Single cell gel electrophoresis (SCGE), more commonly known as the Comet assay, is an uncomplicated, affordable and versatile method for investigating DNA damage and repair. Existing comet–assay based methods were modified and applied in this study in order to examine the effects of different perturbations on the DNA repair capacity of different samples. Mitochondrial functioning has a vast effect on overall cell physiology and does not simply involve the production of energy in the form of ATP that sustains common biological processes, but is also associated with important cellular occurrences such as apoptosis and ROS production. It is suggested that a change in mitochondrial function may lead to extensive ROS production which may negatively affect macromolecules, including proteins involved in DNA repair pathways, and impaired energy formation which in turn may hamper the proper occurrence of energy driven processes. Complex I and ?III knock–down systems established in 143B cells are used to investigate the effect that perturbations of the energy metabolism may have on DNA repair capacity. Metallothioneins (MTs) are known to play an imperative role in trace element homeostasis and detoxification of metals and are effective ROS scavengers. The prooxidant environment that heavy metal imbalance causes may result in mutagenesis and transformation through DNA damage. It is suggested that an imbalance in the metal homeostasis caused by MT knock–out may create an environment favourable for DNA damage formation and at the same time impair DNA repair pathways. Because of the multi–functionality and involvement of metallothioneins in such a wide variety of biological processes, it was considered interesting and essential to extend the investigation on the effect of the absence of metallothioneins on DNA repair. A metallothionein I and ?II knock–out mouse model is employed to determine the effect of MT knock–out on DNA repair capacity. It was clear from the results obtained that transfection of cells, as used to investigate a perturbation in the energy metabolism in 143B cells, has an impairing effect on DRC. It was also confirmed that metallothioneins play an important and diverse role in cell biology since the absence thereof inhibits both BER and NER. / Thesis (M.Sc. (Biochemistry))--North-West University, Potchefstroom Campus, 2011.

The main topic of this thesis is based on multiple-input multiple-output (MIMO) wireless communications, which is a novel technology that has attracted great interest in the last twenty years. Conventional MIMO systems using up to eight antennas play a vital role in the urban cellular network, where the deployment of multiple antennas have significantly enhanced the throughput without taking extra spectrum or power resources. The massive MIMO systems “scales” up the benefits that offered by the conventional MIMO systems. Using sixty four or more antennas at the BS not only improves the spectrum efficiency significantly, but also provides additional link robustness. It is considered as a key technology in the fifth generation of mobile communication technology standards network, and the design of new algorithms for these two systems is the basis of the research in this thesis. Firstly, at the receiver side of the conventional MIMO systems, a general framework of bit error rate (BER) approximation for the detection algorithms is proposed, which aims to support an adaptive modulation scheme. The main idea is to utilize a simplified BER approximation scheme, which is based on the union bound of the maximum-likelihood detector (MLD), whereby the bit error rate (BER) performance of the detector for the varying channel qualities can be efficiently predicted. The K-best detector is utilized in the thesis because its quasi- MLD performance and the parallel computational structure. The simulation results have clearly shown the adaptive K-best algorithm, by applying the simplified approximation method, has much reduced computational complexity while still maintaining a promising BER performance. Secondly, in terms of the uplink channel estimation for the massive MIMO systems with the time-division-duplex operation, the performance of the Grassmannian line packing (GLP) based uplink pilot codebook design is investigated. It aims to eliminate the pilot contamination effect in order to increase the downlink achievable rate. In the case of a limited channel coherence interval, the uplink codebook design can be treated as a line packing problem in a Grassmannian manifold. The closed-form analytical expressions of downlink achievable rate for both the single-cell and multi-cell systems are proposed, which are intended for performance analysis and optimization. The numerical results validate the proposed analytical expressions and the rate gains by using the GLP-based uplink codebook design. Finally, the study is extended to the energy efficiency (EE) of the massive MIMO system, as the reduction carbon emissions from the information and communication technology is a long-term target for the researchers. An effective framework of maximizing the EE for the massive MIMO systems is proposed in this thesis. The optimization starts from the maximization of the minimum user rate, which is aiming to increase the quality-of-service and provide a feasible constraint for the EE maximization problem. Secondly, the EE problem is a non-concave problem and can not be solved directly, so the combination of fractional programming and the successive concave approximation based algorithm are proposed to find a good suboptimal solution. It has been shown that the proposed optimization algorithm provides a significant EE improvement compared to a baseline case.

To take advantage of the high speed in an optic fiber, one of the basic concept in fiber optic communication is to allow several users to simultaneously transmit data over the channel. One technique that provides multiple access is it fiber optic-code division multiple access (FO-CDMA). In FO-CDMA each user is assigned one or more signature sequences called codewords, which are subsets of a type of optical orthogonal code (OOC). The channel input/output consists of the superposition of several users codewords and at the receiver end an optical correlator extracts the information. In the parallel code constructions, presented in this report, each user j is assigned a subset Cj from a code C. The subsets are disjoint and their union is the whole set C. A new way to map the information bits is to insert up to L zeros before each codeword from Cj and let this represent information aswell. This gives high rates for active users but an investigation is needed to ensure that this does not compromise the systems wanted property of sending information with a small probability of errors for all users. Therefore a simulation environment has been implemented in Matlab. The result from these simulations shows that BER for the L parallel codes is acceptable and not much higher than for the traditional constructions. Because of the higher rate these construction should be preferred but an analysis if a hardware implementation is possible.

Since past few decades different types of cellular networks were launched and went successful on the radio links such as WiMAX, that became very popular because of its high data rate (70Mbps) and support for providing wireless internet services over 50km distance. The UMTS Long Term Evolution (LTE) is an emerging technology in the evolution of 3G cellular services. LTE runs on an evolution of the existing UMTS infrastructure already used by over 80 percent of mobile subscribers globally. We have very limited resources in cellular technologies and it is important to utilize them with high efficiency. Single Carrier Frequency Division Multiple Access (SC-FDMA) & Orthogonal Division Multiple Access (OFDMA) are major part of LTE. OFDMA was well utilized for achieving high spectral efficiency in communication system. SC-FDMA is introduced recently and it became handy candidate for uplink multiple access scheme in LTE system that is a project of Third Generation Partnership Project (3GPP). The Multiple Access Scheme in Advanced Mobile radio system has to meet the challenging requirements for example high throughput, good robustness, efficient Bit Error Rate (BER), high spectral efficiency, low delays, low computational complexity, low Peak to Average Power Ratio (PAPR), low error probability etc. Error probability is playing vital role in channel estimation and there are many ways to do channel estimation, like Wiener Channel Estimation, Bayesian Demodulation etc. In our thesis, we investigate the performance of SC-FDMA and OFDMA of LTE physical layer by considering different modulation schemes (BPSK, QPSK, 16QAM and 64QAM) on the basis of PAPR, BER, power spectral density (PSD) and error probability by simulating the model of SC-FDMA & OFDMA. We use Additive White Gaussian Noise (AWGN) channel and introduce frequency selective (multipath) fading in the channel by using Rayleigh Fading model to evaluate the performance in presence of noise and fading. A set of conclusions is derived from our results describing the effect of higher order modulation schemes on BER and error probability for both OFDMA and SC-FDMA. The power spectral densities of both the multiple access techniques (OFDMA and SC-FDMA) are calculated and result shows that the OFDMA has high power spectral density. The considered modulation schemes also have a significant impact on the PAPR of both OFDMA and SC-FDMA such that the higher order modulations increase PAPR in SC-FDMA and decrease PAPR in OFDMA. However, the overall value of PAPR is minimum in SC-FDMA for all modulation schemes. The PSD calculation results also support the remarks given on PAPR. / Author 01: Abdul Samad Shaikh, Phone # 0046-760915236 Author 02 : Khatri Chandan Kumar, Phone # 0046-762649745

HF communication has been used for more than a century and to this day still fulfils an important function in communications networks. In order to interface with modern communications protocols, solutions have to be designed to facilitate data communication over HF (High Frequency). STANAG 5066 is one such solution which provides an application independent ARQ (Automatic Repeat Request) bearer service for client applications. A need exists within the STANAG 5066 specification for a DRC algorithm. The objective of such an algorithm is to select the optimum data rate and interleaver size, based upon current HF channel conditions, to maximise the data throughput over the HF link. In this dissertation previous implementations of DRC algorithms were studied and evaluated. In literature it was found that algorithm implementations used the FER and no channel information to make a data rate choice. This resulted in algorithms that tended to oscillate between data rate choices, and was very slow to react to changes in the HF channel. A new DRC algorithm was designed and simulated that uses the SNR (Signal-to-Noise Ratio) and the BER estimate to make a data rate choice. The DRC algorithm was implemented in a commercial STANAG 5066 system and tested using HF data modems and a simulated HF channel. The results of the implementation and testing show that the designed DRC algorithm gives a better performance, is quicker to adapt and is more robust than previous DRC algorithms. This is also the first DRC algorithm that has been designed to use channel information, such as the SNR and BER, to make a data rate choice. / Dissertation (MEng)--University of Pretoria, 2007. / Electrical, Electronic and Computer Engineering / unrestricted

Master's thesis The Signal Processing in ZigBee System is focused on properties of Physical Layer of ZigBee (standard IEEE 802.15.4 - 2003). The work consists of three parts. The first part contains common view on using and properties of ZigBee. The next part focuses on the Medium Access Control Layer and in detail on the Physical Layer. There described signal processing in the Physical Layer in individual radio bands. The last part of the project contains the process of modeling in the MATLAB for both models of system ZigBee (bands 868/915 MHz and 2450 MHz). The last part of thesis deals with the simulations of BER depending on Carrier-to-Noise Ratio. Also examined the coexistence of systems operating in the same or a nearby frequency band. Based on the results of simulations there are given recommendations for the use of the ZigBee system in minimizing BER.

The main objective of this work is to study methods of reducing BER and suggest possible resolution of matched filter. In the first part, the methods are theoretically analyzed and subsequently their function models are sugested in the computer programme Matlab Simulink. On these models, the behaviour for different input values is simulated and on their basis, the output depending on probability of the false income on SNR for each of models is worked out. In the second part, the design of the laboratory preparation with a view to the matched filter is described. This suggestion is divided into the parts which are subsequently described and outputs from the implementation of the suggested resolution are added. Thereinafter, the implementation of the proposed resolution and the results achieved at measurement of the realized produkt are closely described. This product is to be made for educational and laboratory purposes in terms of lessons The Theory of Communication.

The aim of this thesis are problematics about LDPC codes. There are described metods to create parity check matrix, where are important structured metods using finite geometry: Euclidean geometry and projectice geometry. Next area in this thesis is decoding LDPC codes. There are presented four metods: Hard-Decision algorithm, Bit-Flipping algorithm, The Sum-Product algorithm and Log Likelihood algorithm, where is mainly focused on iterative decoding methods. Practical output of this work is program LDPC codes created in environment Matlab. The program is divided to two parts -- Practise LDPC codes and Simulation LDPC codes. The result reached by program Simulation LDPC codes is used to create a comparison of creating and decoding methods LDPC codes. For comparison of decoding methods LDPC codes were used BER characteristics and time dependence each method on various parameters LDPC code (number of iteration or size of parity matrix).

This project has been carried out at the Electronic Embedded Systems Architecture Department at Volvo Construction Equipment (VCE), Eskilstuna, Sweden. It forms the baseline for a stepwise systematic research initiative to convert wired technologies used for certain in-vehicle control and communication components to wireless technologies. In-vehicle wireless networks are being increasingly improvised and researched to minimize the manufacturing and maintenance cost of the total amount of wiring harnesses within the vehicles. Fault tracking and maintenance becomes convenient within a wireless network. Wireless intra-vehicular communication provides an open architecture that can accommodate new components and applications. One such usability has been studied in this thesis for the Display Control Unit of Volvo paver machines. A newly designed hardware demands new technologies to ensure operator safety, security, comfort, convenience, and information. The research conducted in this thesis takes into account five probable use-cases in terms of control and communication around the new hardware, and studies suitable wireless technologies that could replace the wired technology that will be used. From a detailed literature study and the specifications provided by VCE, WAVE/IEEE802.11p and DMG/IEEE 802.11ad have been selected as optimal candidates. These two have been modelled at the physical layer of the system. After comparing the results of WAVE for 4 different channel models and 8 different coding and modulation schemes, it has been found that 1/2BPSK(3 Mbps) and 1/2 QPSK(6 Mbps) are optimal for the 3 Rician Fading Channels of Rural LOS, Urban LOS, and Highway LOS. For use-cases that involve larger distances and a large exchange of control signals, WAVE is a good choice. DMG has 19 modulation schemes for Single Carrier Modes and some of them are extremely robust at low SNR. Around SNR 20, it shows lesser packet errors than WAVE. The lower error rate is also evident from the BER values. For use-cases that involve smaller distances and a lot of image data, DMG is preferable. The work, however, does not study the safety and security aspects. Thean alysis and modelling are theoretical being based on literature studies and the necessary parameters provided by VCE. The model needs to be evaluated against field studies and practical measurements with a prototype before implementation inside the paver.

Introduction This study aims to investigate the possibility of driving multiple NFC antennas with a single NFC-controller by using a multiplexer. An artifact was developed and experiments were conducted in order to evaluate the design choice and in addition, to observe the impact of a multiplexer in an NFC system with respect to the number of successful tag detections, bit error rate (BER), the utilization of automatic antenna tuning (AAT) and the physical distance to the NFC tag. Data collected from the experiments was analyzed, and the results were discussed. The purpose of the thesis was concretized by formulating three research questions: [RQ1] How can the design proposed in the problem statement be implemented? [RQ2] How does the multiplexer impact the system’s ability to detect an NFC tag and read its contents at different distances? [RQ3] To which degree does the AAT-technology compensate for the issues caused by the multiplexer? Method This research has been conducted according to the design science research (DSR) methodology. DSR is a well-established methodology and suits the nature of this research, therefore it is used to answer the research questions. Findings The thesis demonstrates a viable solution using a multiplexer in NFC systems, with reduced detection distance as a factor to consider. The impact of AAT remains inconclusive, requiring further research. Implications This study shows that using a multiplexer in NFC systems can save costs and space, leading to more affordable and compact devices. It enables scalable, advanced NFC devices for diverse applications, encouraging wider adoption. However, developers must consider the impact of a multiplexer on detection distance when designing NFC-based applications Limitations This study has certain limitations. It focuses on a particular multiplexer and NFC antenna type, and specific testing conditions. It does not delve into the potential profitability, diverse applications, security or encryption concerns, compatibility with other devices, compliance with regulations, or hands-on verification of part connectivity.