6 research outputs found
Open Systems, Entanglement and Quantum Optics
The subject of this book is a presentation of some aspects of modern theory of open quantum systems. It introduces several up-to- date topics, such as detecting quantum entanglement, modeling of quantum noise, quantum communication processes, and computational complexity in the analysis of quantum operations. Also discussed are light propagation in optically dressed media, as well as entropy and information measure for quantized electromagnetic fields media. This book is intended for researchers and students interested in the theory of open quantum systems, quantum information theory and quantum systems interacting with electromagnetic fields
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Adaptive Coded Modulation Classification and Spectrum Sensing for Cognitive Radio Systems. Adaptive Coded Modulation Techniques for Cognitive Radio Using Kalman Filter and Interacting Multiple Model Methods
The current and future trends of modern wireless communication systems place heavy demands on fast data transmissions in order to satisfy end users’ requirements anytime, anywhere. Such demands are obvious in recent applications such as smart phones, long term evolution (LTE), 4 & 5 Generations (4G & 5G), and worldwide interoperability for microwave access (WiMAX) platforms, where robust coding and modulations are essential especially in streaming on-line video material, social media and gaming. This eventually resulted in extreme exhaustion imposed on the frequency spectrum as a rare natural resource due to stagnation in current spectrum management policies. Since its advent in the late 1990s, cognitive radio (CR) has been conceived as an enabling technology aiming at the efficient utilisation of frequency spectrum that can lead to potential direct spectrum access (DSA) management. This is mainly attributed to its internal capabilities inherited from the concept of software defined radio (SDR) to sniff its surroundings, learn and adapt its operational parameters accordingly. CR systems (CRs) may commonly comprise one or all of the following core engines that characterise their architectures; namely, adaptive coded modulation (ACM), automatic modulation classification (AMC) and spectrum sensing (SS).
Motivated by the above challenges, this programme of research is primarily aimed at the design and development of new paradigms to help improve the adaptability of CRs and thereby achieve the desirable signal processing tasks at the physical layer of the above core engines. Approximate modelling of Rayleigh and finite state Markov channels (FSMC) with a new concept borrowed from econometric studies have been approached. Then insightful channel estimation by using Kalman filter (KF) augmented with interacting multiple model (IMM) has been examined for the purpose of robust adaptability, which is applied for the first time in wireless communication systems. Such new IMM-KF combination has been facilitated in the feedback channel between wireless transmitter and receiver to adjust the transmitted power, by using a water-filling (WF) technique, and constellation pattern and rate in the ACM algorithm. The AMC has also benefited from such IMM-KF integration to boost the performance against conventional parametric estimation methods such as maximum likelihood estimate (MLE) for channel interrogation and the estimated parameters of both inserted into the ML classification algorithm. Expectation-maximisation (EM) has been applied to examine unknown transmitted modulation sequences and channel parameters in tandem. Finally, the non-parametric multitaper method (MTM) has been thoroughly examined for spectrum estimation (SE) and SS, by relying on Neyman-Pearson (NP) detection principle for hypothesis test, to allow licensed primary users (PUs) to coexist with opportunistic unlicensed secondary users (SUs) in the same frequency bands of interest without harmful effects. The performance of the above newly suggested paradigms have been simulated and assessed under various transmission settings and revealed substantial improvements
Model Order Reduction
An increasing complexity of models used to predict real-world systems leads to the need for algorithms to replace complex models with far simpler ones, while preserving the accuracy of the predictions. This three-volume handbook covers methods as well as applications. This third volume focuses on applications in engineering, biomedical engineering, computational physics and computer science
Etude de la Performance du Contrôle Autonome d'Intégrité pour les Approches à Guidage Vertical
L'Organisation de l'Aviation Civile Internationale (OACI) a reconnu la navigation par satellite, Global Navigation Satellite System (GNSS), comme un élément clé des systèmes CNS/ATM (Communications, Navigation, and Surveillance / Air Traffic Management) et comme une base sur laquelle les Etats peuvent s'appuyer afin de délivrer des services de navigation aérienne performants. Mais l'utilisation des systèmes de navigation par satellites pour des applications de type aviation civile ne va pas sans répondre à des exigences en terme de précision, de continuité, d'intégrité et de disponibilité. Ces exigences opérationnelles liées aux différentes phases de vol requièrent pour les systèmes GNSS l'appui de moyens d'augmentation tels ceux utilisant des stations de surveillance sol pour vérifier la validité des signaux satellitaires et calculer des corrections ou ceux fonctionnant de manière autonome, tel le RAIM (Receiver Autonomous Integrity Monitoring). Ce dernier moyen est particulièrement intéressant car il engendre des coûts de mise en oeuvre réduits et il constitue à l'heure actuelle un moyen simple et efficace d'effectuer des approches de non précision. La prochaine mise en place du système de navigation européen Galileo ainsi que la modernisation du système historique américain GPS vont entrainer une nette amélioration, à la fois en terme de nombre et de qualité, des mesures satellitaires disponibles, laissant entrevoir la possible utilisation du RAIM pour des approches à guidage vertical, très intéressantes du point de vue opérationnel. Les différentes notions liées aux exigences de l'aviation civile sont définies dans le chapitre 2, notamment les différents critères de performance. Chaque phase de vol, et plus particulièrement chaque catégorie d'approche, y est également décrite ainsi que les niveaux de performance associés. Plusieurs types d'erreurs sont susceptibles d'affecter les mesures GNSS. Parmi elles il convient de distinguer les erreurs systématiques ou nominales des perturbations liées à une défaillance du système de navigation. Ces dernières peuvent être dues soit à un problème matériel survenant au niveau d'un des satellites ou du récepteur, soit d'une perturbation de l'environnement de propagation des signaux GNSS. Ces aspects sont adressés dans le chapitre 3 à l'issu duquel un modèle complet de mesure de pseudo distance GNSS est proposé. Les algorithmes de contrôle d'intégrité ont été développés pour détecter ces anomalies et exclure les mesures erronées de la solution de navigation. Il s'agit de méthodes uniquement basées sur la redondance des mesures satellite, éventuellement enrichies de celles d'autres capteurs, devant déterminer si les conditions sont réunies pour occasionner une erreur de position dépassant une limite spécifiée. Devant répondre à des exigences relatives aux performances décrites dans le chapitre 2, le choix du type d'algorithme de contrôle d'intégrité est laissé à l'utilisateur. Le chapitre 4 étudie plusieurs de ces méthodes et propose des innovations.l'algorithme de surveillance doivent être réexaminées. En effet, elles pourraient avoir une plus petite amplitude et des taux d'occurrence qui ne sont pas clairement définie pour le moment. C'est dans ce contexte que la Direction Générale de l'Aviation Civile a initié cette thèse dont l'objectif est d'évaluer le potentiel des algorithmes RAIM pour les approches à guidage vertical. On tachera de savoir dans quelle mesure l'augmentation du nombre de satellites et de l'amélioration de qualité de mesures de pseudodistance pourraient elles permettre l'utilisation de RAIM les approches à guidage vertical. Cette thèse est organisée de la manière suivante. Tout d'abord, le chapitre 2 présente les exigences de l'aviation civile quant à l'utilisation du GNSS. Cette section inclut une description des différentes phases de vol et plus particulièrement des phases d'approche. Elle introduit les concepts RNAV et RNP et définit également les critères de performance requis par l'OACI pour chaque les phases de vol. Finalement, les termes de détectionet d'exclusion de faute, plus spécifiques au contrôle autonome d'intégrité, sont définis. Le chapitre 3 a pour objectif de donner un modèle complet des mesures GNSS en adressant aussi bien le mode nominal et le mode défectueux, en tenant compte des pannes satellite et de l'effet des interférences. Le chapitre 4 a pour but d'étudier differents algorithmes RAIM mais certains aspects généraux comme l'estimation de la position d'utilisateur ou le calcul du plus petit biais sur une mesure de pseudo distance entrainant une erreur de positionnement sont d'abord présentés. La manière dont les exigences aviation civile et le modèle d'erreur sont interprétés afin de constituer les paramètres d'entrée des algorithmes RAIM est discutée au chapitre 5. Le chapitre 6 présente des résultats des simulations qui ont été effectuées pour évaluer la performance RAIM pour les approches à guidage vertical. Cette évaluation a été réalisée grâce à des simulations Matlab. Finalement, le chapitre 7 résume les principaux résultats de ce travail de doctorat et propose quelques pistes de reflexion quant à de futurs travaux. ABSTRACT : The International Civil Aviation Organization (ICAO) has recognized the Global Navigation Satellite System (GNSS) as a key element of the Communications, Navigation, and Surveillance / Air Traffic Management (CNS/ATM) systems as well as a foundation upon which States can deliver improved aeronautical navigation services. But civil aviation requirements can be very stringent and up to now, the bare systems cannot alone be used as a means of navigation. Therefore, in order to ensure the levels required in terms of accuracy, integrity, continuity of service and availability, ICAO standards define different architectures to augment the basic constellations. Some of them use control stations to monitor satellite signals and provide corrections, others only use measurement redundancy. This study focuses on this last type of augmentation system and more particularly on Receiver Autonomous Integrity Monitoring (RAIM) techniques and performance. RAIM is currently a simple and efficient solution to check the integrity of GNSS down to Non Precision Approaches. But the future introduction of new satellite constellations such as the European satellite navigation system Galileo or modernized Global Positioning System (GPS) will imply great improvements in the number as well as the quality of available measurements. Thus, more demanding phases of flight such as APproaches with Vertical guidance could be targeted using RAIM to provide integrity monitoring. This would result in some interesting safety, operational and environmental benefits. This Ph.D. evaluates the potential capacity of RAIM algorithms to support approach and landing phases of flight with vertical guidance. A thorough bibliographic study of civil aviation requirements is first presented; some candidate LPV200 signal in space performance requirements not yet included in the ICAO standards are also provided. To evaluate GNSS positioning performance, pseudorange measurements have to be modeled as precisely as possible and especially the different errors that affect them. The main sources of error are signal propagation delays caused by the ionosphere and the troposphere, space vehicle clock error, satellite position estimation error, multipath, receiver errors which main source is code tracking loop noise. Thus, these errors can be due to the space segment, the control segment or the user segment. Systematic errors are gathered in the fault free case measurement model; unusual errors, that may cause a dangerous positioning failure and that may have to be detected, are gathered in the faulty case measurement model. Finally, a complete model of pseudo range measurements, including interference effects and satellite failures, is given. A special attention is put on the User Equivalent Range Error (UERE) variance computation. Indeed, among all input parameters of RAIM availability simulator, UERE has, by far, the most significant impact on the estimated availability. Three distinct classes of RAIM algorithms are studied in this thesis. The Least Square Residual method in which the sum of the squares of the pseudorange residuals plays the rôle of the basic observable is first recalled. The Maximum Solution Separation method which is based on the observation of the separation between the position estimate generated by a fullset filter (using all the satellite measurements) and the position estimate generated by each one of the subset filters (each using all but one of the satellite measurements) is then discussed and an improved way of computing the associated protection level is proposed. Finally, a new promising method based on the Generalized Likelihood Ratio test is presented and several implementations are described. The way these different methods are implemented to take into account both civil aviation requirements and threat model is then detailed. In particular some methods to obtain the inner probability values that RAIM algorithms need to use are presented. Indeed, high level requirements interpretation for RAIM design is not clearly standardized. Finally simulations results are presented. They permit to evaluate RAIM ability to provide integrity monitoring for approaches with vertical guidance operations considering various scenarios. The main contributions of this thesis are a detailed computation of user equivalent range error variance, an analysis of the effect of interferences on pseudorange measurement, an adaptation of LSR RAIM algorithm to nominal biases, an improvement of MSS protection levels computation, the implementation of GLR algorithm as a RAIM including the computation of an analytical expression of the threshold that satisfies the false alarm probability and the prediction of the probability of missed detection, design of a sequential GLR algorithm to detect step plus ramp failure and an analysis of the amplitude of smallest single biases that lead to a positioning failure. Least Squared Residual, Maximum Solution Separation and constrained Generalized Likelihood Ratio RAIM availabilities have been computed for APVI and LPV200 approaches using both GPS L1/L5 and Galileo E1/E5b pseudorange measurements. It appears that both APV I and LPV200 (VAL=35m) operations are available using GPS/Galileo + RAIM to provide integrity as an availability of 100 % has been obtained for the detection function of the three studied algorithms. An availability of 100 % has also been obtained for the LSR exclusion function. On the contrary, LSR RAIM FDE availabilities seem not sufficient to have Galileo + RAIM or GPS +RAIM as a sole means of navigation for vertically guided approaches