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Dissertations / Theses on the topic 'Bloch space'
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1
Allen, Robert Francis. "A class of operators with symbol on the bloch space of a bounded homogeneous domain." Fairfax, VA : George Mason University, 2009. http://hdl.handle.net/1920/4541.
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Thesis (Ph.D.)--George Mason University, 2009.Vita: p. 158. Thesis director: Flavia Colonna. Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Mathematics. Title from PDF t.p. (viewed Oct. 11, 2009). Includes bibliographical references (p. 150-157). Also issued in print.
2
Mauthner, Ulrich [Verfasser], Herbert [Akademischer Betreuer] Spohn, and Stefan [Akademischer Betreuer] Teufel. "Space-adiabatic perturbation theory for Dirac-Bloch electrons / Ulrich Mauthner. Gutachter: Stefan Teufel. Betreuer: Herbert Spohn." München : Universitätsbibliothek der TU München, 2006. http://d-nb.info/1058138499/34.
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Pak, Anne On-Yi 1977. "Euclidean space codes as space-time block codes." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/86722.
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Afdideh, Fardin. "Block-sparse models in multi-modality : application to the inverse model in EEG/MEG." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAT074/document.
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De nombreux phénomènes naturels sont trop complexes pour être pleinement reconnus par un seul instrument de mesure ou par une seule modalité. Par conséquent, le domaine de recherche de la multi-modalité a émergé pour mieux identifier les caractéristiques riches du phénomène naturel de la multi-propriété naturelle, en analysant conjointement les données collectées à partir d’uniques modalités, qui sont en quelque sorte complémentaires. Dans notre étude, le phénomène d’intérêt multi-propriétés est l’activité du cerveau humain et nous nous intéressons à mieux la localiser au moyen de ses propriétés électromagnétiques, mesurables de manière non invasive. En neurophysiologie, l’électroencéphalographie (EEG) et la magnétoencéphalographie (MEG) constituent un moyen courant de mesurer les propriétés électriques et magnétiques de l’activité cérébrale. Notre application dans le monde réel, à savoir le problème de reconstruction de source EEG / MEG, est un problème fondamental en neurosciences, allant des sciences cognitives à la neuropathologie en passant par la planification chirurgicale. Considérant que le problème de reconstruction de source EEG /MEG peut être reformulé en un système d’équations linéaires sous-déterminé, la solution (l’activité estimée de la source cérébrale) doit être suffisamment parcimonieuse pour pouvoir être récupérée de manière unique. La quantité de parcimonie est déterminée par les conditions dites de récupération. Cependant, dans les problèmes de grande dimension, les conditions de récupération conventionnelles sont extrêmement strictes. En regroupant les colonnes cohérentes d’un dictionnaire, on pourrait obtenir une structure plus incohérente. Cette stratégie a été proposée en tant que cadre d’identification de structure de bloc, ce qui aboutit à la segmentation automatique de l’espace source du cerveau, sans utiliser aucune information sur l’activité des sources du cerveau et les signaux EEG / MEG. En dépit du dictionnaire structuré en blocs moins cohérent qui en a résulté, la condition de récupération conventionnelle n’est plus en mesure de calculer la caractérisation de la cohérence. Afin de relever le défi mentionné, le cadre général des conditions de récupération exactes par bloc-parcimonie, comprenant trois conditions théoriques et une condition dépendante de l’algorithme, a été proposé. Enfin, nous avons étudié la multi-modalité EEG et MEG et montré qu’en combinant les deux modalités, des régions cérébrales plus raffinées sont apparuesThree main challenges have been addressed in this thesis, in three chapters.First challenge is about the ineffectiveness of some classic methods in high-dimensional problems. This challenge is partially addressed through the idea of clustering the coherent parts of a dictionary based on the proposed characterisation, in order to create more incoherent atomic entities in the dictionary, which is proposed as a block structure identification framework. The more incoherent atomic entities, the more improvement in the exact recovery conditions. In addition, we applied the mentioned clustering idea to real-world EEG/MEG leadfields to segment the brain source space, without using any information about the brain sources activity and EEG/MEG signals. Second challenge raises when classic recovery conditions cannot be established for the new concept of constraint, i.e., block-sparsity. Therefore, as the second research orientation, we developed a general framework for block-sparse exact recovery conditions, i.e., four theoretical and one algorithmic-dependent conditions, which ensure the uniqueness of the block-sparse solution of corresponding weighted mixed-norm optimisation problem in an underdetermined system of linear equations. The mentioned generality of the framework is in terms of the properties of the underdetermined system of linear equations, extracted dictionary characterisations, optimisation problems, and ultimately the recovery conditions. Finally, the combination of different information of a same phenomenon is the subject of the third challenge, which is addressed in the last part of dissertation with application to brain source space segmentation. More precisely, we showed that by combining the EEG and MEG leadfields and gaining the electromagnetic properties of the head, more refined brain regions appeared
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Masoud, Masoud. "Space-time block coding for wireless communications." Thesis, University of Hertfordshire, 2008. http://hdl.handle.net/2299/2548.
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Wireless designers constantly seek to improve the spectrum efficiency/capacity, coverage of wireless networks, and link reliability. Space-time wireless technology that uses multiple antennas along with appropriate signalling and receiver techniques offers a powerful tool for improving wireless performance. Some aspects of this technology have already been incorporated into various wireless network and cellular mobile standards. More advanced MIMO techniques are planned for future mobile networks, wireless local area network (LANs) and wide area network (WANs). Multiple antennas when used with appropriate space-time coding (STC) techniques can achieve huge performance gains in multipath fading wireless links. The fundamentals of space-time coding were established in the context of space-time Trellis coding by Tarokh, Seshadri and Calderbank. Alamouti then proposed a simple transmit diversity coding scheme and based on this scheme, general space-time block codes were further introduced by Tarokh, Jafarkhani and Calderbank. Since then space-time coding has soon evolved into a most vibrant research area in wireless communications. Recently, space-time block coding has been adopted in the third generation mobile communication standard which aims to deliver true multimedia capability. Space-time block codes have a most attractive feature of the linear decoding/detection algorithms and thus become the most popular among different STC techniques. The decoding of space-time block codes, however, requires knowledge of channels at the receiver and in most publications, channel parameters are assumed known, which is not practical due to the changing channel conditions in real communication systems. This thesis is mainly concerned with space-time block codes and their performances. The focus is on signal detection and channel estimation for wireless communication systems using space-time block codes. We first present the required background materials, discuss different implementations of space-time block codes using different numbers of transmit and receive antennas, and evaluate the performances of space-time block codes using binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), and quadrature amplitude modulation (QAM). Then, we investigate Tarokh’s joint detection scheme with no channel state information thoroughly, and also propose a new general joint channel estimation and data detection scheme that works with QPSK and 16-QAM and different numbers of antennas. Next, we further study Yang’s channel estimation scheme, and expand this channel estimation scheme to work with 16-QAM modulation. After dealing with complex signal constellations, we subsequently develop the equations and algorithms of both channel estimation schemes to further test their performances when real signals are used (BPSK modulation). Then, we simulate and compare the performances of the two new channel estimation schemes when employing different number of transmit and receive antennas and when employing different modulation methods. Finally, conclusions are drawn and further research areas are discussed.
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Songulen, Nazli. "Space Organisation In Urban Block: Interfaces Among Public, Common And Private Spaces Based On Conzen Method In Bahcelievler." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614461/index.pdf.
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Space organisation of urban blocks is a significant topic of urban design field to achieve correlated urban parts that enhance the variety in urban spaces. However, the rapid urban transformation experienced in the Turkish cities resulted in the generation of similar urban blocks with the lack of spatial variety. Therefore, a re-evolution of space organisation concepts for urban blocks emerges as a design problem in order to cope with the defined problem.
From this point of view, the interfaces among public, common and private spaces as the formative parts of space organisation process constitute the essence of this study. Thus, the morphological elements of urban blocks as street, plot and building are constantly reshaped and redefined based on the correlations of this realms. Within this scope, Conzen&rsquos town plan method has been adopted in this study for Bahç
elievler Housing Cooperative Site, to reveal the transformation experienced and the changing relations of street, plot and building throughout the morphological formation processes. In the light of this problem case and method implemented, this research indicates that in Bahç
elievler, the changing relations between street, plot and buildings are an outcome of the interfaces among public, common and private regarding the permeability along boundaries. Based on this outcome, this study suggests that a new understanding of space organisation in urban blocks regarding the interfaces among public, common and private spaces as counterparts of street, plot and buildings arises as a significant issue that needs to be reconsidered by urban designers, planners, architects and public authorities while defining the design and planning process.
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Paudyal, Bhupendra. "Eigenfunctions of Composition Operators on Bloch-type Spaces." University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1404663222.
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Baker, Dirk A. "Space-time block coding with imperfect channel estimates." Morgantown, W. Va. : [West Virginia University Libraries], 2001. http://etd.wvu.edu/templates/showETD.cfm?recnum=1843.
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Thesis (M.S.)--West Virginia University, 2001.Title from document title page. Document formatted into pages; contains iv, 74 p. : ill. Includes abstract. Includes bibliographical references (p. 73-74).
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Ali, Saajed. "Concatenation of Space-Time Block Codes with ConvolutionalCodes." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/9724.
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Multiple antennas help in combating the destructive effects of fading as well as improve the spectral efficiency of a communication system. Receive diversity techniques like maximal ratio receive combining have been popular means of introducing multiple antennas into communication systems. Space-time block codes present a way of introducing transmit diversity into the communication system with similar complexity and performance as maximal ratio receive combining. In this thesis we study the performance of space-time block codes in Rayleigh fading channel. In particular, the quasi-static assumption on the fading channel is removed to study how the space-time block coded system behaves in fast fading. In this context, the complexity versus performance trade-off for a space-time block coded receiver is studied. As a means to improve the performance of space-time block coded systems concatenation by convolutional codes is introduced. The improvement in the diversity order by the introduction of convolutional codes into the space-time block coded system is discussed. A general analytic expression for the error performance of a space-time block coded system is derived. This expression is utilized to obtain general expressions for the error performance of convolutionally concatenated space-time block coded systems utilizing both hard and soft decision decoding. Simulation results are presented and are compared with the analytical results.Master of Science
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Castiñeira, Moreira Jorge. "Signal space coding over rings." Thesis, Lancaster University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322886.
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Liao, Huiyong. "Lattice based space-time block codes for MIMO system." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 155 p, 2007. http://proquest.umi.com/pqdweb?did=1251904861&sid=2&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Ding, Zhiguo. "Receiver algorithm design for space time block coding systems." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420523.
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Pau, Nicholas. "Robust High Throughput Space-Time Block Coded MIMO Systems." Thesis, University of Canterbury. Electrical and Computer Engineering, 2007. http://hdl.handle.net/10092/1167.
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In this thesis, we present a space-time coded system which achieves high through- put and good performance with low processing delay using low-complexity detection and decoding. Initially, Hamming codes are used in a simple interleaved bit-mapped coded modulation structure (BMCM). This is concatenated with Alamouti's or- thogonal space-time block codes. The good performance achieved by this system indicates that higher throughput is possible while maintaining performance. An analytical bound for the performance of this system is presented. We also develop a class of low density parity check codes which allows flexible "throughput versus performance" tradeoffs. We then focus on a Rate 2 quasi-orthogonal space-time block code structure which enables us to achieve an overall throughput of 5.6 bits/symbol period with good performance and relatively simple decoding using iterative parallel interference cancellation. We show that this can be achieved through the use of a bit-mapped coded modulation structure using parallel short low density parity check codes. The absence of interleavers here reduces processing delay significantly. The proposed system is shown to perform well on flat Rayleigh fading channels with a wide range of normalized fade rates, and to be robust to channel estimation errors. A comparison with bit-interleaved coded modulation is also provided (BICM).
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Lubbad, Bashar. "Designed oppression : Space of resistance in Palesine the block." Thesis, Linnéuniversitetet, Institutionen för design (DE), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-104009.
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The block is a design research project exploring and mapping out the designconstructions ranging from the actual material to the shape it takes changing thePalestinian landscape. As a way to understand the physical boundaries, I attempt toshowcase some of the realities that the indigenous population lives under. Throughthis work, I navigate various layers of oppressions manifested in the Block. TheBlock is a barricade, a tunnel gate, a barbed wire, it is the overpopulatedconcentration of Palestinians completely surrounded by military and walls. Peopleliving under these conditions are forced to cope with and more importantly, standresilient against the day-to-day incursion on humanity, normality, and peace.
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Sengupta, Avik. "Redundant residue number system based space-time block codes." Thesis, Kansas State University, 2012. http://hdl.handle.net/2097/14111.
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Master of ScienceDepartment of Electrical and Computer Engineering
Balasubramaniam Natarajan
Space-time coding (STC) schemes for Multiple Input Multiple Output (MIMO) systems have been an area of active research in the past decade. In this thesis, we propose a novel design of Space-Time Block Codes (STBCs) using Redundant Residue Number System (RRNS) codes, which are ideal for high data rate communication systems. Application of RRNS as a concatenated STC scheme to a MIMO wireless communication system is the main motivation for this work. We have optimized the link between residues and complex constellations by incorporating the “Direct Mapping” scheme, where residues are mapped directly to Gray coded constellations. Knowledge of apriori probabilities of residues is utilized to implement a probability based “Distance-Aware Direct Mapping” (DA) scheme, which uses a set-partitioning approach to map the most probable residues such that they are separated by the maximum possible distance. We have proposed an “Indirect Mapping” scheme, where we convert the residues back to bits before mapping them. We have also proposed an adaptive demapping scheme which utilizes the RRNS code structure to reduce the ML decoding complexity and improve the error performance. We quantify the upper bounds on codeword and bit error probabilities of both Systematic and Non-systematic RRNS-STBC and characterize the achievable coding and diversity gains assuming maximum likelihood decoding (MLD). Simulation results demonstrate that the DA Mapping scheme provides performance gain relative to a Gray coded direct mapping scheme. We show that Systematic RRNS-STBC codes provide superior performance compared to Nonsystematic RRNS-STBC, for the same code parameters, owing to more efficient binary to residue mapping. When compared to other concatenated STBC and Orthogonal STBC (OSTBC) schemes, the proposed system gives better performance at low SNRs.
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Gregoratti, David. "Randomized space-time block coding for the multiple-relay channel." Doctoral thesis, Universitat Politècnica de Catalunya, 2010. http://hdl.handle.net/10803/6949.
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En la última década, la cooperación entre usuarios ha generado un gran interés por la posibilidad de mejorar la velocidad de transmisión en las redes de comunicaciones inalámbricas. El objetivo es formar un array con las antenas de todos los dispositivos y, de esta forma, aplicar técnicas de procesado espacio-temporal. El esquema de cooperación más sencillo es el canal con relays: todos los terminales que escuchen una comunicación entre dos puntos pueden ayudar a la fuente retransmitiendo lo que hayan recibido.En un sistema realista, los relays no disponen de información sobre el canal en trasmisión. En este escenario, los códigos espacio-temporales (STC, del inglés space-time coding) son la alternativa más eficiente para aprovechar la diversidad introducida por los relays. Sin embargo, los STC clásicos están diseñados para un número limitado y fijo de antenas transmisoras y no se adaptan bien a sistemas cooperativos donde el número de relays puede ser elevado y, sobretodo, puede variar en el tiempo, según los usuarios entren o salgan de la red. El problema principal es la necesidad de usar un código nuevo cada vez que cambie la configuración de la red, generando un importante tráfico de señalización.
Esta tesis analiza un código espacio-temporal a bloques de dispersión lineal (LD-STBC, del inglés linear-dispersion space-time block coding), aleatorio y distribuido: a cada relay se le asigna una matriz aleatoria que aplica una transformación lineal al vector que contiene los símbolos de la fuente. Cada matriz se genera de forma independiente y sin ninguna relación con el número de usuarios involucrados. De esta manera, el número de nodos puede variar sin necesidad de modificar los códigos existentes.
La forma más intuitiva de construir matrices de dispersión lineal independientes es que sus elementos sean variables aleatorias independientes e idénticamente distribuidas (i.i.d.). Por esta razón, se estudia primero la eficiencia espectral obtenida por este tipo de LD-STBC. Es importante remarcar que la eficiencia espectral es una cantidad aleatoria, ya que es una función de los códigos aleatorios anteriormente descritos. Sin embargo, cuando las dimensiones de las matrices crecen infinitamente pero manteniendo constante la tasa del código (relación entre número de símbolos de la fuente sobre el número de símbolos de los relays), la eficiencia espectral converge rápidamente hacia una cantidad determinista. Este resultado se demuestra usando la teoría de las matrices aleatorias. Por esta razón, el sistema se analiza aproximando la eficiencia espectral con su limite. Por ejemplo, la comparación con el canal directo entre fuente y destino permite definir unas condiciones suficientes en donde el sistema con relays es superior a la comunicación punto a punto.
Posteriormente se debe analizar la probabilidad de outage, es decir la probabilidad de que, debido a la baja calidad del canal, la eficiencia espectral sea menor que la velocidad de transmisión solicitada por el sistema. Como ya se ha mencionado anteriormente, los relays se introducen para aumentar la diversidad del canal y, con ella, el número de caminos independientes entre la fuente y el receptor, reduciendo la probabilidad de outage. Para los LD-STBC i.i.d. las prestaciones en términos de outage dependen del tipo de relay (amplify and forward o decode and forward) y son función de la tasa del código, que debe ser cuidadosamente elegida para maximizar el orden de diversidad sin desperdiciar demasiados recursos.
Finalmente, en el último capítulo de la tesis se considera otro tipo de LD-STBC, distinto del i.i.d. analizado hasta ahora. En este caso, las matrices de dispersión lineal siguen siendo independientes la una de la otra pero se añade la restricción de que cada una tenga columnas (o filas, según la tasa del código) ortogonales. Así, se consigue que el código siga siendo flexible con respecto a las variaciones en el número de usuarios, pero su estructura permite reducir la interferencia generada por cada relay, como se puede notar comparando su eficiencia espectral con la eficiencia espectral obtenida por el código i.i.d. Cabe destacar que el análisis asintótico de estos códigos (llamados isométricos) se basa en herramientas matemáticas más sofisticadas que las anteriores y, por lo tanto, es necesario un estudio más profundo para poder entender cómo se comporta en términos de outage.
In the last decade, cooperation among multiple terminals has been seen as one of the more promising strategies to improve transmission speed in wireless communications networks. Basically, the idea is to mimic an antenna array and apply distributed versions of well-known space-diversity techniques. In this context, the simplest cooperative scheme is the relay channel: all the terminals (relays) that overhear a point-to-point communication between a source and a destination may decide to aid the source by forwarding (relaying) its message.
In a mobile system, it is common to assume that the relays do not have any information about the channel between them and the destination. Under this hypothesis, the best solution to exploit the diversity offered by multiple transmitting antennas is to use space-time coding (STC). However, classical STC's are designed for systems with a fixed and usually low number of antennas. Thus, they are not suitable for relaying in most mobile communications systems where the number of terminals is potentially large and may vary as users join or leave the network. For each new configuration, a new code has to be chosen and notified to the relays, introducing a set-up overhead of signaling traffic.
In this dissertation we will propose and analyze a randomized distributed linear-dispersion space-time block code (LD-STBC): each relay is assigned a specific matrix which linearly transforms (left-multiplies) the column vector of source symbols. Each matrix is independently generated and does not depend on the total number of transmitters, which can thus change without interrupting data transmission for a new code--relay assignment.
The more intuitive way to build independent linear-dispersion matrices is to fill them with independent and identically distributed (i.i.d.) random variables. Therefore, we will first consider these i.i.d. codes and characterize the resulting spectral efficiency. In order to analyze the performance achieved by the system, we consider a large-system analysis based on random matrix theory. We will show that the random spectral efficiency (function of the random linear-dispersion matrices) converges almost surely to a deterministic quantity when the dimensions of the code grow indefinitely while keeping constant the coding rate. Since convergence is very fast, the random spectral efficiency will be approximated by the deterministic limit in the subsequent analysis. By comparison with the direct link, sufficient conditions are derived for the superiority of relaying.
Next, we will analyze the outage probability of the system, that is the probability that the spectral efficiency falls below a given target rate due to channel fading. The main purpose of diversity techniques is to introduce alternative paths from the source to the destination, so that data transmission does not fail when the direct link undergoes deep fading. We will show that the diversity behavior of LD-STBC relaying mainly depends on both the coding rate and the relaying strategy (amplify and forward or decode and forward). It is then important to choose the coding rate that maximizes the diversity order without wasting too many resources.
To conclude the dissertation, we will consider a different code based on independent isometric Haar-distributed random linear-dispersion matrices. The
new code maintains the flexibility of the previous one with respect to variations in the number of relays. However, the more complex structure of the codes allows a noticeable reduction of the interference generated by the relays. Unfortunately, isometric codes also require more sophisticated mathematical tools for their asymptotic analysis. For this reason, we simply introduce the problem by showing that it is possible to have some spectral-efficiency gain with respect to i.i.d. codes. The outage-probability analysis requires a more thorough understanding and will be the subject of future work.
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Sinnokrot, Mohanned Omar. "Space-time block codes with low maximum-likelihood decoding complexity." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31752.
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Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2010.Committee Chair: Barry, John; Committee Co-Chair: Madisetti, Vijay; Committee Member: Andrew, Alfred; Committee Member: Li, Ye; Committee Member: Ma, Xiaoli; Committee Member: Stuber, Gordon. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Lin, Rui. "Hybrid ARQ Schemes for Non-orthogonal Space-time Block Codes." Thesis, University of Canterbury. Electrical and Computer Engineering, 2007. http://hdl.handle.net/10092/1183.
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Automatic Repeat-reQuest (ARQ) schemes are extensively used in communication systems and computer networks to achieve reliable transmission. Using space-time codes (STCs) with multiple input multiple output (MIMO) or multiple input single output (MISO) systems is an effective way to combat multipath fading, which is the most severe impairment for wireless communication systems. STCs are designed to use the rich scattering multipath environment provided by using multiple transmit antennas. The work done in this thesis focuses on the use of ARQ schemes with non-orthogonal space-time block codes (NOSTBCs) based on Reed Solomon codes. The truncated-selective ARQ (TS-ARQ) scheme is considered and three novel hybrid ARQ (HARQ) schemes are proposed. Simulation results reveal that, compared to using TS-ARQ with orthogonal space-time block codes (OSTBCs), using NOSTBCs with any of the three proposed HARQ schemes can provide significant gains in terms of dropped packet rate and spectral efficiency at the cost of increased decoding complexity. The performance can be further improved by using the water filling principle to adaptively allocate transmit power among transmit antennas.
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Oruç, Özgür Altınkaya Mustafa Aziz. "Differential and coherent detection schemes for space-time block codes/." [s.l.]: [s.n.], 2002. http://library.iyte.edu.tr/tezler/master/elektrikveelektronikmuh/T000133.pdf.
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Elazreg, A. M. "Distributed space time block coding in asynchronous cooperative relay networks." Thesis, Loughborough University, 2013. https://dspace.lboro.ac.uk/2134/12032.
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The design and analysis of various distributed space time block coding schemes for asynchronous cooperative relay networks is considered in this thesis. Rayleigh frequency flat fading channels are assumed to model the links in the networks, and interference suppression techniques together with an orthogonal frequency division multiplexing type transmission approach are employed to mitigate the synchronization errors at the destination node induced by the different delays through the relay nodes. Closed-loop space time block coding is first considered in the context of decode-and-forward (regenerative) networks. In particular, quasi orthogonal and extended orthogonal coding techniques are employed for transmission from four relay nodes and parallel interference cancellation detection is exploited to mitigate synchronization errors. Availability of a direct link between the source and destination nodes is studied, and a new Alamouti space time block coding technique with parallel interference cancellation detection which does not require such a direct link connection and employs two relay nodes is proposed. Outer coding is then added to gain further improvement in end-to-end performance and amplify-and-forward (non regenerative) type networks together with distributed space time coding are considered to reduce relay node complexity. Novel detection schemes are then proposed for decode-and-forward networks with closed-loop extended orthogonal coding which reduce the computational complexity of the parallel interference cancellation. Both sub-optimum and near-optimum detectors are presented for relay nodes with single or dual antennas. End-to-end bit error rate simulations confirm the potential of the approaches and their ability to mitigate synchronization errors. A relay selection approach is also formulated which maximizes spatial diversity gain and attains robustness to timing errors. Finally, a new closed-loop distributed extended orthogonal space time block coding solution for amplify-and-forward type networks which minimizes the number of feedback bits by using a cyclic rotation phase is presented. This approach utilizes an orthogonal frequency division multiplexing type transmission structure with a cyclic prefix to mitigate synchronization errors. End-to-end bit error performance evaluations verify the efficacy of the scheme and its success in overcoming synchronization errors.
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Wang, Ruoyu. "Performance of Space-Time Block Code in MISO-OFDM system." Thesis, California State University, Long Beach, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10196062.
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Space-Time Code (STC) has caused wide public concern in the field of wireless communications over the recent years. Due to interference or signal attenuation, it may cause errors or data loss when the data stream is transmitted through a wireless channel. The Space-Time Block Code (STBC), which combines the technique of channel coding and antenna diversity, is an effective approach of increasing the capacity of a wireless channel by increasing both the coding gain and diversity gain. Using STBC in Orthogonal Frequency-Division Multiplexing (OFDM), multiple antennas transmit multiple copies of the data stream, and the receiver can integrate these copies for optimal data. In this system, the wireless signal is more reliable and able to meet more remote wireless transmissions. In this project, three STBCs are applied in 2x1, 3x1, and 4x1 OFDM system respectively, to provide different data rates and reliability.
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Söderberg, Stefan. "A parallel block-based PDE solver with space-time adaptivity." Licentiate thesis, Uppsala universitet, Avdelningen för teknisk databehandling, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-86002.
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A second order space and time adaptive method for parallel solution of hyperbolic PDEs on structured grids is presented. The grid is adapted to the underlying solution by successive refinement in blocks. Therefore, there may be jumps in the cell size at the block faces. Special attention is needed at the block boundaries to maintain second order accuracy and stability. The stability of the method is proven for a model problem. The step sizes in space and time are selected based on estimates of the local truncation errors and an error tolerance provided by the user. The global error in the solution is also computed by solving an error equation similar to the original problem on a coarser grid. The performance of the method depends on the number of blocks used in the domain. A method of predicting the optimal number of blocks is presented. The cells are distributed in blocks over the processor set using a number of different partitioning schemes. The method is used to successfully solve a number of test problems where the method selects the appropriate space and time steps according to the error tolerance.
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Barth, Bernhard [Verfasser], and L. [Akademischer Betreuer] Weis. "The Bloch Transform on Lp-Spaces / Bernhard Barth. Betreuer: L. Weis." Karlsruhe : KIT-Bibliothek, 2013. http://d-nb.info/1046362658/34.
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Lifchits, Andrei. "Improving disk read performance through block-level replication into free space." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/892.
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Disk performance for random access fares significantly worse compared to
sequential access. Time required to transfer random blocks to or from disk is
dominated by seeking and rotational delay. To improve the throughput and
reduce the latency, one can apply techniques to increase the sequentiality of
disk accesses, such as block rearrangement and replication.
We introduce an approach to improve read performance by replicating
blocks into file system free space at the block level. This makes the replication
module independent of the file system and therefore easier to implement
and verify. A solution that requires no changes to the file system is
also easier to adopt. Supporting a new file system is a matter of writing a
user-space component that understands its free block data structures. We
implemented a prototype as a stacked device driver for Linux and evaluated
its performance on a number of workloads.
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Delestre, Fabien. "Channel estimation and performance analysis of MIMO-OFDM communications using space-time and space-frequency coding schemes." Thesis, University of Hertfordshire, 2011. http://hdl.handle.net/2299/6397.
Full textAbstract:
This thesis is concerned with channel estimation and data detection of MIMO-OFDM communication systems using Space-Time Block Coding (STBC) and Space-Frequency Block Coding (SFBC) under frequency selective channels. A new iterative joint channel estimation and signal detection technique for both STBC-OFDM and SFBC-OFDM systems is proposed. The proposed algorithm is based on a processive sequence of events for space time and space frequency coding schemes where pilot subcarriers are used for channel estimation in the first time instant, and then in the second time instant, the estimated channel is used to decode the data symbols in the adjacent data subcarriers. Once data symbols are recovered, the system recursively performs a new channel estimation using the decoded data symbols as pilots. The iterative process is repeated until all MIMO-OFDM symbols are recovered. In addition, the proposed channel estimation technique is based on the maximum likelihood (ML) approach which offers linearity and simplicity of implementation. Due to the orthogonality of STBC and SFBC, high computation efficiency is achieved since the method does not require any matrix inversion for estimation and detection at the receiver. Another major novel contribution of the thesis is the proposal of a new group decoding method that reduces the processing time significantly via the use of sub-carrier grouping for transmitted data recovery. The OFDM symbols are divided into groups to which a set of pilot subcarriers are assigned and used to initiate the channel estimation process. Designated data symbols contained within each group of the OFDM symbols are decoded simultaneously in order to improve the decoding duration. Finally, a new mixed STBC and SFBC channel estimation and data detection technique with a joint iterative scheme and a group decoding method is proposed. In this technique, STBC and SFBC are used for pilot and data subcarriers alternatively, forming the different combinations of STBC/SFBC and SFBC/STBC. All channel estimation and data detection methods for different MIMO-OFDM systems proposed in the thesis have been simulated extensively in many different scenarios and their performances have been verified fully.
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Michaud-Rioux, Vincent. "Real space DFT by locally optimal block preconditioned conjugate gradient method." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110628.
Full textAbstract:
In condensed matter physics, atomistic first principle calculations are often necessary to achieve a microscopic understanding of the observed experimental phenomena and to make quantitative predictions of physical properties. In practice, atomic scale systems have irregularities (e.g. surface roughness) or defects (e.g. substitutional atoms or vacancies) that are too strong to be ignored or treated as small perturbations. In this thesis, we report the development of a real space DFT code for studying atomic scale systems from first principles. Our code, named MatRcal, which stands for "Matlab-based real space calculator", is developed in the technical computing language Matlab. The physics is described by density functional theory. The method itself is based on projecting the Kohn-Sham Hamiltonian on a uniform Cartesian grid. High-order finite-differencing is used to discretize the Laplacian operator. The potential due to the atomic nuclei is approximated with ab initio pseudopotentials. The pseudopotentials are generated following the procedure proposed by Troullier and Martins. We use the fully separable form introduced by Kleinman and Bylander. We argue that the method is simpler and yet has many advantages compared with conventional spectral methods. We provide relevant mathematical techniques and implementation details. In particular, we present and compare different eigensolvers used to diagonalize the Kohn-Sham Hamiltonian. We validate our software by comparing the HOMO-LUMO gaps of many organic and inorganic molecules obtained using our method with those obtained with the commercial code Gaussian. Our results are in excellent agreement. Our method gains in computational speed and algorithm parallelism, and its power in handling real space boundary conditions will be a major advantage for future applications in nanoelectronic device modelling.En physique de la matière condensée, les calculs numériques sont souvent nécessaires pour parvenir à comprendre les phénomènes microscopiques observés lors d'expériences ou à prédire quantitativement des propriétés physiques. En pratique, les systèmes d'échelle atomique sont irréguliers (rugosité de surface) ou comportent des défauts (atomes de substitution ou lacunes), ce qui induit des effets trop sévères pour être ignorés ou traités comme des perturbations. Dans cette thèse, nous présentons une méthode qui permet d'étudier des systèmes d'échelle atomique à partir des lois fondamentales de la physique. Notre logiciel, nommé MatRcal, qui signifie "Matlab-based real space calculator", est développé dans le langage Matlab. La physique est décrite par la théorie de la fonctionnelle de la densité. La méthode projette l'Hamiltonien de Kohn-Sham sur un maillage Cartésien uniforme. Le calcul des différences finies est utilisé pour discrétiser l'opérateur Laplacien. Le potentiel dû aux noyaux atomiques est approximé par des pseudopotentiels non-empiriques. Les pseudopotentiels sont générés en suivant la procédure proposée par Troullier et Martins. Nous utilisons la forme séparable introduite par Kleinman et Bylander. Nous soutenons que la méthode est plus simple et pourtant présente de nombreux avantages par rapport aux conventionnelles méthodes spectrales. Nous introduisons plusieurs techniques mathématiques pertinentes à notre étude et certains détails d'implémentation. Entre autres, nous présentons et comparons plusieurs algorithmes de calcul de vecteurs propres utilisés pour diagonaliser l'Hamiltonien de Kohn-Sham. Nous validons notre méthode en comparant la largeur de bande interdite "HOMO-LUMO" de nombreuses molécules organiques et inorganiques prédites par notre méthode avec celles prédites par le logiciel commercial Gaussian. Notre méthode permet des gains en rapidité et en parallélisme, mais la possibilité de traiter des conditions limites non-périodiques sera le principal atout pour de futures simulations de dispositifs nanoélectroniques.
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Chu, Alice Pin-Chen. "High-Rate Space-Time Block Codes in Frequency-Selective Fading Channels." Thesis, University of Canterbury. Electrical and Computer Engineering, 2012. http://hdl.handle.net/10092/10360.
Full textAbstract:
The growing popularity of wireless communications networks has resulted in greater bandwidth contention and therefore spectrally efficient transmission schemes are highly sought after by designers.
Space-time block codes (STBCs) in multiple-input, multiple-output (MIMO) systems are able to increase channel capacity as well as reduce error rate. A general linear space-time structure known as linear dispersion codes (LDCs) can be designed to achieve high-data rates and has been researched extensively for flat fading channels. However, very little research has been done on frequency-selective fading channels. The combination of ISI, signal interference from other transmitters and noise at the receiver mean that maximum likelihood sequence estimation (MLSE) requires high computational complexity. Detection schemes that can mitigate the signal interference can significantly reduce the complexity and allow intersymbol interference (ISI) equalization to be performed by a Viterbi decoder.
In this thesis, detection of LDCs on frequency-selective channels is investigated. Two predominant detection schemes are investigated, namely linear processing and zero forcing (ZF). Linear processing depends on code orthogonality and is only suited for short channels and small modulation schemes. ZF cancels interfering signals when a sufficient number of receive antennas is deployed. However, this number increases with the channel length. Channel decay profiles are investigated for high-rate LDCs to ameliorate this limitation. Performance improves when the equalizer assumes a shorter channel than the actual length provided the truncated taps carry only a small portion of the total channel power.
The LDC is also extended to a multiuser scenario where two independent users cooperate over half-duplex frequency-selective channels to achieve cooperative gain. The cooperative scheme transmits over three successive block intervals. Linear and zero-forcing detection are considered.
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Manna, Mustafa A. "Modified quasi-orthogonal space-time block coding in distributed wireless networks." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/16629.
Full textAbstract:
Cooperative networks have developed as a useful technique that can achieve the same advantage as multi-input and multi-output (MIMO) wireless systems such as spatial diversity, whilst resolving the difficulties of co-located multiple antennas at individual nodes and avoiding the effect of path-loss and shadowing. Spatial diversity in cooperative networks is known as cooperative diversity, and can enhance system reliability without sacrificing the scarce bandwidth resource or consuming more transmit power. It enables single-antenna terminals in a wireless relay network to share their antennas to form a virtual antenna array on the basis of their distributed locations. However, there remain technical challenges to maximize the benefit of cooperative communications, e.g. data rate, asynchronous transmission and outage. In this thesis, therefore, firstly, a modified distributed quasi-orthogonal space-time block coding (M-D-QO-STBC) scheme with increased code gain distance (CGD) for one-way and two-way amplify-and-forward wireless relay networks is proposed. This modified code is designed from set partitioning a larger codebook formed from two quasi-orthogonal space time block codes with different signal rotations then the subcodes are combined and pruned to arrive at the modified codebook with the desired rate in order to increase the CGD. Moreover, for higher rate codes the code distance is maximized by using a genetic algorithm to search for the optimum rotation matrix. This scheme has very good performance and significant coding gain over existing codes such as the open-loop and closed-loop QO-STBC schemes. In addition, the topic of outage probability analysis in the context of multi-relay selection from $N$ available relay nodes for one-way amplify-and-forward cooperative relay networks is considered together with the best relay selection, the $N^{th}$ relay selection and best four relay selection in two-way amplify-and-forward cooperative relay networks. The relay selection is performed either on the basis of a max-min strategy or one based on maximizing exact end-to-end signal-to-noise ratio. Furthermore, in this thesis, robust schemes for cooperative relays based on the M-D-QO-STBC scheme for both one-way and two-way asynchronous cooperative relay networks are considered to overcome the issue of a synchronism in wireless cooperative relay networks. In particular, an orthogonal frequency division multiplexing (OFDM) data structure is employed with cyclic prefix (CP) insertion at the source in the one-way cooperative relay network and at the two terminal nodes in the two-way cooperative network to combat the effects of time asynchronism. As such, this technique can effectively cope with the effects of timing errors. Finally, outage probability performance of a proposed amplify-and-forward cooperative cognitive relay network is evaluated and the cognitive relays are assumed to exploit an overlay approach. A closed form expression for the outage probability for multi-relay selection cooperation over Rayleigh frequency flat fading channels is derived for perfect and imperfect spectrum acquisitions. Furthermore, the M-QO-STBC scheme is also proposed for use in wireless cognitive relay networks. MATLAB and Maple software based simulations are employed throughout the thesis to support the analytical results and assess the performance of new algorithms and methods.
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Takele, Berta. "Performance Evaluation of Simple Space-Time Block Coding on MIMO Communication System." Thesis, Växjö University, Växjö University, School of Mathematics and Systems Engineering, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:vxu:diva-6988.
Full textAbstract:
This thesis discuss on new technique called space time block coding (especially Alamouti's code) which is used to increase capacity and reliability of data transmission over time varying multi-path fading channel. The over all work of the thesis included in the following four chapters.
In chapter-1 we are going to cover some theoretical part which is useful to understand thesis work and in chapter-2 we will discuss the comparison between simple space time block code (Alamouti's code) and MRRC (Maximum Ratio Receiver Combining) which is receiver diversity and then in chapter-3 we will see the channel capacity & probability error performance for 2x2 Alamouti code over Rayleigh and Rice fading channel .Finally the conclusion and further work included in chapter-4.
30
Jin, Haizhen 1977. "Wireless channel estimation using Kalman Filtering for space-time block coded systems." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=80113.
Full textAbstract:
In the recent years, we have witnessed an increased interest in space-time coding, because of its effectiveness in overcoming the impairments due to the signal fading phenomenon. A large number of such codes require channel knowledge for decoding. Therefore, research in the area of channel estimation for space-time coding is very important.This thesis deals with the application of the Kalman Filter (KF) to channel estimation in space-time coded systems. For the purpose of deriving such an estimator, we model the multiple antenna channel as a first order Autoregressive process. As test cases, we employ the Alamouti's code as well as a rate ¾ orthogonal code for 3 transmit antennas. We consider a single antenna receiver, with different decoders: the joint optimal, the QR decision feedback and the symbol by symbol decoders.
Through computer simulations, the effect of channel estimation on the system's performance is investigated. With known channel (perfect estimation), the results show that the joint optimal decoder achieves the best performance, followed by the QR decision feedback and the symbol by symbol decoders, respectively. Also, simulation results show that the tracking ability of the KF in its predictive form deteriorates as the Doppler rate increases. When the channels are estimated by the KF, the simulations show that the three decoders yield essentially the same performance, because of estimation errors. The same behavior for the three decoders, with channel estimation, is observed for different modulation formats (BPSK and QPSK) and orthogonal codes. Finally, the numerical evaluation of the error probability for the joint optimal and symbol by symbol decoders, by the use of the residue theorem, shows similar results, backing up the computer simulations. Therefore, to enjoy the benefits of improved decoders, an efficient channel estimator should be also used.
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Nieh, Jo-Yen. "A systematic approach to design of space-time block coded MIMO systems." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2006. http://library.nps.navy.mil/uhtbin/hyperion/06Jun%5FNieh.pdf.
Full textAbstract:
Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, June 2006.Thesis Advisor(s): Murali Tummala. "June 2006." Includes bibliographical references (p.103-104). Also available in print.
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Winger, Lowell LeRoy. "Scalable subband/wavelet coding and space-frequency block matching for digital video." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0004/NQ41533.pdf.
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Wu, Nan. "Generalized space-time block coding for co-located and cooperative MIMO systems." Thesis, University of Southampton, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.494677.
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Qaja, Walid. "Distributed space time block coding and application in cooperative cognitive relay networks." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/18832.
Full textAbstract:
The design and analysis of various distributed space time block coding schemes for cooperative relay networks is considered in this thesis. Rayleigh frequency flat and selective fading channels are assumed to model the links in the networks, and interference suppression techniques together with an orthogonal frequency division multiplexing (OFDM) type transmission approach are employed to mitigate synchronization errors at the destination node induced by the different delays through the relay nodes. Closed-loop space time block coding is first considered in the context of decode-and-forward (regenerative) networks. In particular, quasi orthogonal and extended orthogonal coding techniques are employed for transmission from four relay nodes and parallel interference cancellation detection is exploited to mitigate synchronization errors. Availability of a direct link between the source and destination nodes is studied. Outer coding is then added to gain further improvement in end-to-end performance and amplify-and-forward (non regenerative) type networks together with distributed space time coding are considered to reduce relay node complexity. A novel detection scheme is then proposed for decode-and-forward and amplify-and-forward networks with closed-loop extended orthogonal coding and closed-loop quasi-orthogonal coding which reduce the computational complexity of the parallel interference cancellation. The near-optimum detector is presented for relay nodes with single or dual antennas. End-to-end bit error rate simulations confirm the potential of the approach and its ability to mitigate synchronization errors.
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Siddique, Nafiul Alam. "Spare Block Cache Architecture to Enable Low-Voltage Operation." PDXScholar, 2011. https://pdxscholar.library.pdx.edu/open_access_etds/216.
Full textAbstract:
Power consumption is a major concern for modern processors. Voltage scaling is one of the most effective mechanisms to reduce power consumption. However, voltage scaling is limited by large memory structures, such as caches, where many cells can fail at low voltage operation. As a result, voltage scaling is limited by a minimum voltage (Vccmin), below which the processor may not operate reliably. Researchers have proposed architectural mechanisms, error detection and correction techniques, and circuit solutions to allow the cache to operate reliably at low voltages. Architectural solutions reduce cache capacity at low voltages at the expense of logic complexity. Circuit solutions change the SRAM cell organization and have the disadvantage of reducing the cache capacity (for the same area) even when the system runs at a high voltage. Error detection and correction mechanisms use Error Correction Codes (ECC) codes to keep the cache operation reliable at low voltage, but have the disadvantage of increasing cache access time. In this thesis, we propose a novel architectural technique that uses spare cache blocks to back up a set-associative cache at low voltage. In our mechanism, we perform memory tests at low voltage to detect errors in all cache lines and tag them as faulty or fault-free. We have designed shifter and adder circuits for our architecture, and evaluated our design using the SimpleScalar simulator. We constructed a fault model for our design to find the cache set failure probability at low voltage. Our evaluation shows that, at 485mV, our designed cache operates with an equivalent bit failure probability to a conventional cache operating at 782mV. We have compared instructions per cycle (IPC), miss rates, and cache accesses of our design with a conventional cache operating at nominal voltage. We have also compared our cache performance with a cache using the previously proposed Bit-Fix mechanism. Our result show that our designed spare cache mechanism is 15% more area efficient compared to Bit-Fix. Our proposed approach provides a significant improvement in power and EPI (energy per instruction) over a conventional cache and Bit-Fix, at the expense of having lower performance at high voltage.
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Owojaiye, Gbenga Adetokunbo. "Design and performance analysis of distributed space time coding schemes for cooperative wireless networks." Thesis, University of Hertfordshire, 2012. http://hdl.handle.net/2299/8970.
Full textAbstract:
In this thesis, space-time block codes originally developed for multiple antenna systems are extended to cooperative multi-hop networks. The designs are applicable to any wireless network setting especially cellular, adhoc and sensor networks where space limitations preclude the use of multiple antennas. The thesis first investigates the design of distributed orthogonal and quasi-orthogonal space time block codes in cooperative networks with single and multiple antennas at the destination. Numerical and simulation results show that by employing multiple receive antennas the diversity performance of the network is further improved at the expense of slight modification of the detection scheme. The thesis then focuses on designing distributed space time block codes for cooperative networks in which the source node participates in cooperation. Based on this, a source-assisting strategy is proposed for distributed orthogonal and quasi-orthogonal space time block codes. Numerical and simulation results show that the source-assisting strategy exhibits improved diversity performance compared to the conventional distributed orthogonal and quasi-orthogonal designs.Motivated by the problem of channel state information acquisition in practical wireless network environments, the design of differential distributed space time block codes is investigated. Specifically, a co-efficient vector-based differential encoding and decoding scheme is proposed for cooperative networks. The thesis then explores the concatenation of differential strategies with several distributed space time block coding schemes namely; the Alamouti code, square-real orthogonal codes, complex-orthogonal codes, and quasiorthogonal codes, using cooperative networks with different number of relay nodes. In order to cater for high data rate transmission in non-coherent cooperative networks, differential distributed quasi-orthogonal space-time block codes which are capable of achieving full code-rate and full diversity are proposed. Simulation results demonstrate that the differential distributed quasi-orthogonal space-time block codes outperform existing distributed space time block coding schemes in terms of code rate and bit-error-rate performance. A multidifferential distributed quasi-orthogonal space-time block coding scheme is also proposed to exploit the additional diversity path provided by the source-destination link.A major challenge is how to construct full rate codes for non-coherent cooperative broadband networks with more than two relay nodes while exploiting the achievable spatial and frequency diversity. In this thesis, full rate quasi-orthogonal codes are designed for noncoherent cooperative broadband networks where channel state information is unavailable. From this, a generalized differential distributed quasi-orthogonal space-frequency coding scheme is proposed for cooperative broadband networks. The proposed scheme is able to achieve full rate and full spatial and frequency diversity in cooperative networks with any number of relays. Through pairwise error probability analysis we show that the diversity gain of the proposed scheme can be improved by appropriate code construction and sub-carrier allocation. Based on this, sufficient conditions are derived for the proposed code structure at the source node and relay nodes to achieve full spatial and frequency diversity. In order to exploit the additional diversity paths provided by the source-destination link, a novel multidifferential distributed quasi-orthogonal space-frequency coding scheme is proposed. The overall objective of the new scheme is to improve the quality of the detected signal at the destination with negligible increase in the computational complexity of the detector.Finally, a differential distributed quasi-orthogonal space-time-frequency coding scheme is proposed to cater for high data rate transmission and improve the performance of noncoherent cooperative broadband networks operating in highly mobile environments. The approach is to integrate the concept of distributed space-time-frequency coding with differential modulation, and employ rotated constellation quasi-orthogonal codes. From this, we design a scheme which is able to address the problem of performance degradation in highly selective fading environments while guaranteeing non-coherent signal recovery and full code rate in cooperative broadband networks. The coding scheme employed in this thesis relaxes the assumption of constant channel variation in the temporal and frequency dimensions over long symbol periods, thus performance degradation is reduced in frequencyselective and time-selective fading environments. Simulation results illustrate the performance of the proposed differential distributed quasi-orthogonal space-time-frequency coding scheme under different channel conditions.
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Grabner, Mitchell J. "A Cognitive MIMO OFDM Detector Design for Computationally Efficient Space-Time Decoding." Thesis, University of North Texas, 2019. https://digital.library.unt.edu/ark:/67531/metadc1538696/.
Full textAbstract:
In this dissertation a computationally efficient cognitive multiple-input multiple-output (MIMO) orthogonal frequency division duplexing (OFDM) detector is designed to decode perfect space-time coded signals which are able maximize the diversity and multiplexing properties of a rich fading MIMO channel. The adaptive nature of the cognitive detector allows a MIMO OFDM communication system to better meet to needs of future wireless communication networks which require both high reliability and low run-time complexity depending on the propagation environment. The cognitive detector in conjunction with perfect space-time coding is able to achieve up to a 2 dB bit-error rate (BER) improvement at low signal-to-noise ratio (SNR) while also achieving comparable runtime complexity in high SNR scenarios.
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Hassan, Mohamed Abdulla S. "Channel Estimation and Equalisation for Multicarrier Systems Employing Orthogonal Space-Time Block Code." Thesis, University of Newcastle Upon Tyne, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.519490.
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Bilokopytov, Ievgen. "Different Aspects Of Embedding Of Normed Spaces Of Analytic Functions." 2013. http://hdl.handle.net/1993/22089.
Full textAbstract:
In the present work we develop a unified way of looking at normed spaces of analytic functions (NSAF's) and their embedding into the Frechet space of analytic functions on a general domain, by requiring only that the embedding map is bounded. This is a succinct definition of NSAF and derive from it a list of interesting properties. For example Proposition 4.4 describes the behavior of point evaluations and Proposition 4.6 part (i) gives a general sufficient condition for a NSAF to be a Banach space, which as far as we know, are new results. Also, Proposition 4.5, parts (ii) and (iii) of Proposition 4.6 and Proposition 4.7 are results, which are slight generalizations of fairly standard results, which show up elsewhere in a more specific setting. Some of the facts about NSAF's are stated and proven in a more general context. In particular, a significant part of the material is dedicated to the normed space of continuous functions on a metric space. On the other hand, we provide the necessary background on differential geometry and complex analysis, which further determine the peculiarities in the context of spaces of analytic functions. At the end we illustrate our results on two specific examples of NSAF's, namely the Bergman and the Bloch Spaces over a general domain in Cd. We give a new proof of the reflexivity of the Bergman Space Ap(G, μ) for the case p>1 and of the Schur property of A1(G, μ). We also give new proofs for the equivalences of some of the definitions of the Bloch functions.
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Gao, Yang 1987. "Second order semiclassical theory of Bloch electrons in uniform electromagnetic fields." Thesis, 2012. http://hdl.handle.net/2152/27209.
Full textAbstract:
Berry curvature appears in the semi-classical theory of Bloch electrons already to first order in electromagnetic fields, resulting in profound modification of the carrier velocity and phase space density of states. Here we derive the equations of motion for the physical position and crystal momentum to second order in the fields. The dynamics still has a Hamiltonian structure, albeit with noncanonical Poisson brackets between the physical variables. We are able to expand both the carrier energy and the Poisson brackets to second order in the fields with terms of clear physical meaning. To demonstrate the utility of our theory, we obtain with much ease the electromagnetic response and orbital magnetic susceptibility.text
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Arman, Andrii. "Generalizations of Ahlfors lemma and boundary behavior of analytic functions." 2013. http://hdl.handle.net/1993/22095.
Full textAbstract:
In this thesis we will consider and investigate the properties of analytic
functions via their behavior near the boundary of the domain on which they are
defined. To do that we introduce the notion of the hyperbolic distortion and the hyperbolic
derivative. Classical results state that the hyperbolic derivative is
bounded from above by 1, and we will consider the case when it is
bounded from below by some positive constant.
Boundedness from below of the hyperbolic derivative implies
some nice properties of the function near the boundary. For instance Krauss & all in 2007 proved that, if the function is defined on a
domain bounded by analytic curve, then boundedness from below of the hyperbolic derivative implies that the
function has an analytic continuation across the boundary. We extend this result for the domains with slightly more general boundary, namely for smooth Jordan domains, and get that in this case the function and its derivative will have only continuous extensions to the boundary.
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Chou, Feng-Chih, and 周逢智. "Multilevel Space-Time Block Codes." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/30570619539849096824.
Full textAbstract:
碩士中原大學
電機工程研究所
95
The multipath wireless channel suffers severe attenuation. The effective techniques to mitigate multipath fading are time and frequency diversity. In most situations, the wireless channel is slow varying and frequency non-selective. Hence, antenna diversity is a practical technique for reducing the effect of multipath fading. Multiple input multiple output wireless channels can introduce spatial diversity and increased information capacity. These results have motivated a new area in error correcting codes. Space-time codeing(STC) schemes combine the channel code design and the use of multiple transmit antennas. With combining Multi-level coding technique and set partition of space-time block code set, We will propose a novel design of space-time block codes. Using Multi-level coding technique can get lower complexity and the better performance.
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Tsai, Jih-Lin, and 蔡季霖. "Performance Analysis of Space-Time Block Code and Space-Frequency Block Code over Wireless Fading Channel." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/61053280341956313881.
Full textAbstract:
碩士國立中興大學
通訊工程研究所
96
Space-time coding had improved the performance of wireless transmission. And this technology had been implemented into many wireless transmission standards. The reason that we choose this subject as our research field is because of the WiMAX technol-ogy. We take the STBC and OFDM system to simulate the performance results of both STBC only and STBC-OFDM system. The environment is using the European standard COST 207 as the channel to transmit datas. First, we will take the STBC schemes proposed by Alamouti and Tarokh to transmit through the flat-fading channel to see the system performance. Then implying the OFDM system to substitute the transmission in time domain to transmission in fre- quency domain. Later on, we will simulate the system transmission without OFDM and with OFDM over multipath fading channel, to see the improvement of the performance.
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CHANG, CHING-YEN, and 張淨嚴. "Multilevel Product-Coded Space-Time Block Codes." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/p34e56.
Full textAbstract:
碩士國立臺北科技大學
電機工程系
107
Nowadays, the communication system is required to have high performance, high stability and high reliability. In this thesis, we use space-time block codes in the wireless communication system. An expanded QPSK signal set is partitioned into five levels. Then, multilevel product codes are used as the component codes. Simulation results are performed to verify the error performance.
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Chen, Chi-Chung, and 陳起忠. "Space-time Block Coding for Sensor Networks." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/33724406791865358111.
Full textAbstract:
碩士國防管理學院
國防資訊研究所
92
Space-time block coding is one of the most significant technical breakthroughs in modern communications. The technology figures prominently on the list of recent technical advances with a chance of resolving the bottleneck of traffic capacity in future Internet-intensive wireless networks. This is because it can used channel capacity, bandwidth efficiently , noise mitigation under non increase of the complexity. This paper propose in coding or increase some of the time and space dimension to provide more coding gain under the STBC design in the sensor networks, to adapted in the different fading environment. we can used different matrix in order to received signals with low BER. It also can get balance between system complexity and coded gain.
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Chen, Juin-Da, and 陳俊達. "Concatenated Space-Time Block Coding With Block Coded Modulation For Noncoherent detection." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/65678090342831840575.
Full textAbstract:
碩士國立中央大學
通訊工程研究所
92
In this thesis, combing block coded modulation (BCM) and space-time block coding (STBC) with channel estimation is discussed. Taking advantage of the channel estimation using training symbols, noncoherent detection can be easily employed by STBC.The impact of STBC using training symbols concatanated with different block length of BCM is also investigate. Finally, we compare the system with unitary space-time modulation in the quasi-static flat fading channel
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Cheng, Hao-Wei, and 鄭皓瑋. "Twofold Concatenated High-Rate Space-Time Block Codes." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/s3sxw4.
Full textAbstract:
碩士國立臺北科技大學
電機工程系
106
The 5th generation mobile networks (5G) meets the requirements of high transmission rate and communication stability. The technology of 5G also provides higher spectral efficiency, wider coverage rate, and lower signal delay than those of 4G. In this thesis, we concentrate on the study of high-rate space-time block codes in the MIMO system. Multilevel coding scheme is adopted to improve the coding gain. Then, Reed-Solomon Codes are further concatenated to provide better error correcting capability. Computer simulation is performed to verify the error performance.
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Tarasak, Poramate. "Improving performance of differential space-time block codes." 2004. http://hdl.handle.net/1828/359.
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Chuang, Ya-Shen, and 莊雅善. "Differential Space-Time Block Codes under Rayleigh Fading." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/70099555865287744871.
Full textAbstract:
碩士國立成功大學
電機工程學系碩博士班
93
Space-time coding and modulation exploit the presence of multiple transmit antennas to improve the performance on multipath radio channels. Various space-time coding schemes have been proposed. However so far, most research on space-time coding has assumed that perfect estimates of current channel fading conditions are available at the receiver. However, in certain situations, we may want to forego channel estimation in order to reduce the complexity and cost of the handset, or perhaps fading conditions change so rapidly that channel estimation is difficult or requires too many training symbols. The thesis presents several practical, feasible, and simple transmission schemes for exploiting diversity given by multiple transmit antennas when neither the transmitter nor the receiver has access to channel state information. The new detection scheme can use equal energy constellations and encoding is simple. At the receiver, decoding is achieved with low decoding complexity. The transmission requires no channel state side information at the receiver. The schemes can be considered as the extension of differential detection schemes to two transmit antennas.
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Zhuang, Wen-Hao, and 莊雯皓. "Space-Time-Frequency Block Code for Wireless Communication." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/75297184421154922874.
Full textAbstract:
碩士中原大學
電子工程研究所
94
In the wireless communication system, space time block code (STBC) has been proved that it is a coding technology to combat fading channel effectively and it has a low complexity in decoding. OFDM system is well-known to be effective against multipath distortion. Space-Time-Frequency Block coded OFDM scheme combines OFDM and STBC so that the diversity in space, time and frequency is exploited to provide high quality of transmission for wireless communications over frequency selective fading channel and it has low complexity in decoding. Previous works assume that known channel state information is available for decoding processes, but it is not the case in practice. Therefore, we apply the pilot tone technique to estimate channel state in decoding. Finally, we will get our simulation results according to some important parameters.