Dissertations / Theses on the topic 'MIMO'
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Ladaycia, Abdelhamid. "Annulation d’interférences dans les systèmes MIMO et MIMO massifs (Massive MIMO)." Thesis, Sorbonne Paris Cité, 2019. http://www.theses.fr/2019USPCD037.
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Les systèmes de communications MIMO utilisent des réseaux de capteurs qui peuvent s’étendre à de grandes dimensions (MIMO massifs) et qui sont pressentis comme solution potentielle pour les futurs standards de communications à très hauts débits. Un des problème majeur de ces systèmes est le fort niveau d’interférences dû au grand nombre d’émetteurs simultanés. Dans un tel contexte, les solutions ’classiques’ de conception de pilotes ’orthogonaux’ sont extrêmement coûteuses en débit utile permettant ainsi aux solutions d’identification de canal dites ’aveugles’ou ’semi-aveugles’ de revenir au-devant de la scène comme solutions intéressantes d’identification ou de déconvolution de ces canaux MIMO. Dans cette thèse, nous avons commencé par une analyse comparative des performances, en nous basant sur les CRB, afin de mesurer la réduction potentielle de la taille des séquences pilotes et ce en employant les méthodes dites semi-aveugles. Les résultats d’analyse montrent que nous pouvons réduire jusqu’à 95% des pilotes sans affecter les performances d’estimation du canal. Nous avons par la suite proposé de nouvelles méthodes d’estimation semi-aveugle du canal, permettant d’approcher la CRB. Nous avons proposé un estimateur semi-aveugle, LS-DF qui permet un bon compromis performance / complexité numérique. Un autre estimateur semi-aveugle de type sous-espace a aussi été proposé ainsi qu’un algorithme basé sur l’approche EM pour lequel trois versions à coût réduit ont été étudiées. Dans le cas d’un canal spéculaire, nous avons proposé un algorithme d’estimation paramétrique se basant sur l’estimation des temps d’arrivés combinée avec la technique DFMIMO systems use sensor arrays that can be of large-scale (massive MIMO) and are seen as a potential candidate for future digital communications standards at very high throughput. A major problem of these systems is the high level of interference due to the large number of simultaneous transmitters. In such a context, ’conventional’ orthogonal pilot design solutions are expensive in terms of throughput, thus allowing for the so-called ’blind’ or ’semi-blind’ channel identification solutions to come back to the forefront as interesting solutions for identifying or deconvolving these MIMO channels. In this thesis, we started with a comparative performance analysis, based on CRB, to quantify the potential size reduction of the pilot sequences when using semi-blind methods that jointly exploit the pilots and data. Our analysis shows that, up to 95% of the pilot samples can be suppressed without affecting the channel estimation performance when such semi-blind solutions are considered. After that, we proposed new methods for semi-blind channel estimation, that allow to approach the CRB. At first, we have proposed a SB estimator, LS-DF which allows a good compromise between performance and numerical complexity. Other SB estimators have also been introduced based on the subspace technique and on the ML approach, respectively. The latter is optimized via an EM algorithm for which three reduced cost versions are proposed. In the case of a specular channel model, we considered a parametric estimation method based on times of arrival estimation combined with the DF technique
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Botonjic, Aida. "MIMO kanalmodeler." Thesis, Linköping University, Department of Science and Technology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2188.
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The objective of this diploma work is to investigate a set of Multiple Input Multiple Output (MIMO) channel models compatible with the emerging IEEE 802.11n standard. This diploma work validates also advanced, innovative tools and wireless technologies that are necessary to facilitate wireless applications while maximizing spectral efficiency and throughput.
MIMO channel models can be used to evaluate new Wireless Local Area Network (WLAN) proposals based on multiple antenna technologies.
The purpose of this thesis is to investigate means of channel models and their implementation in different environments such as: Matlab, C++ and Advanced Design Systems (ADS). The investigation considers also a comparison between the channel models based on theoretical data and parameter setup to the channel models based on statistical characteristics obtained from measured data.
Investigation and comparison of a MIMO channel models consider steering channel matrix H, spatial correlation coefficients, power delay profiles, fading characteristics and Doppler power spectrum.
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Choi, Lai U. "Multi-user MISO and MIMO transmit signal processing for wireless communication /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202003%20CHOI.
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Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2003.Includes bibliographical references (leaves 167-170). Also available in electronic version. Access restricted to campus users.
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Ma, Shaodan. "Semi-blind signal detection for MIMO and MIMO-OFDM systems." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B36846569.
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Ma, Shaodan, and 馬少丹. "Semi-blind signal detection for MIMO and MIMO-OFDM systems." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B36846569.
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Negrão, João Lucas. "Efficient detection : from conventional Mimo to massive Mimo communication systems." Universidade Estadual de Londrina. Centro de Tecnologia e Urbanismo. Programa de Pós-Graduação em Engenharia Elétrica, 2018. http://www.bibliotecadigital.uel.br/document/?code=vtls000218370.
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Ao longo deste trabalho, problemas relacionados aos sistemas de comunicação equipados com múltiplas antenas no transmissor e receptor (MIMO - Multiple- Input Multiple-Output) são analisados sob o ponto de vista de detecção clássica, da otimização não-linear, bem como da pré-codificação linear, desde MIMO convencional (algumas antenas no Tx e Rx) até sistemas MIMO de larga-escala (massivo). Inicialmente, a eficiência de detecção de vários detectores MIMO foi analisada sob a prerrogativa de canais altamente correlacionados, situação em que sistemas MIMO apresentam elevada perda de desempenho, além de, em alguns casos, uma crescente complexidade. Diante deste cenário, foi estudado especificamente o comportamento em termos do compromisso complexidade x taxa de erro de bits (BER - Bit Error Rate), para diferentes técnicas de detecção, como o cancelamento de interferências sucessivo (SIC), redução treliça (LR), bem como a combinação de cada uma destas às técnicas lineares de detecção. Nessa análise, também foram considerados diferentes estruturas de antenas uniformes com arranjos geométricos lineares (ULA - uniform linear array) e de arranjo planar (UPA - uniform planar array) em ambos transmissor e receptor. Além disso, também foram considerados diferentes número de antenas e ordem de modulação. Em seguida, o problema de detecção MIMO foi estudado sob uma perspectiva de otimização não-linear, visando especificamente alcançar o desempenho ótimo. Foi analisada a solução de detecção com relaxação semi-definida (SDR - semi- definite relaxation). O detector SDR-MIMO é uma abordagem eficiente capaz de atingir o desempenho muito próximo ao ótimo, especialmente para baixas e médias ordens de modulação. Concentramos nossos esforços no desenvolvimento de uma aproximação computacionalmente eficiente para o algoritmo de detecção de máxima verossimilhança (ML - Maximum Likelihood) MIMO baseado na programação semi-definida (SDP - Semidefinite Programming) para as constelações M-QAM. Finalmente, estuda-se um problema de alocação de potência com o objetivo de maximizar a capacidade de um canal de broadcasting MIMO massivo em uma única célula equipada com pré-codificação forçagem à zero (ZFBF - zero-forcing beamforming) e inversão de canal regularizado (RCI - regularized channel inversion) na estação rádio base (BS). Nosso objetivo é investigar esse problema considerando um sistema massivo no limite, ou seja, quando o número de usuários, K, e antenas na BS, M, tendem ao infinito porém com uma razão constante, β = K M . Primeiramente deriva-se a relação sinal-interferência mais ruído (SINR) para ambos os pré-codificadores escolhidos. Em seguida, investiga-se um esquemas de alocação de potência ótimo que maximiza a soma das capacidades por antena sob uma restrição de potência máxima disponível, conclui-se que o problema é convexo e que a alocação de potência ótima segue a estratégia de watter-filling (WF). Também estudou-se o problema relacionado à alocação de potência em um grupo finito de usuários separados em grupos e determinou-se o impacto desse esquema na capacidade total do sistema.Throughout this work, problems related to communication systems equipped with multiple antennas in the transmitter and receiver (MIMO - Multiple-Input Multiple-Output) are analyzed from the point of view of classical detection, nonlinear optimization, as well as linear pre-coding, from conventional MIMO (some Tx and Rx antennas) to large-scale (massive) MIMO systems. Initially, the detection efficiency of several MIMO detectors were analyzed under the prerogative of highly correlated channels, in which situation, MIMO systems present a high loss of performance, and, in some cases, an increasing complexity. Considering this scenario, we have specifically studied the behavior in terms of compromise complexity x bit error rate (BER), for different detection techniques, such as the successive interference cancellation (SIC), lattice reduction (LR), as well as the combination of each of these with linear detection techniques. In this analysis, different uniform antenna structures with uniform linear array (ULA) and planar array array (UPA) were also considered in both transmitter and receiver side. In addition, different number of antennas and order of modulation were also considered. Next, the MIMO detection problem was studied from a nonlinear optimization perspective, specifically aiming to achieve optimum performance. The detection solution with semi-defined relaxation (SDR - it semidefinite relaxation) were analyzed. The SDR-MIMO detector is an efficient approach capable of achieving near-optimal performance, especially for low and medium modulation orders. We focused our efforts on developing a computationally efficient approach for the maximum likelihood (ML) MIMO detection algorithm based on semi-definite programming (SDP) for M-QAM constellations. Finally, we study an optimal power allocation problem aiming to maximizes the sum-rate capacity of a single cell massive MIMO broadcast channel equipped with zero-forcing beamforming (ZFBF) and regularized channel inversion (RCI) precoding at the base station (BS). Our purpose is to investigate this problem in the large-scale system limit, i.e, when the number of users, K, and antennas at the BS, M, tend to infinity with a ratio β = K/M being held constant. We first derive the signal to interference plus noise (SINR) ratio for both chosen precoders. Then we investigate optimal power allocation schemes that maximize the sum-rate per antenna under an average power constraint and we show that the problem is convex and the power allocation follows the well-known Water-Filling strategy. We also studied a problem related to an optimal power allocation at a finite group of clustered users and determine the impact of this scheme in the ergodic sum-rate capacity.
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Janhunen, J. (Janne). "Programmable MIMO detectors." Doctoral thesis, Oulun yliopisto, 2011. http://urn.fi/urn:isbn:9789514296598.
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Abstract The multiple-input multiple-output (MIMO) technique combined with an orthogonal frequency division multiplexing (MIMO--OFDM) has been introduced as a promising approach for the ever increasing capacity and quality of service (QoS) requirements for wireless communication systems. An efficient radio spectrum utilization expects a flexible transceiver solution, which has been the reason for the development of the software defined radio (SDR) technologies which in their turn are expected to enable the creation of cognitive radios. As a result, any radio solution could be invoked on demand on any platform. In this thesis work, we have studied detector algorithms and programmable processor architectures in order to find practical solutions for the future wireless systems. A programmable receiver can reduce the energy dissipation of the receiver by changing the detection algorithm based on the current channel realizations. To provide a realistic aspect to the implementations in different channel realizations, we present a wide state-of-the-art detector comparison. In addition, we present an extensive number arithmetic and word length study in order to evaluate realistic hardware complexity and energy dissipations of the implementations. The study includes a comprehensive design chain from the algorithm development to the actual processor design and finally programming software for the platforms. We evaluate single and multi-core processor implementations by comparing the achieved results to the Long Term Evolution (LTE) performance requirements. We implement detectors on digital signal processors (DSPs), graphics processing unit (GPU) and transport triggered architecture (TTA). The implementation results are compared in throughput, silicon area and energy efficiency. Finally, we discuss the advantages and disadvantages of the architectures and the implementation effortTiivistelmä Usean antennin tekniikka yhdistettynä ortogonaaliseen taajuusvaihtelumodulointiin lähetin-vastaanotimessa on esitetty eräänä lupaavana ratkaisuna jatkuvasti kasvaviin kapasiteetti- ja palvelunlaatuvaatimuksiin langattomissa tietoliikennejärjestelmissä. Tehokas radiospektrin käyttö edellyttää joustavaa lähetin-vastaanotinratkaisua, mikä on ollut syynä ohjelmistoradioteknologioiden kehitykselle. Ohjelmistoradioiden kehityksen on puolestaan odotettu mahdollistavan kognitiiviradioiden syntymisen. Tuloksena, mikä tahansa radiosovellus voitaisiin herättää tarpeen mukaan millä tahansa ohjelmoitavalla sovellusalustalla. Tässä väitöskirjatyössä tutkitaan ilmaisinalgoritmeja sekä ohjelmoitavia prosessoriarkkitehtuureja tarkoituksena löytää käytännöllisiä ratkaisuja tulevaisuuden langattomiin järjestelmiin. Ohjelmoitavalla vastaanottimella voidaan vähentää vastaanottimen energiankulutusta vaihtamalla ilmaisinalgoritmeja vallitsevan kanavatilan mukaan. Työssä esitellään laaja, viimeisintä tutkimusta edustava ilmaisinalgoritmivertailu, joka antaa realistisen näkökannan toteutuksiin erilaisissa kanavatiloissa. Lisäksi työssä esitellään numeroaritmetiikka- ja sananpituustutkimus, jonka tarkoituksena on arvioida toteutusten realistista kovokompleksisuutta sekä energiankulutusta. Tutkimus sisältää kattavan suunnitteluketjun algoritmikehityksestä todelliseen prosessorisuunnitteluun ja lopulta algoritmin ohjelmointiin tietylle sovellusalustalle. Väitöskirjatyössä arvioidaan yksi- ja moniytimisiä prosessoritoteutuksia vertaamalla saavutettuja tuloksia Long Term Evolution -standardin suorituskykyvaatimuksiin. Ilmaisimia toteutetaan digitaalisilla signaaliprosessoreilla, grafiikkaprosessorilla sekä siirtoliipaisuarkkitehtuurilla. Toteutustuloksia vertaillaan laskentatehona, pinta-alana sekä energiatehokkuutena. Lopuksi käsitellään arkkitehtuurien hyviä ja huonoja puolia sekä suunnittelun työläyttä
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Basnayaka, Dushyantha. "Macrodiversity MIMO Transceivers." Thesis, University of Canterbury. Electrical and Computer Engineering, 2012. http://hdl.handle.net/10092/7266.
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In wireless systems, radio signals are corrupted due to fading,
interference and noise. In order to handle the effects of fading and
interference, modern systems employ various techniques including
multi-antenna transceivers. Initially, multi-antenna systems were
proposed only for point-point communication. More recently,
multi-antenna transceivers have been proposed for multiuser (MU)
wireless systems. There are various topologies in which
multi-antenna transceivers can be used in a multiuser wireless
environment. Among them, macrodiversity is an important concept
driven by many scenarios, including base station cooperation,
coordinated multipoint (CoMP) transmission and network multiple
input multiple output (MIMO).
A communication system where antenna
elements at both source and receiver are widely (geographically)
separated is described as a macrodiversity communication system. For
these macrodiversity systems, every link may have a different
average signal to noise ratio (SNR) since the sources and the
receive antennas are all in different locations. This variation in
average SNR across the links makes the performance analysis of such
systems more complex. For this reason, most of the results currently
available are based on simulation. However, the value of analytical
results can be immense for efficient computation and optimized
operation. Therefore, in this thesis we present a comprehensive, and
rigorous analytical investigation of various aspects of
multiuser macrodiversity MIMO systems.
Two main aspects of macrodiversity MIMO systems are considered: the
multiple access channel (MAC) and uplink user scheduling. In the
earlier chapters of the thesis, we investigate the performance of
uplink transmission employing multi-antenna transmitters and
receivers. We analyze the signal-to-interference plus noise ratio
(SINR) performance, symbol error rate (SER) and ergodic sum capacity
etc. In a later chapter, we consider multiuser scheduling issues in
macrodiversity multiuser MIMO systems. The primary emphasis is on
the MIMO-MAC where we present some systematic performance metrics
and approaches to multiuser scheduling which only require the long
term channel state information (CSI). These methods provide a double
advantage over scheduling using instantaneous CSI. First, the
computational burden is lower and secondly, the delay between
obtaining and using channel estimation is reduced.
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Xiao, Hui. "MIMO channel modeling." Thesis, University of York, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.479187.
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Kančo, Vít. "Simulace MIMO systémů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2010. http://www.nusl.cz/ntk/nusl-218624.
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MIMO systems are mainly used in application for wireless communication. Their principle is to use a large number of antennas for transmition and the reception of a signal. The core of these systems is to use space-time coding and either block or trellis space-time code. In the future, it is assumed enormous enlargement MIMO systems in many applications
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Taparugssanagorn, A. (Attaphongse). "Evaluation of MIMO radio channel characteristics from TDM-switched MIMO channel sounding." Doctoral thesis, University of Oulu, 2007. http://urn.fi/urn:isbn:9789514286506.
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Abstract
The present dissertation deals with the evaluation of multiple-input multiple-output (MIMO) radio channel characteristics from time-division multiplexing (TDM)-switched MIMO channel sounding. The research can be divided into three main areas. First, the impacts of phase noise in TDM-switched MIMO channel sounding on channel capacity are studied. Second, we focus on those impacts on channel parameter estimation using the SAGE algorithm. And in the last part, spatial correlation, channel eigenvalue distribution, and ergodic capacity in realistic environments are analyzed.
The rationale behind the first two areas is that most advanced MIMO radio channel sounders employ the TDM technique, which has significant problems from phase noise of the TX and RX phase locked loop (PLL) oscillators causing measurement errors in terms of estimated channel capacity and parameters. We propose statistical models that reproduce the capacity estimates. The effects of the sounding mode (SM), the length of pseudo-random noise (PN) sequence L of the sounding signal, and the system size are disclosed. The distinctive basis is to consider the impact of the actual phase noise in TDM switched MIMO channel sounding, instead of assuming white Gaussian-type phase noise. In a reality, the short-term phase noise component affecting one measurement cycle of a MIMO system plays an important role in the traditional estimators of the radio channel parameters and capacity. We show that the performance impairment is less than that been under the hypothesis of uncorrelated white Gaussian phase-noises samples. The difference is due to the non-vanishing correlation of phase-noise within the measurement cycle. Two approaches to mitigating the impact of phase noise are proposed. The former is the simple and efficient sliding averaging method, where the signal-to-noise ratio (SNR) of the channel impulse response can be increased. The latter is the choice of SM and L, which is more thorough. In the second part, two approaches to mitigating its impact on channel parameter estimation using the SAGE algorithm are also discussed. Besides the sliding averaging, which in general can increase the SNR, the new SAGE algorithm based channel parameter estimation based on the improved signal model accounting for the phase noise in the measurement device is proposed. Finally, the channel eigenvalue distribution and ergodic capacity based on complex hypergeometric functions and their asymptotic characteristics are analyzed. It is shown that the derived theoretical expressions closely approximate the simulated results of the measured finite-dimensional MIMO channels. The spatial correlation and the eigenvalue statistics in frequency selective channels for single and dual polarized antennas are investigated. This knowledge is useful when different MIMO and beamforming techniques are applied.
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Borgmann, Moritz. "Noncoherent MIMO wideband communications /." Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17352.
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Imran, Muhammad, and Khursheed Khursheed. "MIMO Multiplierless FIR System." Thesis, Department of Electrical Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-20575.
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The main issue in this thesis is to minimize the number of operations and the energy consumption per operation for the computation (arithmetic operation) part of DSP circuits, such as Finite Impulse Response Filters (FIR), Discrete Cosine Transform (DCT), and Discrete Fourier Transform (DFT) etc. More specific, the focus is on the elimination of most frequent common sub-expression (CSE) in binary, Canonic Sign Digit (CSD), Twos Complement or Sign Digit representation of the coefficients of non-recursive multiple input multiple output (MIMO) FIR system , which can be realized using shift-and-add based operations only. The possibilities to reduce the complexity i.e. the chip area, and the energy consumption have been investigated.
We have proposed an algorithm which finds the most common sub expression in the binary/CSD/Twos Complement/Sign Digit representation of coefficients of non-recursive MIMO multiplier less FIR systems. We have implemented the algorithm in MATLAB. Also we have proposed different tie-breakers for the selection of most frequent common sub-expression, which will affect the complexity (Area and Power consumption) of the overall system. One choice (tie breaker) is to select the pattern (if there is a tie for the most frequent pattern) which will result in minimum number of delay elements and hence the area of the overall system will be reduced. Another tie-breaker is to choose the pattern which will result in minimum adder depth (the number of cascaded adders). Minimum adder depth will result in least number of glitches which is the main factor for the power consumption in MIMO multiplier less FIR systems. Switching activity will be increased when glitches are propagated to subsequent adders (which occur if adder depth is high). As the power consumption is proportional to the switching activity (glitches) hence we will use the sub-expression which will result in lowest adder depth for the overall system.
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Wilcox, D. C. "MIMO radar direction finding." Thesis, Queen's University Belfast, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546432.
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Chen, Danshan. "Precoding for MIMO systems." Thesis, University of York, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.535046.
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Choi, Seung-Ho. "Severely Fading MIMO Channels." Thesis, University of Canterbury. Electrical and Computer Engineering, 2007. http://hdl.handle.net/10092/1190.
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In most wireless communications research, the channel models considered experience less severe fading than the classic Rayleigh fading case. In this thesis, however, we investigate MIMO channels where the fading is more severe. In these environments, we show that the coefficient of variation of the channel amplitudes is a good predictor of the link mutual information, for a variety of models. We propose a novel channel model for severely fading channels based on the complex multivariate t distribution. For this model, we are able to compute exact results for the ergodic mutual information and approximations to the outage probabilities for the mutual information. Applications of this work include wireless sensors, RF tagging, land-mobile, indoor-mobile, ground-penetrating radar, and ionospheric radio links. Finally, we point out that the methodology can also be extended to evaluate the mutual information of a cellular MIMO link and the performance of various MIMO receivers in a cellular scenario. In these cellular applications, the channel itself is not severely fading but the multivariate t distribution can be applied to model the effects of intercellular interference.
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Commin, Henry. "Spatiotemporal arrayed MIMO radar." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/12637.
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In the last decade, Multiple Input Multiple Output (MIMO) radar has emerged as a leading candidate for stimulating major new advancement in radar theory. A fundamental challenge in MIMO radar is to identify a theoretical framework within which the radar system may be represented and analysed. In the relatively well-established field of Single Input Multiple Output (SIMO) array signal processing, this task has already been achieved using the array manifold (which is a geometric object that completely characterises the array system). A central objective of this thesis is therefore to bridge the gap between SIMO and MIMO by developing a manifold representation of the MIMO radar system. A new differential geometric framework, based on the complex Cartan matrix, is exploited in this thesis for characterising array manifold curves. New formulas are presented for recursively calculating the strictly orthonormal moving frame, U(s), and corresponding complex Cartan Matrix, C(s), for arbitrary array geometries. The circular approximation of the array manifold is derived under this new framework and compact closed-form expressions are provided for the popular uniform linear array geometry. Based on a number of approximations derived using the circular approximation of the array manifold, the performance capabilites of various popular detection and parameter estimation algorithms are investigated. The figure of merit "C" is then used to place these capabilities into the context of the theoretically ideal algorithm. The concept of a virtual SIMO array system is used as a basis for characterising the full MIMO radar configuration using a single equivalent response vector. By tracing out this response vector across the whole parameter space, a manifold is formed that fully characterises the MIMO radar system. In the important case of orthogonal transmit waveforms, the fundamental performance bounds of the MIMO radar system are studied. A space-time receiver architecture is proposed which exploits the virtual SIMO structure as part of a subspace-based joint Doppler, delay and direction of arrival (DOA) estimation framework. Due to the great computational burden of an exhaustive 3-parameter search, the joint Doppler-delay-DOA estimation is partitioned into an equivalent two-stage algorithm. The proposed approach is evaluated via computer simulation studies and shown to outperform existing methods.
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Du, Hao. "Optical wireless MIMO communication." Thesis, University of Warwick, 2015. http://wrap.warwick.ac.uk/70945/.
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This thesis provides an in-depth investigation and evaluation of infrared optical wireless MIMO communication systems to be applied in both indoor and outdoor environment. The principle objective of the research is to demonstrate both the advantages and disadvantages of the optical wireless MIMO systems using different modulation types. The first part provided analyses of important OW configurations using APD receivers using WMC model and SISO, MISO, SIMO and MIMO configuration. Thus, an analytical expression for 2-1 MISO, 1-2 SIMO and MIMO was successfully developed. This part also illustrates the coding gains possible using diversity schemes for APD OW systems. In the presence of strong fading, the SISO approach is rendered virtually useless, whereas diversity offers acceptable BER values. The results underpin the approach of this thesis, where indoor PIN diode based experimental measurements confirm the gains offered by diversity. In the second part of the work, several optical wireless MIMO systems applicable for the indoor environment are developed for three different modulation types, OOK modulation, PPM modulation and SIR-RZI modulation. These modulations are used in optical MIMO systems are studied for which, mathematical models that evaluate the BER performance of the MIMO system for different axis displacement and for different distances between transmitters and receivers. Based on the results, the PPM system has been shown to present the best BER performance, including high interference-resistance capability. A group of new mathematical models have been evaluated, which demonstrates a high level of correlation with the results derived from empirical models at 93%. Thus, the mathematical models developed and used for the specified evaluation appear to correspond reasonably well, and can be applied in future research on these aspects.
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Čirkić, Mirsad. "Efficient MIMO Detection Methods." Doctoral thesis, Linköpings universitet, Kommunikationssystem, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-103675.
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For the past decades, the demand in transferring large amounts of data rapidly and reliably has been increasing drastically. One of the more promising techniques that can provide the desired performance is multiple-input multiple-output (MIMO) technology where multiple antennas are placed at both the transmitting and receiving side of the communication link. This performance potential is extremely high when the dimensions of the MIMO system are increased to an extreme (in the number of hundreds or thousands of antennas). One major implementation difficulty of the MIMO technology is the signal separation (detection) problem at the receiving side of the MIMO link, which holds for medium-size MIMO systems and even more so for large-size systems. This is due to the fact that the transmitted signals interfere with each other and that separating them can be very difficult if the MIMO channel conditions are not beneficial, i.e., the channel is not well-conditioned. The main problem of interest is to develop algorithms for practically feasible MIMO implementations without sacrificing the promising performance potential that such systems bring. These methods involve inevitably different levels of approximation. There are computationally cheap methods that come with low accuracy and there are computationally expensive methods that come with high accuracy. Some methods are more applicable in medium-size MIMO than in large-size MIMO and vice versa. Some simple methods for instance, which are typically inaccurate for medium-sized settings, can achieve optimal accuracy for certain large-sized settings that offer close-to-orthogonal spatial signatures. However, when the dimensions are overly increased, then even these (previously) simple methods become computationally burdensome. In different MIMO setups, the difficulty in detection shifts since methods with optimal accuracy are not the same. Therefore, devising one single algorithm which is well-suited for feasible MIMO implementations in all settings is not easy. This thesis addresses the general MIMO detection problem in two ways. One part treats a development of new and more efficient detection techniques for the different MIMO settings. The techniques that are proposed in this thesis demonstrate unprecedented performance in many relevant cases. The other part revolves around utilizing already proposed detection algorithms and their advantages versus disadvantages in an adaptive manner. For well-conditioned channels, low-complexity detection methods are often sufficiently accurate. In such cases, performing computationally very expensive optimal detection would be a waste of computational power. This said, for MIMO detection in a coded system, there is always a trade-off between performance and complexity. Intuitively, computational resources should be utilized more efficiently by performing optimal detection only when it is needed, and something simpler when it is not. However, it is not clear whether this is true or not. In trying to answer this, a general framework for adaptive computational-resource allocation to different (“simple” and “difficult”) detection problems is proposed. This general framework is applicable to any MIMO detector and scenario of choice, and it is exemplified using one particular detection method for which specific allocation techniques are developed and evaluated.
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Bennia, Abdelhak. "Mimo systems parameters identification." Thesis, Virginia Tech, 1986. http://hdl.handle.net/10919/41579.
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In this thesis, a presentation of a new canonical representation of multi-input multioutput systems is given. The new characterization covers the full range of practical situations in linear systems according to the structural properties and model of the perturbations which are known. Its direct link to ARMA processes as well as to classical state space representation ls also given.
The importance of the new representation lies in the fact that all unknown parameters and state variables appear linearly multlplied by either external variables (inputs and outputs) that appear in the data record, or by matrices that are only composed of ieroes and ones. This property enables us to perform a joint state and parameters estimation. Moreover, if the noises are gaussian and their statistics are known, an on-line algorithm that involves a standard dlscrete-time time-varying Kalman filter is proposed and used successfully in the estimation of unknown parameters for simulated examples.
Master of Science
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Luo, Kai. "MIMO radar : target localisation." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/11148.
Full textAbstract:
The research presented in this thesis is concerned with multi-target localisation in MIMO radar. In particular, the aim is to develop novel algorithms which can improve the performance of target localisation. Firstly, a general spatiotemporal received signal model for MIMO radar is formulated. When the targets' relative delays are negligible, the general model turns into the spatial only signal model in which, in order to enjoy the enhanced parameter identifiability brought by the waveform diversity, a combined approach based on the virtual array structure is proposed for the multiple targets' directions and path gains estimation. The virtual array structure enables the proposed approach to identify more targets with accurate estimation. Besides, inspired by STAR manifold in communications, a novel spatiotemporal signal model for MIMO radar is proposed, which enables the existing multi-target localisation methods designed for the spatial only model working for the spatiotemporal one. Secondly, the multi-target localisation of MIMO radar operating in an envi- ronment with closely located targets is concerned. In such a scenario, the mu- tual interferences among targets severely degrade the performance of the current multi-target parameter estimators. Thus, an optimisation which takes account of the suppression of the mutual interferences for multi-target parameter estimation is formulated and the solutions to it are derived. Thirdly, based on these solu- tions, two novel multi-target parameter estimators are presented. By suppressing the interferences in the estimation, both the proposed methods outperform the existing ones. Finally, for the purpose of exploiting the high directional gain provided by the Tx beamforming in the multi-target localisation of MIMO radar, a joint Tx and Rx multi-target localisation approach is proposed. The cooperation between the Tx beamforming and target localisation enables the proposed approach to achieve better performance for the localisation of multiple targets.
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Karlsson, Marcus. "Aspects of Massive MIMO." Licentiate thesis, Linköpings universitet, Kommunikationssystem, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-132718.
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Next generation cellular wireless technology faces tough demands: increasing the throughput and reliability without consuming more resources, be it spectrum or energy. Massive mimo (Multiple-Input Multiple-Output) has proven, both in theory and practice, that it is up for the challenge. Massive mimo can offer uniformly good service to many users using low-end hardware, simultaneously, without increasing the radiated power compared to contemporary system. In Massive mimo, the base stations are equipped with hundreds of antennas. This abundance of antennas brings many new, interesting aspects compared to single-user mimo and multi-user mimo. Some issues of older technologies are nonexistent in massive mimo, while new issues in need of solutions arise. This thesis considers two aspects, and how these aspects differ in a massive mimo context: physical layer security and transmission of system information. First, it is shown that a jammer with a large number of antennas can outperform a traditional, single-antenna jammer in degrading the legitimate link. The excess of antennas gives the jammer opportunity to find and exploit structure in signals to improve its jamming capability. Second, for transmission of system information, the vast number of antennas prove useful even when the base station does not have any channel state information, because of the increased availability of space-time coding. We show how transmission without channel state information can be done in massive mimo by using a fixed precoding matrix to reduce the pilot overhead and simultaneously apply space-time block coding to use the excess of antennas for spatial diversity.Det ställs hårda krav på nästa generations cellulära trådlösa system: att simultant öka datatakten på kommunikationen och dess tillförlitlighet utan att konsumera mer resurser, oavsett om det spektrum eller energi. Massiv mimo (eng: Multiple-Input Multiple-Output) har visat, både i teori och praktik, att tekniken är redo att tackla utmaningen. Massiv mimo kan betjäna många användare samtidigt, med god service, utan att öka den utstrålade effekten jämfört med nuvarande system. Massiv mimo, där basstationerna är utrustade med hundratals antenner, skiljer sig från dagens system vilket gör att många nya problem dyker upp och nya infallsvinklar på befintliga problem krävs. Denna avhandling analyserar två problem, och hur dessa förändras i ett massiv mimo sammanhang: säkerhet för fysiska lagret och överföring av systeminformation. Särskiljt visas att en störsändare med ett stort antal antenner kan överträffa en traditionell störsändare med en enda antenn. Antalet antenner ger störsändaren möjlighet att hitta strukturer i signaler och utnyttja detta för att förbättra störningens effekt. Det stora antalet antenner visar sig vara användbart även för överföring av systeminformation, där basstationen inte har någon kanalkännedom. Antennerna ger möjligheten att tillämpa spatial kodning (eng: space-time block coding). Vi visar hur överföringen utan kanalkännedom kan göras i massiv mimo genom att använda en fix förkodningsmatris för att reducera antalet pilotsymboler. Samtidigt kodar vi spatiellt över antennerna för att tillhandahålla spatiell diversitet.
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Wannas, Hussain. "Full Duplex Multiuser MIMO with Massive Arrays." Thesis, Linköpings universitet, Institutionen för systemteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-105268.
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Half-Duplex Multiuser Multiple-Input Multiple-Output (HD MU-MIMO) systemscurrently employed in communication systems are not experiencing the selfinterference(SI) problem but they are not optimal in terms of efficiency and interms of resources used (time and frequency resources). Ignoring the effect of largescalefading, we start by explaining the uplink (UL) and downlink (DL) parts ofthe MU-MIMO system and how the sum-rate is calculated. We also introduce thethree linear receivers/precoders, Maximum-Ratio Combining (MRC)/Maximum-Ratio Transmission (MRT), Zero-Forcing (ZF), and Minimum Mean-Square Error(MMSE) and which of the three types is going to be used in the study of Full-Duplex Multiuser Multiple-input Multiple-output (FD MU-MIMO) system. Thenwe introduce FD MU-MIMO system, and how the equation used to calculate thesum-rate of the UL part changes when the SI occurs, and why SI problem is notpresent in the DL part. Next, we introduce the spectral efficiency (SE), and howto calculate it and why it is taken as a parameter to compare HD and FD systems.Also the effect of SI on FD MU-MIMO system is presented through simulationgraphs, then we move to show how to reduce SI effect by increasing the number ofantennas in the base-station (BS). Lastly, we take the effect of large scale fading inorder to reach a simple statistical model in the form cumulative distribution function(CDF) graph for different values of SI and compare those of FD MU-MIMOsystem to HD MU-MIMO. The results show that FD MU-MIMO together withmassive MIMO technology is very promising and would save time and frequencyresources which means an increase in the SE but SI must be below a certain level.
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Sharma, Maneesha. "Effective channel state information (CSI) feedback for MIMO systems in wireless broadband communications." Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/71549/2/Maneesha_Sharma_Thesis.pdf.
Full textAbstract:
This research has analysed both reciprocity and feedback mechanisms in multi-antenna wireless systems. It has presented the basis of an effective CSI feedback mechanism that efficiently provides the transmitter with the minimum information to allow the accurate knowledge of a rapidly changing channel. The simulations have been conducted using MATLAB to measure the improvement when the channel is estimated at the receiver in a 2 X 2 multi-antenna system and compared to the case of perfect channel knowledge at the receiver.
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Lessa, Carmen Lúcia Avelar. "Esquema para transmissão utilizando MIMO com cooperação de usuários." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/261418.
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Orientador: Gustavo FraidenraichDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
Made available in DSpace on 2018-08-19T21:07:30Z (GMT). No. of bitstreams: 1 Lessa_CarmenLuciaAvelar_M.pdf: 2504273 bytes, checksum: 47a502a9d17e8b31113225b0cb9926c3 (MD5) Previous issue date: 2011
Resumo: Neste trabalho é proposta uma estratégia para transmissão digital utilizando cooperação de usuários em conjunto com a tecnologia de múltiplas antenas (MIMO - do inglês. Multiple Input Multiple Output). Em um primeiro modelo de sistema foi utilizada a tecnologia CDMA (do inglês, Code Division Multiple Access) para distinção entre as mensagens dos usuários. Já em um segundo modelo sugerido foram utilizadas as técnicas do Descorrelacionador e a Decomposição em Valores Singulares (SVD - do inglês, Singular Value Decomposition) para permitir a cooperação entre os usuários sem a necessidade de multiplexação por código. Neste trabalho é apresentado como a cooperação entre os usuários pode ser feita utilizando várias antenas. Como exemplo foi considerado um regime de cooperação para o canal MIMO com dois usuários com uma única antena e o receptor com duas antenas. O cálculo da probabilidade de erro para este caso foi desenvolvido
Abstract: This work proposes user cooperation strategy using multiple antennas technology (MIMO). In a first model it was used a Code Division Multiple Access (CDMA) system and in a second model was applied the techniqucs of the Decorrclator and Singular Value Decomposition (SVD) to allow cooperation of users. It is show how cooperation using different numbers of antennas can be accomplished. It was considered a cooperation scheme for MIMO MAC channel with two users having single antenna and the reciver with two antennas. The results show that user cooperation with multiple antennas reduces the bit error probability
Mestrado
Telecomunicações e Telemática
Mestre em Engenharia Elétrica
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Fu, Wenjun. "From the conventional MIMO to massive MIMO systems : performance analysis and energy efficiency optimization." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/25672.
Full textAbstract:
The main topic of this thesis is based on multiple-input multiple-output (MIMO) wireless communications, which is a novel technology that has attracted great interest in the last twenty years. Conventional MIMO systems using up to eight antennas play a vital role in the urban cellular network, where the deployment of multiple antennas have significantly enhanced the throughput without taking extra spectrum or power resources. The massive MIMO systems “scales” up the benefits that offered by the conventional MIMO systems. Using sixty four or more antennas at the BS not only improves the spectrum efficiency significantly, but also provides additional link robustness. It is considered as a key technology in the fifth generation of mobile communication technology standards network, and the design of new algorithms for these two systems is the basis of the research in this thesis. Firstly, at the receiver side of the conventional MIMO systems, a general framework of bit error rate (BER) approximation for the detection algorithms is proposed, which aims to support an adaptive modulation scheme. The main idea is to utilize a simplified BER approximation scheme, which is based on the union bound of the maximum-likelihood detector (MLD), whereby the bit error rate (BER) performance of the detector for the varying channel qualities can be efficiently predicted. The K-best detector is utilized in the thesis because its quasi- MLD performance and the parallel computational structure. The simulation results have clearly shown the adaptive K-best algorithm, by applying the simplified approximation method, has much reduced computational complexity while still maintaining a promising BER performance. Secondly, in terms of the uplink channel estimation for the massive MIMO systems with the time-division-duplex operation, the performance of the Grassmannian line packing (GLP) based uplink pilot codebook design is investigated. It aims to eliminate the pilot contamination effect in order to increase the downlink achievable rate. In the case of a limited channel coherence interval, the uplink codebook design can be treated as a line packing problem in a Grassmannian manifold. The closed-form analytical expressions of downlink achievable rate for both the single-cell and multi-cell systems are proposed, which are intended for performance analysis and optimization. The numerical results validate the proposed analytical expressions and the rate gains by using the GLP-based uplink codebook design. Finally, the study is extended to the energy efficiency (EE) of the massive MIMO system, as the reduction carbon emissions from the information and communication technology is a long-term target for the researchers. An effective framework of maximizing the EE for the massive MIMO systems is proposed in this thesis. The optimization starts from the maximization of the minimum user rate, which is aiming to increase the quality-of-service and provide a feasible constraint for the EE maximization problem. Secondly, the EE problem is a non-concave problem and can not be solved directly, so the combination of fractional programming and the successive concave approximation based algorithm are proposed to find a good suboptimal solution. It has been shown that the proposed optimization algorithm provides a significant EE improvement compared to a baseline case.
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Lüthi, Peter Jan. "VLSI circuits for MIMO preprocessing." Konstanz Hartung-Gorre, 2009. http://d-nb.info/100000290X/04.
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Stanković, Veljko. "Multi-user MIMO wireless communications." [S.l.] : [s.n.], 2007. http://deposit.ddb.de/cgi-bin/dokserv?idn=985258039.
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Srinivasan, Ramya. "Throughput optimization in MIMO networks." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42735.
Full textAbstract:
Enabling multi-hop wireless mesh networks with multi-input multi-output (MIMO) functionality boosts network throughput by transmitting over multiple orthogonal
spatial channels (spatial multiplexing) and by performing interference cancellation,
to allow links within interference range to be concurrently active. Furthermore,
if the channel is in a deep fade, then multiple antenna elements at the
transmitter and/or receiver can be used to transmit a single stream, thereby improving
signal quality (diversity gain).
However, there is a fundamental trade-off between boosting individual link performance
and reducing interference, which must be modeled in the process of optimizing
network throughput. This is called the diversity-multiplexing-interference suppression
trade-off. Optimizing network throughput therefore, requires optimizing the trade-off
between the amounts of diversity employed on each link, the number of streams multiplexed
on each link and the number of interfering links allowed to be simultaneously
active in the network.
We present a set of efficient heuristics for one-shot link scheduling and stream
allocation that approximately solve the problem of optimizing network throughput
in a single time slot. We identify the fundamental problem of verifying the feasibility
of a given stream allocation. The problems of general link scheduling and stream
allocation are very closely related to the problem of verifying feasibility.
We present a set of efficient heuristic feasibility tests which can be easily incorporated
into practical scheduling schemes. We show for some special MIMO network
scenarios that feasibility is of polynomial complexity. However, we conjecture that in
general, this problem, which is a variation of Boolean Satisablility, is NP-Complete.
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Aldayel, Omar. "Evaluation of MIMO Non- Stationarity." Thesis, KTH, Signalbehandling, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-53761.
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The transmission performance of MIMO systems can be highly improved under stationary channel conditions where the channel statistics are constant. Unfortunately, mobile radio channels are not stationary all the time. Instead, they are stationary for finite time durations, so-called the stationarity regions. If these stationarity regions are relatively large, then the channel statistics can be utilized during each stationarity region to enhance the transmission performance. Therefore, it is necessary to examine the stationarity of mobile channels and characterize the stationarity regions. This thesis investigates the non-stationarity of measured MIMO channels and proposes some stationarity metrics to measure it. These metrics are: the CMD proposed by [1 ], NCMD and DES. Each one of the metrics is relevant to different types of transmission schemes and scenarios. The CMD may not be accurate for some transmission scenarios; therefore, the NCMD, which is a normalized version of CMD, is proposed. Theoretically, the NCMD can be at most 100% higher than the CMD for a 4x4 MIMO system. For beamforming scenario, the DES metric can be used to describe the non-stationarity of few eigenvectors taken from the channel variance. Under the measured MIMO channels, it was found that the CMD overestimates the stationarity regions compared to the NCMD and DES metrics particularly under the NLOS routes.
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Weikert, Oomke Einar. "Blinde Demodulation in MIMO-Übertragungssystemen." Berlin dissertation.de, 2007. http://www.dissertation.de/buch.php3?buch=5228.
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Jayasooriya, Chandana K. K. "Compact antennas for mimo communications." Diss., Wichita State University, 2013. http://hdl.handle.net/10057/7024.
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The newest cellular communication standard, 4G-LTE (Long Term Evolution) provides an all internet protocol (IP)-based solutions to the high data rate required of mobile communication applications. It offers 100 Mbit/s and 1 Gbit/s for low mobility and high mobility applications, respectively. These high data rates are possible mainly due to the use of multiple antennas at both ends of the communication system. Therefore, antenna design for this new cellular standard is of high interest. Due to the size limitations of a hand-held device (typically, 120 mm x 65 mm x 5 mm (L x W x H)) designing antennas has become more challenging. Minimal antenna size, mutual coupling between different antennas, and compliance with radiation restrictions are some of the challenges that influence the design of antennas for this new standard.
This work focuses on designing compact antennas to be used in mobile handsets as well as wireless routers such as in the IEEE 802.11n standard. The first attempt was to design a two-port co-located circular patch antenna (CPA) and an annular ring antenna (ARA) that utilizes pattern diversity. The idea behind pattern diversity is to generate two orthogonal radiation patterns associated with each port. To reduce the size of the antenna, ferrite material is used as the substrate material. Even though the use of ferrite material leads to a significant size reduction, the dimensions of those antennas are too large to fit in a cellular mobile handset. Therefore, a spatially separated half-cycle meander structure was investigated. This antenna was designed to fit into a mobile handset using FEKO simulations, and then fabricated and tested. By using the simulated S-parameters and radiation patterns, all of these antennas were investigated for communication theoretic performance parameters such as bit error rate (BER) and capacity.Thesis (Ph.D.)--Wichita State University, College of Engineering, Dept. of Electrical Engineering and Computer Science
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Liu, Di. "Tensor precoding for MIMO systems." Thesis, University of York, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546819.
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Manning, David Patrick. "Analysis of MIMO Relay Chains." Thesis, University of Canterbury. Electrical and Computer Engineering, 2011. http://hdl.handle.net/10092/5885.
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This thesis is split into two parts: first a statistical analysis of multi-hop MIMO relay networks, followed by a simulation of the perfomance of a P25 SISO multi-hop relay network. The basis of the MIMO section is the developement of an end to end statistical model of the multiple relay channel. This end to end model simplifies the statistics involved, making the analysis of systems with large numbers of relays and antennas more practical. A partial system model is obtained. This is exact for a multiple input single output network and can be used to describe the received signal at a single antenna in a multiple output system. We go on to look at the relationship between end to end system parameters and the paramters of individual inter-relay channels. The SISO section contains a characterisation of BER for P25 relay chains. The effect of the SNR at each relay node, the nature of the channel and the number of relay hops on the BER is determined. Furthermore, the performance trends are compared for a range of common relaying protocols, including amplify and forward and two types of decode and forward.
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Shang, Cheng Yu Andy. "Linear transceivers for MIMO relays." Thesis, University of Canterbury. Electrical and Electronic Engineering, 2014. http://hdl.handle.net/10092/9514.
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Relays can be used in wireless communication systems to provide cell coverage extension, reduce coverage holes and increase throughput. Full duplex (FD) relays, which transmit and receive in the same time slot, can have a higher transmission rate compared with half duplex (HD) relays. However, FD relays suffer from self interference (SI) problems, which are caused by the transmitted relay signal being received by the relay receiver. This can reduce the performance of FD relays. In the literature, the SI channel is commonly nulled and removed as it simplifies the problem considerably. In practice, complete nulling is impossible due to channel estimation errors. Therefore, in this thesis, we consider the leakage of the SI from the FD relay. Our goal is to reduce the SI and increase the signal to noise ratio (SNR) of the relay system. Hence, we propose different precoder and weight vector designs. These designs may increase the end to end (e2e) signal to interference and noise ratio (SINR) at the destination. Here, a precoder is multiplied to a signal before transmission and a weight vector is multiplied to the received signal after reception.
Initially, we consider an academic example where it uses a two path FD multiple input and multiple output (MIMO) system. The analysis of the SINR with the implementation of precoders and weight vectors shows that the SI component has the same underlying signal as the source signal when a relay processing delay is not being considered. Hence, to simulate the SI problem more realistically, we alter our relay design and focus on a one path FD MIMO relay system with a relay processing delay. For the implementation of precoders and weight vectors, choosing the optimal scheme is numerically challenging. Thus, we design the precoders and weight vectors using ad-hoc and near-optimal schemes. The ad-hoc schemes for the precoders are singular value decomposition (SVD), minimising the signal to leakage plus noise ratio (SLNR) using the Rayleigh Ritz (RR) method and zero forcing (ZF). The ad-hoc schemes for the weight vectors are SVD, minimum mean squared error (MMSE) and ZF. The near-optimal scheme uses an iterative RR method to compute the source precoder and destination weight vector and the relay precoder and weight vector are computed using the ad-hoc methods which provide the best performance.
The average power and the instantaneous power normalisations are the two methods to constrain the relay precoder power. The average power normalisation method uses a novel closed form covariance matrix with an optimisation approach to constrain the relay precoder. This closed form covariance matrix is mathematically derived using matrix vectorization techniques. For the instantaneous power normalisation method, the constraint process does not require an optimisation approach. However, using this method the e2e SINR is difficult to calculate, therefore we use symbol error rate (SER) as a measure of performance.
The results from the different precoder and weight vector designs suggest that reducing the SI using the relay weight vector instead of the relay precoder results in a higher e2e SINR. Consequently, to increase the e2e SINR, performing complicated processing at the relay receiver is more effective than at the relay transmitter.
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Alnajjar, Khawla. "Receiver Design for Massive MIMO." Thesis, University of Canterbury. Electrical and Computer Engineering, 2015. http://hdl.handle.net/10092/10517.
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Massive multiple-input-multiple-output (MM) is becoming a promising candidate for wireless
communications. The idea behind MM is to use a very large number of antennas to increase
throughput and energy efficiency by one or more orders of magnitude. In order to make MM
feasible, many challenges remain. In the uplink a fundamental question is whether to deploy
single massive arrays or to build a virtual array using cooperative base stations. Also, in such
large arrays the signal processing involved in receiver combining is non-trivial. Therefore, low
complexity receiver designs and deployment scenarios are essential aspects of MM and the
thesis mainly focuses on these two areas.
In the first part, we investigate three deployment scenarios: (i) a massive co-located array
at the cell center; (ii) a massive array clustered at B discrete locations; and (iii) a massive
distributed array with a uniform distribution of individual antennae. We also study the effect of
propagation parameters, system size, correlation and channel estimation error. We demonstrate
by analysis and simulation that in the absence of any system imperfections, a massive distributed
array is preferable. However, an intermediate deployment such as a massive array clustered at a
few discrete locations can be more practical to implement and more robust to imperfect channel
state information. We then focus on the performance of the co-located scenario with different
types of antenna array, uniform square and linear arrays. With MM, it may be the case that
large numbers of antennas are closely packed to fit in some available space. Hence, channel
correlations become important and therefore we investigate the space requirements of different
array shapes. In particular, we evaluate the system performance of uniform square and linear
arrays by using ergodic capacity and capacity outage. For a range of correlation models, we
demonstrate that the uniform square array can yield similar performance to a uniform linear
array while providing considerable space saving.
In the second part of the thesis we focus on low complexity receiver designs. Due to the high dimension of MM systems there is a considerable interest in detection schemes with a
better complexity-performance trade-off. We focus on linear receivers (zero forcing (ZF) and
maximum ratio combining (MRC)) used in conjuction with a Vertical Bell Laboratories Layered
Space Time (V-BLAST) structure. Our first results show that the performance of MRC
V-BLAST approaches that of ZF V-BLAST under a range of imperfect CSI levels, different
channel powers and different types of arrays as long as the channel correlations are not too
high. Subsequently, we propose novel low complexity receiver designs which maintain the
same performance as ZF or ZF V-BLAST. We show that the performance loss of MRC relative
to ZF can be removed in certain situations through the use of V-BLAST. The low complexity
ordering scheme based on the channel norm (C-V-BLAST) results in a V-BLAST scheme with
MRC that has much less complexity than a single ZF linear combiner. An analysis of the SINR
at each stage of the V-BLAST approach is also given to support the findings of the proposed
technique. We also show that C-V-BLAST remains similar to ZF for more complex adaptive
modulation systems and in the presence of channel estimation error, C-V-BLAST can be superior.
These results are analytically justified and we derive an exhaustive search algorithm for
power control (PC) to bound the potential gains of PC. Using this bound, we demonstrate that
C-V-BLAST performs well without the need for additional PC. The final simplification is based
on the idea of ordering users based on large scale fading information rather than instantaneous
channel knowledge for a V-BLAST scheme with MRC (P-V-BLAST). An explicit closed form
analysis for error probability for both co-located and distributed BSs is provided along with a
number of novel performance metrics which are useful in designing MM systems. It is shown
that the error performance of the distributed scenario can be well approximated by a modified
version of a co-located scenario. Another potential advantage of P-V-BLAST is that the ordering
can be obtained as soon as the link gains are available. Hence, it is possible that mean
SINR values could be used for scheduling and other link control functions. These mean values are solely functions of the link gains and hence, scheduling, power adaptation, rate adaptation,
etc. can all be performed more rapidly with P-V-BLAST. Hence, the P-V-BLAST structure may
have further advantages beyond a lower complexity compared to C-V-BLAST.
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Wu, Zhuo. "MIMO techniques in cellular systems." Thesis, University of York, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.423603.
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Fan, Yijia. "MIMO communications over relay channels." Thesis, University of Edinburgh, 2006. http://hdl.handle.net/1842/10884.
Full textAbstract:
In this thesis we investigate MIMO techniques for relay channels. We first concentrate on the single antenna relay networks, where each node is equipped with a single antenna. In this scenario, a scheme called cooperative diversity has been discussed widely, where multiple relays are united in the network as a “virtual antenna array”, to mimic a MIMO system. We propose a novel cooperative diversity scheme that can improve the spectral efficiency of the network, especially for high signal to noise ratios (SNR). We analyze the capacity bounds for such schemes and also describe a signalling method to approach this capacity bound. We then move to the multi-antenna node scenario, where each node is equipped with multiple antennas. We propose different signalling methods and routing protocols for MIMO relay channels and use capacity as a performance metric to evaluate and compare them. The proposed signalling methods can be applied together with the proposed routing schemes. Incorporating them can facilitate the cross-layer design. Finally, we discuss a network scenario where some nodes are equipped with multiple antennas, others are equipped with single antennas. We constrain ourselves to the case where the source and destination are equipped with a single antenna. We characterize the capacity performance and the diversity-multiplexing tradeoff of such a network. We show that relaying can offer a significant performance advantage over non-relay transmission in certain scenarios, by applying signal combining techniques for the point-to-point MIMO link into relay channels.
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Iltis, Ronald A. "Localization Using CDMA-MIMO Radar." International Foundation for Telemetering, 2010. http://hdl.handle.net/10150/605975.
Full textAbstract:
ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, CaliforniaA MIMO radar system for target localization is presented which uses direct-sequence CDMA (DS-CDMA) waveforms. The received DS-CDMA signal at each antenna is expressed directly in terms of the target positions. The waveforms employed are Gold sequences, and hence are not exactly orthogonal. A generalized successive interference cancellation (GSIC) approach is used to resolve multiple scatterers and reduce clutter. Simulation results are presented which suggest the capability to detect weak scatterers in the presence of clutter using the cancellation method.
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Gonzalez, Perez Miryam Guadalupe. "Scaling up virtual MIMO systems." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31321.
Full textAbstract:
Multiple-input multiple-output (MIMO) systems are a mature technology that has been incorporated into current wireless broadband standards to improve the channel capacity and link reliability. Nevertheless, due to the continuous increasing demand for wireless data traffic new strategies are to be adopted. Very large MIMO antenna arrays represents a paradigm shift in terms of theory and implementation, where the use of tens or hundreds of antennas provides significant improvements in throughput and radiated energy efficiency compared to single antennas setups. Since design constraints limit the number of usable antennas, virtual systems can be seen as a promising technique due to their ability to mimic and exploit the gains of multi-antenna systems by means of wireless cooperation. Considering these arguments, in this work, energy efficient coding and network design for large virtual MIMO systems are presented. Firstly, a cooperative virtual MIMO (V-MIMO) system that uses a large multi-antenna transmitter and implements compress-and-forward (CF) relay cooperation is investigated. Since constructing a reliable codebook is the most computationally complex task performed by the relay nodes in CF cooperation, reduced complexity quantisation techniques are introduced. The analysis is focused on the block error probability (BLER) and the computational complexity for the uniform scalar quantiser (U-SQ) and the Lloyd-Max algorithm (LM-SQ). Numerical results show that the LM-SQ is simpler to design and can achieve a BLER performance comparable to the optimal vector quantiser. Furthermore, due to its low complexity, U-SQ could be consider particularly suitable for very large wireless systems. Even though very large MIMO systems enhance the spectral efficiency of wireless networks, this comes at the expense of linearly increasing the power consumption due to the use of multiple radio frequency chains to support the antennas. Thus, the energy efficiency and throughput of the cooperative V-MIMO system are analysed and the impact of the imperfect channel state information (CSI) on the system's performance is studied. Finally, a power allocation algorithm is implemented to reduce the total power consumption. Simulation results show that wireless cooperation between users is more energy efficient than using a high modulation order transmission and that the larger the number of transmit antennas the lower the impact of the imperfect CSI on the system's performance. Finally, the application of cooperative systems is extended to wireless self-backhauling heterogeneous networks, where the decode-and-forward (DF) protocol is employed to provide a cost-effective and reliable backhaul. The associated trade-offs for a heterogeneous network with inhomogeneous user distributions are investigated through the use of sleeping strategies. Three different policies for switching-off base stations are considered: random, load-based and greedy algorithms. The probability of coverage for the random and load-based sleeping policies is derived. Moreover, an energy efficient base station deployment and operation approach is presented. Numerical results show that the average number of base stations required to support the traffic load at peak-time can be reduced by using the greedy algorithm for base station deployment and that highly clustered networks exhibit a smaller average serving distance and thus, a better probability of coverage.
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Singh, Parth Raj. "Source localization with MIMO systems." Thesis, Nantes, 2017. http://www.theses.fr/2017NANT4043/document.
Full textAbstract:
Dans cette thèse, nous considérons la dernière génération du radar. Il s’agit d’un radar MIMO bistatique qui est composé de plusieurs antennes d’émission et de réception. Pour ce système, les antennes émettrices transmettent des signaux linéairement indépendants afin qu’ils puissent être identifiés à l’aide d’un banc de filtres adaptés au niveau des antennes de réception. Les signaux filtrés sont alors traités pour extraire les paramètres des cibles, tels que les DOA, DOD, vitesse, etc. Un radar MIMO bistatique offre une grande diversité spatiale et une excellente identifiabilité des paramètres, etc., ce qui nous a incités à l’utiliser dans ce travail. La situation en champ lointain d’un radar MIMO bistatique est largement traitée dans la littérature. Mais, peu de travaux existe sur la situation en champ proche, c’est ce qui a motivé le travail de cette thèse. La localisation de cibles en champ proche est importante en raison de nombreuses applications à l’intérieur des constructions. A ce sujet, la plupart des méthodes actuelles utilisent l’approximation de Fresnel dans laquelle le front d’onde sphérique des signaux reçus est supposé quadrique plutôt que planaire comme en champ lointain. Dans ce travail de thèse, nous avons proposé une nouvelle méthode de localisation des cibles en champ proche qui utilise l’approximation de Fresnel. Celle-ci conduit à une estimation biaisée des paramètres de localisation car en réalité le front d’onde est sphérique. Nous avons proposé alors deux méthodes de correction pour réduire les effets de l’approximation de Fresnel et deux autres méthodes qui utilisent directement le modèle exacte basé sur le front d’onde sphériqueSources localization is used in radar, sonar, and telecommunication. Radar has numerous civilian and military applications. Radar system has gone through many developments over the last few decades and reached the latest version known as MIMO radar. A MIMO radar is composed of multiple transmitting and receiving antennas like a conventional phased array radar. However, its transmitting antennas transmit linearly independent signals so that they can be easily identified by the matched filters bank at its receiving end. The matched filtered signals are then processed to extract the ranges, DOAs, DODs, velocities, etc. of the targets. A bistatic MIMO radar system provides high resolution, spatial diversity, parameter identifiability, etc. which inspired us to use it in this work. There are many existing methods to deal with the far field region of MIMO radar system. However, little work can be found on the near field region of a bistatic MIMO radar which motivated the work in this thesis. Near field targets localization is also important because of many indoor applications. Most of the existing near field sources localization techniques use Fresnel approximation in which the real spherical wavefront is assumed quadric unlike planar in far field situation. In this work we have proposed a novel near field targets localization method using Fresnel approximation. The Fresnel approximation leads to a biased estimation of the location parameters because the true wavefront is spherical. Consequently, we have proposed two correction methods to reduce the effects of Fresnel approximation and other two methods which directly use the exact signal model based on spherical wavefront
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Булашенко, А. В., and О. С. Вус. "Технологія MIMO в безпровідному зв'язку." Thesis, Сумський державний університет, 2017. http://essuir.sumdu.edu.ua/handle/123456789/66969.
Full textAbstract:
Безпровідний зв'язок завжди був складною технологією для охоронних систем.
Зазвичай вони зверталися до радіоканалів лише в тому випадку, коли ніяка інша
технологія не може вирішити поставлену задачу. Розробникам необхідно було брати до
уваги масу аспектів: інтерференцію хвиль, взаємне розташування антен та їх
настроювання, лінії прямої видимості, грозова активність.
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Mota, Susana de Jesus. "Channel modelling for MIMO systems." Doctoral thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/14961.
Full textAbstract:
Doutoramento em Engenharia ElectrotécnicaSystems equipped with multiple antennas at the transmitter and at the receiver, known as MIMO (Multiple Input Multiple Output) systems, offer higher capacities, allowing an efficient exploitation of the available spectrum and/or the employment of more demanding applications. It is well known that the radio channel is characterized by multipath propagation, a phenomenon deemed problematic and whose mitigation has been achieved through techniques such as diversity, beamforming or adaptive antennas. By exploring conveniently the spatial domain MIMO systems turn the characteristics of the multipath channel into an advantage and allow creating multiple parallel and independent virtual channels. However, the achievable benefits are constrained by the propagation channel’s characteristics, which may not always be ideal. This work focuses on the characterization of the MIMO radio channel. It begins with the presentation of the fundamental results from information theory that triggered the interest on these systems, including the discussion of some of their potential benefits and a review of the existing channel models for MIMO systems. The characterization of the MIMO channel developed in this work is based on experimental measurements of the double-directional channel. The measurement system is based on a vector network analyzer and a two-dimensional positioning platform, both controlled by a computer, allowing the measurement of the channel’s frequency response at the locations of a synthetic array. Data is then processed using the SAGE (Space-Alternating Expectation-Maximization) algorithm to obtain the parameters (delay, direction of arrival and complex amplitude) of the channel’s most relevant multipath components. Afterwards, using a clustering algorithm these data are grouped into clusters. Finally, statistical information is extracted allowing the characterization of the channel’s multipath components. The information about the multipath characteristics of the channel, induced by existing scatterers in the propagation scenario, enables the characterization of MIMO channel and thus to evaluate its performance. The method was finally validated using MIMO measurements.
Os sistemas equipados com múltiplas antenas no emissor e no recetor, conhecidos como sistemas MIMO (Multiple Input Multiple Output), oferecem capacidades mais elevadas, permitindo melhor rentabilização do espectro e/ou utilização de aplicações mais exigentes. É sobejamente sabido que o canal rádio é caracterizado por propagação multipercurso, fenómeno considerado problemático e cuja mitigação tem sido conseguida através de técnicas como diversidade, formatação de feixe ou antenas adaptativas. Explorando convenientemente o domínio espacial os sistemas MIMO transformam as características multipercurso do canal numa mais-valia e permitem criar vários canais virtuais, paralelos e independentes. Contudo, os benefícios atingíveis são condicionados pelas características do canal de propagação, que poderão não ser sempre as ideais. Este trabalho centra-se na caracterização do canal rádio para sistemas MIMO. Inicia-se com a apresentação dos resultados fundamentais da teoria da informação que despoletaram todo o entusiamo em torno deste tipo de sistemas, sendo discutidas algumas das suas potencialidades e uma revisão dos modelos existentes para sistemas MIMO. A caracterização do canal MIMO desenvolvida neste trabalho assenta em medidas experimentais do canal direcional adquiridas em dupla via. O sistema de medida é baseado num analisador de redes vetorial e numa plataforma de posicionamento bidimensional, ambos controlados por um computador, permitindo obter a resposta em frequência do canal rádio nos vários pontos correspondentes à localização dos elementos de um agregado virtual. As medidas são posteriormente processadas com o algoritmo SAGE (Space-Alternating Expectation-Maximization), de forma a obter os parâmetros (atraso, direção de chegada e amplitude complexa) das componentes multipercurso mais significativas. Seguidamente, estes dados são tratados com um algoritmo de classificação (clustering) e organizados em grupos. Finalmente é extraída informação estatística que permite caracterizar o comportamento das componentes multipercurso do canal. A informação acerca das características multipercurso do canal, induzidas pelos espalhadores (scatterers) existentes no cenário de propagação, possibilita a caracterização do canal MIMO e assim avaliar o seu desempenho. O método foi por fim validado com medidas MIMO.
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Rashid, Imran. "MIMO multi-hop relay systems." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/mimo-multihop-relay-systems(f8d60fed-c19c-419d-b14f-7defc4721bc3).html.
Full textAbstract:
Multiple Input Multiple Output (MIMO) systems use multiple transmit and receive antennas to achieve higher data rates by transmitting multiple independent data systems. Transmission errors can be reduced by using Hybrid Automatic Repeat request (HARQ) combining techniques with MIMO systems. In this thesis, the use of HARQ for MIMO multi-hop communication is studied. We propose two MIMO HARQ combining methods which are based on using pre-combiningonly and a joint pre and post combining techniques. In addition to conventional single-hop transmission, HARQ schemes for MIMO multi-hop relay systems are also investigated. A novel approach is proposed to deal with the parallel HARQ processes in MIMO relay scenario. An information theoretic throughput analysis is performed to evaluate the performance of the relay system by employing various transmission techniques for relay-destination link. Evaluation is carried out on the delay involved while employing the relay systems as compared to single hop systems. Simulation results show that the proposed system can enhance the overall throughput performance of MIMO single-hop and multi-hop relay systems. Considering the recent research interest in green radio and requirements of reduced energy consumption by the wireless networks, we evaluated the energy efficiency of existing and proposed MIMO HARQ techniques for sensor and cellular networks. The results show that the proposed scheme is more energy efficient compared to other schemes in single-hop as well as multi-hop scenarios.
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Gaur, Sudhanshu. "Interference management in MIMO networks." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24769.
Full textAbstract:
Thesis (Ph.D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2008.Committee Chair: Mary Ann Ingram; Committee Member: Geoffrey Li; Committee Member: Gregory Durgin; Committee Member: Prasad Tetali; Committee Member: Raghupathy Sivakumar.
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Shahabuddin, S. (Shahriar). "MIMO detection and precoding architectures." Doctoral thesis, Oulun yliopisto, 2019. http://urn.fi/urn:isbn:9789526222837.
Full textAbstract:
Abstract Multiple-input multiple-output (MIMO) techniques have been adopted since the third generation (3G) wireless communication standard to increase the spectral efficiency, data rate and reliability. The blessings of MIMO technologies for the baseband transceiver comes with the price of added complexity. Therefore, research on VLSI architectures for MIMO signal processing has generated a lot of interest over the past two decades. The advent of massive MIMO as a key technology for the fifth generation (5G) era also increased the interest in VLSI architectures related to MIMO communication research. In this thesis, we explored different VLSI architectures for MIMO detection and precoding algorithms. The detection and precoding are the most complex parts of a MIMO baseband transceiver. We focused on algorithm and architecture optimization and presented several VLSI architectures for MIMO detection and precoding. The thesis proposed an application specific instruction-set processor (ASIP) for a multimode small-scale MIMO detector. In a single design the detector supports minimum mean-square error (MMSE), selective spanning with fast enumeration (SSFE) and list sphere detection (LSD). In addition, a multiprocessor architecture is proposed in this thesis for a lattice reduction (LR) algorithm. A modified Lenstra-Lenstra-Lovasz (LLL) algorithm is proposed for LR to reduce the complexity of the original LLL algorithm. We also propose a massive MIMO detection algorithm based on alternating direction method of multipliers (ADMM). The algorithm is referred to as ADMM based infinity norm (ADMIN) constrained equalization. The ADMIN detection algorithm is implemented as an application-specific integrated circuit (ASIC) and for field programmable gate array (FPGA). A multimode precoder ASIP is also proposed in this thesis. In a single design, the ASIP supports norm-based scheduling, QR-decomposition, MMSE precoding and dirty paper coding (DPC) based precodingTiivistelmä Moni-tulo moni-lähtö (MIMO) -tekniikoita on sopeutettu kolmannen sukupolven (3G) langattomasta viestintästandardista alkaen spektritehokkuuden, tiedonsiirtonopeuden ja luotettavuuden parantamiseksi. MIMO-teknologioilla on useita hyviä puolia suhteessa peruskaistan vastaanottimeen, mutta samalla monimutkaisuus on lisääntynyt. VLSI-arkkitehtuurien tutkimus MIMO-signaalinkäsittelyssä on sen vuoksi herättänyt paljon kiinnostusta viimeisen kahden vuosikymmenen aikana. Myös MIMO:n saavuttama asema viidennen sukupolven (5G) viestintästandardin pääteknologiana on lisännyt kiinnostusta VLSI-arkkitehtuureihin MIMO-viestinnän tutkimuksessa. Tässä tutkielmassa on tutkittu erilaisia VLSI-arkkitehtuureja MIMO-signaalien tunnistus- ja esikoodausalgoritmeissa. Signaalien tunnistus ja esikoodaus ovat peruskaistaa käyttävän MIMO-vastaanottimen monimutkaisimmat osa-alueet. Tutkielmassa on keskitytty algoritmien ja arkkitehtuurien optimointiin ja esitetty useita VLSI-arkkitehtuureja MIMO-signaalien tunnistusta ja esikoodausta varten. Tutkielmassa on ehdotettu sovelluskohtaisen prosessorin (Application Specific Instruction-set Processor eli ASIP) käyttä pienen mittakaavan monimuotodetektorissa. Detektorin rakenne tukee samanaikaisesti keskineliöpoikkeaman minimointia (MMSE), SSFE (Selective Spanning with Fast Enumeration) -algoritmia ja LSD (List Sphere Detection) -algoritmia. Lisäksi tässä tutkielmassa ehdotetaan monisuoritinarkkitehtuuria hilan redusointialgoritmille (Lattice Reduction eli LR). LR-algoritmia varten ehdotetaan muokattua Lenstra-Lenstra-Lovasz (LLL) -algoritmia vähentämään alkuperäisen LLL-algoritmin monimutkaisuutta. Lisäksi MIMO-signaalien tunnistusalgoritmin perustaksi ehdotetaan vuorottelevaa kertoimien suuntaustapaa Alternating Direction Method of Multipliers eli ADMM). ADMM-perustaisesta taajuusvasteen rajoitetusta ääretön-normi-korjauksesta (infinity norm constrained equalization) käytetään nimitystä ADMIN-algoritmi. ADMIN-tunnistusalgoritmi toteutetaan sovelluskohtaisena integroituna piirinä (Application-Specific Integrated Circuit eli ASIC) ohjelmoitavaa porttimatriisia (Field Programmable Gate Array eli FPGA) varten. Lisäksi ehdotetaan ASIP-monimuotoesikooderin käyttöä. ASIP-esikooderin rakenne tukee normiperustaista aikataulutusta, QR-hajotelmaa, MMSE-esikoodausta ja likaisen paperin koodaukseen (Dirty Paper Coding eli DPC) perustuvaa esikoodausta
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Stimming, Christian. "Multiple antenna concepts in OFDM transmission systems." Göttingen Cuvillier, 2009. http://d-nb.info/995846030/04.
Full text
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Chan, Wing Chau. "Performance limits of MIMO wireless communications /." View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?ECED%202006%20CHANW.
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Mathew, Jerry George. "MIMO equalization." Thesis, 2005. http://hdl.handle.net/10413/2815.
Full textAbstract:
In recent years, space-time block co'des (STBC) for multi-antenna wireless systems have emerged as attractive encoding schemes for wireless communications. These codes provide full diversity gain and achieve good performance with simple receiver structures without the additional increase in bandwidth or power requirements. When implemented over broadband channels, STBCs can be combined with orthogonal frequency division multiplexing (OFDM) or single carrier frequency domain (SC-FD) transmission schemes to achieve multi-path diversity and to decouple the broadband frequency selective channel into independent flat fading channels. This dissertation focuses on the SC-FD transmission schemes that exploit the STBC structure to provide computationally cost efficient receivers in terms of equalization and channel estimation. The main contributions in this dissertation are as follows: • The original SC-FD STBC receiver that bench marks STBC in a frequency selective channel is limited to coherent detection where the knowledge of the channel state information (CSI) is assumed at the receiver. We extend this receiver to a multiple access system. Through analysis and simulations we prove that the extended system does not incur any performance penalty. This key result implies that the SC-FD STBC scheme is suitable for multiple-user systems where higher data rates are possible. • The problem of channel estimation is considered in a time and frequency selective environment. The existing receiver is based on a recursive least squares (RLS) adaptive algorithm and provides joint equalization and interference suppression. We utilize a system with perfect channel state information (CSI) to show from simulations how various design parameters for the RLS algorithm can be selected in order to get near perfect CSI performance. • The RLS receiver has two modes of operation viz. training mode and direct decision mode. In training mode, a block of known symbols is used to make the initial estimate. To ensure convergence of the algorithm a re-training interval must be predefined. This results in an increase in the system overhead. A linear predictor that utilizes the knowled~e of the autocorrelation function for a Rayleigh fading channel is developed. The predictor is combined with. the adaptive receiver to provide a bandwidth efficient receiver by decreasing the training block size.· The simulation results show that the performance penalty for the new system is negligible. • Finally, a new Q-R based receiver is developed to provide a more robust solution to the RLS adaptive receiver. The simulation results clearly show that the new receiver outperforms the RLS based receiver at higher Doppler frequencies, where rapid channel variations result in numerical instability of the RLS algorithm. The linear predictor is also added to the new receiver which results in a more robust and bandwidth efficient receiver.Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2005.
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Cabral, Lorenzo Jose Barbosa. "Massive MIMO." Master's thesis, 2017. http://hdl.handle.net/10071/14821.
Full textAbstract:
Com a chegada da quinta geração de comunicações móveis (5G) espera-se que
os sistemas de comunicação sem fios possam oferecer novos e melhores serviços
com ritmos de transmissão elevadíssimos. O aumento significativo do bit rate que
se prevê com o incremento dos utilizadores e dos dispositivos a ligar a rede, a entrada da IoT e outas tecnologias, isto sem perder de vista as inúmeras dificuldades
da elevada dispersão associada à propagação multipercurso dos sinais, as elevadas
taxas de eficiência e potência exigidas e a grande capacidade e flexibilidade esperadas nos novos sistemas, são fatores que contribuem para um aumento significativo
da complexidade do sistema. A solução de todas estas prolemáticas torna possível
o desenvolvimento destas novas tecnologias.
A tecnologia massive MIMO apresenta-se como um forte candidato com potencial para satisfazer todas as necessidades exigidas pela nova quinta geração de
comunicações móveis e para lidar com todas as futuras tecnologias de forma eficiente, segura, fiável. Contudo, todos estes benefícios trazem consigo um enorme
aumento da complexidade devido aos múltiplos sinais envolvidos na transmissão
de dezenas de antenas. Por outro lado, existem técnicas que implementam ambientes de enorme complexidade utilizando esquemas de recepção OFDM, SC-FDE
e IB-DFE e que oferecem ótimos resultados em termos de eficiência mas que resultam numa enorme complexidade devido a operações matriciais envolvidas na
sua lógica. Existem também algoritmos de processamento como MRC e EGC que
por não incluir operações demasiado complexas na sua lógica contribuem para
uma diminuição significativa da complexidade embora, a custa de uma perda de
eficiência considerável.
Este trabalho científico traz como proposta a implementação dum receptor de má-
ximo desempenho do tipo IB-DFE combinado com técnicas MRC/EGC, capaz de
operar em ambientes Massive MIMO, no sentido uplink da ligação, e no domínio
da frequência. Desta forma será possível tirar o máximo partido de ambas as abordagens de maneira a garantir o máximo desempenho do sistema e uma redução da
complexidade de implementação.As the 5th Generation of wireless comunications approaches we antecipate the provision of better services with much higher transmission speeds. This leads inevitably to an increase of the devices and users of the network, due to new technologies, such as the IoT. On the other hand there are numerous difficulties associated with high signal dispersion due to its multipath propagation, highth rates and high power efficiency as well as the expection of larger capacity and flexibility in this new system. In a nutshell: the growth of the complexity of these systems is the great challenge of the 5G. The answer for all this issues is essencial for the development of these wireless technologies. The massive MIMO technology presents itself as a strong candidate for the requirements demanded by 5G and it promises to be efficient, safe and reliable. However, all these benefits bring a huge increase of complexity due to the multiple signals involved in the transmission of a large number of antennas. On the other hand, there are techniques that implement very complex environments employing OFDM, SC-FDE and IB-DFE reception schemes, which offer great performance in terms of efficiency at the expense of an increase of complexity due to matrix opperations involved. Besides, there are algorithms that employ MRC and EGC techniques that help to significantly reduce the complexity of the system since they do not include matrix operations. Notwithstanding, these techniques lose performance to the other ones. Having said that, our proposal is the implementation of an optimal performance frequency-domain IB-DFE receiver, combined with MRC/EGC techniques, that is able to perform in massive MIMO environment and uplink transmission. Therefore we will be able to get the best of both approaches, ensuring the optimal performance of the system and a reduction of the complexity of the implementation.