Dissertations / Theses on the topic 'Multi input and multi output (MIMO) control'
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Nguyen, Chuong Hoang. "Adaptive Predictor-Based Output Feedback Control of Unknown Multi-Input Multi-Output Systems: Theory and Application to Biomedical Inspired Problems." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/71312.
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Functional Electrical Stimulation (FES) is a technique that applies electrical currents to nervous tissue in order to actively induce muscle contraction. Recent research has shown that FES provides a promising treatment to restore functional tasks due to paralysis caused by spinal cord injury, head injury, and stroke, to mention a few. Therefore, the overarching goal of this research work is to develop FES controllers to enable patients with movement-disorder to control their limbs in a desired manner and, in particular, to aid Parkinson's patients to suppress hand tremor. In our effort to develop strategies for muscle stimulation control, we first implement a model-based control technique assuming that all the states are measurable. The Hill-type muscle model coupled with a simplified 2DoF model of the arm is used to study the performance of our proposed adaptive sliding mode controller for simulation purpose. However, in the more practical situations, human limb dynamics are extremely complicate and it is inadequate to use model based controllers, especially considering there are still technical limitations that allow in vivo measurements of muscle activity. To tackle these challenges, we have developed output feedback adaptive control approaches for a class of unknown multi-input multi-output systems. Such control strategies are first developed for linear systems, and then extended to the nonlinear case. The proposed controllers, supported by experimental results, require minimum knowledge of the system dynamics and avoid many restrictive assumptions typically found in the literature. Therefore, we expect that the results introduced in this dissertation can provide a solution for a wide class of nonlinear uncertain systems, with focus on practical issues such as partial state measurement and the presence of mismatched uncertainties.Ph. D.
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Jiang, Ping, and H. Chen. "Nussbaum gain based iterative learning control for a class of multi-input multi-output nonlinear systems." IEEE, 2005. http://hdl.handle.net/10454/3500.
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YesAn adaptive iterative learning control(ILC) approach is proposed for a class of multi-input multi-output (MIMO) uncertain nonlinear systems without prior knowledge about system control gain matrices. The Nussbaum-type gain and the positive definite discrete matrix kernel are proposed for dealing with selection of the unknown control gain and learning of the repeatable uncertainties, respectively. Asymptotic convergence for a trajectory tracking within a finite time interval is achieved through repetitive tracking. Simulations are carried out to show the validity of the proposed control method.
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Erpek, Tugba. "Multi-layer Optimization Aspects of Deep Learning and MIMO-based Communication Systems." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/102705.
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This dissertation addresses multi-layer optimization aspects of multiple input multiple output (MIMO) and deep learning-based communication systems. The initial focus is on the rate optimization for multi-user MIMO (MU-MIMO) configurations; specifically, multiple access channel (MAC) and interference channel (IC). First, the ergodic sum rates of MIMO MAC and IC configurations are determined by jointly integrating the error and overhead effects due to channel estimation (training) and feedback into the rate optimization.
Then, we investigated methods that will increase the achievable rate for parallel Gaussian IC (PGIC) which is a special case of MIMO IC where there is no interference between multiple antenna elements. We derive a generalized iterative waterfilling algorithm for power allocation that maximizes the ergodic achievable rate. We verified the sum rate improvement with our proposed scheme through extensive simulation tests.
Next, we introduce a novel physical layer scheme for single user MIMO spatial multiplexing systems based on unsupervised deep learning using an autoencoder. Both transmitter and receiver are designed as feedforward neural networks (FNN) and constellation diagrams are optimized to minimize the symbol error rate (SER) based on the channel characteristics. We first evaluate the SER in the presence of a constant Rayleigh-fading channel as a performance upper bound.
Then, we quantize the Gaussian distribution and train the autoencoder with multiple quantized channel matrices. The channel is provided as an input to both the transmitter and the receiver. The performance exceeds that of conventional communication systems both when the autoencoder is trained and tested with single and multiple channels and the performance gain is sustained after accounting for the channel estimation error.
Moreover, we evaluate the performance with increasing number of quantization points and when there is a difference between training and test channels. We show that the performance loss is minimal when training is performed with sufficiently large number of quantization points and number of channels.
Finally, we develop a distributed and decentralized MU-MIMO link selection and activation protocol that enables MU-MIMO operation in wireless networks. We verified the performance gains with the proposed protocol in terms of average network throughput.Doctor of Philosophy
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Yin, Liangzhen. "Intelligent control for performance optimization of proton exchange membrane fuel cell system." Electronic Thesis or Diss., Bourgogne Franche-Comté, 2023. http://www.theses.fr/2023UBFCA013.
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Le système de pile à combustible à membrane échangeuse de protons (PEMFC) a été considéré comme la nouvelle technologie de production d'énergie, car il présente l'avantage d'une densité de puissance élevée, d'une absence d'émissions, d'un rendement élevé et d'un démarrage rapide. C'est pourquoi cette thèse est consacrée à la recherche sur l'intégration du système, le contrôle des paramètres du système et l'optimisation des performances du système pour les systèmes PEMFC à cathode ouverte et à cathode fermée. Pour les systèmes PEMFC à cathode ouverte, la température de la pile est le facteur clé affectant la performance de sortie du système. Afin d'améliorer les performances de suivi dynamique de la température dans des conditions de changement de charge, un contrôle adaptatif inverse et une prédiction grise basés sur un contrôle adaptatif sans modèle sont proposés pour un contrôle optimal de la température du système. En outre, afin d'améliorer l'efficacité du système, une stratégie de contrôle de l'efficacité maximale basée sur l'optimisation de l'efficacité maximale et la commande prédictive généralisée par contrainte est proposée dans cette thèse. Pour le système PEMFC à cathode fermée, compte tenu de la non-linéarité existante et du fort couplage entre les paramètres de fonctionnement tels que la température de la pile et le taux d'excès d'oxygène (OER), une stratégie de contrôle multivariable à double boucle basée sur un contrôle adaptatif en mode glissant sans modèle MIMO est proposée pour la régulation de la température de la pile et du débit d'air du système PEMFC à cathode fermée. En outre, un banc d'essai de système PEMFC à cathode ouverte de 300 W et un banc d'essai de système PEMFC à cathode fermée de 5 kW sont établis. Toutes les stratégies de contrôle et d'optimisation des performances sont vérifiées sur le banc d'essai des systèmes PEMFC à cathode ouverte et à cathode ferméeProton exchange membrane fuel cell (PEMFC) system has been considered as the new power generation technology as it has the advantage of high power density, zero emission, high efficiency, and fast start-up characteristics. Therefore, this thesis is devoted to researching system integration, system parameter trcking control, and system performance optimization for open-cathode and closed-cathode PEMFC systems. For open-cathode PEMFC system, the stack temperature is the key factor sffecting the output performance of the system. In order to improve the dynamic temperature tracking performance under load changing conditions, adaptive inverse control and grey prediction based model free adaptive control is proposed for optimal temperature control of system. Further, in order to enhance the system efficiency of system, a maximum efficiency control strategy based on maximum efficiency optimization and constraint generalized predictive control is proposed in this thesis. For closed-cathode PEMFC system, considering the existed nonlinearity and strong coupling between operating parameters such as stack temperature and oxygen excess ratio (OER), a dual loop multivariable control strategy based on MIMO model free adaptive sliding mode control is proposed for stack temperature and air flow rate regulation of closed-cathode PEMFC system. Moreover, a 300 W open-cathode PEMFC system test bench and a 5-kW closed-cathode PEMFC system tests bench are established. All the control strategies and the performance optimization strategies are verified on the established test bench of open-cathode and closed-cathode PEMFC systems
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Ghazali, Abu Baker MHD. "Advanced controllers for building energy management systems. Advanced controllers based on traditional mathematical methods (MIMO P+I, state-space, adaptive solutions with constraints) and intelligent solutions (fuzzy logic and genetic algorithms) are investigated for humidifying, ventilating and air-conditioning applications." Thesis, University of Bradford, 1996. http://hdl.handle.net/10454/4197.
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This thesis presents the design and implementation of control strategies for building
energy management systems (BEMS). The controllers considered include the multi PI-loop controllers, state-space designs, constrained input and output MIMO adaptive
controllers, fuzzy logic solutions and genetic algorithm techniques. The control
performances of the designs developed using the various methods based on aspects such
as regulation errors squared, energy consumptions and the settling periods are
investigated for different designs. The aim of the control strategy is to regulate the room
temperature and the humidity to required comfort levels.
In this study the building system under study is a 3 input/ 2 output system subject to external disturbances/effects. The three inputs are heating, cooling and humidification,
and the 2 outputs are room air temperature and relative humidity. The external
disturbances consist of climatic effects and other stochastic influences. The study is
carried out within a simulation environment using the mathematical model of the test
room at Loughborough University and the designed control solutions are verified
through experimental trials using the full-scale BMS facility at the University of
Bradford.
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Baskar, Siddharth. "Architecture for Multi Input Multi Output CompressiveRadars." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1503302518672948.
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Jaber, Dana N. "Multi-input multi-output (MIMO) detection by a colony of ants." [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1778.
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Coskun, Adem. "Downlink Transmission Techniques For Multi User Multi Input Multi Output Wireless Communications." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/2/12608750/index.pdf.
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Multi-user MIMO (MIMO-MU) communication techniques make use of available channel state information at the transmitter to mitigate the inter-user interference. The goal of these techniques is to provide the least interference at the mobile stations by applying a precoding operation. In this thesis a comparison of available techniques in the literature such as Channel Decomposition, SINR Balancing, Joint-MMSE optimization is presented. Novel techniques for the MIMO multi-user downlink communication systems, where a single stream is transmitted to each user are proposed. The proposed methods, different from the other methods in the literature, use a simple receiver to combat the interference. It has been shown that MRC based receivers are as good as more complicated joint MMSE receivers.
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Allen, Matthew Scott. "Global and Multi-Input-Multi-Output (MIMO) Extensions of the Algorithm of Mode Isolation (AMI)." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6877.
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A wide range of dynamic systems can be approximated as linear and time invariant, for which a wealth of tools are available to characterize or modify their dynamic characteristics. Experimental modal analysis (EMA) is a procedure whereby the natural frequencies, damping ratios and mode shapes which parameterize vibratory, linear, time invariant systems are derived from experimentally measured response data. EMA is commonly applied in a multitude of applications, for example, to generate experimental models of dynamic systems, validate finite element models and to characterize dissipation in vibratory systems. Recent EMA has also been used to characterize damage or defects in a variety of systems.
The Algorithm of Mode Isolation (AMI), presented by Drexel and Ginsberg in 2001, employs a unique strategy for modal parameter estimation in which modes are sequentially identified and subtracted from a set of FRFs. Their natural frequencies, damping ratios and mode vectors are then refined through an iterative procedure. This contrasts conventional multi-degree-of-freedom (MDOF) identification algorithms, most of which attempt to identify all of the modes of a system simultaneously. This dissertation presents a hybrid multi-input-multi-output (MIMO) implementation of the algorithm of mode isolation that improves the performance of AMI for systems with very close or weakly excited modes. The algorithmic steps are amenable to semi-automatic identification, and many FRFs can be processed efficiently and without concern for ill-conditioning, even when many modes are identified. The performance of the algorithm is demonstrated on noise contaminated analytical response data from two systems having close modes, one of which has localized modes while the other has globally responsive modes. The results are compared with other popular algorithms. MIMO-AMI is also applied to experimentally obtained data from shaker excited tests of the Z24 highway bridge, demonstrating the algorithm's performance on a data set typical of many EMA applications. Considerations for determining the number of modes active in the frequency band of interest are addressed, and the results obtained are compared to those found by other groups of researchers.
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El, Rashid Mohamad. "Study of Multiport Antenna Systems on Terminals for WLAN : MIMO Technology." Thesis, University of Gävle, Ämnesavdelningen för elektronik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-4420.
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Using more than just on antenna can significantly speed up the data rate in a wireless communication system. These systems are commonly referred to as Diversity- and MIMO-systems. Due to tight volume restriction for the antennas, e.g. in a mobile phone, electromagnetic coupling between the antennas will degrade the capacity of the wireless system and lower the coverage.
In the proposed thesis, a thorough study of Ethertronics’ standard antennas will be established in which the antennas will be used in a multiport system, e.g. MIMO. The thesis will be strongly related to Ethertronics’ engagement in Chase and therefore also dependent on the latest progresses on MPA (Multiport Analyzer) developed in Chase. The thesis will result in a working methodology how to use MPA plus design-, location- and orientation rules for the standard antennas used in a multiport system.
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Crowder, Douglas Cale. "Reinforcement Learning for Control of a Multi-Input, Multi-Output Model of the Human Arm." Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case162513783500859.
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Chu, Tzyy-Wen. "Eigenstructure analysis of automobile steering dynamics with application to robust four wheel steering control." Thesis, University of Warwick, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246817.
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Sevelimedu, Veeravalli Vinodh. "Study of MIMO, orthogonal codes and core operator architecture design for ML decoder." Thesis, Linköping University, Department of Electrical Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-10155.
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In the high-end research process of wireless systems and in the race for the development of the new technologies, MIMO (Multiple Input, Multiple Output) is getting more attention now days. It has a high potential usage in the 3G and 4G communications and beyond. The MIMO based system has got the ability to increase the data throughput in spectrum-limited conditions. With the increase and complexity of wireless applications, the spectrum efficiency improvement in the physical layer will be saturated. MIMO is predicted to be one of the major features for the next generation wireless networking. This thesis work is a part of an ongoing project of the Generic MIMO decoder design carried out at the research laboratory, LESTER at Lorient, France. I was involved in the study of MIMO concepts, orthogonal and Space-time codes and later involved in the design and optimization of the architecture for the core operator for the ML decoder used in the reception of the MIMO system,which is presented in this report work.
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Yankevich, Evgeny. "Design of an Airborne Multi-input Multi-output Radar Emulator Testbed for Ground Moving Target Identification Applications." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1345571650.
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Shi, Yan. "Robust Signaling, Scheduling and Authentication in the Multi-User Multiple-Input-Multiple-Output Channel." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2808.
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Multiple-input multiple-output (MIMO) networks are known to be able to achieve throughput performance superior to that available from single-input single-output (SISO) systems. However, when applying MIMO in multi-user networks, achieving this throughput advantage requires efficient precoding and optimal network scheduling. Furthermore, MIMO radios can help ensure security in a multi-user network. Previous work has proposed various precoding techniques for the MIMO broadcast channel, based either on channel state information (CSI) or channel distribution information (CDI), which achieve optimal or near- optimal MIMO channel throughput. The performance of these techniques largely depends on the availability of the channel information at the transmitter that must be fed back from the receiver. However, the past work has not examined the impact of latency caused by feedback of channel information and computation. This research proposes a performance metric to measure the throughput degradation caused by compression and feedback of channel information. We further propose an effective data compression technique based on the Karhunen-Lo`eve (KL) Transform and show that linear precoding (beamforming) based on CDI can achieve superior performance by providing stable channel throughput in both time- varying and frequency-selective channels. Very little prior work exists on optimal scheduling for multi-user MIMO networks, particularly in time-varying channels. One reason for this is that hybrid MIMO channels permit much more complex channel structures, such as broadcast channel (BC) and multiple access channel (MAC), whose capacity is limited not only by random channel noise but also by the multi-user interference. Furthermore, the achieved MIMO channel throughput depends on the spatial characteristics of the multi-user channels, a feature not captured by traditional network models based on signal-to-noise ratio and Doppler. Therefore, achieving near optimal performance requires development of scheduling techniques that depend on detailed channel characteristics. This dissertation proposes a novel parametric representation of the channel that simply describes the complex multi-user MIMO channels and allows for efficient scheduling. Because of the computational and feedback efficiency enabled by this parametric approach, it achieves low latency and therefore excellent performance.Finally, in any network setting, security is an important consideration. Specifically authentication ensures that unauthorized users do not gain network access. Unfortunately, user identity can be relatively easy to forge. This work therefore explores the user of radio- metric fingerprinting that uniquely identifies a device by unique imperfections in its transmitted waveform. This work shows that by applying this fingerprinting technique to MIMO devices, authentication reliability can be dramatically improved. The work also develops an information-theoretic approach to identify the optimal set of radiometric features to use for authentication and further considers the impact of drift in radiometric features on authentication performance.
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Spencer, Quentin H. "Transmission Strategies for Wireless Multi-user, Multiple-Input, Multiple-Output Communication Channels." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd378.pdf.
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Peters, Gavin M. "Time Division Duplex (TDD) Multi-User Multiple-Input, Multiple-Output (MU-MIMO) Mobile Ad-Hoc Network(MANET)." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563525886227608.
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Atapattu, Lakmali Nadisha Kumari. "Channel tracking in SDMA-based multi-user MIMO-OFDM communications systems." Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/65272/1/Lakmali_Atapattu_Thesis.pdf.
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Capacity of current and future high data rate wireless communications depend significantly on how well changes in the wireless channel are predicted and tracked. Generally, this can be estimated by transmitting known symbols. However, this increases overheads if the channel varies over time. Given today’s bandwidth demand and the increased necessity for mobile wireless devices, the contributions of this research are very significant. This study has developed a novel and efficient channel tracking algorithm that can recursively update the channel estimation for wireless broadband communications reducing overheads, therefore increasing the speed of wireless communication systems.
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Pedretti, Davide. "Design and Development of a Multi-Purpose Input Output Controller Board for the SPES Control System." Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3425405.
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This PhD work has been carried out at the Legnaro National Laboratories (LNL), one of the four national labs of the National Institute for Nuclear Physics (INFN). The mission of LNL is to perform research in the field of nuclear physics and nuclear astrophysics together with emerging technologies. Technological research and innovation are the key to promote excellence in science, to excite competitive industries and to establish a better society. The research activities concerning electronics and computer science are an essential base to develop the control system of the Selective Production of Exotic Species (SPES) project. Nowadays, SPES is the most important project commissioned at LNL and represents the future of the Lab. It is a second generation Isotope Separation On-Line (ISOL) radioactive ion beam facility intended for fundamental nuclear physics research as well as experimental applications in different fields of science, such as nuclear medicine; radio-pharmaceutical production for therapy and diagnostic. The design of the SPES control system demands innovative technologies to embed the control of several appliances with different requirements and performing different tasks spanning from data sharing and visualization, data acquisition and storage, networking, security and surveillance operations, beam transport and diagnostic. The real time applications and fast peripherals control commonly found in the distributed control network of particle accelerators are accompanied by the challenge of developing custom embedded systems.
In this context, the proposed PhD work describes the design and development of a multi-purpose Input Output Controller (IOC) board capable of embedding the control of typical accelerator instrumentation involved in the automatic beam transport system foreseen for the SPES project.
The idea behind this work is to extend the control reach to the single device level without losing in modularity and standardization.
The outcome of the research work is a general purpose embedded computer that will be the base for standardizing the hardware layer of the frontend computers in the SPES distributed control system.
The IOC board is a Computer-on-Module (COM) carrier board designed to host any COM Express type 6 module and is equipped with a Field Programmable Gate Array (FPGA) and user application specific I/O connection solutions not found in a desktop pc. All the generic pc functionalities are readily available in off-the-shelf modules and the result is a custom motherboard that bridges the gap between custom developments and commercial personal computers.
The end user can deal with a general-purpose pc with a high level of hardware abstraction besides being able to exploit the on-board FPGA potentialities in terms of fast peripherals control and real time digital data processing.
This document opens with an introductory chapter about the SPES project and its control system architecture and technology before to describe the IOC board design, prototyping, and characterization. The thesis ends describing the installation in the field of the IOC board which is the core of the new diagnostics data readout and signal processing system. The results of the tests performed under real beam conditions prove that the new hardware extends the current sensitivity to the pA range, addressing the SPES requirements, and prove that the IOC board is a reliable solution to standardize the control of several appliances in the SPES accelerators complex where it will be embedded into physical equipment, or in their proximity, and will control and monitor their operation replacing the legacy VME technology. The installation in the field of the IOC board represents a great personal reward and crowns these years of busy time during which I turned what was just an idea in 2014, into a working embedded computer today.Questo lavoro di dottorato è stato svolto presso ai Laboratori Nazionali di Legnaro (LNL), uno dei quattro laboratori nazionali dell’Istituto Nazionale di Fisica Nucleare. La missione principale dei LNL è la ricerca di base nella fisica e astrofisica nucleare, sostenuta da un’importante ricerca relativa alle tecnologie emergenti. Le attività di ricerca nell’ambito dell’elettronica e dell’informatica sono essenziali per lo sviluppo del sistema di controllo del progetto SPES (produzione selettiva di specie esotiche). SPES è il progetto piú importante e rappresenta il futuro dei laboratori di Legnaro. Si tratta di una infrastruttura di tipo ISOL (separazione di isotopi in linea), di seconda generazione, il cui obiettivo è quello di generare e accelerare un fascio di ioni radioattivi dedicato alla ricerca nel campo della fisica nucleare, astrofisica nucleare, e ad applicazioni sperimentali in diversi campi della scienza come la produzione di particolari radionuclidi per la medicina nucleare che saranno utili per la diagnosi e la cura di patologie oncologiche. Il progetto del sistema di controllo di SPES sarà basato su tecnologie innovative che consentiranno di monitorare e controllare dispositivi tra loro molto diversi e che eseguono funzioni differenti che vanno dall’acquisizione e visualizzazione dei dati, condivisione dei dati in rete, memorizzazione delle informazioni, operazioni di sorveglianza, diagnostiche e trasporto del fascio. In questo contesto, il dottorato di ricerca proposto descrive il progetto e la realizzazione di una scheda elettronica di controllo (IOC) multifunzione capace di controllare quasi tutte le apparecchiature coinvolte nel trasporto del fascio di ioni radioattivi. L’idea di base di questo lavoro è quella di estendere il controllo a livello di singola apparecchiatura o piccoli gruppi di dispositivi senza rinunciare alla modularità e alla standardizzazione dell’elettronica. Il risultato del lavoro di dottorato è un computer embedded multifunzione progettato con tecnologie all’avanguardia che diventerà lo standard, a livello hardware, su cui si baserà il sistema di controllo distribuito di SPES. Questo controllore multifunzione integra tutte le funzionalità di un computer commerciale e in aggiunta è equipaggiato con un dispositivo programmabile sul campo (FPGA) e alcune periferiche non standard dedicate ad applicazioni di controllo specifiche. L’utente finale potrà sfruttare questa scheda elettronica come un qualunque pc commerciale, oppure, potrà sfruttare le potenzialità della FPGA per le elaborazioni digitali dei dati in tempo reale, per il trasferimento dei dati ad alta velocità su fibra ottica, per chiudere anelli di controllo a larga banda e per avere tempi di risposta agli stimoli in ingresso dal campo deterministici e molto brevi. Il documento apre con una introduzione sul progetto SPES prima di descrivere la progettazione, prototipizzazione e validazione della scheda IOC dando particolare risalto alle attività in cui il mio contributo è stato fondamentale. La tesi si chiude descrivendo l’integrazione della scheda IOC nel sistema di diagnostiche di fascio di SPES. Le misure del profilo di fascio eseguite sul campo e l’estensione della sensibilità di corrente a pochi pA confermano che la scheda elettronica progettata è una soluzione affidabile per standardizzare, a livello hardware, il controllo di diverse apparecchiature nel complesso degli acceleratori del progetto SPES. Questa scheda sostituirà la tecnologia VME in diverse applicazioni e sarà la base su cui implementare un sistema di trasporto di fascio automatico e di qualità, fondamentale per il successo delle attività di ricerca ai LNL. L’installazione in campo della scheda elettronica rappresenta una soddisfazione personale enorme e corona questi anni di duro lavoro durante ai quali ho trasformato quella che nel 2014 era solo un’idea, in un computer embedded pienamente funzionante.
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Potter, Chris. "Single Bounce Air to Ground Communication Channel Capacity for MIMO Applications." International Foundation for Telemetering, 2006. http://hdl.handle.net/10150/604770.
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ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, CaliforniaThis paper addresses the air-to-ground communication problem, where multiple transmit antennas are used on the aircraft to combat multi-path interference. The channel is assumed to have a line-of-sight component and a single ground reflection. Multiple input multiple output (MIMO) techniques can be used in this situation, to increase the reliability and data rate. In this paper we discuss how the MIMO channel capacity changes, with the aircraft antenna configuration, altitude, velocity, range, and a number of other parameters. For comparison, the MIMO results are compared to systems which have single antennas at the transmitter, at the receiver, or at both ends.
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Budhathoki, Krishna Ram. "Precoder Design for Cooperative Cognitive Radio Systems." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1363180310.
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Ihekire, Chika Lucy. "Decoupling control of a multiple-input, multiple-output process| Case studies of multi-tank system and distillation column." Thesis, California State University, Long Beach, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10001543.
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Multiple Input-Multiple Output (MIMO) systems are very common in process industries, but can be difficult to control. A phenomenon called coupling occurs in a MIMO system when the controller output from one loop acts as disturbance to other control loops. This thesis studies a solution to coupling by introducing a decoupler to a Proportional Integral Differential (PID) control system. A decoupler is a feed-forward controller added to the traditional feedback loop to cancel out loop disturbance. The effect of a decoupler on the performance of control system was explored by comparing (1) the time it takes to achieve control and (2) the combined error incurred during the control process. In this study, a simulation software, LoopPro is used to model and control two systems; multi-tank system and distillation column. Step test data were used to identify process model and a tuning procedure based on Internal Model Control is illustrated. The extent of loop interaction was also analyzed from the Relative Gain Matrix.
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Cao, Pan. "Resource Allocation for Multiple-Input and Multiple-Output Interference Networks." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-161382.
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To meet the exponentially increasing traffic data driven by the rapidly growing mobile subscriptions, both industry and academia are exploring the potential of a new genera- tion (5G) of wireless technologies. An important 5G goal is to achieve high data rate. Small cells with spectrum sharing and multiple-input multiple-output (MIMO) techniques are one of the most promising 5G technologies, since it enables to increase the aggregate data rate by improving the spectral efficiency, nodes density and transmission bandwidth, respectively. However, the increased interference in the densified networks will in return limit the achievable rate performance if not properly managed.
The considered setup can be modeled as MIMO interference networks, which can be classified into the K-user MIMO interference channel (IC) and the K-cell MIMO interfering broadcast channel/multiple access channel (MIMO-IBC/IMAC) according to the number of mobile stations (MSs) simultaneously served by each base station (BS). The thesis considers two physical layer (PHY) resource allocation problems that deal with the interference for both models: 1) Pareto boundary computation for the achiev- able rate region in a K-user single-stream MIMO IC and 2) grouping-based interference alignment (GIA) with optimized IA-Cell assignment in a MIMO-IMAC under limited feedback. In each problem, the thesis seeks to provide a deeper understanding of the system and novel mathematical results, along with supporting numerical examples. Some of the main contributions can be summarized as follows.
It is an open problem to compute the Pareto boundary of the achievable rate region for a K-user single-stream MIMO IC. The K-user single-stream MIMO IC models multiple transmitter-receiver pairs which operate over the same spectrum simultaneously. Each transmitter and each receiver is equipped with multiple antennas, and a single desired data stream is communicated in each transmitter-receiver link. The individual achievable rates of the K users form a K-dimensional achievable rate region. To find efficient operating points in the achievable rate region, the Pareto boundary computation problem, which can be formulated as a multi-objective optimization problem, needs to be solved. The thesis transforms the multi-objective optimization problem to two single-objective optimization problems–single constraint rate maximization problem and alternating rate profile optimization problem, based on the formulations of the ε-constraint optimization and the weighted Chebyshev optimization, respectively. The thesis proposes two alternating optimization algorithms to solve both single-objective optimization problems. The convergence of both algorithms is guaranteed. Also, a heuristic initialization scheme is provided for each algorithm to achieve a high-quality solution. By varying the weights in each single-objective optimization problem, numerical results show that both algorithms provide an inner bound very close to the Pareto boundary. Furthermore, the thesis also computes some key points exactly on the Pareto boundary in closed-form.
A framework for interference alignment (IA) under limited feedback is proposed for a MIMO-IMAC. The MIMO-IMAC well matches the uplink scenario in cellular system, where multiple cells share their spectrum and operate simultaneously. In each cell, a BS receives the desired signals from multiple MSs within its own cell and each BS and each MS is equipped with multi-antenna. By allowing the inter-cell coordination, the thesis develops a distributed IA framework under limited feedback from three aspects: the GIA, the IA-Cell assignment and dynamic feedback bit allocation (DBA), respec- tively. Firstly, the thesis provides a complete study along with some new improvements of the GIA, which enables to compute the exact IA precoders in closed-form, based on local channel state information at the receiver (CSIR). Secondly, the concept of IA-Cell assignment is introduced and its effect on the achievable rate and degrees of freedom (DoF) performance is analyzed. Two distributed matching approaches and one centralized assignment approach are proposed to find a good IA-Cell assignment in three scenrios with different backhaul overhead. Thirdly, under limited feedback, the thesis derives an upper bound of the residual interference to noise ratio (RINR), formulates and solves a corresponding DBA problem. Finally, numerical results show that the proposed GIA with optimized IA-Cell assignment and the DBA greatly outperforms the traditional GIA algorithm.
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Dioum, Ibra. "Conception de systèmes multi-antennaires pour techniques de diversité et MIMO : application aux petits objets nomades communicants." Phd thesis, Université Nice Sophia Antipolis, 2013. http://tel.archives-ouvertes.fr/tel-00935084.
Full textAbstract:
La demande de transmissions à débits de plus en plus élevés s'accentue davantage avec l'essor de nouveaux services dans les réseaux de communication sans fils. Pour répondre à cette demande, une solution consiste à augmenter la capacité de transmission du canal radiofréquence entre la station de base et le terminal portatif. Ceci peut être réalisé en augmentant le nombre d'éléments rayonnant impliqués à l'émission et à la réception de cette liaison radiofréquence : on parle alors de technique MIMO (Multiple Input, Multiple Output). Cette thèse porte principalement sur la conception, l'optimisation et la caractérisation de systèmes multi-antennaires pour techniques de diversité et MIMO en bandes LTE (Long Term Evolution). Trois prototypes multi-bandes sont proposés dont deux systèmes planaires et un système d'antennes IFAs compactes. De nouvelles solutions multi-bandes et l'influence de la position de l'antenne sur le plan de masse sont étudiées pour réaliser de la diversité spatiale, de polarisation et de diagramme de rayonnement avec une faible corrélation entre les signaux reçus sur chaque antenne mais surtout une bonne efficacité totale. Une ligne de neutralisation est utilisée pour isoler les antennes et un fonctionnement multi-bande est réalisé. L'impédance d'entrée des antennes est étudiée avec la méthode de Youla & Carlin afin d'améliorer la bande passante de la structure compacte de type IFA. Les performances en diversité et en MIMO de ces systèmes sont évaluées dans différents environnements de propagation. Elles montrent que ces systèmes peuvent être utilisés efficacement pour des applications en diversité et MIMO.
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German, Gus Ryan. "A Ray-Based Investigation of the Statistical Characteristics and Efficient Representation of Multi-Antenna Communication Channels." BYU ScholarsArchive, 2004. https://scholarsarchive.byu.edu/etd/145.
Full textAbstract:
Multi-antenna communication systems are attracting research interest as a means to increase the information capacity, reliability, and spectral efficiency of wireless information transfer. Ray-tracing methods predict the behavior of wireless channels using a model of the propagation environment and are a low-cost alternative to direct measurements. We use ray tracing simulations to validate the statistical time and angle of arrival characteristics of an indoor multipath channel and compare model parameter estimates with estimates derived from channel sounding measurements. Ray tracing predicts the time and angle clustering of multipaths observed in the measurements and provides model parameter estimates which are closely correlated with measured estimates. The ray tracing parameters relating to power characteristics show more deviation from measurements than the time and angle related parameters. Our results also indicate that the description of reflective scatterers in the propagation environment is more important to the quality of the predicted statistical behavior than the description of bulk materials. We use a ray synthesis model to investigate means of efficiently representing the channel for feedback information to the transmitter as a means to increase the information capacity. Several methods of selecting the ray-model feedback information are demonstrated with results from simulated and measured channels. These results indicate that an ESPRIT algorithm coupled with ad hoc transmit/receive pairing can yield better than 90% of the ideal waterfilling capacity when adequate training-based channel estimates are available. Additionally, we investigate a covariance feedback method for providing channel feedback for increased capacity. Both the ray-based and covariance-based feedback methods yield their highest capacity improvements when the signal to noise ratio is low. This results because of the larger benefit of focusing transmit power into the most advantageous eigenmodes of the channel when fewer eigenmodes have power allocated to them by the waterfilling capacity solution. In higher signal to noise ratio cases, more eigenmodes of the channel receive power when waterfilling, and the capacity improvement from feedback information decreases relative to a uniform power allocation. In general, ray model feedback methods are preferable because the covariance feedback quickly requires higher computational effort as the array sizes increase and typically results in lower capacity for a given amount of feedback information.
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Abouseif, Akram. "Emerging DSP techniques for multi-core fiber transmission systems." Electronic Thesis or Diss., Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAT013.
Full textAbstract:
Les systèmes de communication optique ont connu plusieurs phases de développement au cours des dernières décennies. Ils approchent aujourd'hui les limites de capacité du cana non-linéaire. L'espace est aujourd'hui le dernier degré de liberté à mettre en œuvre afin de continuer à répondre aux demandes de capacité à venir pour les prochaines années. Par conséquent, des recherches intensives sont menées pour explorer tous les aspects concernant le déploiement du système de multiplexage par division spatiale (SDM). Plusieurs dégradations ont un impact sur les systèmes SDM en raison de l'interaction des canaux spatiaux qui dégrade les performances du système. Dans cette thèse, nous nous concentrons sur les fibres multicœurs (MCF) comme l'approche la plus prometteuse pour être le premier représentant du système SDM. Nous présentons différentes solutions numériques et optiques pour atténuer l'effet non unitaire connu sous le nom de perte dépendante du cœur (CDL). La première partie est consacrée à l'étude des performances de la transmission MCF en tenant compte des dégradations de propagation qui impactent les systèmes MCF. Nous proposons un modèle de canal qui aide à identifier le système MCF. La deuxième partie est consacrée à la technique optique pour améliorer les performances de transmission avec une solution optimale pour la réduction des CDL. Ensuite, nous avons introduit des techniques numériques pour des améliorations supplémentaires, la pré-compensation Zero Forcing et le codage spatio-temporel pour une atténuation CDL supplémentaire. Tous les résultats de simulation sont validés analytiquement en dérivant les bornes supérieures de probabilité d'erreurOptical communication systems have seen several phases in the last decades. It is predictable that the optical systems as we know will reach the non-linear capacity limits. At the moment, the space is the last degree of freedom to be implemented in order to keep delivering the upcoming capacity demands for the next years. Therefore, intensive researches are conducted to explore all the aspects concerning the deployment of the space-division multiplexing (SDM) system. Several impairments impact the SDM systems as a result from the interaction of the spatial channels which degrades the system performance. In this thesis, we focus on the multi-core fibers (MCFs) as the most promising approach to be the first representative of the SDM system. We present different digital and optical solutions to mitigate the non-unitary effect known as the core dependent loss (CDL). The first part is dedicated to study the performance of the MCF transmission taking into account the propagating impairments that impact the MCF systems. We propose a channel model that helps to identify the MCFs system. The second part is devoted to optical technique to enhance the transmission performance with an optimal solution. After, we introduced digital techniques for further enhancement, the Zero Forcing pre-compensation and the space-time coding for further CDL mitigation. All the simulation results are validated analytically by deriving the error probability upper bounds
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Hameed, Khalid W. H. "Multiuser Multi Input Single Output (MU-MISO) Beamforming for 5G Wireless and Mobile Networks. A Road Map for Fast and Low Complexity User Selection, Beamforming Scheme Through a MU-MISO for 5G Wireless and Mobile Networks." Thesis, University of Bradford, 2019. http://hdl.handle.net/10454/18445.
Full textAbstract:
Multi-User Multi-Input Multi-Output (MU-MIMO) systems are considered to be the sustainable technologies of the current and future of the upcoming wireless and mobile networks generations. The perspectives of these technologies under several scenarios is the focus of the present thesis.
The initial system model covers the MU-MIMO, especially in the massive form that is considered to be the promising ideas and pillars of the 5G network. It is observed that the optimal number of users should be served in the time-frequency resource even though the maximum limitation of the MU-MIMO is governed by the total receiving antennas (K) is less than or equal to the base station antennas (M). The system capacity of the massive MIMO (mMIMO) under perfect channel state information (CSI) of uncorrelated channel is investigated and studied. Two types of precoders were applied, one is directly based on channel inversion, and the other uses the Eigen decomposition that is derived subject to the signal to a leakage maximization problem. The two precoders show a degree of equivalency under certain assumptions for the number of antennas at the user end.
The convex optimization of multi-antenna networks to achieve the design model of optimum beamformer (BF) based on the uniform linear array (ULA) is studied. The ULA is selected for its simplicity to analyse many scenarios and its importance to match the future network applied millimetre wave (mmWave) spectrum. The maximum beams generated by the ULA are explored in terms of several physical system parameters. The duality between the MU-MIMO and ULA and how they are related based on beamformer operation are detailed and discussed.
Finally, two approaches for overloaded systems are presented when the availability of massive array that is not guaranteed due to physical restrictions since the existence of a large number of devices will result in breaking the dimension rule (i.e., K ≤ M). As a solution, a low complexity users selection algorithm is proposed. The channel considered is uncorrelated with full and perfect knowledge at the BS. In particular, these two channel conditions may not be available in all scenarios. The CSI may be imperfect, and even the instantaneous form does not exist. A hybrid precoder between the mixed CSI (includes imperfect and statistical) and rate splitting approach is proposed to deal with an overloaded system under a low number of BS antennas.Ministry of Higher Education and Scientific Research of Iraq
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Nobilet, Jean-Michel. "Systèmes MIMO (" Multiple Input Multiple Output ") à porteuses multiples :Etude et optimisation de la combinaison de codes temps-espace et des techniques MC-CDMA (" Multi-carrier code division multiple access ")." Rennes, INSA, 2004. http://www.theses.fr/2004ISAR0006.
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Dans la recherche de modulations adaptées à la voie descendante des systèmes cellulaires 4G, les systèmes MC-CDMA s'affirment comme des solutions à fort potentiel. En parallèle, les systèmes MIMO constituent une nouvelle voie très prometteuse améliorant notablement l'efficacité spectrale des systèmes hertziens via la dimension spatiale. Cette thèse porte sur l'optimisation de systèmes MIMO/MCCDMA par l'étude des codes temps-espace en blocs ou en treillis. Après un état de l'art, nous proposons de nouveaux codes STBC orthogonaux, puis une représentation des STTC basée sur une notation polynômiale permettant la comparaison des codes existants. La combinaison STBC/MC-CDMA étudiée améliore sensiblement les performances d'un système MC-CDMA SISO avec un décodage peu complexe. Leur optimisation repose sur des techniques de détection mono-utilisateurs ou multi-utilisateurs. Leur performances sont évaluées sur des canaux théoriques ou réalistes. Enfin, la combinaison STTC/MC-CDMA est étudiéeIn the context of the research of new modulation schemes for the downlink of the 4th Generation mobile radio systems, the MC-CDMA schemes are the most promising candidates. On the other hand, MIMO systems inherit space diversity to mitigate fading effects and improve dramatically the spectrum efficiency. This thesis deals with the optimisation of MIMO/MC-CDMA systems through the use of space-time block coding or trellis coding. We propose new orthogonal STBC and a new representation of STTC based on a polynomial notation. The studied STBC/MC-CDMA systems improve the performance of a MC-CDMA SISO system with a low complex decoding. Their optimisation is based on single-user and multiple-user detection schemes. Their performance are evaluated on theoretical and realistic channels. Finally, the STTC/MC-CDMA is studied
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Grønkær, Nikolaj, Lasse Nørby Nielsen, Frederik Ødum Nielsen, Søren Ketelsen, and Lasse Schmidt. "Multi-objective control of a self-locking compact electro-hydraulic cylinder drive." Technische Universität Dresden, 2020. https://tud.qucosa.de/id/qucosa%3A71094.
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The field of self-contained linear hydraulic drives based on variable-speed electrical motors and fixed displacement pumps is gaining interest from both industry and academia. Some of the main reasons for this is the possibility to improve the energy efficiency of such drives compared to conventional valve controlled drives, and the possibility for electrical regeneration allowing power sharing between multiple drives [1]. The main drawback for such types of drive concepts is a low pressure in the nonload carrying cylinder chamber. This induces a low drive stiffness limiting the achievable drive bandwidth and hence the application range. However, a so-called self-locking compact drive architecture recently proposed allows maintaining a proper drive stiffness by virtue of separate forward and return flow paths, combining the advantages of efficient flow control into the cylinder and a throttle driven flow out of the cylinder. The multiple inputs available in this architecture allow the control to target several objectives concurrently, for example piston motion, drive stiffness and fluid temperature. The purpose of the study presented is to analyse the dynamic couplings between the control objectives via relative gain array (RGA) methods, and the realization of input- and output transformations effectively decoupling relevant dynamic interactions. These transformations allow the usage of simple SISO-controllers for each control objective, and a method for controlling motion and fluid temperature concurrently, is proposed and experimentally verified.
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Abaza, Mohamed. "Cooperative MIMO techniques for outdoor optical wireless communication systems." Thesis, Brest, 2015. http://www.theses.fr/2015BRES0073/document.
Full textAbstract:
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 FSOFree-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
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Ghazali, Abu Baker Mhd. "Advanced controllers for building energy management systems : advanced controllers based on traditional mathematical methods (MIMO P+I, state-space, adaptive solutions with constraints) and intelligent solutions (fuzzy logic and genetic algorithms) are investigated for humidifying, ventilating and air-conditioning applications." Thesis, University of Bradford, 1996. http://hdl.handle.net/10454/4197.
Full textAbstract:
This thesis presents the design and implementation of control strategies for building energy management systems (BEMS). The controllers considered include the multi PI-loop controllers, state-space designs, constrained input and output MIMO adaptive controllers, fuzzy logic solutions and genetic algorithm techniques. The control performances of the designs developed using the various methods based on aspects such as regulation errors squared, energy consumptions and the settling periods are investigated for different designs. The aim of the control strategy is to regulate the room temperature and the humidity to required comfort levels. In this study the building system under study is a 3 input/ 2 output system subject to external disturbances/effects. The three inputs are heating, cooling and humidification, and the 2 outputs are room air temperature and relative humidity. The external disturbances consist of climatic effects and other stochastic influences. The study is carried out within a simulation environment using the mathematical model of the test room at Loughborough University and the designed control solutions are verified through experimental trials using the full-scale BMS facility at the University of Bradford.
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Diameh, Yousef A. "The optimization of multiple antenna broadband wireless communications. A study of propagation, space-time coding and spatial envelope correlation in Multiple Input, Multiple Output radio systems." Thesis, University of Bradford, 2013. http://hdl.handle.net/10454/6361.
Full textAbstract:
This work concentrates on the application of diversity techniques and space time block coding for future mobile wireless communications.
The initial system analysis employs a space-time coded OFDM transmitter over a multipath Rayleigh channel, and a receiver which uses a selection combining diversity technique. The performance of this combined scenario is characterised in terms of the bit error rate and throughput. A novel four element QOSTBC scheme is introduced, it is created by reforming the detection matrix of the original QOSTBC scheme, for which an orthogonal channel matrix is derived. This results in a computationally less complex linear decoding scheme as compared with the original QOSTBC. Space time coding schemes for three, four and eight transmitters were also derived using a Hadamard matrix.
The practical optimization of multi-antenna networks is studied for realistic indoor and mixed propagation scenarios. The starting point is a detailed analysis of the throughput and field strength distributions for a commercial dual band 802.11n MIMO radio operating indoors in a variety of line of sight and non-line of sight scenarios. The physical model of the space is based on architectural schematics, and realistic propagation data for the construction materials. The modelling is then extended and generalized to a multi-storey indoor environment, and a large mixed site for indoor and outdoor channels based on the Bradford University campus.
The implications for the physical layer are also explored through the specification of antenna envelope correlation coefficients. Initially this is for an antenna module configuration with two independent antennas in close proximity. An operational method is proposed using the scattering parameters of the system and which incorporates the intrinsic power losses of the radiating elements. The method is extended to estimate the envelope correlation coefficient for any two elements in a general (N,N) MIMO antenna array. Three examples are presented to validate this technique, and very close agreement is shown to exist between this method and the full electromagnetic analysis using the far field antenna radiation patterns.
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Dia'meh, Yousef Ali. "The optimization of multiple antenna broadband wireless communications : a study of propagation, space-time coding and spatial envelope correlation in Multiple Input, Multiple Output radio systems." Thesis, University of Bradford, 2013. http://hdl.handle.net/10454/6361.
Full textAbstract:
This work concentrates on the application of diversity techniques and space time block coding for future mobile wireless communications. The initial system analysis employs a space-time coded OFDM transmitter over a multipath Rayleigh channel, and a receiver which uses a selection combining diversity technique. The performance of this combined scenario is characterised in terms of the bit error rate and throughput. A novel four element QOSTBC scheme is introduced, it is created by reforming the detection matrix of the original QOSTBC scheme, for which an orthogonal channel matrix is derived. This results in a computationally less complex linear decoding scheme as compared with the original QOSTBC. Space time coding schemes for three, four and eight transmitters were also derived using a Hadamard matrix. The practical optimization of multi-antenna networks is studied for realistic indoor and mixed propagation scenarios. The starting point is a detailed analysis of the throughput and field strength distributions for a commercial dual band 802.11n MIMO radio operating indoors in a variety of line of sight and non-line of sight scenarios. The physical model of the space is based on architectural schematics, and realistic propagation data for the construction materials. The modelling is then extended and generalized to a multi-storey indoor environment, and a large mixed site for indoor and outdoor channels based on the Bradford University campus. The implications for the physical layer are also explored through the specification of antenna envelope correlation coefficients. Initially this is for an antenna module configuration with two independent antennas in close proximity. An operational method is proposed using the scattering parameters of the system and which incorporates the intrinsic power losses of the radiating elements. The method is extended to estimate the envelope correlation coefficient for any two elements in a general (N,N) MIMO antenna array. Three examples are presented to validate this technique, and very close agreement is shown to exist between this method and the full electromagnetic analysis using the far field antenna radiation patterns.
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Salah, Adham M. S. "Investigation of Integrated Decoupling Methods for MIMO Antenna Systems. Design, Modelling and Implementation of MIMO Antenna Systems for Different Spectrum Applications with High Port-to-Port Isolation Using Different Decoupling Techniques." Thesis, University of Bradford, 2019. http://hdl.handle.net/10454/18427.
Full textAbstract:
Multiple-Input-Multiple-Output (MIMO) antenna technology refers to an antenna with
multiple radiators at both transmitter and receiver ends. It is designed to increase the data rate in
wireless communication systems by achieving multiple channels occupying the same bandwidth
in a multipath environment. The main drawback associated with this technology is the coupling
between the radiating elements. A MIMO antenna system merely acts as an antenna array if the
coupling between the radiating elements is high. For this reason, strong decoupling between the
radiating elements should be achieved, in order to utilize the benefits of MIMO technology.
The main objectives of this thesis are to investigate and implement several printed MIMO
antenna geometries with integrated decoupling approaches for WLAN, WiMAX, and 5G
applications. The characteristics of MIMO antenna performance have been reported in terms of
scattering parameters, envelope correlation coefficient (ECC), total active reflection coefficient
(TARC), channel capacity loss (CCL), diversity gain (DG), antenna efficiency, antenna peak gain
and antenna radiation patterns.
Three new 2×2 MIMO array antennas are proposed, covering dual and multiple spectrum
bandwidths for WLAN (2.4/5.2/5.8 GHz) and WiMAX (3.5 GHz) applications. These designs
employ a combination of DGS and neutralization line methods to reduce the coupling caused by
the surface current in the ground plane and between the radiating antenna elements. The minimum
achieved isolation between the MIMO antennas is found to be better than 15 dB and in some
bands exceeds 30 dB. The matching impedance is improved and the correlation coefficient values
achieved for all three antennas are very low. In addition, the diversity gains over all spectrum
bands are very close to the ideal value (DG = 10 dB).
The forth proposed MIMO antenna is a compact dual-band MIMO antenna operating at
WLAN bands (2.4/5.2/5.8 GHz). The antenna structure consists of two concentric double square
rings radiating elements printed symmetrically. A new method is applied which combines the
defected ground structure (DGS) decoupling method with five parasitic elements to reduce the
coupling between the radiating antennas in the two required bands.
A metamaterial-based isolation enhancement structure is investigated in the fifth proposed
MIMO antenna design. This MIMO antenna consists of two dual-band arc-shaped radiating
elements working in WLAN and Sub-6 GHz 5th generation (5G) bands. The antenna placement
and orientation decoupling method is applied to improve the isolation in the second band while
four split-ring resonators (SRRs) are added between the radiating elements to enhance the
isolation in the first band.
All the designs presented in this thesis have been fabricated and measured, with the simulated
and measured results agreeing well in most cases.Higher Committee for Education Development in Iraq (HCED)
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Boora, Arash Abbasalizadeh. "Flexible high-power multi DC-DC converters for train systems." Thesis, Queensland University of Technology, 2010. https://eprints.qut.edu.au/33208/1/Arash_Boora_Thesis.pdf.
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This thesis reports on the investigations, simulations and analyses of novel power electronics topologies and control strategies. The research is financed by an Australian Research Council (ARC) Linkage (07-09) grant. Therefore, in addition to developing original research and contributing to the available knowledge of power electronics, it also contributes to the design of a DC-DC converter for specific application to the auxiliary power supply in electric trains. Specifically, in this regard, it contributes to the design of a 7.5 kW DC-DC converter for the industrial partner (Schaffler and Associates Ltd) who supported this project. As the thesis is formatted as a ‘thesis by publication’, the contents are organized around published papers. The research has resulted in eleven papers, including seven peer reviewed and published conference papers, one published journal paper, two journal papers accepted for publication and one submitted journal paper (provisionally accepted subject to few changes). In this research, several novel DC-DC converter topologies are introduced, analysed, and tested. The similarity of all of the topologies devised lies in their ‘current circulating’ switching state, which allows them to store some energy in the inductor, as extra inductor current. The stored energy may be applied to enhance the performance of the converter in the occurrence of load current or input voltage disturbances. In addition, when there is an alternating load current, the ability to store energy allows the converter to perform satisfactorily despite frequently and highly varying load current. In this research, the capability of current storage has been utilised to design topologies for specific applications, and the enhancement of the performance of the considered applications has been illustrated. The simplest DC-DC converter topology, which has a ‘current circulating’ switching state, is the Positive Buck-Boost (PBB) converter (also known as the non-inverting Buck-Boost converter). Usually, the topology of the PBB converter is operating as a Buck or a Boost converter in applications with widely varying input voltage or output reference voltage. For example, in electric railways (the application of our industrial partner), the overhead line voltage alternates from 1000VDC to 500VDC and the required regulated voltage is 600VDC. In the course of this research, our industrial partner (Schaffler and Associates Ltd) industrialized a PBB converter–the ‘Mudo converter’–operating at 7.5 kW. Programming the onboard DSP and testing the PBB converter in experimental and nominal power and voltage was part of this research program. In the earlier stages of this research, the advantages and drawbacks of utilization of the ‘current circulating’ switching state in the positive Buck-Boost converter were investigated. In brief, the advantages were found to be robustness against input voltage and current load disturbances, and the drawback was extra conduction and switching loss. Although the robustness against disturbances is desirable for many applications, the price of energy loss must be minimized to attract attention to the utilization of the PBB converter. In further stages of this research, two novel control strategies for different applications were devised to minimise the extra energy loss while the advantages of the positive Buck-Boost converter were fully utilized. The first strategy is Smart Load Controller (SLC) for applications with pre-knowledge or predictability of input voltage and/or load current disturbances. A convenient example of these applications is electric/hybrid cars where a master controller commands all changes in loads and voltage sources. Therefore, the master controller has a pre-knowledge of the load and input voltage disturbances so it can apply the SLC strategy to utilize robustness of the PBB converter. Another strategy aiming to minimise energy loss and maximise the robustness in the face of disturbance is developed to cover applications with unexpected disturbances. This strategy is named Dynamic Hysteresis Band (DHB), and is used to manipulate the hysteresis band height after occurrence of disturbance to reduce dynamics of the output voltage. When no disturbance has occurred, the PBB converter works with minimum inductor current and minimum energy loss. New topologies based on the PBB converter have been introduced to address input voltage disturbances for different onboard applications. The research shows that the performance of applications of symmetrical/asymmetrical multi-level diode-clamped inverters, DC-networks, and linear-assisted RF amplifiers may be enhanced by the utilization of topologies based on the PBB converter. Multi-level diode-clamped inverters have the problem of DC-link voltage balancing when the power factor of their load closes to unity. This research has shown that this problem may be solved with a suitable multi-output DC-DC converter supplying DClink capacitors. Furthermore, the multi-level diode-clamped inverters supplied with asymmetrical DC-link voltages may improve the quality of load voltage and reduce the level of Electromagnetic Interference (EMI). Mathematical analyses and experiments on supplying symmetrical and asymmetrical multi-level inverters by specifically designed multi-output DC-DC converters have been reported in two journal papers. Another application in which the system performance can be improved by utilization of the ‘current circulating’ switching state is linear-assisted RF amplifiers in communicational receivers. The concept of ‘linear-assisted’ is to divide the signal into two frequency domains: low frequency, which should be amplified by a switching circuit; and the high frequency domain, which should be amplified by a linear amplifier. The objective is to minimize the overall power loss. This research suggests using the current storage capacity of a PBB based converter to increase its bandwidth, and to increase the domain of the switching converter. The PBB converter addresses the industrial demand for a DC-DC converter for the application of auxiliary power supply of a typical electric train. However, after testing the industrial prototype of the PBB converter, there were some voltage and current spikes because of switching. To attenuate this problem without significantly increasing the switching loss, the idea of Active Gate Signalling (AGS) is presented. AGS suggests a smart gate driver that selectively controls the switching process to reduce voltage/current spikes, without unacceptable reduction in the efficiency of switching.
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Shang, Lei, and lei shang@ieee org. "Modelling of Mobile Fading Channels with Fading Mitigation Techniques." RMIT University. Electrical and Computer Engineering, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20061222.113303.
Full textAbstract:
This thesis aims to contribute to the developments of wireless communication systems. The work generally consists of three parts: the first part is a discussion on general digital communication systems, the second part focuses on wireless channel modelling and fading mitigation techniques, and in the third part we discuss the possible application of advanced digital signal processing, especially time-frequency representation and blind source separation, to wireless communication systems. The first part considers general digital communication systems which will be incorporated in later parts. Today's wireless communication system is a subbranch of a general digital communication system that employs various techniques of A/D (Analog to Digital) conversion, source coding, error correction, coding, modulation, and synchronization, signal detection in noise, channel estimation, and equalization. We study and develop the digital communication algorithms to enhance the performance of wireless communication systems. In the Second Part we focus on wireless channel modelling and fading mitigation techniques. A modified Jakes' method is developed for Rayleigh fading channels. We investigate the level-crossing rate (LCR), the average duration of fades (ADF), the probability density function (PDF), the cumulative distribution function (CDF) and the autocorrelation functions (ACF) of this model. The simulated results are verified against the analytical Clarke's channel model. We also construct frequency-selective geometrical-based hyperbolically distributed scatterers (GBHDS) for a macro-cell mobile environment with the proper statistical characteristics. The modified Clarke's model and the GBHDS model may be readily expanded to a MIMO channel model thus we study the MIMO fading channel, specifically we model the MIMO channel in the angular domain. A detailed analysis of Gauss-Markov approximation of the fading channel is also given. Two fading mitigation techniques are investigated: Orthogonal Frequency Division Multiplexing (OFDM) and spatial diversity. In the Third Part, we devote ourselves to the exciting fields of Time-Frequency Analysis and Blind Source Separation and investigate the application of these powerful Digital Signal Processing (DSP) tools to improve the performance of wireless communication systems.
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Jalboub, Mohamed K. "Investigation of the application of UPFC controllers for weak bus systems subjected to fault conditions. An investigation of the behaviour of a UPFC controller: the voltage stability and power transfer capability of the network and the effect of the position of unsymmetrical fault conditions." Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/5699.
Full textAbstract:
In order to identify the weakest bus in a power system so that the Unified Power Flow Controller could be connected, an investigation of static and dynamic voltage stability is presented. Two stability indices, static and dynamic, have been proposed in the thesis. Multi-Input Multi-Output (MIMO) analysis has been used for the dynamic stability analysis. Results based on the Western System Coordinate Council (WSCC) 3-machine, 9-bus test system and IEEE 14 bus Reliability Test System (RTS) shows that these indices detect with the degree of accuracy the weakest bus, the weakest line and the voltage stability margin in the test system before suffering from voltage collapse.
Recently, Flexible Alternating Current Transmission systems (FACTs) have become significant due to the need to strengthen existing power systems. The UPFC has been identified in literature as the most comprehensive and complex FACTs equipment that has emerged for the control and optimization of power flow in AC transmission systems. Significant research has been done on the UPFC. However, the extent of UPFC capability, connected to the weakest bus in maintaining the power flows under fault conditions, not only in the line where it is installed, but also in adjacent parallel lines, remains to be studied. In the literature, it has normally been assumed the UPFC is disconnected during a fault period. In this investigation it has been shown that fault conditions can affect the UPFC significantly, even if it occurred on far buses of the power system. This forms the main contribution presented in this thesis. The impact of UPFC in minimizing the disturbances in voltages, currents and power flows under fault conditions are investigated. The WSCC 3-machine, 9-bus test system is used to investigate the effect of an unsymmetrical fault type and position on the operation of UPFC controller in accordance to the G59 protection, stability and regulation. Results show that it is necessary to disconnect the UPFC controller from the power system during unsymmetrical fault conditions.Libyan Government
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Jalboub, Mohamed. "Investigation of the application of UPFC controllers for weak bus systems subjected to fault conditions : an investigation of the behaviour of a UPFC controller : the voltage stability and power transfer capability of the network and the effect of the position of unsymmetrical fault conditions." Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/5699.
Full textAbstract:
In order to identify the weakest bus in a power system so that the Unified Power Flow Controller could be connected, an investigation of static and dynamic voltage stability is presented. Two stability indices, static and dynamic, have been proposed in the thesis. Multi-Input Multi-Output (MIMO) analysis has been used for the dynamic stability analysis. Results based on the Western System Coordinate Council (WSCC) 3-machine, 9-bus test system and IEEE 14 bus Reliability Test System (RTS) shows that these indices detect with the degree of accuracy the weakest bus, the weakest line and the voltage stability margin in the test system before suffering from voltage collapse. Recently, Flexible Alternating Current Transmission systems (FACTs) have become significant due to the need to strengthen existing power systems. The UPFC has been identified in literature as the most comprehensive and complex FACTs equipment that has emerged for the control and optimization of power flow in AC transmission systems. Significant research has been done on the UPFC. However, the extent of UPFC capability, connected to the weakest bus in maintaining the power flows under fault conditions, not only in the line where it is installed, but also in adjacent parallel lines, remains to be studied. In the literature, it has normally been assumed the UPFC is disconnected during a fault period. In this investigation it has been shown that fault conditions can affect the UPFC significantly, even if it occurred on far buses of the power system. This forms the main contribution presented in this thesis. The impact of UPFC in minimizing the disturbances in voltages, currents and power flows under fault conditions are investigated. The WSCC 3-machine, 9-bus test system is used to investigate the effect of an unsymmetrical fault type and position on the operation of UPFC controller in accordance to the G59 protection, stability and regulation. Results show that it is necessary to disconnect the UPFC controller from the power system during unsymmetrical fault conditions.
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Amhoud, El Mehdi. "Coding techniques for space-division multiplexed optical fiber systems." Electronic Thesis or Diss., Paris, ENST, 2017. http://www.theses.fr/2017ENST0067.
Full textAbstract:
Les deux dernières décennies ont connu une croissance exponentielle de la demande pour plus de capacité dans les réseaux optiques. Cette croissance a été principalement causée par le développement d'Internet et le trafic croissant généré par le nombre croissant des utilisateurs. La fibre optique offre plusieurs degrés de liberté pour augmenter la capacité. La fréquence, le temps, la phase, la polarisation ont déjà été utilisés pour satisfaire la demande de bande passante, ainsi le multiplexage spatial (SDM) reste le seul degré de liberté disponible pouvant être utilisé dans les systèmes optiques afin d'augmenter la capacité. Cependant, les interactions entre les différents canaux spatiaux dans le même milieu de propagation est inévitable. Ces interactions, si elles ne sont pas compensées, entraînent des dégradations qui détériorent les performances du système. À cette fin, des recherches intensives sont menées récemment afin de développer un traitement de signal avancé capable de traiter ces détériorations dans les systèmes à multiplexage spatial. Motivés par le rôle potentiel des fibres optiques multimodes (MMF) dans les futurs systèmes SDM, dans cette thèse, nous présentons des solutions de codage modernes pour réduire la diaphonie non-unitaire qui affecte les modes spatiaux dans les fibres multimodes entraînant une dégradation des performancesIn a very fast pace, the last two decades have known an exponential growth in the demand for more optical network capacity, this growth was mainly caused by the built-out of the Internet and the growing traffic generated by an increasing number of users. Since frequency, time, phase, polarization have already been used to satisfy the demand for bandwidth, space-division multiplexing (SDM) remains the only available degree of freedom that can be used in optical transmission systems in order to increase the capacity. However, interactions between spatial channels in the same propagation medium is inevitable. These interactions, if not compensated, result in impairments that deteriorate the system performance. For this purpose, intensive research is being carried out in recent years in order to provide advanced signal processing capable to deal with these impairments in spatial multiplexing systems. Motivated by the potential role of multi-mode fibers (MMFs) in future SDM systems, in this thesis, we present modern coding solutions to mitigate the non-unitary crosstalk known as mode-dependent loss (MDL) that affects spatial modes of MMFs resulting in degraded system performance
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Mungara, Ratheesh Kumar. "System-level performance of interference-aware spatial frequency reuse." Doctoral thesis, Universitat Pompeu Fabra, 2016. http://hdl.handle.net/10803/400869.
Full textAbstract:
Spatial frequency reuse is a long-established approach for enhancing the capacity of wireless systems through increased spectral efficiency (bits per second per unit bandwidth). The future 5th generation of wireless systems is expected to incorporate various forms of frequency reuse. This includes multiple-input multiple-output (MIMO) communication enabling frequency reuse across antennas, device-to-device (D2D)-based densification allowing spectrum reuse across direct communication links, and full duplexing utilizing the same spectrum for communication in the transmit and receive directions.
This dissertation aims at determining the performance limits of emerging wireless systems underpinned by dense spatial frequency reuse and interference suppression, and to glean key system design insights. Stochastic geometry is the toolbox invoked to conduct the analysis, with network locations modeled as points of a Poisson process. A new framework is developed by introducing a Gaussian fit to the interference and variable degrees of spatial averaging, which enable more meaningful results and compact expressions compared to those of existing analyses.
Within this framework, we first consider MIMO spatial multiplexing and interference alignment (IA). The former scheme utilizes all available spatial dimensions for signaling and the latter minimizes interference at the expense of knowing the instantaneous fading states at both transmitters and receivers and of a reduction in spatial signaling dimensions. Despite the intense work on IA and spatial multiplexing, there is limited work aimed at understanding their engineering tradeoff in the context of practically relevant cellular settings such as propagation losses, fading dynamics due to user mobility and imperfect knowledge of the fading states. We have studied this problem in depth through both system- and link-level analyses. Even under perfect knowledge of the fading, IA is seen to be beneficial over spatial multiplexing only in very specific and relatively infrequent network situations, and IA loses all its advantages at vehicular speeds when the fading knowledge is imperfect.
Second, we focus on ITLinQ and FlashLinQ, the two principal channelization schemes proposed to date for controlling the interference in D2D networks. An analytical characterization of ITLinQ scheme is provided, opening the door to optimizing its controllable parameters. It is shown that both channelization schemes outperform the unchannelized baseline, with a slight edge for ITLinQ. On the most unfavorable network geometries, ITLinQ yields multiple-fold improvements in spectral efficiency with respect to an unchannelized network.
Finally, we introduce full-duplex transceivers in cellular networks and characterize the impact of increased interference on their performance. It is established through analysis and complemented by simulations on a Vodafone LTE field test network that additional user-to-user interference only has a minor impact while base-to-base interference would render full-duplex operation unfeasible in dense microcellular networks without any interference management.
In summary, MIMO spatial multiplexing and D2D-based densification are seen to play a vital role in improving wireless system capacity while IA and full duplexing are found to be ineffective.La reutilització de la freqüència espacial és l’aproximació més acceptada per tal de millorar la capacitat dels sistemes wireless mitjançant l'increment de l'eficiència espectral (bits per segon per unitat d'ample de banda). S'espera que la futura cinquena generació de sistemes wireless incorpori diverses formes de reutilització de freqüència. Això inclou la comunicació multi-input multi-output (MIMO) que permet la reutilització a través d'antenes, densificació dispositiu-a-dispositiu (D2D) que permet reutilitzar l'espectre a través d’enllaços de comunicació directa, així com un full-dúplex emprant el mateix espectre per a la comunicació en la transmissió i recepció de direccions. Aquest treball pretén determinar els límits de rendiment dels sistemes wireless emergents, basats en una densa reutilització de la freqüència espacial i en la supressió d'interferències, així com espigolar coneixement clau per al disseny de sistemes d'aquest tipus. La geometria estocàstica és l'eina que s'aplicarà a l'anàlisi que es durà a terme, modelitzant les localitzacions dins la xarxa com a punts d'un procés de Poisson. La introducció d'un ajust Gaussià a la interferència, conjuntament amb la consideració de nivells variables d'expectació espacial, han permès definir un nou marc matemàtic que fa possible unes expressions més compactes i uns resultats més significatius en comparació amb els anàlisis existents. Dins d'aquest marc, en primer lloc es prenen en consideració la multiplexació MIMO i l'aliniament d'interferència (IA, en les seves sigles en anglès). El primer esquema empra totes les dimensions espacials disponibles per a la senyalització i el segon minimitza la interferència a costa de conèixer els estats de esvaïment instantani dels transmissors i receptors, i d'una reducció en les dimensions de senyalització espacial. Malgrat l'intens treball en l'IA i la multiplexació espacial, s'ha prestat escassa atenció a tractar de comprendre el seu balanç d’enginyeria en el context d'xarxes cel.lulars de rellevància pràctica, com els de propagació de pèrdues, o les dinàmiques de esvaïment degudes a la mobilitat de l'usuari i al coneixement imperfecte dels estats de esvaïment. En aquest treball s'ha estudiat en profunditat aquest problema a través d'anàlisis tant a nivell dels enllaços com del sistema. Fins i tot en condicions de coneixement perfecte del esvaïment, l'IA resulta beneficiós sobre la multiplexació només en situacions de xarxa molt específiques i relativament infreqüents, mentre que perd tots els seus avantatges a velocitats vehiculars quan el coneixement del esvaïment és imperfecte. En segon lloc, el treball es centra en el ITLinQ i el FlashLinQ, els dos principals esquemes de canalització proposats fins al moment per controlar la interferència en xarxes D2D. S'ofereix una caracterització analítica de l'esquema ITLinQ, obrint així la porta a l'optimització dels seus paràmetres controlables. Es mostra que tots dos esquemes de canalització aconsegueixen millors resultats que l'esquema no canalitzat, amb un lleuger avantatge per al ITLinQ. Considerant la geometria de xarxa més desfavorable, el ITLinQ produeix millores múltiples en l'eficiència espectral en comparació amb la xarxa no canalitzada. Finalment, el treball introdueix els transreceptors full-dúplex en xarxes cel.lulars i caracteritza l'impacte de la interferència incrementada en el seu funcionament. A través d'anàlisis i de simulacions complementàries en una xarxa de test de Vodafone LTE, s'estableix que la interferència d'usuari a usuari té un impacte poc significatiu mentre que la interferència de base a base faria inviable l'operació full-dúplex en xarxes microcell.lulars sense gestió de les interferències. En resum, aquest tesis doctoral aporta evidència de que el multiplexat MIMO i la densificació basada en D2D juguen un paper vital en la millora de la capacitat dels sistemes wireless mentre que el IA i el full-dúplex resulten inefectius.
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Scarlato, Michele. "Sicurezza di rete, analisi del traffico e monitoraggio." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/3223/.
Full textAbstract:
Il lavoro è stato suddiviso in tre macro-aree.
Una prima riguardante un'analisi teorica di come funzionano le intrusioni, di quali software vengono utilizzati per compierle, e di come proteggersi (usando i dispositivi che in termine generico si possono riconoscere come i firewall).
Una seconda macro-area che analizza un'intrusione avvenuta dall'esterno verso dei server sensibili di una rete LAN.
Questa analisi viene condotta sui file catturati dalle due interfacce di rete configurate in modalità promiscua su una sonda presente nella LAN.
Le interfacce sono due per potersi interfacciare a due segmenti di LAN aventi due maschere
di sotto-rete differenti. L'attacco viene analizzato mediante vari software.
Si può infatti definire una terza parte del lavoro, la parte dove vengono analizzati i file
catturati dalle due interfacce con i software che prima si occupano di analizzare i dati di
contenuto completo, come Wireshark, poi dei software che si occupano di analizzare i dati di
sessione che sono stati trattati con Argus, e infine i dati di tipo statistico che sono stati trattati
con Ntop.
Il penultimo capitolo, quello prima delle conclusioni, invece tratta l'installazione di Nagios, e
la sua configurazione per il monitoraggio attraverso plugin dello spazio di disco rimanente su
una macchina agent remota, e sui servizi MySql e DNS. Ovviamente Nagios può essere
configurato per monitorare ogni tipo di servizio offerto sulla rete.
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Posse, Carlos Filipe Raposo. "Controlo unfalsified em sistemas MIMO." Master's thesis, 2014. http://hdl.handle.net/10362/14472.
Full textAbstract:
Com o crescente progresso tecnológico, surgem sistemas mais eficientes, mas também
mais complexos e não-lineares. Isto torna-se mais evidente em sistemas Multi-Input
Multi-Output (MIMO), devido a diferentes efeitos que uma entrada possa ter sobre diversas
saídas. Para estes sistemas, a obtenção de modelos matemáticos que capturem, com
precisão aceitável, a dinâmica do sistema, torna-se cada vez mais complexa e custosa.
Sendo que muitos dos sistemas utilizados hoje em dia são MIMO, a diminuição na
precisão dos modelos matemáticos é uma adversidade à eficiência dos sistemas de controlo.
Isto deve-se a grande parte dos métodos de projeto de controladores terem como
base o modelo do sistema.
O trabalho realizado nesta dissertação pretende desenvolver uma estrutura de supervisão
para sistemas MIMO, com base em controlo Unfalsified, ou Unfalsified Control (UC).
Este consiste numa abordagem de controlo adaptativo, cujo processo de adaptação se
traduz na seleção de um controlador, de entre um conjunto pré-determinado. Em cada
momento é selecionado o controlador que mais se adequa ao objetivo de controlo pretendido.
A utilização de UC representa uma possível solução para o problema apresentado,
pois utiliza apenas dados experimentais recolhidos do funcionamento do processo. Assim,
contorna a necessidade da existência de modelos do processo.
Existem, no entanto, dificuldades associadas à comutação de controladores, pelo que
este trabalho pretende também desenvolver uma estrutura de Bumpless Transfer (BT), de
forma a reduzir estes efeitos. Finalmente, a utilização de dados experimentais implica
que a aplicação de UC a um processo está apenas limitada ao ajuste dos parâmetros do
sistema de supervisão, e à existência de um conjunto de controladores adequados.
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Wu, Hui-Nan, and 吳惠南. "MIMO (Multi Input Multi Output) in Next Generation of Mobile Communications." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/6amwke.
Full textAbstract:
碩士元智大學
通訊工程學系
105
Multi-antenna technologies such as beamforming and Multiple-Input, Multiple-Output (MIMO) are anticipated to play a key role in next generation mobile communications system, which are expected to be deployed in the year 2020 and beyond. The MIMO (Multiple-Input Multiple-Output) technologies have directionality, improve spectral efficiency and high network capacity. In this paper, we discuss MIMO architectures where the types of transmit MIMO, processing and applications. We will focus on the principles and applications for MIMO. Multiple-input multiple-output (MIMO) technology uses multiple antennas at the both link ends and does not need to increase additional transmit power and spectrum, leading to promising link capacity gains of several-fold increase in spectrum efficiency. MIMO technology has been adopted in IEEE 802.16 standard and also has been applied in IEEE 802.11. It is normally though that the spatial correlations reduce the capacity of MIMO system, but in fact, with correlation matrices available, a transmitter can apply the stochastic power allocation and the antenna selection. Stochastic power allocation is applied on these selected antennas instead to all to get maximum capacity and accelerate the antenna selection process. MIMO technology will play an important role in the 4G wireless system. The early studies of MIMO system are mostly based on the ideal channel model that the elements of channel matrix are independently and identically distributed complex Gaussian random variables, but the real MIMO channels may have spatial correlation. Moreover, using MIMO systems will lead to the increase of system cost and complexity, which constrains the development of MIMO technology, however, the fast antenna selection scheme based on correlation matrix can efficiently reduce the complexity of MIMO system.
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Huang, Chi-Hsiung, and 黃啟雄. "A Multi-Input Multi-Output(MIMO) Antenna with Wave-Traps Design." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/89714290716603868662.
Full textAbstract:
碩士樹德科技大學
電腦與通訊系碩士班
102
This paper presents a kind of Wave-trap multiple-input multiple-output antenna. The main structure is fed into a large metal sheet, with an element coupled to ground, and then placed in mirror-symmetrical manner to the upper region of the substrate to form a 2 × 2 antenna configuration. This antenna design is simple, the area occupy narrow and can excite WLAN operating band mode for radiator. Because added the wave suppression components coupling element, which results not only improves the impedance characteristics of the antenna, and in required frequency band isolation but also has good results. Prove that antenna structure plays a role in suppressing the interference of energy. This design can really be applied to wireless local area network （WLAN）of the communications on the system.
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Lian, Rui-Jing, and 連瑞敬. "The Intelligent Control of Multi-input/Multi-output Systems." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/70300365965034328592.
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Njue, Danson Gitonga. "A game theoretic power allocation scheme for multi-user multi input multi output (MIMO) system." Thesis, 2010. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000336.
Full textAbstract:
M. Tech. Electrical Engineering.In the recent past, there has been an increase in demand for high data rate services and system designers are always looking for ways to improve the capacity and quality of service (QoS) of wireless communication networks. The main objective of the study is to propose an asynchronous power allocation scheme based on the classical waterfilling algorithms in a multi-user MIMO uplink system. The proposed algorithm is fully distributed and eliminates the need for user synchronization during power allocation. Each user in the system competes with one another in choosing the capacity maximizing transmit power while treating the multi-user interference as noise. The problem is reduced to finding the optimal transmit covariance matrix of the users that maximizes the sum capacity of the system. We formulate the power allocation problem as a non-cooperative game and show the existence and uniqueness of the Nash Equilibrium (NE) point. The proposed Semi-Asynchronous MIMO Waterfilling algorithm maximizes the system sum capacity without the need for synchronization among users when updating their power allocation.
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Chung, Ying-Jer, and 鐘英哲. "Nonlinear Robust Control for Multi-Input-Multi-Output Magnetic Levitation System." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/05251229815586957155.
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Xu, Kevin. "Multi-Input Multi-Output Repetitive Control Theory And Taylor Series Based Repetitive Control Design." Thesis, 2012. https://doi.org/10.7916/D8SB4CPN.
Full textAbstract:
Repetitive control (RC) systems aim to achieve zero tracking error when tracking a periodic command, or when tracking a constant command in the presence of a periodic disturbance, or both a periodic command and periodic disturbance. This dissertation presents a new approach using Taylor Series Expansion of the inverse system z-transfer function model to design Finite Impulse Response (FIR) repetitive controllers for single-input single-output (SISO) systems, and compares the designs obtained to those generated by optimization in the frequency domain. This approach is very simple, straightforward, and easy to use. It also supplies considerable insight, and gives understanding of the cause of the patterns for zero locations in the optimization based design. The approach forms a different and effective time domain design method, and it can also be used to guide the choice of parameters in performing in the frequency domain optimization design. Next, this dissertation presents the theoretical foundation for frequency based optimization design of repetitive control design for multi-input multi-output (MIMO) systems. A comprehensive stability theory for MIMO repetitive control is developed. A necessary and sufficient condition for asymptotic stability in MIMO RC is derived, and four sufficient conditions are created. One of these is the MIMO version of the approximate monotonic decay condition in SISO RC, and one is a necessary and sufficient condition for stability for all possible disturbance periods. An appropriate optimization criterion for direct MIMO is presented based on minimizing a Frobenius norm summed over frequencies from zero to Nyquist. This design process is very tractable, requiring only solution of a linear algebraic equation. An alternative approach reduces the problem to a set of SISO design problems, one for each input-output pair. The performances of the resulting designs are studied by extensive examples. Both approaches are seen to be able to create RC designs with fast monotonic decay of the tracking error. Finally, this dissertation presents an analysis of using an experiment design sequence for parameter identification based on the theory of iterative learning control (ILC), a sister field to repetitive control. This is suggested as an alternative to the results in optimal experiment design. Modified ILC laws that are intentionally non-robust to model errors are developed, as a way to fine tune the use of ILC for identification purposes. The non-robustness with respect to its ability to improve identification of system parameters when the model error is correct is studied. It is demonstrated that in many cases the approach makes the learning particularly sensitive to relatively small parameter errors in the model, but sensitivity is sometimes limited to parameter errors of a specific sign.
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Huang, W. H., and 黃文豪. "Fuzzy Sliding Mode Control of the Twin Rotor Multi-Input Multi-Output System." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/67120533222419347740.
Full textAbstract:
碩士國立宜蘭大學
電機工程學系碩士班
96
In this paper, we investigate a control problem called the Twin Rotor Multi-input Multi-output system (TRMS). The designed TRMS is illustrated to position the TRMS in a less time period. The TRMS system is an unstable and high nonlinear coupling effect between two propellers. It is existence very sensitive to the disturbances, it is usually used to test the performance of controllers. However, in order to simplify the designed of controller with TRMS, in the system coupling effect ignores. Therefore, after the TRMS simplify will not overhang the actions and characters of the system originally, and reduce the integral performance with TRMS. To simplify the position control, the TRMS is decomposed into a tail subsystem and a main subsystem. With the coupling effects considered as the uncertainties, the highly coupled nonlinear TRMS is decomposed. In this paper, a novel hybrid controller is presented for TRMS. This controller design can be combined with two is contains two kinds of controllers (main and tail propellers position). A main propeller and tail propellers controller is designed to position the pitch and yaw angle of TRMS. First, a fuzzy sliding and fuzzy integral sliding controller (FSFISC) is designed to position the yaw and pitch angles of a TRMS. FSFISC consists of a fuzzy sliding controller (FSC) for the position control of the yaw angle and a fuzzy integral sliding controller (FISC) for the position control of the pitch angle. The standard (first order) sliding mode usage is, restricted due to the chattering effect caused by control switching. Based on this factor, this research gets the second order sling mode into the FSSSIC controller, and a fuzzy second order sliding and fuzzy second order integral sliding controller (FSSSIC) is designed to position of a TRMS. It also hopes the controller have eliminating effect chattering. Simulation results also indicate that the TRMS with the presented novel hybrid controller are the great performance and robust to the external disturbances.
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Hsiao, Shun-Yen, and 蕭舜晏. "Indirect Adaptive Pole-Placement Control for Linear Multi-Input Multi-Output Stochastic Systems." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/93113974174002431928.
Full textAbstract:
碩士大同大學
電機工程研究所
90
In this thesis, we consider indirect adaptive pole-placement control of unknown closed-loop linear multi-input multi-output (MIMO) stochastic systems. The basic idea is to combine an on-line parameter estimation procedure with some control system design techniques to produce a control law with self-tuning capability. In order to identify the unknown MIMO system, we construct a recursive least square algorithm which applying the {\it a posteriori} prediction errors. We will prove that in the presence of noise the outputs will be global asymptotically stability as well as an unbiased parameter estimation will be obtained under richness and strictly positive real conditions. In the control strategy, we would like to use the pole-placement control method to the closed-loop system so that the desired closed-loop performance will be achieved. Therefore, for a unknown linear MIMO system, we should need to combine the least square estimation algorithm with the indirect pole-placement control law to achieve the control object. We will see that in the presence of noise the system outputs and the control inputs will be bounded under strictly positive real condition. When the desired closed-loop performance changed, the adaptive algorithm will be able to self-tuning to achieve the desired performance again. Also, a near supermartingale method will be applied to prove the convergence properties through this thesis. By this way, we first need to find an appropriate near supermartingale sequence which to some extent can be considered as a Lyapunov function. Simulation studies are also presented to validate the theoretical findings.