Rapid growth in the field of communications industry has led to newer opportunities and challenges in the design of CMOS based monolithic integrated circuits. ASK modulators are a class of digital modulators which are known for their relative simplicity of implementation for low cost applications in the industrial and biomedical domains. This thesis presents a LC-based CMOS Amplitude Shift Keying (ASK) modulator scheme which demonstrates promising capability for radio frequency designs. This work describes the design and implementation of differential cross-coupled NMOS only LC power oscillator with ASK modulation to operate at 2.4 GHz frequency. In this work, 65nm CMOS process technology has been used for implementation. The work mainly focused on system parameters such as oscillation frequency, output signal power, power consumption and phase noise. The LC tank was created with a centre-tap on-chip differential spiral inductor and a Metal Insulator Metal (MIM) capacitor. The method of a current mirror with switching technique is employed for biasing the LC oscillator as well as ASK modulation output. The oscillator circuit has been optimised by using a simulation based approach to study the design and measurements to gain a greater insight into the performance of the ASK modulator. An output signal power of -1.59dBm at 2.30 GHz with a phase noise of -115.39dBc/Hz@1MHz and a power consumption of 5.92mW has been achieved at the layout level. Optimal ASK modulated output performance has been obtained for the data rate of up to around 40Mbits/s. In this thesis, simulation results have been presented for both the schematic and the layout levels.

No description available.

Au cours de la dernière décennie, les communications optiques en espace libre (FSO) ont pris de l’ampleur dans les deux domaines académiques et industriels. L’importance de FSO s’appuie sur la possibilité de faire un système de transmission économique et écologique avec un débit élevé et sans licence à l’opposition des systèmes de transmission radiofréquences (RF). Dans la plupart des travaux antécédents sur les systèmes multi-émetteurs, seulement les canaux décorrélés ont été considérés. Un canal décorrélé nécessite un espace suffisant entre les émetteurs. Cette condition devient difficile et non-réalisable dans certaines applications. Pour cette raison, nos études se focalisent sur les performances des codes à répétition RC (Repitition Codes) et les codes OSTBC (Orthogonal Space-Time Block Codes) dans des canaux log-normaux corrélés en utilisant une modulation d’intensité et une détection directe (IM/DD). En addition, les effets des différentes conditions météorologiques sur le taux d’erreur moyen (ABER) sont étudiés. Les systèmes FSO à multi-entrées/ multi-sorties MIMO (Multiple-Input Multiple-Output) avec une modulation SSK (Space Shift Keying) ont été abordés. Les résultats obtenus montrent que la SSK est supérieure aux RC avec une modulation d’impulsion (Multiple Pulse Amplitude Modulation) pour toute efficacité spectrale égale ou supérieure à 4 bit/s/Hz. Nous avons aussi analysé les performances d’un système à sauts multiples (Multi-Hop) et des relais à transmission directe (forward relays). Nos simulations montrent que le système ainsi considéré est efficace pour atténuer les effets météorologiques et les pertes géométriques dans les systèmes de communication FSO. Nous avons montré qu’un tel système avec plusieurs entrées et une sortie (MISO, i.e. multiple-input single-output) à sauts multiples est supérieur à un système MISO avec un lien direct (direct link) avec une forte atténuation. Pour satisfaire la demande croissante des réseaux de communication à débits élevés, la communauté scientifique s'intéresse de plus en plus aux systèmes FSO avec des relais full-duplex (FD). Pour ces derniers systèmes, nous avons étudié la probabilité d'erreur moyenne (ABER) et nous avons analysé leurs performances. En considérant des différentes conditions de transmission, les performances de relais FD ont été comparées à celles d'un système avec un lien direct ou des relais half-duplex. Les résultats obtenus montrent que les relais FD ont le minimum ABER. En conséquence, les résultats obtenus dans cette thèse sont très prometteurs pour la prochaine génération de FSO. / Free-space optical (FSO) communication has been the subject of ongoing research activities and commercial attention in the past few years. Such attention is driven by the promise of high data rate, license-free operation, and cheap and ecological friendly means of communications alternative to congested radio frequency communications. In most previous work considering multiple transmitters, uncorrelated channel conditions have been considered. An uncorrelated channel requires sufficient spacing between transmitters. However, this can be difficult and may not be always feasible in some applications. Thereby, this thesis studies repetition codes (RCs) and orthogonal space-time block codes performance in correlated log-normal FSO channels using intensity modulation and direct detection (IM/DD). Furthermore, the effect of different weather conditions on the average bit error rate (ABER) performance of the FSO links is studied. Multiple-input multiple-output (MIMO) FSO communication systems using space shift keying (SSK) modulation have been also analyzed. Obtained results show that SSK is a potential technique for spectral efficiencies equal or greater than 4 bits/s/Hz as compared to RCs with multiple pulse amplitude modulations. The performance analysis of a multi-hop decode and forward relays for FSO communication system using IM/DD is also considered in this thesis. It is shown that multi-hop is an efficient technique to mitigate atmospheric turbulence and different weather attenuation effects and geometric losses in FSO communication systems. Our simulation results show that multiple-input single-output (MISO) multi-hop FSO systems are superior to direct link and MISO systems over links exhibiting high attenuation. Meeting the growing demand for higher data rates communication networks, a system with full-duplex (FD) relays is considered. For such a system, the outage probability and the ABER performance are analyzed under different turbulence conditions, misalignment error and path loss effects. FD relays are compared with the direct link and half-duplex relays. Obtained results show that FD relays have the lowest ABER and the outage probability as compared to the two other systems. Finally, the obtained results in this thesis are very promising towards the next generation of FSO systems.

This thesis deals with optical synthesis of unmodulated and modulated microwave signals. Generation of microwave signals based on optical heterodyning is discussed in detail. The effect of phase noise of laser on heterodyned output has been studied for different phase noise profiles. Towards this, we propose a generic algorithm to numerically model the linewidth broadening of a laser due to phase noise. Generation of microwave signals is demonstrated practically by conducting an optical heterodyning experiment. Signals ranging in frequency from 12.5 MHz to 27 GHz have been generated. Limitations of optical heterodyning based approach in terms of phase noise performance and frequency stability are discussed and practically demonstrated. A hardware-efficient Optical Phase Locked Loop (OPLL) is proposed to overcome these issues. Phase noise tracking performance of the proposed OPLL has been experimentally demonstrated. Phase noise values as low as -105 dBc/Hz at 10 KHz offset have been achieved. Optical modulators, owing to their extremely low electro-optic response time, can support high frequency modulating signals. This makes them highly attractive in comparison to their microwave counterparts. In this thesis, we propose techniques to generate microwave signals modulated at very high bit rates by down-converting the corresponding modulated optical signals to microwave domain. Down-conversion required for this process is achieved by optical heterodyning. The proposed concept has been theoretically analyzed, simulated and experimentally validated. Amplitude Modulated and ASK modulated microwave signals have been generated as Proof-of-Concept. Limitations posed by OPLL in generation of angle modulated microwave signals by optical heterodyning have been brought out. Schemes overcoming these limitations have been proposed towards generation of BPSK and QPSK modulated microwave signals. Integrated Optics (IO) technology has been studied as a means of implementation of the proposed concepts. IO components like Sinusoidal bends, Y-branch splitters and Electro-Optic-Modulators (EOMs) have been designed towards optical synthesis of modulated microwave signals. Propagation of modulated optical signal through these IO components has also been studied. An all-optic scheme based on Optical Beam Forming is proposed for transmission of QPSK modulated signal. Limitation of phase-shifting based approach, in terms of beam-squint, has been brought out. True-Time-Delay based approach has been proposed for applications demanding wide instantaneous bandwidth to avoid beam-squint. Algorithms / numerical methods required for analyses and simulations associated with the above-mentioned tasks have been evolved. This study is envisaged to provide useful insight into the realization of high-speed, compact, light-weight data transmitting systems based on Integrated Optics for future onboard spacecraft applications. This work, we believe, is a step towards realization of an Integrated Optic System-on-Chip solution for specific microwave data transmission applications.

L'UWB (Ultra Wide Band) consiste à transmettre des signaux entre 3.1 et 10.6 GHz avec une puissance limitée à -41.3 dBm/MHz. Pour les communications hauts débits (100 à 500 Mbit/s) et courtes portées (1 à 10 m), les solutions de l'état de l'art reposent sur des traitements numériques complexes. Mitsubishi ITE propose une solution alternative multi-bandes (MB) impulsionnelle basée sur un récepteur non-cohérent. La démodulation OOK est effectuée par une détection d'énergie originale avec un seuillage adapté dynamiquement suivant les conditions de propagation. La parallélisation complète de ce système MB-OOK permet à la fois d'éviter les interférences inter-symboles et de récupérer la quasi totalité de l'énergie disponible. En outre, l'approche impulsionnelle limite les évanouissements du signal sur canal multi-trajets. La comparaison des systèmes MB-OOK et MB-OFDM démontre la pertinence de la solution proposée pour des applications très hauts débits, courte portée et faible consommation.

<p>The task of the project was to evaluate a differential phase shift keying demodulation technique by replacing a Mach-Zehnder interferometer receiver with an optical filter (Fiber Bragg Grating). Computer simulations were made with single optical transmission, multi channel systems and transmission with combined angle/intensity modulated optical signals. The simulations showed good results at both 10 and 40 Gbit/s. Laboratory experiments were made at 10 Gbit/s to verify the simulation results. It was found that the demodulation technique worked, but not with satisfactory experimental results. The work was performed at Eindhoven University of Technology, Holland, within the framework of the STOLAS project at the department of Electro-optical communication.</p>

The task of the project was to evaluate a differential phase shift keying demodulation technique by replacing a Mach-Zehnder interferometer receiver with an optical filter (Fiber Bragg Grating). Computer simulations were made with single optical transmission, multi channel systems and transmission with combined angle/intensity modulated optical signals. The simulations showed good results at both 10 and 40 Gbit/s. Laboratory experiments were made at 10 Gbit/s to verify the simulation results. It was found that the demodulation technique worked, but not with satisfactory experimental results. The work was performed at Eindhoven University of Technology, Holland, within the framework of the STOLAS project at the department of Electro-optical communication.

Direct-Sequence Code Division Multiple Access (DS-CDMA), over the last few years, has become a popular technique and finds a place in many modern communication systems. The performance of this technique is closely linked to the signature (or spreading) sequences employed in the system. In the past, there have been many successful attempts by research groups to construct families of signature sequences that offer the potential gains promised by theoretical bounds. In this thesis, we present constructions of families of signature sequences over the AM-PSK and QAM alphabet with low correlation. In this thesis, we construct a family of sequences over the 8-ary AM-PSK constella- tion, Family AOpt(16) that is asymptotically optimal with respect to the Welch bound on maximum magnitude of correlation for complex sequences. The maximum magnitude of correlation for this family, θmax, is upper bounded by √N , where N is the period of the sequences. The 8-ary AM-PSK constellation is a subset of the 16-QAM constellation. We also construct two families of sequences over 16-QAM, Family A16A, and Family A16,B , with the maximum magnitude of correlation upper bounded by √2√N . We construct a family, A(M 2), of sequences over the 2m+1-ary AM-PSK constellation of period N = 2r- 1 and family size (N + 1)/2m-1 . The 2m+1-ary AM-PSK constellation is a subset of the M 2-QAM constellation with M =2m . The maximum nontrivial normalized correlation parameter is bounded above by θmax < a √N where a ranges from 1.34 in the case of M 2 = 16 to √5 for large m. Apart from low correlation values, the family possesses several interesting and useful features. In Family A(M 2), users have the ability to transmit 2m bits of data per period of the spreading sequence. The sequences in Family A(M 2) are balanced; all points from the 2m+1-ary AM-PSK constellation occur approximately equally often in sequences of long period. The Euclidean distance between the signals assigned to a particular user in A(M 2), corresponding to different data symbols, is larger than the corresponding value for the case when 2m+1-PSK modulation and spreading is used. Perhaps most interestingly, Family A(M 2) permits users on the reverse link of a CDMA system to communicate asynchronously at varying data rates by switching between different QAM constellations. Family A(M 2) is compatible with QPSK sequence families S(p) in the sense that the maximum correlation magnitude is increased only slightly if one adds sequences from (p) S(p)\ S(0) to Family A(M 2). We also construct families of sequences over AM-PSK that tradeoff data rate per sequence period and θmax for a given family size. We have extended the construction of sequences over AM-PSK constellation to construct sequences over the M 2-QAM constellation for M =2m . The QAM sequence families, Families (AM 2), have size, data rate and minimum squared Euclidean distance same as the corresponding AM-PSK construction but have higher values of θmax. Also included in the thesis are constructions for large families of sequences over the M 2-QAM alphabet.

La performance de démodulation des signaux GNSS existants, GPS L1 C/A, L2C ou L5, est satisfaisante en environnements ouverts où le C/N0 disponible est assez élevé. Cependant, en milieu urbain, le niveau de C/N0 du signal reçu est souvent très bas et est affecté de variations rapides qui peuvent nuire la démodulation des messages GNSS. Donc, car les applications du marché de masse sont appelées à être déployées dans ces environnements, il est nécessaire d'étudier et de chercher des méthodes de démodulation/décodage qui améliorent la performance de démodulation des messages GNSS dans ces environnements. Il est aussi nécessaire de considérer les nouveaux signaux GPS L1C et GALILEO E1. Ces signaux doivent fournir un service de positionnement par satellite dans tout type d'environnement, et spécifiquement en milieu urbain. Ainsi, cette thèse analyse aussi les performances de démodulation des nouveaux signaux GNSS tels que définis dans les documents publics actuels. De plus, de nouvelles structures de message GALILEO E1 sont proposées et analysées afin d'optimiser la performance de démodulation ainsi que la quantité d'information diffusée. En conséquence, le but principal de cette thèse est d'analyser et améliorer la performance de démodulation des signaux GNSS ouverts au public, spécifiquement en milieu urbain, et de proposer de nouvelles structures de messages de navigation pour GALILEO E1. La structure détaillée des chapitres de cette thèse est donnée ci-après. En premier lieu, le sujet de cette thèse est introduit, ses contributions originales sont mises en avant, et le plan du rapport est présenté. Dans le 2ième chapitre, la thèse décrit la structure actuelle des signaux GNSS analysés, en se concentrant sur la structure du message de navigation, les codages canal implantés et leurs techniques de décodage. Dans le 3ième chapitre, deux types de modèles de canal de propagation sont présentés pour deux différents types de scénarios. D'un côté, un canal AWGN est choisi pour modéliser les environnements ouverts. De l'autre côté, le modèle mathématique de Perez-Fontan d'un canal mobile est choisi pour représenter les environnements urbains et indoor. Dans le 4ième chapitre, une tentative pour effectuer une prédiction binaire d'une partie du message de navigation GPS L1 C/A est présentée. La prédiction est essayée en utilisant les almanachs GPS L1 C/A, grâce à un programme de prédiction à long terme fourni par TAS-F, et des méthodes de traitement du signal: estimation spectrale, méthode de PRONY et réseau de neurones. Dans le 5ème chapitre, des améliorations à la performance de démodulation du message de GPS L2C et L5 sont apportées en utilisant leur codage canal de manière non traditionnelle. Deux méthodes sont analysées. La première méthode consiste à combiner les codages canal internes et externes du message afin de corriger davantage de mots reçus. La deuxième méthode consiste à utiliser les probabilités des données d'éphémérides afin d'améliorer le décodage traditionnel de Viterbi. Dans le 6ième chapitre, la performance de démodulation des messages de GPS L1C et du Open Service GALILEO E1 est analysée dans différents environnements. D'abord, une étude de la structure de ces deux signaux est présentée pour déterminer le C/N0 du signal utile reçu dans un canal AWGN. Puis, la performance de démodulation de ces signaux est analysée grâce à des simulations dans différents environnements, avec un récepteur se déplaçant à différentes vitesses et avec différentes techniques d'estimation de la phase porteuse du signal. / The demodulation performance achieved by any of the existing GPS signals, L1 C/A, L2C or L5, is satisfactory in open environments where the available C/N0 is quite high. However, in indoor/urban environments, the C/N0 level of the received signal is often very low and suffers fast variations which can further affect the GNSS messages demodulation. Therefore, since the mass-market applications being designed nowadays are aimed at these environments, it is necessary to study and to search alternative demodulation/decoding methods which improve the GNSS messages demodulation performance in these environments. Moreover, new GNSS signals recently developed, such as GPS L1C and GALILEO E1, must also be considered. These signals aim at providing satellite navigation positioning service in any kind of environment, giving special attention to indoor and urban environments. Therefore, the demodulation performances of the new GNSS signals as they are defined in the current public documents is also analysed. Moreover, new GALILEO E1 message structures are proposed and analysed in order to optimize the demodulation performance as well as the quantity of broadcasted information. Therefore, the main goal of this dissertation is to analyse and to improve the demodulation performance of the current open GNSS signals, specifically in indoor and urban environments, and to propose new navigation message structures for GALILEO E1. A detailed structure of this dissertation sections is given next. First, the subject of this thesis is introduced, original contributions are highlighted, and the outline of the report is presented. Second, this dissertation begins by a description of the current structure of the different analysed GNSS signals, paying special attention to the navigation message structure, implemented channel code and their decoding techniques. In the third section, two types of transmission channel models are presented for two different types of environments. On one hand, an AWGN channel is used to model the signal transmission in an open environments. On the other hand, the choice of a specific mobile channel, the Perez-Fontan channel model, is chosen to model the signal transmission in an urban environment. In the fourth section, a tentative to make a binary prediction of the broadcasted satellite ephemeris of the GPS L1 C/A navigation message is presented. The prediction is attempted using the GPS L1 C/A almanacs data, a long term orbital prediction program provided by TAS-F, and some signal processing methods: spectral estimation, the PRONY method, and a neural network. In the fifth section, improvements to the GPS L2C and GPS L5 navigation message demodulation performance are brought by using their channel codes in a non-traditional way. Two methods are inspected. The first method consists in sharing information between the message inner and outer channel codes in order to correct more received words. The second method consists in using the ephemeris data probabilities in order to improve the traditional Viterbi decoding. In the sixth section, the GPS L1C and GALILEO E1 Open Service demodulation performance is analysed in different environments. First, a brief study of the structure of both signals to determine the received C/N0 in an AWGN channel is presented. Second, their demodulation performance is analysed through simulations in different environments, with different receiver speeds and signal carrier phase estimation techniques.

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.