This thesis describes environmental data collection and transmission from the field to a server using Wi-Fi. Also discussed are components, radio wave propagation, received power calculations, and throughput tests. Measured receive power resulted close to calculated and simulated values. Throughput tests resulted satisfactory. The thesis provides detailed systematic procedures for Wi-Fi radio link setup and techniques to optimize the quality of a radio link.

The thesis is focused on the description of LTE system in terms of signaling on interfaces of LTE and EPC subsystems, such as UE initial network connection. The next section describes the types of diagnostic methods for mobile networks using OSS, drive testing and flow analysis. The thesis also aims at description of key performance indicators (RSRP, RSSI, etc.) and the proposal for measuring of the LTE network physical layer and the data transmission speed.

Lors du développement d’un nouvel avion, la phase précédant l’obtention du certificat de navigabilité est basée sur de nombreux essais au sol ou en vol. Dans le domaine spatial, le lancement est l’une des phases les plus critiques pour les systèmes et des essais au sol particulièrement rigoureux sont donc réalisés afin de vérifier que la charge utile ne sera pas endommagéeDes milliers de capteurs de pression ou de jauges de contrainte sont ainsi utilisés par les industriels du secteur pour ce type d’essais. Mais tous ces éléments sont aujourd’hui connectés par des fils, ce qui engendre des contraintes de temps, de coût et de limitation du nombre de capteurs. Leur remplacement par des réseaux de capteurs sans fil est une solution évidente qui permet également d’augmenter le nombre de points de mesure. Cependant, il n’existe aujourd’hui aucun protocole permettant de répondre aux attentes et besoins des professionnels de l’aéronautique et du spatial. Les travaux présentés dans cette thèse ont ainsi vocation à répondre aux besoins d’un canal de communication très haut débit, basse consommation, à faible puissance d’émission, fiable et autorisant un grand nombre de nœuds. Un prototype de couche physique basée sur un système OFDM ultra large bande a été réalisé, testé et validé, et permet d’atteindre un débit de plus de 200 Mbits/s. / To evaluate a system's compliance with its specified requirements, Hardware System Testing is conducted on the complete and integrated system. This phase is essential in all industry branches, especially in the very regulated and critical aerospace world. In the final phase of the development of an airplane, flight test equipment gathers and analyzes data during flight to evaluate the flight characteristics of the aircraft and validate its design, including safety aspects. One of the most critical tests is the measure of the pressure around the wings during flight. All new aircrafts are computer designed with the use of virtual wind tunnels. So very accurate measures have to be done on the aircraft to validate the model before the aircraft can be industrially produced. In the case of satellites, vibration and mechanical stress are two critical phenomena a satellite endures during launch. This is leading to the necessity for accurate ground tests using strain gauges or thermal sensors before allowing a launch. All such systems used by aircraft and satellite manufacturers today are wired systems. Sensors put around the wings or inside the satellite compartments are wired to a concentrator inside the cabin or the operator’s room. Although good performances are observed in terms of measurement accuracy, these systems have strong drawbacks. The two most important ones are the weight and the cost of both the systems and their installation. An additional drawback concerning its use on aircrafts is due to the installation of a system that increases the weight of the aircraft and immobilizes it during many weeks due to the routing of every cable inside the wings. The cost and the complexity of such systems don’t allow a great number of measurement points. The replacement of conventional measurement networks by wireless sensor networks is not an obvious solution. Despite the great interest in wireless sensor networks in the recent years, the technological barriers are still very numerous and there is currently no protocol to meet the expectations and needs of aviation professionals. The work presented in this thesis aims to meet the needs of a high-speed, low power consumption, low emission and reliable communication layer. Measurements have been performed in real conditions using commercial devices based on the protocol MB-OFDM/Wimedia, the most common standard that approach the need expressed, and have served to define the basis of the study and have helped to select best development tracks. Measurements have demonstrated also the specificity of the propagation channel. In order to reduce the time between the choice of algorithms and their testing in real conditions, it became necessary to use a design flow called Specification - Exploration – Improvement based on automatic synthesis tools. This development cycle has identified specific material needs for the design of the demonstrator.The physical layer is based on an OFDM system and UWB to achieve a data rate of over 150 Mb/s. A fully functional demonstrator, implemented on FPGA and composed of four communicating nodes was presented and has been used to validate the physical layer. Finally first steps to develop a digital ASIC are presented to achieve the goal of low power consumption

Today’s world is becoming increasingly automated and interconnected with billions of smart devices coming online, leading to a steep rise in energy consumption from small microelectronics. This coincides with an urgent push to transform global energy production to green energies, causing disruptions and energy shortages, and making the case for efficient energy use ever more pressing. Two major areas where high growth is expected are the fields of wireless communication and radar sensors. Millimeter-wave frequency bands are planned for fifth-generation (5G) and sixth-generation (6G) cellular communication standards, as well as automotive frequency-modulated continuous wave (FMCW) radar systems for driving assistance and automation. Fast silicon-based technologies enable these advances by operating at high maximum frequencies, such as the silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) technologies. However, even the fastest transistors suffer from low and energy expensive gains at millimeter-wave frequencies. Rather than incremental improvements in circuit efficiency using conventional approaches, a disruptive revolution for green microelectronics could be enabled by exploring the low-power benefits of the super-regenerative receiver for some applications. The super-regenerative receiver uses a regenerative oscillator circuit to increase the gain by positive feedback, through coupling energy from the output back into the input. Careful bias and control of the circuit enables a very large gain from a small number of transistors and a very low energy dissipation. Thus, the super-regenerative oscillator could be used to replace amplifier circuits in high data rate wireless communication systems, or as active reflectors to increase the range of FMCW radar systems, greatly reducing the power consumption. The work in this thesis presents fundamental scientific research into the topic of energy-efficient millimeter-wave super-regenerative receivers for use in civilian wireless communication and radar applications. This research work covers the theory, analysis, and simulations, all the way up to the proof of concept, hardware realization, and experimental characterization. Analysis and modeling of regenerative oscillator circuits is presented and used to improve the understanding of the circuit operation, as well as design goals according to the specific application needs. Integrated circuits are investigated and characterized as a proof of concept for a high data rate wireless communication system operating between 140–220 GHz, and an automotive radar system operating at 60 GHz. Amplitude and phase regeneration capabilities for complex modulation are investigated, and principles for spectrum characterization are derived. The circuits are designed and fabricated in a 130 nm SiGe HBT technology, combining bipolar and complementary metal-oxide semiconductor (BiCMOS) transistors. To prove the feasibility of the research concepts, the work achieves a wireless communication link at 16 Gbit/s over 20 cm distance with quadrature amplitude modulation (QAM), which is a world record for the highest data rate ever reported in super-regenerative circuits. This was powered by a super-regenerative oscillator circuit operating at 180 GHz and providing 58 dB of gain. Energy efficiency is also considerably high, drawing 8.8 mW of dc power consumption, which corresponds to a highly efficient 0.6 pJ/bit. Packaging and module integration innovations were implemented for the system experiments, and additional broadband circuits were investigated to generate custom quench waveforms to further enhance the data rate. For radar active reflectors, a regenerative gain of 80 dB is achieved at 60 GHz from a single circuit, which is the best in its frequency range, despite a low dc power consumption of 25 mW.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-04-18T15:01:39Z No. of bitstreams: 1 MARCELL MANFRIN BARBACENA - DISSERTAÇÃO PPGCC 2014..pdf: 1468565 bytes, checksum: b94d20ffdace21ece654986ffd8fbb63 (MD5) / Made available in DSpace on 2018-04-18T15:01:39Z (GMT). No. of bitstreams: 1 MARCELL MANFRIN BARBACENA - DISSERTAÇÃO PPGCC 2014..pdf: 1468565 bytes, checksum: b94d20ffdace21ece654986ffd8fbb63 (MD5) Previous issue date: 2014 / Impulsionadas pela crescente demanda por sistemas de segurança para proteção do indivíduo e da propriedade nos dias atuais, várias pesquisas têm sido desenvolvidas com foco na implantação de sistemas de vigilância por vídeo com ampla cobertura. Um dos problemas de pesquisa em aberto nas áreas de visão computacional e redes de computadores envolvem a escalabilidade desses sistemas, principalmente devido ao aumento do número de câmeras transmitindo vídeos em tempo real para monitoramento e processamento. Neste contexto, o objetivo geral deste trabalho é avaliar o impacto que a redução da taxa de transmissão dos fluxos de vídeos impõe na eficácia dos algoritmos de detecção de pessoas utilizados em sistemas inteligentes de videovigilância. Foram realizados experimentos utilizando vídeos em alta resolução no contexto de vigilância com tomadas externas e com um algoritmo de detecção de pessoas baseado em histogramas de gradientes orientados, nos quais se coletou, como medida de eficácia do algoritmo, a métrica de área sob a curva de precisão e revocação para, em sequência, serem aplicados os testes estatísticos de Friedman e de comparações múltiplas com um controle na aferição das hipóteses levantadas. Os resultados obtidos indicaram que é possível uma redução da taxa de transmissão em mais de 70% sem que haja redução da eficácia do algoritmo de detecção de pessoas. / Motivated by the growing demand for security systems to protect persons and properties in the nowadays, several researches have been developed focusing on the deployment of widearea video coverage surveillance systems. One open research problem in the areas of computer vision and computer networks involves the scalability of these systems, mainly due to the increasing number of cameras transmitting real-time video for monitoring and processing. In this context, the aim of this study was to evaluate the impact that transmission data-rate reduction of video streams imposes on the effectiveness of people detection algorithms used in intelligent video surveillance systems. With a proposed experimental design, experiments were performed using high-resolution wide-area external coverage video surveillance and using an algorithm for people detection based on histograms of oriented gradients. As a measure of effectiveness of the people detection algorithm, the metric of area under the precision-recall curve was collected and statistical tests of Friedman and multiple comparisons with a control were applied to evaluate the hypotheses. The results indicated that it is possible to reduce transmission rate by more than 70% without decrease in the effectiveness of the people detection algorithm.

Les Oscillateurs Spintronique (STNO) sont un nouveau type d'oscillateurs à fréquence radio (RF) qui utilisent l'effet « Spin Transfer Torque (STT) » dans un dispositif de jonction tunnel magnétique (MTJ) pour produire des oscillations entretenues à haute fréquence. Les STNO fournissent des solutions compactes pour la communication sans fil utilisées dans « wireless sensor network (WSN) » car leur fréquence peut être réglée via un courant continu. Ce réglage de fréquence permet de coder l'information via « Frequency shift keying (FSK) » par modulation numérique entre deux valeurs discrètes sans besoin d'un RF mixer, ce qui conduit à des composants RF potentiellement moins complexes. Dans cette thèse, la faisabilité de FSK a été étudiée pour des STNO MTJ à aimantation dans le plan en vue des communications sans fil utilisées dans les WSN. Les paramètres abordés dans cette étude sont le décalage de fréquence et le taux de modulation maximum, auquel la fréquence peut être décalée entre deux valeurs discrètes.Pour caractériser le taux de modulation maximum, des simulations macrospin et des études expérimentales ont été réalisées. Les simulations révèlent que le taux de modulation maximum pour FSK par courant est limité par la fréquence de relaxation du STNO, qui est de l'ordre de quelques centaines de MHz pour les STNO à aimantation dans le plan. Cela signifie que le taux de modulation maximum est limité à quelques centaines de Mbps, ce qui est ciblé ici pour une communication sans fil à débit de données modéré utilisées dans les WSN. Des études expérimentales du FSK par modulation de courant dans les STNO ont été effectuées pour des STNO autonomes et pour des STNO intégrés dans des systèmes hyperfréquences. Le FSK sur les STNO autonomes montre un décalage de fréquence autour de 200 MHz (le décalage de fréquence entre ≈ 8,9 GHz et ≈9,1 GHz) au taux de modulation de 10Mbps. Ce taux de modulation est inférieur à la limite supérieure donnée par la fréquence de relaxation du STNO comme prévu dans la simulation numérique en raison du bruit de phase relativement élevé du dispositif mesuré. Afin de tester la faisabilité du STNO dans les systèmes hyperfréquences, la modulation FSK des STNO a été effectuée sur un émetteur de carte de circuit imprimé (PCB). L'émetteur de PCB a été réalisé et développé par le partenaire du projet Mosaic FP7, TUD University. L'analyse confirme qu'un changement de fréquence autour de 300 MHz (le décalage de fréquence entre ≈9 GHz et ≈9,3 GHz) a été observé avec un taux de modulation de 20 Mbps. Le taux de données est limité par les caractéristiques de l'émetteur de PCB et non intrinsèque au STNO. Les études de simulation et d'expérience de la modulation de fréquence des STNO démontrent que le débit de données est adéquat pour la communication sans fil utilisée dans WSN.Cependant, d'autres améliorations dans les matériaux et la nanofabrication de STNO sont nécessaires pour améliorer la puissance de sortie et améliorer les caractéristiques spectrales des oscillations pour pousser les débits de données à des valeurs plus élevées avec un grand décalage de fréquence / Spin Transfer Nano-Oscillators (STNOs) are a novel type of Radio Frequency (RF) oscillators that make use of the Spin Transfer Torque (STT) effect in a magnetic tunnel junction (MTJ) device to produce high-frequency auto-oscillations. STNOs are attractive for applications in wireless communications due to their nanometric size and their frequency tuning capabilities via either a dc current or an applied field. This frequency tuning permits to encode the information via frequency shift keying (FSK) by digital modulation of the current or applied field between two discrete values without the need of an external RF mixer, leading to potentially less complex RF components. In this thesis, the feasibility of the digital frequency modulation (frequency shift keying (FSK)) using in-plane magnetized MTJ STNOs has been studied. For this, the maximum modulation rate, up to which a signal can be modulated or the frequency can be shifted between two discrete values, is an important aspect that need to be characterized.The characterization of the maximum modulation rate for in-plane magnetized MTJ STNOs has been studied via numerical macrospin simulation for different modulation configurations, i.e. modulation by a sinusoidal RF current and a sinusoidal RF field. It revealed that the maximum modulation rate under RF current modulation is given by the amplitude relaxation frequency fp of the STNO. Under RF field modulation, i.e. an RF field applied parallel to the easy axis, an enhanced modulation rate above fp can be achieved since the frequency is modulated directly via the field and not via the amplitude. This suggests an important strategy for the design of STNO-based wireless communications and to achieve high data rates. Besides numerical simulation, experimental studies of frequency shift keying (FSK) by current modulation in STNOs have been also demonstrated. The first demonstration is the FSK in standalone STNOs. The analysis confirmed that the FSK was successfully observed with a frequency shift around 200MHz (the frequency shift between ≈8.9 GHz and ≈9.1 GHz) at the modulation rate of 10Mbps. This modulation rate is however less than the upper limit, which is given by the relaxation frequency fp of the STNO as predicted in the numerical simulation, because of the relatively high phase noise of the device measured. In order to test the feasibility of the STNO within microwave systems, the FSK modulation of STNOs was performed on a printed circuit board (PCB) emitter. FSK with a frequency shift around 300MHz (the frequency shift between ≈9 GHz and ≈9.3 GHz) was observed with a modulation rate of 20 Mbps. The data rate here was limited by characteristics of the PCB emitter and not intrinsic to the STNO. The simulation and experiment studies of frequency modulation of STNOs demonstrate that the data rate of is adequate for wireless communication used in WSN. However, further improvements in materials and nanofabrication of STNOs are required to enhance the output power and improve the spectral characteristics of the oscillations to push the data rates to higher values with large frequency shift.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-07-19T18:40:00Z No. of bitstreams: 1 victorfernandes.pdf: 1092306 bytes, checksum: 4a32aa04ed1256ce18768180de089629 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-08-09T12:20:45Z (GMT) No. of bitstreams: 1 victorfernandes.pdf: 1092306 bytes, checksum: 4a32aa04ed1256ce18768180de089629 (MD5) / Made available in DSpace on 2017-08-09T12:20:45Z (GMT). No. of bitstreams: 1 victorfernandes.pdf: 1092306 bytes, checksum: 4a32aa04ed1256ce18768180de089629 (MD5) Previous issue date: 2017-02-23 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Essa dissertação tem por objetivo mostrar os benefícios em termos de desempenho e confiabilidade de um modelo de canal híbrido de baixa taxa de dados que pode ser aplicado a smart grids e internet das coisas. Esse modelo é chamado de hybrid power line communication-wireless single-relay channel (HSRC), que consiste do uso paralelo e mútuo dos modelos single-relay channel baseado em transmissão de dados via rede elétrica e sem fio. Para mostrar os benefícios do mesmo, foi considerado que a posição do nó de retransmissão é variável, também foi assumida alocação de potência uniforme e ótima sob restrição de potência, bem como o uso de dois protocolos de cooperação: amplify-andforward (AF) e decode-and-forward (DF). Além disso, essa dissertação discute o modelo HSRC incompleto, que é caracterizado pela perda de um enlace de comunicação de dados ou uma interface de comunicação de um nó no modelo HSRC. Primeiramente, foi apresentada a formulação matemática no que tange a taxa de dados ergódica e probabilidade de outage dos dois modelos mencionados. Em seguida, foi realizada a análise numérica dos mesmos. Por fim, os resultados numéricos foram analisados e mostraram que tanto o HSRC quanto o HSRC incompleto têm performance melhores do que o single-relay channel baseado em transmissão de dados via rede elétrica ou sem fio para todas as posições do nó de retransmissão e protocolos de cooperação considerados. Também, os resultados mostraram que a posição relativa entre os nós de fonte, destino e de retransmissão impactam significativamente na taxa de dados ergódica bem como na probabilidade de outage. Ainda, foi mostrado o impacto da perda de cada enlace de comunicação de dados ou interface de comunicação de um nó (HSRC incompleto) quando a posição relativa do nó de retransmissão muda. Por último, é mostrado que a diferença de desempenho entre os protocolos de cooperação AF e DF reduz quando o modelo HSRC é utilizado e que a melhor posição para o nó de retransmissão é entre os nós fonte e destino em termos de taxa de dados ergódica. / This dissertation aims at discussing improvements of performance and reliability of lowbit rate data communication technologies applied to smart grids and internet of things. In this regard, a comprehensive analysis of the ergodic achievable data rate and the outage probability of the so-called low-bit rate hybrid power line communication-wireless singlerelay channel (HSRC) model, which jointly and in parallel uses power line and wireless channels for data transmission, is presented. In order to highlight the benefits of such hybrid channel model for the target applications when the relative position of relay node changes, optimal and uniform power allocations under sum power constraint, amplifyand-forward (AF) and decode-and-forward (DF) cooperative protocols are taken into account. Moreover, this dissertation discusses the so-called incomplete HSRC which is characterized by the loss of one data communication link or node communication interface in a HSRC. Numerical results show that the HSRC and incomplete HSRC remarkably outperform power line or wireless single-relay channels for all considered positions of the relay node and the chosen cooperative protocols. Furthermore, these results show that the relative distances among source, relay and destination nodes significantly impact the achievable data rate and outage probabilities. In addition, the impact of each missing data communication link or node communication interface (incomplete HSRC) when the relay position, relative to source and destination nodes, changes is quantified. Finally, but not the least, it is shown that the performance difference between AF and DF protocols reduces when the HSRC model is taken into account and that the best relay position is in the middle between source and destination nodes.

Submitted by Geandra Rodrigues (geandrar@gmail.com) on 2018-04-18T18:31:55Z No. of bitstreams: 1 mateusdelimafilomeno.pdf: 952346 bytes, checksum: 0eb883e1ceabb6c297f58be445761d84 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-04-19T13:28:21Z (GMT) No. of bitstreams: 1 mateusdelimafilomeno.pdf: 952346 bytes, checksum: 0eb883e1ceabb6c297f58be445761d84 (MD5) / Made available in DSpace on 2018-04-19T13:28:21Z (GMT). No. of bitstreams: 1 mateusdelimafilomeno.pdf: 952346 bytes, checksum: 0eb883e1ceabb6c297f58be445761d84 (MD5) Previous issue date: 2018 / Esta dissertação tem como objetivo discutir as comunicações cooperativas híbrida e não híbrida aplicadas a sistemas de comunicação de dados em banda larga e em ambientes residenciais. Nesse sentido, o modelo de canal com retransmissor único em dois estágios é investigado para sistemas de comunicação em banda larga através da rede de energia elétrica. Este modelo de canal cooperativo é formado pela concatenação de dois canais com retransmissor único, cobrindo enlaces de comunicação de dados com até dois saltos. Além disso, um modelo de canal híbrido com retransmissor único, utilizando rede elétrica e ar, é analisado para sistemas de comunicação de dados em banda larga em que enlaces de até um salto são considerados. Expressões de taxas de dados alcançáveis ergódicas são derivadas para os modelos de canais cooperativos híbridos e não híbridos, a fim de compará-los. Devido às características de canais e ruído das redes de energia elétrica, os resultados numéricos são baseados em um conjunto de dados constituído por estimativas de canais e medições de ruído cobrindo a faixa de frequência de 1, 7 a 100 MHz e diferentes posições do nó retransmissor. Para os canais sem fio, o modelo HIPERLAN/2 com a mesma largura de banda é utilizado, considerando uma freqüência central de 5 GHz, enquanto o ruído aditivo é considerado branco gaussiano. Com relação aos sistemas de comunicação através da rede energia elétrica, mostra-se que o modelo de canal com retransmissor único em dois estágios é a melhor opção quando o enlace da fonte ao destino encontra-se severamente degradado (por exemplo, alta atenuação de sinal devido à longa distância entre nós fonte e destino e/ou presença de ruído de alta potência). Quando a degradação do canal não é acentuada, o modelo de canal de dois saltos é mais apropriado. Acerca dos sistemas híbridos, constata-se que, quando o retransmissor está no meio do caminho entre fonte e destino, o modelo de canal híbrido com retransmissor único apresenta o melhor desempenho em termos de taxa de dados alcançável ergódica, enquanto o modelo de canal híbrido de um salto oferece os melhores resultados para outros casos. / This dissertation aims to discuss hybrid and non-hybrid cooperative communications applied to in-home broadband data communication systems. In this sense, the two-stage single-relay channel model is investigated for in-home broadband power line communication systems. This cooperative channel model consists of the concatenation of two single-relay channels, covering data communication links with up to two hops. Moreover, a hybrid power line/wireless single-relay channel model is analyzed for broadband data communication systems, considering one-hop links. Ergodic achievable data rate expressions are derived for both hybrid and non-hybrid cooperative channel models in order to compare them. Due to channel and noise characteristics of electric power grids, numerical results are based on a data set constituted by power line channel estimates and additive noise measurements covering the frequency band from 1.7 up to 100 MHz and different relay positions. For wireless channels, the HIPERLAN/2 model with the same bandwidth is used, but at a central frequency of 5 GHz, while the additive noise is considered to be Gaussian white. Regarding only power line communication systems, it is shown that the two-stage single-relay channel model is the best option when the source-to-destination link is severely degraded (e.g., high signal attenuation due to the long distance between source and destination nodes and/or high-power noise presence). When the channel degradation is not severe, the two-hop channel model is more appropriate. Concerning hybrid systems, it is observed that, when the relay is halfway between source and destination nodes, the hybrid single-relay channel model presents the best performance in terms of ergodic achievable data rate, while the hybrid one-hop channel model yields the best results for other cases.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2015-12-16T14:08:06Z No. of bitstreams: 1 michellesoarespereira.pdf: 4441399 bytes, checksum: 19c7a2a01a8d195e44aa21afaacc4de5 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2015-12-16T15:15:37Z (GMT) No. of bitstreams: 1 michellesoarespereira.pdf: 4441399 bytes, checksum: 19c7a2a01a8d195e44aa21afaacc4de5 (MD5) / Made available in DSpace on 2015-12-16T15:15:37Z (GMT). No. of bitstreams: 1 michellesoarespereira.pdf: 4441399 bytes, checksum: 19c7a2a01a8d195e44aa21afaacc4de5 (MD5) Previous issue date: 2015-05-29 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Este trabalho aborda a análise de protocolos de cooperação para melhorar o desempenho de sistemas powerline communication (PLC). O estudo se baseia em um conjunto de dados de canais PLC in-home. As análises discutidas abordam a capacidade teórica do canal quando protocolos amplify-and-forward (AF) e decode-and-forward (DF) são considerados. Estudos similares são realizados a respeito da taxa máxima de dados adquirida quando Hermitian − symmetric orthogonal frequency division multiplexing (HS-OFDM) juntamente com as técnicas equal gain combining (EGC), selection combining (SC) and maximal ratio combining (MRC) são considerados. Além disso, são analisadas as influências da largura de banda de freqüência e da alocação ótima e uniforme da potência de transmissão. Os resultados obtidos mostram que a distância relativa entre os nós da fonte, relay e destino impactam severamente no desempenho do sistema. Os resultados numéricos revelam uma gama de potência de transmissão ótima e de frequência em que a melhoria pode ser verificada. Tambà c m observa-se que a vantagem do protocolo DF relacionada com a do protocolo AF termina quando o erro de detecção de símbolo no relay atinge um limiar. Adicionalmente, mostra-se que as técnicas de combinação, MRC e SC apresentam resultados semelhantes. Embora MRC ofereça desempenho ligeiramente melhor, considerando a complexidade computacional, recomenda-se a técnica SC. Finalmente, uma análise de máxima taxa de dados adquirida, considerando HS-OFDM com equalização baseada nos critérios zero forcing e minimum mean square error, mostra que o primeiro oferece quase o mesmo desempenho que o último. / This work focuses on analyses of cooperative protocols to enhance the performance of in-home power line communication (PLC) systems based on a data set consisting of measurements of in-home PLC channels. The discussed analyses address theoretical channel capacity when amplify-and-forward (AF) and decode-and-forward (DF) protocols are considered. Similar investigations are performed for the maximum data rate attained by using Hermitian-symmetric orthogonal frequency division multiplexing (HS-OFDM) together with equal gain combining (EGC), selection combining (SC) and maximal ratio combining (MRC) techniques. Also, the influences of optimally and uniformly allocated transmission power and frequency bandwidth are analyzed. The attained results show that the relative distance among source, relay, and destination nodes severely impacts the system performance. Also, numerical results reveal a range of optimal transmission power and frequency bandwidth in which improvement can be verified. Moreover, it is observed that the advantage of the DF protocol related to AF one ends, when the symbol detection error achieves a threshold. Additionally, it is shown that among the combining techniques, MRC and SC present similar results with MRC offering slightly better performance, but considering computational complexity, a decision in favor of SC is recommended. Finally, a maximum data rate analysis of HS-OFDM with frequency domain equalizer based on zero forcing and minimum mean square error shows that the former scheme offers almost the same performance as the latter.

For ultra-high speed communication systems at high center frequencies above 100 GHz, we propose a disruptive change in system architecture to address major issues regarding amplifier chains with a large number of amplifier stages. They cause a high noise figure and high power consumption when operating close to the frequency limits of the underlying semiconductor technologies. Instead of scaling a classic homodyne transceiver system, we employ repeated amplification in single-stage amplifiers through positive feedback as well as synthesizer-free self-mixing demodulation at the receiver to simplify the system architecture notably. Since the amplitude and phase information for the emerging oscillation is defined by the input signal and the oscillator is only turned on for a very short time, it can be left unstabilized and thus come without a PLL. As soon as gain is no longer the most prominent issue, relaxed requirements for all the other major components allow reconsidering their implementation concepts to achieve further improvements compared to classic systems. This paper provides the first comprehensive overview of all major design aspects that need to be addressed upon realizing a SPARS-based transceiver. At system level, we show how to achieve high data rates and a noise performance comparable to classic systems, backed by scaled demonstrator experiments. Regarding the transmitter, design considerations for efficient quadrature modulation are discussed. For the frontend components that replace PA and LNA amplifier chains, implementation techniques for regenerative sampling circuits based on super-regenerative oscillators are presented. Finally, an analog-to-digital converter with outstanding performance and complete interfaces both to the analog baseband as well as to the digital side completes the set of building blocks for efficient ultra-high speed communication.