida i compacta de l'entrada visual. També presentem una generalització d'aquest paradigma de codificació-decodificació optimitzat que apliquem a diferents tasques de visió per computador i a la visió dins del context de la robòtica. Els resultats del nostre estudi suggereixen que la representació d'escenes visuals complexes, com cares humanes, gestos amb les mans i senyals del medi ambient podrien ser codificades pel TPC el qual es pot considerar un poderós marc biològic per reconeixement d'objectes en temps real. A més a més, els nostres resultats suggereixen que la representació de l'entrada sensorial pot ser integrada en un codi espai-temporal interpretat i analitzat en una serie de components Wavelet per àrees visuals superiors.

Zugl.: Bremen, Univ., Diss., 2009

Univ., Diss.--Trier, 2004. / Literaturverz. S. 374 - 444.