The thesis focuses on the optical access networks and deals with the issue of transmission parameters of the physical layer, their negative impact on the quality of the services parameters and the possibilities of reducing their effect using the polarization multiplexing. The first and second chapter describe the theoretical background necessary for understanding the subsequent parts. The third chapter contains the practical part of the thesis. At first the optical routes in the Czech Republic in terms of polarization mode dispersion, which is together with insertion loss the main limiting parameter of high-speed optical networks, are evaluated. In the following part the measuring of the temperature changes effects on the polarization mode dispersion of the passive components and the effect of temperature changes to the polarization multiplexed signal are evaluated. To double the bandwidth and reduce the influence of polarization mode dispersion on the quality of services, the two simulation models of optical access networks using polarization multiplexing were carried out. These theoretical outputs were verified by the practical measurements in the laboratory and subsequently on the real optical route. Finally, a draft of the broadband optical access network based on wavelength and polarization multiplexing was designed based on obtained knowledge.

UWB has the huge potential to impact the present communication systems due to its enormous available bandwidth, range/data rate trade-off, and potential for very low cost operation. According to FCC, Ultra Wideband (UWB) radio signal defined as a signal that occupies a bandwidth of 500 MHz or fractional bandwidth larger than 20% with strict limits on its power spectral density to -41.3dBm/MHz in the range 3.1GHz to 10.6GHz. Decades of research in the area of wide-band systems have lead us to new possibilities in the design of low power, low complexity radios, comparing with existing narrowband radio systems. In particular, impulse radio based ultra wideband (IR-UWB) is a promising solution for short-range radio communications such as low power radio-frequency identification (RFID), wireless sensor network's and wireless personal area network (WPAN) etc. Since a simple circuit, architecture adopted in the IR-UWB system, the non-idealities of receiver front end may lead to degrade the overall performance. Therefore, it is important to study these effects in order to create robust and efficient UWB system. However, majorities of recent studies are formed on the channel analysis, rather than the receiver system. The main objectives of this thesis work are, (a) System level modeling of non-coherent IR-UWB receiver, (b) Performance analysis of IR-UWB receiver with the help of bit error rate (BER) estimation, (c) A study on the impact of receiver front end non-idealities over BER, (d) Analysis of charge leakage in integrator and its effect on overall performance of UWB receiver. In this work, IR-UWB non-coherent energy detector receiver operating in the frequency band of 3GHz-5GHz based on the on-off keying (OOK) modulation was simulated in Matlab/Simulink. The effect of receiver front end non idealities and integrator charge leakages were discussed in detail with respect to overall performance of the receiver. The results show that non idealities and leakage degrade the performance as expected. In order to achieve a specific BER of 10-2 with the integrator leakage of 25%, the SNR should be increased by 2.1 dB compared to the SNR with no leakage at a data rate of 200Mbps. Finally, integrator design and its specifications were discussed.

Afin d'accélérer ce processus de conception des systèmes embarqués, un environnement de simulation rapide et performant peut s’avérer indispensable. Pour la rendre performante, les modèles comportementaux des composants élémentaires du système doivent être capables de remplacer les éléments réels dans leurs influences et réponses à tous les phénomènes influents: perturbations, affaiblissements, retards...Nos travaux de thèse visent à contribuer à cette approche méthodologique : ils traitent le développement d’un émulateur des RCSFs. Pour ce faire deux types de simulateurs ont été étudiés:• le premier est un simulateur « software » basé sur la création de modèles comportementaux, décrits en langage VHDL-AMS.• le deuxième est un simulateur hardware basé sur la création des modèles logiques comportementaux, décrits en langage VHDL synthétisable. La simulation s’effectuera sur un composant FPGA cible. Des modifications peuvent être faites sur l’architecture de manière dynamique / To accelerate the design process of embedded systems, a fast and efficient simulation environment is needed. To make it efficient, the behavioral models of the elementary components of the system must be able to replace the real elements in their influences and responses to all the influential phenomena: disruptions, attenuation, delays...Our thesis work aims to contribute to this methodological approach: we treat the development of an emulator for WSNs. To do, two types of simulators have been studied:• The first is a software simulator based on the creation of behavioral models, described in VHDL-AMS.• The second is a hardware simulator based on the creation of behavioral logic models, described in synthesizable VHDL. The simulation will be done on an FPGA target. Changes may be made on the architecture dynamically

Indiana University-Purdue University Indianapolis (IUPUI) / Ends of linear chromosomes are maintained by specialized structures known as telomeres. These structures are protected by a number of essential protein complexes including the shelterin complex and CST (CTC1 – STN1 – TEN1) complex. CST is an RPA-like ssDNA binding protein that is vital for telomere length maintenance via inhibition of telomerase and stimulation of DNA polymerase α -primase during C-strand fill-in synthesis. CST is also known to possess additional genome-wide roles in regulating DNA replication and repair including helping facilitate replication re-start at stalled forks, activating checkpoint signaling at double-strand breaks, and promoting replication origin firing. Proper and efficient repair of DNA is critical in order to protect the integrity of the genome and prevent extreme mutagenesis. Telomeres have a strong predisposition to oxidative DNA damage in the form of 8-oxoguanine caused by exposure to reactive oxygen species and free radicals. These oxidative lesions are repaired by the base-excision repair (BER) pathway. Previous work has implicated telomeric proteins such as the shelterin complex in mediating BER. Here we show for the first time that the CST complex and individual subunits robustly stimulate a myriad of proteins involved in the BER pathway including Pol β, APE1, FEN1, and LIGI. CST’s ability to augment these BER-associated proteins could be instrumental in promoting efficient DNA repair. Additionally, we find that CTC1 and STN1 are able to significantly enhance the polymerase activity of Pol δ and Pol α on both random-sequence and telomeric-sequence DNA substrates in vitro. What is more, we establish the ability of CST to resolve G4 structure and promote Pol δ synthesis, which we predict is a key feature of CST’s involvement in DNA replication at telomeres, which are known to form replication-inhibiting G4’s. Our results define important mechanistic insight into CST’s role in DNA replication and repair, and provide a strong foundation for future studies relating defective telomere maintenance to aging disorders and cancers which impact human health.

No description available.

This thesis is part of a project at Bombardier’s Object Controller System. This system acts as a communication interface for several sub-systems that control the railway traffic. Therefore, part of the safety and availability of railway transportation is dependent on the performance and reliability of this system especially the digital communication system that handles the board-to-board communication. Thus, Bombardier has implemented new high-speed LVDS channels to use instead of the implemented RS-485 channels to improve the board-to-board communication performance in the Object Controller System but they lack a transceiver. This thesis work explores possible transceiver solutions that achieve Bombardier requirements. Reusability is very important for Bombardier for safety compliance and certification. Therefore, the investigation was carried out by looking into what is currently implemented and then was carried on by looking into transceivers that used in highspeed communication and check their suitability and compliance for the FPGA and the requirements. This exploration results in three experiments for different transceiver architecture. The first experiment exploits the currently implemented transceiver architecture and it is not suitable for high-speed data rate due to a limitation in the buffer. The second experiment overcomes the buffer limitation by using a clock domain crossing buffer and results in a 100-time faster system. The third experiment aimed to achieve a higher data rate by using a clock and data recovery transceiver and results in a promising solution but needs some enhancements. For testing, a verification methodology following the one-way stress test architecture has been developed using VHDL for simulation and for in-chip testing and the results were verified using ChipScope logic analyzer from Xilinx. In addition, a thermal test for the solution from the second experiment has been performed. / Denna avhandling är en del av ett projekt på Bombardiers Object Controller System. Detta system fungerar som ett kommunikationsgränssnitt för flera delsystem som styr järnvägstrafiken. Därför är en del av säkerheten och tillgängligheten av järnvägstransporten beroende av systemets prestanda och tillförlitlighet, särskilt det digitala kommunikationssystemet som hanterar kommunikationen ombord. Bombardier har sålunda implementerat nya höghastighets LVDS-kanaler för att använda istället för de implementerade RS-485-kanalerna för att förbättra kommunikationsprestandan ombord i objektkontrollen, men de saknar en transceiver. Denna avhandling arbetar med att undersöka möjliga transceiverlösningar som uppnår Bombardier-krav. Återanvändbarhet är mycket viktigt för Bombardier för säkerhetsöverensstämmelse och certifiering. Undersökningen genomfördes därför genom att undersöka vad som för närvarande implementeras och sedan genomföras genom att titta på transceivers som används i höghastighetskommunikation och kontrollera deras lämplighet och överensstämmelse för FPGA och kraven. Denna undersökning resulterar i tre experiment för olika transceiverarkitektur. Det första experimentet utnyttjar den nuvarande implementerade transceiverarkitekturen. Den är inte lämplig för höghastighetsdatakommunikation på grund av en begränsning i bufferten. Det andra experimentet övervinns buffertbegränsningen genom att använda en klockdomänöverföringsbuffert vilket resulterar i ett 100-timmars snabbare system. Det tredje experimentet syftade till att uppnå en högre datahastighet genom att använda en klockoch dataåterställningstransceiver vilket resulterar i en lovande lösning men behöver vissa förbättringar. För testning har en verifieringsmetod som följer envägsstresstestarkitekturen utvecklats med hjälp av VHDL för simulering och för inchip-testning. Resultaten verifierades med hjälp av ChipScope logic analyzer från Xilinx. Dessutom har ett termiskt test för lösningen från det andra experimentet utförts.

Over the years, the Internet has become increasingly popular and people's dependence on it has increased dramatically. Whether it be to communicate to someone across the world, find blueprints, or check sports scores, the Internet has become a necessary resource for everyone. In emergency situations, this need increases further. After the terrorist attacks on the Pentagon, it took several days to restore communications. This is not an acceptable time frame when people's lives are at stake. Virginia Tech's Center for Wireless Telecommunication has developed a prototype of a rapidly deployable high bandwidth wireless communication system at 28 GHz (Local Multipoint Distribution Service frequency). This system provides a large bandwidth radio link to a disaster zone up to 5 km away and puts Ethernet speeds and 802.11 accesses to users within hours. Because of the possible variability in locations that the system can be deployed, it is necessary to find the most useable channel at the site as quickly as possible. In addition to 28GHz radio links, the system also has a built-in channel sounder that measures and captures the channel impulse response of the current channel. Until now, there has been limited research on the relationship between the channel impulse response and the usability of the channel quantified using bit error rate. This thesis examines several different channels captured by CWT's channel sounder and simulates the BER using Cadence's SPW with time-domain models of the channels. This thesis goes on further to show that BER greatly depends on the channel impulse response and the symbol rate. / Master of Science

No / A proposed method for cancelling or reducing the effect of the transmitted power within the transceiver MIMO unit is investigated and discussed using a feedback signal process between the elements. Several parameters including the level of feedback power mismatch, the transmitted power and the received power are considered in this work to test the performance of the system in term of the bit error rate (BER) versus signal to noise ratio (SNR). A new software programme using MATLAB is implemented to evaluate the proposed method. The results showed that the performances of the system are heavily dependent on the amount of the transmitted power, the received power, and the mismatch in the feedback component.

Yes / Recent studies suggest that multicarrier systems using wavelets outperform conventional OFDM systems using the FFT, in that they have well-contained side lobes, improved spectral efficiency and BER performance, and they do not require a cyclic prefix. Here we study the wavelet packet and discrete wavelet transforms, comparing the BER performance of wavelet transform-based multicarrier systems and Fourier based OFDM systems, for multipath Rayleigh channels with AWGN. In the proposed system zero-forcing channel estimation in the frequency domain has been used. Results confirm that discrete wavelet-based systems using Daubechies wavelets outperform both wavelet packet transform- based systems and FFT-OFDM systems in terms of BER. Finally, Alamouti coding and maximal ratio combining schemes were employed in MIMO environments, where results show that the effects of multipath fading were greatly reduced by the antenna diversity.

The Motorola Inc. paging protocol FLEX is discussed. The design and construction of a FLEX paging protocol decoder is discussed in detail. It proposes a decoding solution that includes a radio frequency (RF) receiver and a decoder board. The RF receiver will be briefly discussed. The decoder design is the main focus of this thesis as it transforms the RF frequency modulated (FM) data from the receiver and converts it to FLEX data words. The decoder is designed to handle bit sampling, bit clock synchronization, FLEX packet detection, and FLEX data word collection. The FLEX data words are then sent by the decoder to an external computer through a serial link for bit processing and storage. A FLEX transmitter will send randomly generated data so that a bit error rate (BER) calculation can be made at a PC. Each receiver'9s noise power and noise bandwidth will be measured so that noise spectral density may be calculated. A complete measurement set-up will be shown on how these noise measurements are made. The BER at a known power level is recorded. This enables Eb/No curves to be generated so that results of the decoding algorithm may be compared. This is performed on two different receivers. / Master of Science