The Orthogonal frequency division multiplexing (OFDM) modulator with redundancy has been adopted in many wireless communication systems for higher data rate transmissions .The block transmission of signal-blocks through the channel will suffer from the inter-block interference (IBI) and inter-symbol interference (ISI). In the traditional transmitter of the OFDM systems, redundancy (or guard interval), such cyclic prefix (CP) or zero padding (ZP), with sufficient length, is inserted in the transmitted block to avoid the IBI. In this thesis, we propose a novel pseudo random cyclic postfix (PRCP-) OFDM system configuration and joint a blind channel shortening algorithm which named MERRY algorithm [18], which adopts the PRCP as redundancy and combines with multiple antennas. In fact, the multiple input and multiple output (MIMO) system, which exploits the spatial diversity, it can be used to further enhance the channel capacity and achieve high data-rate, and we extend the PRCP-OFDM to the MIMO case with space-time block coding. In redundancy insufficient case, the blind channel shortening algorithm be adopted for suppressing the IBI. The main property of PRCP-OFDM modulation is that it exploits the cyclic-postfix sequences to estimate channel information with a low complexity method. For CP-OFDM, it overcomes the channel null problem. Compared with ZP-OFDM, it uses the additional information to estimate channel which is replaced by zero samples in ZP-OFDM. Moreover, PRCP-OFDM avoids the interference of signals to the desired postfix when we estimate channel impulse response (CIR) and which is different from pseudo random postfix (PRP-) OFDM [8]. Thus, when SNR grows, PRCP-OFDM can have better performance than PRP-OFDM. With the help of [9], [12] and [13]. Via computer simulation, we verify that the performance is improved.

To effectively combat MAI and MI in wireless networks, we exploit complementary code technique in this thesis. Terminals in cooperative communication system are not only doing the transmission or relaying, but also involve a novel strategy "network coding" which has been investigated widely. In our work, we aim to combine network coding into the conventional cooperative communication system, but we face certain problems in it. Cooperative system has diversity at the destination, but when network coding operation involved, theoretically, it violate the rules of diversity, since the new signals transmitted by relay are no longer as same as the signals from sources. However, we discover a method to solve this problem, which is using the multiplier in relay nodes to replace the conventional network coding operation- XOR. After creating the network coding-based system, our goal is to achieve diversity in cooperative communication system. In this work, we use MRC (maximum ratio combining) for the performance analysis, which is the optimal strategy. Many math works will be shown in the following chapters.

The study of architectural parameterization has long neglected other parameterizations in favour of code selector descriptions. In this dissertation, we are concerned with providing linguistic notations for modelling architectures with special emphasis on translation. We focus on high level descriptions to aid code selection and storage allocation. The view taken in the thesis is that a description specializes a framework with a particular architecture. Independently, the framework must support other translation algorithms without constraining their freedom or forcing them towards architecture-specific idioms. The first contribution is an architectural description language with features tuned towards better parameterizability. Emphasis is laid on addressing site (compile time) parameterizability. Within the notation, the type system of the machine is decoupled from that of the language with the mapping being left to the user as a compile-time parameterization. This gives one more degree of freedom for the user to decide on the precision required based on the available realizations. We also give adequate representation to addressing modes. They are considered to be almost equivalent to operations in complexity. This makes the specification simpler for operations. From the framework's perspective, as a second contribution, we propose an algorithm for maintaining registers during allocation. Register allocation algorithms depend on the framework to inform them when registers are exhausted. In such a situation, we pro- pose an adaptation of bipartite graph matching to keep track of register usage during translation in the presence of architec- tural constraints. The research also aims at structuring both the specification and software to prevent the closed-syntax bottle- neck of a lot of specification languages. We also describe the architecture of the implementation in terms of a very flexible model called the blackboard model.

published_or_final_version / Language Studies / Master / Master of Arts

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.