Broadband wireless technologies have the potential to provide integrated data and multimedia services in several niche areas. There is a growing need to develop high-performance communication systems that can satisfy high-end data processing requirements inherent in these technologies. The speed and complexity of these systems necessitates designers to break away from traditional architectures and design methodologies. A more comprehensive and demanding design and verification process including both hardware and software is required. Field-programmable gate arrays (FPGA) offer an attractive alternative to the low efficiency of Digital Signal Processor (DSP) based systems and low flexibility of Application Specific Integrated Circuits(ASIC). The availability of high-density, high-performance field-programmable gate arrays with several capabilities, like embedded memory and advanced routing, together with the adaptability that they offer make them highly desirable for developing hardware prototypes of communication systems. This thesis describes the development of a configurable architecture and FPGA-based design methodology used in the development of a Local Multipoint Distribution Service (LMDS) gateway for a disaster response network. The design of the gateway posed several challenges due to high data rates (120 Mbits/sec) and adaptive features like variable Forward Error Correction Coding and optional link-level retransmissions. The design decisions and simulation results of the verification process are discussed in detail. Finally, the aspects of testing and integration of the prototype in the overall system are discussed. / Master of Science

Résumé : Il est généralement admis que les cassures double-brin (CDB) de l’ADN sont parmi les lésions les plus toxiques induites par les radiations ionisantes (RI). Les CDBs non ou mal réparées peuvent conduire à une instabilité génomique et à la mort cellulaire. La chimioradiothérapie concomitante est l’une des modalités la plus efficace pour le traitement de certains cancers surtout en stade avancé. Le rendement des CDBs a augmenté quand l’ADN a été irradié en présence de cisplatine avec des électrons de basse énergie (EBEs). Notre étude a pour objectif de réévaluer la contribution des CDBs et d’autres lésions induites par les RI dans la létalité cellulaire. L'effet des RI sur la fonctionnalité de l’ADN plasmidique modifié ou non de façon covalente par le cisplatine a été étudié par mesure de l'efficacité de transformation du plasmide dans E. coli. Les complexes cisplatine-ADN ont été préparés de telle sorte qu’il y avait en moyenne deux adduits de cisplatine par plasmide tel que mesuré par ICP-MS. Nos échantillons ont été irradiés en solution avec des doses croissantes de rayonnements gamma (137Cs). La présence de cisplatine a augmenté la formation des CDBs par un facteur de 2.6 par comparaison avec l'ADN non modifié. Malgré cette augmentation, le rendement des CDBs reste très faible et ne peut pas expliquer la perte de fonctionnalité observée. Alors que, les dommages multiples localisés (LMDS) (non-DSB cluster damage) donnant naissance à des CDBs sous l’action des enzymes de réparation la formamidopyrimidine [fapy]-DNA glycosylase (Fpg) et l’endonuclease III (Nth) où leur rendement a été augmenté d’un facteur de 2.1 lorsque l’ADN a été irradié en présence de cisplatine, ont pu expliquer la perte de fonctionnalité observée. Ces résultats suggèrent que le cisplatine peut agir, non seulement comme un agent chimiothérapeutique, mais aussi comme un radiosensibilisateur efficace par addition d’autres lésions à l’ADN. Aussi, pour la première fois nous avons pu évaluer l’effet des EBEs sur la létalité cellulaire. Des films d'ADN ont été préparés en utilisant la méthode d’adsorption douce sur un substrat de graphite pyrolytique, en présence de 1,3- diaminopropane (Dap[indice supérieur]2+) et ont été irradiées avec des EBEs 10 eV. Nous avons pu conclure, qu’en plus des CSBs, CDBs et des dommages de base, les EBEs sont capables aussi d’induire des LMDS (non-DSB cluster damage) et induire la perte de fonctionnalité de l’ADN. Le rendement des CDBs est très faible d’où ils n’ont pas pu expliquer la perte de fonctionnalité de plasmide observée, après irradiation avec les EBEs. Le rendement très faible des LMDS (non-DSB cluster damage) ne peut pas expliquer la perte de fonctionnalité de l’ADN. Il semble que les EBEs sont capables d’induire des dommages très proches les uns des autres et qui ne peuvent pas être révélés par les enzymes de réparation Fpg et Nth. Plus les dommages sont proches les uns des autres, plus leur réparation est difficile, car une de ces lésions peut inhiber la réparation de l’autre la plus proche. // Abstract : It is generally accepted that DNA double-strand breaks (DSB) are among the most toxic lesions induced by ionizing radiation (IR). Unrepaired or misrepaired DSB can lead to genomic instability and cell death. It is known that concomitant chemoradiation therapy is one of the most preferred methods for the treatment of certain cancers especially in advanced stage. The yield of DSBs was increased when DNA was irradiated with low energy electron (LEEs). The aims of our study was to reassess the contribution of DSBs and other lesions induced by indirect and direct effect of IR in cell lethality. The effect of IR on the DNA functionality of the plasmid modified covalently with cisplatin was studied by measuring the transformation efficiency of the plasmid in E. coli. Cisplatin-DNA complexes were prepared such that there was an average of two cisplatin adducts per plasmid as measured by ICP-MS. Aqueous solutions of the samples were irradiated with 137Cs [gamma]-rays at various doses. Gel electrophoresis analysis shows that cisplatin enhances, by a factor of 2.6, the formation of DSB by [gamma]-rays relative to those in unmodified DNA. Despite this increase, the yield of DSBs is very low and cannot explain the loss of functionality observed after transformation with plasmids modified with cisplatin. While locally multiple damaged sites (LMDS) revealed by repair enzymes Fpg (Formamidopyrimidine [fapy]-DNA glycosylase) and Nth (Endonuclease III) as DSB (nonDSB cluster damage), where their yield was increased by a factor of 2.1 when DNA was irradiated in the presence of cisplatin were able to explain the observed loss of DNA functionality. These results suggest that cisplatin may act not only as a chemotherapeutic agent, but also as an effective radiosensitizer by addition of other DNA lesions. For the first time, we could also evaluate the effect of low energy electrons (LEEs) on DNA functionality. Highly ordered DNA films were prepared on pyrolytic graphite by molecular self-assembly using 1,3-diaminopropane ions (Dap[superscript]2+) to bind together the plasmids and irradiated with LEE (10 eV). We concluded that in addition to CSBs, DSBs and base damage, LEEs induced the formation of non-DSB cluster damage and also induced the loss of DNA functionality under LEE irradiation. The yields of DSBs and of non-DSB cluster damage are too low and so one unable to explain the loss of DNA functionality. It seems that LEEs are able to induce a high complex damage that cannot be revealed by repair enzymes Fpg and Nth. The high complex damage is difficult to repair possibly because the repair of one lesion, may inhibit the repair of another.

L'Efficacité Biologique Relative (EBR) des faisceaux de protons énergétiques (70-250 MeV) utilisés dans les différents centres de protonthérapie est classiquement estimée à 1,10 par rapport aux photons du Cobalt-60. Bien qu'en accord avec la mesure de la régénération des cryptes intestinales chez la souris après exposition à une dose unique de 10 à 15 Gy, cette valeur moyenne a été contestée par la microdosimétrie. Ces incertitudes nous ont conduits à analyser l'effet des protons mis en œuvre dans les deux faisceaux médicaux (76 et 201 MeV) du Centre de Protonthérapie de l’Institut Curie à Orsay (ICPO) sur deux lignées cellulaires humaines tumorales, et en partie sur une lignée fibroblastique. Les résultats font apparaître une différence de la valeur de l'EBR pour la survie au rayonnement dans la partie distale du SOBP (Spread-Out Bragg Peak) en fonction de l'énergie incidente, ainsi qu'une absence de corrélation entre la réponse en survie et l'incidence des cassures double-brin de l'ADN dans le faisceau de 76 MeV. Nous montrons cependant, grâce à l'utilisation de lignées défectives dans les voies de signalisation et de réparation des cassures double-brin de l'ADN par le D-NHEJ, que ces voies déterminent la valeur de l'EBR dans la partie distale du SOBP de 76 MeV. La réponse aux dommages de l'ADN dans cette région suggère que les dommages létaux appartiennent à la classe des “lésions complexes” (LMDS) de l'ADN. D'autre part, il apparaît que la fluence des particules constitue un paramètre majeur qui doit être pris en compte dans la partie distale des faisceaux. / Treatment planning in proton therapy uses a generic value for the Relative Biological Efficiency (RBE) of 1.1 relative to 60Co gamma-rays throughout the Spread Out Bragg Peak (SOBP). We have studied the variation of the RBE at three positions in the SOBP of the 76 and 201 MeV proton beams used for cancer treatment at the Institut Curie Proton Therapy in Orsay (ICPO) in two human tumor cell lines using clonogenic cell death and the incidence of DNA double-strand breaks (DSB) as measured by pulse-field gel electrophoresis without and with endonuclease treatment to reveal clustered lesions as endpoints.The RBE for induced cell killing by the 76 MeV beam increased with depth in the SOBP. However for the 201 MeV protons it was close to that for 137Cs gamma-rays and did not vary significantly. The incidence of DSBs and clustered lesions was higher for protons than for 137Cs g-rays, but did not depend on the proton energy or the position in the SOBP.In the second part of our work, we have shown using cell clones made deficient for known repair genes by stable or transient shRNA transfection, that the D-NHEJ pathway determine the response to protons. The response of DNA damages created in the distal part of the 76 MeV SOBP suggests that those damages belong to the class of DNA "complex lesions" (LMDS). It also appears that the particle fluence is a major determinant of the outcome of treatment in the distal part of the SOBP.

This research focuses on radio wave propagation at millimeter-wave frequencies. A measurement based channel characterization approach is taken in the investigation. First, measurement techniques are analyzed. Three types of measurement systems are designed, and implemented in measurement campaigns: a narrowband measurement system, a wideband measurement system based on Vector Network Analyzer, and sliding correlator systems at 5.8+AH4AXA-mbox{GHz}, 38+AH4AXA-mbox{GHz} and 60+AH4AXA-mbox{GHz}. The performances of these measurement systems are carefully compared both analytically and experimentally. Next, radio wave propagation research is performed at 38+AH4AXA-mbox{GHz} for Local Multipoint Distribution Services (LMDS). Wideband measurements are taken on three cross-campus links at Virginia Tech. The goal is to determine weather effects on the wideband channel properties. The measurement results include multipath dispersion, short-term variation and signal attenuation under different weather conditions. A design technique is developed to estimate multipath characteristics based on antenna patterns and site-specific information. Finally, indoor propagation channels at 60+AH4AXA-mbox{GHz} are studied for Next Generation Internet (NGI) applications. The research mainly focuses on the characterization of space-time channel structure. Multipath components are resolved both in time of arrival (TOA) and angle of arrival (AOA). Results show an excellent correlation between the propagation environments and the channel multipath structure. The measurement results and models provide not only guidelines for wireless system design and installation, but also great insights in millimeter-wave propagation. / Ph. D.

This thesis describes the theoretical development, design, and implementation of a novel measurement system, called a Sampling Swept Time Delay Short Pulse (SSTDSP) wireless channel sounder, capable of real time in field performance characterization of high speed fixed wireless links. The SSTDSP sounder has been designed to provide vital performance metrics for fixed point high data rate applications in the 28 GHz LMDS band at a fraction of the cost and complexity of existing wideband channel sounders. The SSTDSP sounder monitors the behavior of the LMDS channel by sampling the impulse response of the channel in real time. This digitized impulse response is used to assemble a power delay profile and render real-time channel performance metrics such as the mean excess delay, RMS delay spread, maximum excess delay for a given multipath threshold, and coherence bandwidth. The SSTDSP sounder is capable of recording these metrics through three modes of operation - continuous channel monitoring, single instant channel snapshot, or data logging. Swept time delay time dilation processing is combined with precise sample and hold gating to reduce the analog to digital converter sampling rate required to digitize the nanosecond short pulses from 2 Gsps to 1 Msps, while retaining the required effective Nyquist sampling rate of 2 Gsps. This dramatically reduces the memory, digital signal processing, and data logging storage requirements as well as the overall cost of the sounder system. The thesis presents the theory behind channel sounding and discusses whether there is a "bounce path" available to LMDS. Several existing channel sounding methods are compared for this application. A number of specific design and performance criteria from each of these methods are synthesized to produce the Sampling Swept Time Delay Short Pulse Sounder architecture. The design and implementation process used to realize the SSTDSP sounder is presented, including a system overview, module details, and algorithm development details. A calibration and measurement test procedure is outlined and system verification results are presented. Current work in progress on the test platform and future improvements to the modular system are outlined, as well as conclusions and future implications of the system. / Master of Science

Approved for public release, distribution is unlimited / Despite the increase in the demand for high speed Internet services, the last-mile solutions currently available neither are inexpensive enough to attract the majority of the population, nor are they available in low density populated areas. This thesis examines Fixed Broadband Wireless (FBW) as an alternative technology to the current last-mile solutions. The analysis shows that LMDS and MMDS are the most promising emerging FBW technologies and that they are able, by utilizing microwave radio as their fundamental transport medium and using high modulation schemes, to provide digital two-way voice, data, video and Internet services. The thesis shows that both technologies are constrained by free space loss and line-of-sight impairments with rain absorption being the most significant cause of attenuation in the LMDS case, while vegetation and multipath fading play a significant role mostly in the MMDS case. Additionally, it is shown that there is a positive association between the data rate achieved and the level of influence due to Additive White Gaussian Noise (AWGN). Based on the analysis and using the coverage areas, the total capacity, the achieved data rates, the weather and line-of-sight limitations as well as the cost as the most important criteria, it is concluded that LMDS is a preferable solution for enterprise end-users in densely populated urban areas outside the reach of fiber networks, while MMDS targets residential end-users in rural or suburban areas that are not able to receive service through high-speed wireline connections. / Lieutenant Junior Grade, Hellenic Navy

L'Efficacité Biologique Relative (EBR) des faisceaux de protons énergétiques (70-250 MeV) utilisés dans les différents centres de protonthérapie est classiquement estimée à 1,10 par rapport aux photons du Cobalt-60. Bien qu'en accord avec la mesure de la régénération des cryptes intestinales chez la souris après exposition à une dose unique de 10 à 15 Gy, cette valeur moyenne a été contestée par la microdosimétrie. Ces incertitudes nous ont conduits à analyser l'effet des protons mis en œuvre dans les deux faisceaux médicaux (76 et 201 MeV) du Centre de Protonthérapie de l'Institut Curie à Orsay (ICPO) sur deux lignées cellulaires humaines tumorales, et en partie sur une lignée fibroblastique. Les résultats font apparaître une différence de la valeur de l'EBR pour la survie au rayonnement dans la partie distale du SOBP (Spread-Out Bragg Peak) en fonction de l'énergie incidente, ainsi qu'une absence de corrélation entre la réponse en survie et l'incidence des cassures double-brin de l'ADN dans le faisceau de 76 MeV. Nous montrons cependant, grâce à l'utilisation de lignées défectives dans les voies de signalisation et de réparation des cassures double-brin de l'ADN par le D-NHEJ, que ces voies déterminent la valeur de l'EBR dans la partie distale du SOBP de 76 MeV. La réponse aux dommages de l'ADN dans cette région suggère que les dommages létaux appartiennent à la classe des "lésions complexes" (LMDS) de l'ADN. D'autre part, il apparaît que la fluence des particules constitue un paramètre majeur qui doit être pris en compte dans la partie distale des faisceaux.

The advent of Internet based digital services, and bandwidth-intensive business and personal applications has necessitated deployment of broadband network access technologies. Research analysts project that the U.S. market for broadband wireless networking will grow to nearly $2 billion by 2004 and Local Multipoint Distribution Services (LMDS) have enormous potential to emerge as the most reliable and cost-effective solution. However, in order to design and deploy LMDS systems, it is vital for system designers to be able to predict the behavior of mm-waves (28, 38 and 60GHz) during different weather conditions, especially rain. This research attempts to characterize the performance of pico-cell scenario broadband wireless channels by measuring path loss statistics during different weather conditions. Hardware and software components of a wideband direct-sequence spread spectrum (DSS) channel sounding system, used extensively throughout measurement campaigns, are discussed in detail in this dissertation. The measurement plan comprehensively describes the methodology, logistics, equipment setup, and calibration procedures for propagation measurement campaigns. Power Delay Profile (PDP) snapshots recorded during measurement campaigns are thoroughly analyzed using the 'Channel Imaging Analysis Suite' and Path Loss as well as Rain Attenuation statistics, calculated from recorded PDP data files, are classified and tabulated on the basis of measurement locations, propagation frequencies and antenna polarizations. Path Loss Exponent values are also calculated and Rain Attenuation statistics are compared with popular rain models. Results from Frequency Diversity measurement campaigns are also presented. / Master of Science