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Abdelaziz, Amr Mohamed. "Information Theoretical Studies on MIMO Channel with Limited Channel State Information." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1500592938716914.
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Pastore, Adriano. "Communication rates for fading channels with imperfect channel-state information." Doctoral thesis, Universitat Politècnica de Catalunya, 2014. http://hdl.handle.net/10803/279247.
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The present thesis studies information rates for reliable transmission of information over fading channels in the realistic situation where the receiver has only imperfect channel-state knowledge. Of particular interest are analytical expressions of achievable transmission rates under imperfect and no CSI, that is, lower bounds on the mutual information and on the Shannon capacity. A well-known mutual information lower bound for Gaussian codebooks is obtained when conflating the additive (thermal) noise with the multiplicative noise due to the imperfections of the CSIR into a single effective noise term, and then assuming that this term is independent Gaussian. This so-called worst-case-noise approach allows to derive a strikingly simple and well-known lower bound on the mutual information of the channel.
A first part of this thesis proposes a simple way to improve this worst-case-noise bound by means of a rate-splitting approach: by expressing the Gaussian input as a sum of several independent Gaussian inputs, and by assuming that the receiver performs successive decoding of the corresponding information streams, we show how to derive a larger mutual information lower bound. On channels with a single transmit antenna, the optimal allocation of transmit power across the different inputs is found to be approached as the number of inputs (so-called layers) tends to infinity, and the power assigned to each layer tends to zero. This infinite-layering limit gives rise to a mutual information bound expressible as an integral. On channels with multiple transmit antennas, an analogous result is derived. However, since multiple transmit antennas open up more possibilities for spatial multiplexing, the rate-splitting approach gives rise to a whole family of infinite-layering bounds.
This family of bounds is closely studied for independent and identically zero-mean Gaussian distributed fading coefficients (so-called i.i.d. Rayleigh fading). Most notably, it is shown that for asymptotically perfect CSIR, any bound from the family is asymptotically tight at high signal-to-noise ratios (SNR). Specifically, this means that the difference between the mutual information and its lower bound tends to zero as the SNR tends to infinity, provided that the CSIR tends to be exact as the SNR tends to infinity.
A second part of this thesis proposes a framework for the optimization of a class of utility functions in black-Rayleigh fading multiple-antenna channels with transmit-side antenna correlation, and no CSI at the receiver. A fraction of each fading block is reserved for transmitting a sequence of training symbols, while the remaining time instants are used for transmission of data. The receiver estimates the channel matrix based on the noisy training observation and then decodes the data signal using this channel estimate. For utilities that are symmetric functions of the eigenvalues of the matrix-valued effective SNR (such as, e.g., the worst-case-noise bound), the problems consisting in optimizing the pilot sequence and the linear precoder are cast into convex (or quasi-convex) problems for concave (or quasi-concave) utility functions. We also study an important subproblem of the joint optimization, which consists in computing jointly Pareto-optimal pilot sequences and precoders. By wrapping these optimization procedures into a cyclic iteration, we obtain an algorithm which converges to a local joint optimum for any utility.Aquesta tesi estudia les taxes d'informació per la transmissió fiable d'informació en canals amb esvaïments sota la hipòtesi realista de que el receptor té un coneixement tan sols imperfecte de l'esvaïment aleatori. De particular interès són les expressions analítiques de les taxes de transmissió assolibles amb coneixement imperfecte i sense coneixement de l'estat del canal, és a dir, cotes inferiors de la informació mútua i de la capacitat de Shannon. Una cota inferior de la informació mútua per a codis gaussians ben coneguda s'obté combinant el soroll additiu (tèrmic) amb el terme de soroll multiplicatiu causat per les imperfeccions del coneixement de l'estat del canal en un únic soroll efectiu, i assumint que el soroll és gaussià i independent. Aquesta aproximació del pitjor soroll permet obtenir una expressió molt simple i ben coneguda de la informació mútua del canal. Una primera part d'aquesta tesi proposa un procediment senzill per a millorar aquesta cota associada al pitjor cas mitjançant una estratègia de repartiment de taxa: expressant l'entrada gaussiana del canal com a la suma de diverses entrades gaussianes independents i suposant que el receptor realitza una descodificació seqüencial dels fluxos d'informació, es mostra com obtenir una major cota inferior de la informació mútua del canal. En canals amb una única antena en transmissió, la distribució òptima de potència als diferents fluxos s'obté quan el seu nombre (capes) tendeix a infinit, i la potència associada a cada capa tendeix a zero. El límit associat a un nombre infinit de capes dóna lloc a una expressió integral de la cota de la informació mútua. En canals amb múltiples antenes s'obté un resultat similar. No obstant això, atès que la utilització de múltiples antenes proporciona més possibilitats de multiplexat espacial, el procediment dóna lloc a tota una família de cotes inferiors de la informació mútua associades a una combinació de capes infinita. S'estudia en detall aquesta família de cotes per al cas de coeficients d'esvaïments gaussians de mitjana zero, independents i idènticament distribuïts (conegut com esvaïment i.i.d. Rayleigh). S'obtenen diverses propietats de la família de cotes. És important destacar que per a coneixement asimptòtic perfecte del canal en recepció, qualsevol membre de la família de cotes és asimptòticament ajustat per alta relació senyal a soroll (SNR). En concret, la diferència entre la informació mútua i la seva cota inferior tendeix a zero quan la SNR tendeix a infinit sempre que el coneixement del canal tendeixi a ser exacte a mesura que la SNR tendeix a infinit. Una segona part d'aquesta tesi proposa un marc per a l'optimització d'una classe de funcions d'utilitat en canals amb múltiples antenes i esvaïments Rayleigh per blocs amb correlació en transmissió i sense informació sobre el canal a recepció. Una fracció temporal de cada bloc d'esvaïment es reserva per transmetre una seqüència de símbols d'entrenament mentre que la resta de mostres temporals s'utilitzen per transmetre informació. El receptor estima la matriu del canal partint de la seva observació sorollosa i descodifica la informació mitjançant la seva estimació del canal. Per a una classe de funcions d'utilitat que són funcions simètriques dels autovalors de la SNR matricial efectiva, els problemes consistents en optimitzar la seqüència pilot i el precodificador lineal són transformats en problemes convexos (o quasi-convexos) per a funcions d'utilitat còncaves (o quasi-còncaves). També s'estudia un subproblema important de l'optimització conjunta, que consisteix en el càlcul de les seqüències d'entrenament i dels precodificadors conjuntament Pareto-òptims. Integrant aquests procediments d'optimització en una iteració cíclica, s'obté un algoritme que convergeix a un òptim local conjunt per a qualsevol utilitat quasi-còncava
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Yang, Jingnong. "Channel State Information in Multiple Antenna Systems." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14120.
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In a MIMO system, a transmitter with perfect knowledge of the underlying channel state information (CSI) can achieve a higher channel capacity compared to transmission without CSI. When reciprocity of the wireless channel does not hold, the identification and utilization of partial CSI at the transmitter are important issues.
This thesis is focused on partial CSI acquisition and utilization techniques for MIMO
channels. We propose a feedback algorithm for tracking the dominant channel subspaces for MIMO systems in a continuously time-varying environment. We exploit the correlation between channel states of adjacent time instants and quantize the variation of channel states. Specifically, we model a subspace as one point in a Grassmann manifold, treat the variations in principal right singular subspaces of the channel matrices as a piecewise-geodesic process in the Grassmann manifold, and quantize the velocity matrix of the geodesic.
We design a complexity-constrained MIMO OFDM system where the transmitter has knowledge of channel correlations. The transmitter is constrained to perform at most one inverse Discrete Fourier Transform per OFDM symbol on the average. We show that in the MISO case, time domain beamforming can be used to do two-dimensional eigen-beamforming. For the MIMO case, we derive design criteria for the transmitter beamforming and receiver combining weighting vectors and show some suboptimal solutions.
The feedback channel may have uncertainties such as unexpected delay or error. We consider channel mean feedback with an unknown delay and propose a broadcast approach that is able to adapt to the quality of the feedback.
Having considered CSI feedback problems where the receiver tries to convey its attained
CSI to the transmitter, we turn to noncoherent coding design for fast fading channels, where the receiver does not have reliable CSI. We propose a data-dependent superimposed training scheme to improve the performance of training based codes. The transmitter is equipped with multiple training sequences and dynamically selects a training sequence for each data sequence to minimize channel estimation error. The set of training sequences are optimized to minimize pairwise error probability between codewords.
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Chen, Luan. "Enhancing indoor location fingerprinting using channel state information." Electronic Thesis or Diss., Paris, CNAM, 2020. http://www.theses.fr/2020CNAM1281.
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Grâce au développement rapide des communications sans fil, la localisation par empreinte digitale (LF) a favorisé des services géodépendants considérables dans le domaine de l’Internet des objets. Dans cette thèse, nous avons d’abord proposé le système EntLoc, qui adopte l’entropie de modélisation autorégressive (AR) de l’amplitude des informations d’état de canal (CSI) comme empreinte digitale de localisation. Il partage la simplicité structurelle de la force du signal reçu (RSS) tout en réservant les informations de canal statistique les plus spécifiques à l’emplacement. De plus, un système AngLoc amélioré est égalementconçu, dont l’empreinte digitale d’angle d’arrivée (AoA) supplémentaire peut être récupérée avec précision de la phase CSI grâce à un algorithme amélioré basé sur le sous-espace, qui sert à éliminer davantage les candidats au point de référence(RP) sujets aux erreurs. Dans la phase LF en ligne, en exploitant à la fois les informations d’amplitude et de phase CSI, un nouveau schéma de régression par noyau bivarié est proposé pour déduire précisément l’emplacement de la cible. Lesrésultats d’expériences approfondies en intérieur valident la performance de localisation supérieure de notre système proposé par rapport aux approches précédentesWith expeditious development of wireless communications, Location Fingerprinting (LF) has nurtured considerable indoor location based services in the field of Internet of Things. In this thesis, we first proposed EntLoc system, which adopts Autoregressive (AR) modeling entropy of the Channel State Information (CSI) amplitude as location fingerprint. It shares the structural simplicity of the Received Signal Strength (RSS) while reserving the most location-specific statistical channel information. Moreover, an upgraded AngLoc system is further designed, whose additional angle of arrival (AoA) fingerprint can be accurately retrieved from CSI phase through an enhanced subspace based algorithm, which serves to further eliminate the error-prone Reference Point (RP) candidates. In the LF online phase, by exploiting both CSI amplitude and phase information, a novel bivariate kernel regression scheme is proposed to precisely infer the target’s location. Results from extensive indoor experiments validate the superior localization performance of our proposed system over previous approaches
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Huang, Jinliang. "Adaptive MIMO Systems with Channel State Information at Transmitter." Doctoral thesis, KTH, Kommunikationssystem, CoS, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9777.
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This dissertation presents adaptation techniques that can achieve high spectral efficiency for single user multiple-input multiple-output (MIMO) systems. Two types of adaptation techniques, adaptive modulation and adaptive powe allocation, are employed to adapt the rate and the transmit power to fading channels. We start by investigating the adaptive modulation subject to a certain bit-error-ratio (BER) constraint, either instantaneous BER constraint or average BER constraint. The resulting average spectral efficiencies are obtained in closed-form expressions. It turns out that, by employing the average BER constraint, we can achieve the optimal average spectra efficiency at the cost of prohibitive computational complexity. On the other hand, instantaneous BER constraint leads to inferior performance with little computational complexity. In order to achieve comparable performance to the average BER constraint with limited complexity, a non-linear optimization method is proposed. To further enhance the average spectra efficiency, adaptive power allocation schemes are considered to adjust the transmit power across the temporal domain or the spatial domain, depending on the specific situation. Provided the closed-form expressions of the average spectral efficiency, the optimal MIMO coding scheme that offers the highest average spectral efficiency under the same circumstances can be identified. As we take into account the effect of imperfect channel estimation, the adaptation techniques are revised to tolerate interference introduced by the channel estimation errors. As a result, the degradation with respect to the average spectral efficiency is in proportion to signal-to-noise ratio (SNR). In order to facilitate fast development and verification of the adaptation schemes proposed for various MIMO systems, a reconfigurable Link Layer Simulator (LiLaS) which accommodates a variety of wireless/wireline applications is designed in the environment of MATLAB/OCTAVE. The idea of the simulator is originated from Software Defined Radio (SDR) and evolved to suit Cognitive Radio (CR) applications. For the convenience of modification and reconfiguration, LiLaS is functionally divided into generic blocks and all blocks are parameterized.QC 20100812
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Ma, Yongsen. "Improving Wifi Sensing And Networking With Channel State Information." W&M ScholarWorks, 2019. https://scholarworks.wm.edu/etd/1593091976.
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In recent years, WiFi has a very rapid growth due to its high throughput, high efficiency, and low costs. Multiple-Input Multiple-Output (MIMO) and Orthogonal Frequency-Division Multiplexing (OFDM) are two key technologies for providing high throughput and efficiency for WiFi systems. MIMO-OFDM provides Channel State Information (CSI) which represents the amplitude attenuation and phase shift of each transmit-receiver antenna pair of each carrier frequency. CSI helps WiFi achieve high throughput to meet the growing demands of wireless data traffic. CSI captures how wireless signals travel through the surrounding environment, so it can also be used for wireless sensing purposes. This dissertation presents how to improve WiFi sensing and networking with CSI. More specifically, this dissertation proposes deep learning models to improve the performance and capability of WiFi sensing and presents network protocols to reduce CSI feedback overhead for high efficiency WiFi networking. For WiFi sensing, there are many wireless sensing applications using CSI as the input in recent years. To get a better understanding of existing WiFi sensing technologies and future WiFi sensing trends, this dissertation presents a survey of signal processing techniques, algorithms, applications, performance results, challenges, and future trends of CSI-based WiFi sensing. CSI is widely used for gesture recognition and sign language recognition. Existing methods for WiFi-based sign language recognition have low accuracy and high costs when there are more than 200 sign gestures. The dissertation presents SignFi for sign language recognition using CSI and Convolutional Neural Networks (CNNs). SignFi provides high accuracy and low costs for run-time testing for 276 sign gestures in the lab and home environments. For WiFi networking, although CSI provides high throughput for WiFi networks, it also introduces high overhead. WiFi transmitters need CSI feedback for transmit beamforming and rate adaptation. The size of CSI packets is very large and it grows very fast with respect to the number of antennas and channel width. CSI feedback introduces high overhead which reduces the performance and efficiency of WiFi systems, especially mobile and hand-held WiFi devices. This dissertation presents RoFi to reduce CSI feedback overhead based on the mobility status of WiFi receivers. CSI feedback compression reduces overhead, but WiFi receivers still need to send CSI feedback to the WiFi transmitter. The dissertation presents EliMO for eliminating CSI feedback without sacrificing beamforming gains.
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Huang, Jin Liang. "Adaptive MIMO systems with channel state information at transmitter /." Stockholm : KTH Information and Communication Technology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9777.
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Mi, De. "Massive MIMO with imperfect channel state information and practical limitations." Thesis, University of Surrey, 2017. http://epubs.surrey.ac.uk/841236/.
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Multi-user (MU) massive multiple-input-multiple-output (MIMO) is one of the promising technologies for the 5th Generation of wireless communication systems. However, as an emerging technology, various technical challenges that hinder practical use of massive MIMO need to be addressed, e.g., imperfections on channel estimation and channel reciprocity. The overall objective of the proposed research is to investigate some of the key practical challenges of implementation of the massive MIMO system and propose effective solutions for those problems. First, in order to realise promised benefits of massive MIMO, there is a need for a highly accurate technique for provisioning of channel state information (CSI). However, the acquisition of CSI can be considerably influenced by imperfect channel estimation in practice. We therefore analyse the impact of channel estimation error on the performance of massive MIMO uplinks with the considerations of the channel correlation over space. We then propose a novel antenna selection scheme by exploiting the sparsity of the channel gain matrix at the received end, which significantly reduces implementation overhead and complexity compared to the well-adopted scheme, without degrading the system performance. Second, it is known that channel reciprocity in time-division duplexing (TDD) massive MIMO systems can be exploited to reduce the overhead required for the acquisition of CSI. However, perfect reciprocity is unrealistic in practical systems due to random radio-frequency (RF) circuit mismatches in uplink and downlink channels. We model and analyse the impact of the RF mismatches by taking into account the channel estimation error. We derive closed-form expressions of the output signal-to-interference-plus- noise ratio for typical linear precoding schemes, and further investigate the asymptotic performance of the considered precoding schemes to provide insights into the practical system designs, including guidelines for the selection of the effective precoding schemes. Third, our theoretical model for analysing the effect of channel reciprocity error on massive MIMO systems reveals that the imperfections in channel reciprocity might become a performance limiting factor. In order to compensate for these imperfections, we present and investigate two calibration schemes for TDD-based MU massive MIMO systems, namely, relative calibration and inverse calibration. In particular, the design of the proposed inverse calibration takes into account a compound effect of channel reciprocity error and channel estimation error. To compare two calibration schemes, we derive closed-form expressions for the ergodic sum-rate and the receive mean-square error for downlinks. We demonstrate that the proposed inverse calibration outperforms the relative calibration, thanks to its greater robustness to the compound effect of both errors.
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Jetlund, Ola. "Adaptive coded modulation : design and simulation with realistic channel state information." Doctoral thesis, Norwegian University of Science and Technology, Department of Electronics and Telecommunications, 2005. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-818.
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Spectrally efficient transmission schemes are becoming a more common requirement for digital communication systems. Especially in wireless communication since the bandwidth of available frequencies is a shared resource. In addition, wireless communication systems suffer from transmission media with varying conditions. Adaptive coded modulation (ACM) has been suggested as a bandwidth-efficient transmission technique in wireless fading environments. The use of ACM is motivated by its ability to improve spectral efficiency (SE) by adapting the transmission rates to the variations in channel signal-to-noise ratio. Any ACM scheme rely on being able to predict future states of the transmission medium. Under idealized conditions, such as the prediction being perfect, an ACM scheme can be configured to maximize the SE under the condition of the bit error rate (BER) being below a specified target BER. Here, computer simulations of an example system show that such systems in some cases fail to achieve the target BER, since the idealized conditions used in the design process do not hold in a realistic setup.
By limiting the number of transmission modes, introducing imperfect prediction, and other practical conditions such as delay in the communication system and probability of outage, a more practical ACM scheme can be considered. We show that it is still possible to optimize the performance of such schemes. A wireless communication channel with a Rayleigh fading envelope is assumed here since most results then can be presented in closed form expressions. For other distributions of the fading, results can be found numerically. By optimizing the performance of an idealized ACM scheme using capacity achieving channel codes, we have been able to upper bound the SE of practical ACM schemes. The results also provide us with a technique to control the average BER in the case of imperfect knowledge of future channel states. Simulation results for a modified ACM scheme that uses this technique is shown to have an average BER that is less than the target BER
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Huang, Wei. "Linear transceiver design in MIMO system with imperfect channel state information /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?ECE%202007%20HUANG.
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He, Wenmin. "Cooperative Channel State Information Dissemination Schemes in Wireless Ad-hoc Networks." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-theses/288.
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This thesis considers a novel problem of obtaining global channel state information (CSI) at every node in an ad-hoc wireless network. A class of protocols for dissemination and estimation are developed which attempt to minimize the staleness of the estimates throughout the network. This thesis also provides an optimal protocol for CSI dissemination in networks with complete graph topology and a near optimal protocol in networks having incomplete graph topology. In networks with complete graph topology, the protocol for CSI dissemination is shown to have a resemblance to finding Eulerian tours in complete graphs. For networks having incomplete graph topology, a lower bound on maximum staleness is given and a near optimal algorithm based on finding minimum connected dominating sets and proper scheduling is described in this thesis.
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Yao, Weijie. "Fine-Grained Hand Pose Estimation System based on Channel State Information." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1593211557742674.
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Sacristán, Murga Daniel Francisco. "Feedback of channel state information in multi-antenna systems based on quantization of channel Gram matrices." Doctoral thesis, Universitat Politècnica de Catalunya, 2012. http://hdl.handle.net/10803/124839.
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This dissertation deals with the proper design of efficient feedback strategies for Multiple-Input Multiple-Output (MIMO) communication systems. MIMO systems outperform single antenna systems in terms of achievable throughput and are more resilient to noise and interference, which are becoming the limiting factors in the current and future communications. Apart from the clear performance advantages, MIMO systems introduce an additional complexity factor, since they require knowledge of the propagation channel in order to be able to adapt the transmission to the propagation channel’s characteristics and achieve optimum performance. This channel knowledge, also known as Channel State Information (CSI), is estimated at the receiver and sent
to the transmitter through a limited feedback link.
In this dissertation, first, the minimum channel information necessary at the transmitter for the optimum precoding design is identified. This minimum information for the optimum design of the system corresponds to the channel Gram matrix. It is essential for the design of optimized systems to avoid the transmission of redundant feedback information. Following this idea, a quantization algorithm that exploits the differential geometry of the set of Gram matrices and the correlation in time present in most propagation channels is developed in order to greatly improve the feedback performance. This scheme is applied first to single-user MIMO communications, then to some particular multiuser scenarios, and finally it is extended to general multiuser
broadcast communications. To conclude, the feedback link sizing is studied. An analysis of the tradeoff between size of the forward link and size of the feedback link isformulated and the radio resource allocation problem, in terms of transmission energy, time, and bandwidth of the forward and feedback links is presented.En un mundo cada vez más interconectado, donde hay una clara tendencia hacia un mayor número de comunicaciones inalámbricas simultáneas (comunicaciones M2M: Machine to Machine, redes de sensores, etc.) y en el que las necesidades de capacidad de transmisión de los enlaces de comunicaciones aumentan de manera vertiginosa (audio, video, contenidos multimedia, alta definición, etc.) el problema de la interferencia se convierte en uno de los factores limitadores de los enlaces junto con los desvanecimientos del nivel de señal y las pérdidas de propagación. Por este motivo los sistemas que emplean múltiples antenas tanto en la transmisión como en la recepción (los llamados sistemas MIMO: Multiple-Input Multiple-Output) se presentan como una de las soluciones más interesantes para satisfacer los crecientes requisitos de capacidad y comportamiento relativo a interferencias. Los sistemas MIMO permiten obtener un mejor rendimiento en términos de tasa de transmisión de información y a su vez son más robustos frente a ruido e interferencias en el canal. Esto significa que pueden usarse para aumentar la capacidad de los enlaces de comunicaciones actuales o para reducir drásticamente el consumo energético manteniendo las mismas prestaciones. Por otro lado, además de estas claras ventajas, los sistemas MIMO introducen un punto de complejidad adicional puesto que para aprovechar al máximo las posibilidades de estos sistemas es necesario tener conocimiento de la información de estado del canal (CSI: Channel State Information) tanto en el transmisor como en el receptor. Esta CSI se obtiene mediante estimación de canal en el receptor y posteriormente se envía al transmisor a través de un canal de realimentación. Esta tesis trata sobre el diseño del canal de realimentación para la transmisión de CSI, que es un elemento fundamental de los sistemas de comunicaciones del presente y del futuro. Las técnicas de transmisión que consideran activamente el efecto de la interferencia y el ruido requieren adaptarse al canal y, para ello, la realimentación de CSI es necesaria. En esta tesis se identifica, en primer lugar, la mínima información sobre el estado del canal necesaria para implementar un diseño óptimo en el transmisor, con el fin de evitar transmitir información redundante y obtener así un sistema más eficiente. Esta información es la matriz de Gram del canal MIMO. Seguidamente, se desarrolla un algoritmo de cuantificación adaptado a la geometría diferencial del conjunto que contiene la información a cuantificar y que además aprovecha la correlación temporal existente en los canales de propagación inalámbricos. Este algoritmo se implementa y evalúa primero en comunicaciones MIMO punto a punto entre dos usuarios, después se implementa para algunos casos particulares con múltiples usuarios, y finalmente se amplía para el caso general de sistemas broadcast multi-usuario. Adicionalmente, esta tesis también estudia y optimiza el dimensionamiento del canal de realimentación en función de la cantidad de recursos radio disponibles, en términos de ancho de banda, tiempo y potencia de transmisión. Para ello presenta el problema de la distribución óptima de dichos recursos radio entre el enlace de transmisión de datos y el enlace de realimentación para transmisión de información sobre estado del canal como un problema de optimización.
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Pascual, Iserte Antonio. "Channel state Information and joint transmitter-receiver design in multi-antenna systems." Doctoral thesis, Universitat Politècnica de Catalunya, 2005. http://hdl.handle.net/10803/6890.
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Esta tesis aborda el problema del diseño de sistemas multiantena, donde el caso más general corresponde a un canal multi-input-multi-output (MIMO) con un transmisor y un receptor con más de una antena. La ventaja de estos sistemas es que ofrecen un rendimiento mucho mejor que los de una única antena, tanto en términos de calidad en la transmisión como en capacidad entendida como número de usuarios a los que se les puede prestar servicio simultáneamente.El objetivo es diseñar conjuntamente el transmisor y el receptor, lo que depende directamente de la calidad y la cantidad de información del canal de la que se dispone. En esta tesis se analiza el impacto de dicha información en el diseño.
Primero se ha estudiado un sistema MIMO de un único usuario usando la modulación orthogonal frequency division multiplexing (OFDM) y asumiendo un conocimiento perfecto del canal en ambos extremos. La arquitectura propuesta se basa en conformación conjunta por portadora, calculándose los conformadores óptimos y proponiéndose diversas estrategias de distribución de potencia entre las portadoras con una baja complejidad. Se han analizado también las relaciones asintóticas de estas distribuciones de potencia con otras soluciones clásicas con mayor coste.
El diseño anterior se ha extendido a sistemas MIMO multiusuario, donde todos los terminales en el escenario tienen más de una antena y la información del canal es perfecta. El objetivo es la minimización de la potencia total transmitida sujeto a restricciones de tasa de error máxima para cada enlace. El problema matemático obtenido es no convexo, por lo que estrategias clásicas basadas en algoritmos de gradiente o de optimización sucesiva pueden llevar a soluciones subóptimas. Como posible alternativa se ha propuesto la aplicación de simulated annealing, una potente herramienta heurística y estocástica que permite hallar el diseño global óptimo incluso cuando el problema es no convexo.
Los errores en la información de canal disponible pueden empeorar el rendimiento del sistema si éstos no se tienen en cuenta explícitamente durante el diseño. La degradación del sistema MIMO-OFDM de un único usuario se ha estudiado en esta situación, obteniendo una expresión analítica de una cota superior de la máxima degradación relativa de la relación señal a ruido más interferencia.
El rendimiento se puede mejorar usando técnicas robustas que tengan en cuenta la presencia de dichos errores. Existen dos aproximaciones clásicas: las Bayesianas y las maximin. En las soluciones Bayesianas el problema se formula estadísticamente, donde el objetivo es optimizar el valor medio de una función de rendimiento promediada sobre la estadística del canal real condicionado a su estimación. Por otro lado, los diseños maximin se caracterizan por optimizar el peor rendimiento para cualquier posible error en la información del canal dentro de una cierta región de incertidumbre que modela el conocimiento imperfecto del mismo.
Se han mostrado dos ejemplos de diseños Bayesianos. Primero, una distribución de potencia en un sistema OFDM de una única antena que minimiza el valor medio de una cota superior de la tasa de error, y después un diseño de un transmisor multiantena con un banco de filtros que maximiza la relación señal a ruido media (SNR) o minimiza el error cuadrático medio.
Finalmente, se ha obtenido el diseño robusto maximin de un sistema MIMO de un único usuario donde en el transmisor se combinan un código bloque ortogonal espacio-tiempo, una distribución de potencia y un banco de conformadores correspondientes a los modos espaciales del canal estimado. La distribución de potencia se ha diseñado acorde a una región de incertidumbre para el error en la estimación de canal de manera que se maximiza la peor SNR en dicha región. Posteriormente, este diseño se ha extendido al caso de modulaciones adaptativas y multiportadora, mostrando que el rendimiento es mejor que para los códigos bloque otrogonales y la conformación no robusta.
This Ph.D. dissertation addresses the design of multi-antenna systems, where the most general case corresponds to a transmitter and a receiver with more than one antenna, i.e., a multiple-input-multiple-output (MIMO) channel. The main advantage is that they can provide a much better performance than single-antenna systems, both in terms of transmission quality and system capacity, i.e., number of users that can be served simultaneously.
The objective is to carry out a joint transmitter-receiver design, which depends directly on the quantity and the quality of the available channel state information (CSI). In this dissertation, the impact of the CSI on the design has been analyzed.
First, a single-user MIMO communication system has been designed assuming the use of the orthogonal frequency division multiplexing (OFDM) modulation and according to a perfect CSI at both sides. The proposed architecture is based on a joint beamforming approach per carrier. The optimum beamvectors have been calculated and several power allocation strategies among the subcarriers have been derived. These power allocation solutions have been shown to be asymptotically related to other classical designs but with a much lower computational load.
The previous design has been extended to multi-user communications, where the multi-antenna terminals in the scenario have a perfect CSI. The objective is the minimization of the total transmit power subject to maximum bit error rate (BER) constraints for each link. The mathematical optimization problem is non-convex and, therefore, classical solutions based on gradient search or alternate & maximize schemes may find a local suboptimum design. As a possible solution, the application of the simulated annealing technique has been proposed, a powerful stochastic optimization tool able to find the global optimum design even when the problem is non-convex.
The errors in the available CSI may decrease importantly the system performance if they are not taken into account explicitly in the design. This degradation has been studied for the single-user MIMO-OFDM system. An analytical expression of an upper-bound on the maximum relative signal to noise plus interference ratio degradation has been found.
The system performance can be improved when exploiting an imperfect CSI by using adequate robustness strategies. Two robust approaches have been proposed: the Bayesian and the maximin solutions. The Bayesian approach is a full statistical solution that optimizes the mean value of the performance function averaged over the statistics of the actual channel and the errors in the CSI. On the other hand, the maximin approach provides a design that optimizes the worst system performance for any possible error in a predefined uncertainty region.
Two simple examples of Bayesian designs have been provided. First, a power allocation has been derived for an OFDM system with one transmit and one receive antenna minimizing the mean value of an upper-bound on the BER. Afterwards, a design of a multi-antenna transmitter with a bank of filters and a single-antenna receiver has been proposed, whose objective is either the maximization of the mean signal to noise ratio (SNR) or the minimization of the mean square error.
Finally, a robust maximin design has been proposed for a single-user MIMO system, in which the transmitter is based on the combination of an orthogonal space time block code (OSTBC), a power allocation stage, and a set of beamformers coupling the transmission through the estimated channel eigenmodes. The power allocation has been found according to a channel estimate and an uncertainty region for the error in this estimate, so that the worst SNR for any error in the uncertainty region is maximized. This design has been then extended and applied to adaptive modulation schemes and multicarrier modulations, showing that the performance is much better than that achieved by a pure OSTBC solution or a non-robust beamforming scheme.
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Zheng, Jun. "Design and analysis of MIMO systems with practical channel state information assumptions." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2006. http://wwwlib.umi.com/cr/ucsd/fullcit?p3215292.
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Thesis (Ph. D.)--University of California, San Diego, 2006.Title from first page of PDF file (viewed July 24, 2006). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 221-228).
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Zhao, Peiyue. "Radio Resource Management Algorithms for D2D Communications With Limited Channel State Information." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-177494.
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Network assisted Device-to-Device (D2D) communication has the potential benefits of increasing system capacity, energy efficiency and achievable peak rates while reducing the end-to-end latency. To realize these gains, recent works have proposed power control (PC) and resource allocation (RA) schemes that show near optimal performance in terms of spectral or energy efficiency. Unfortunately, these schemes assume perfect and instantaneous access to either large scale or small scale channel state information (CSI) at some central entity. Obviously, this assumption does not hold in practical implementations and we therefore investigate the performance of D2D communications with limited CSI. First, we analyze existing power control (PC), mode selection (MS) and resource allocation (RA) approaches in terms of the required input parameters, focusing on large scale fading. Then we build up a model in a system simulator to capture the impact of unavailability or CSI errors on the performance of PC, MS and RA algorithms. Through simulations, we find that with proper algorithms, the system gains continuously from having more CSI knowledge. Specially, with additional CSI, the newly implemented Binary Power Control and Matching Allocation increases the throughput impressively with low complexity and proper fairness between D2D layer and cellular layer. Furthermore, we investigate the impact of errors in the channel gains. Simulation results demonstrate that a certain user may suffer or benefit from the errors, however, the system performance is insensitive to the small scale errors. Numerical results also show errors of asymmetric range cause relatively more notable impact than the symmetric errors.
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Zhang, Xi. "Transceiver Design for Multiple Antenna Communication Systems with Imperfect Channel State Information." Doctoral thesis, Stockholm : Elektrotekniska system, Electrical Engineering, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4679.
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Zhao, Bo [Verfasser]. "Limited Feedback of Channel State Information in Wireless Communication Systems / Bo Zhao." Düren : Shaker, 2021. http://d-nb.info/1240853483/34.
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Muralidhar, Aditya. "Multiple-Input Multiple Output System on a Spinning Vehicle with Unknown Channel State Information." International Foundation for Telemetering, 2012. http://hdl.handle.net/10150/581828.
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This paper presents the investigations into the performance of a multiple-input multiple-output (MIMO) system with its transmitters on a spinning vehicle and no available channel state information (CSI) at the transmitter or the receiver. The linear least squares approach is used to estimate the channel and the estimation error is measured. Spinning gives rise to a periodic component in the channel which can be estimated based on the spin rate relative to the data rate of the system. It is also determined that spinning causes the bit error rate of the system to degrade by a few dB.
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Huang, Jinliang. "Adaptation in multiple input multiple output systems with channel state information at transmitter." Licentiate thesis, Stockholm : Institutionen för elektronik, dator- och programvarusystem, Kungliga tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4443.
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Liu, Moyu. "HUMAN BIOMETRIC SIGNALS MONITORING BASED ON WIFI CHANNEL STATE INFORMATION USING DEEP LEARNING." Thesis, The University of Sydney, 2022. https://hdl.handle.net/2123/27463.
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As civilisation has progressed, the public’s attention to health monitoring has increased. Health monitoring equipment has become ubiquitous. Most of the health monitoring instruments mainly detect human biometric signals, such as heart rate and respiratory rate. These indicators can reflect human primary health conditions, both mental and physical and classify sleep stages. The classification of sleep stages, as well as the monitoring of breathing rate and heart rate, can aid in the evaluation of health and the diagnosis of disorders by doctors. Some health problems, such as depression, insomnia, obesity and other diseases, may benefit from it.
A large number of methods have been proposed to detect breathing and heartbeat, for example, by using wearable devices and non-contact devices. Traditional methods (e.g. polysomnography) are mainly used in clinical treatment, which requires patients to stay in hospital and wear a lot of sensors to monitor sleep. Most current monitoring solutions for heart rate and breathing rate use wearable devices attached to the human body. This thesis presents a WiFi-based method combined with convolutional neural networks (CNNs) to predict heart rate and respiratory rate.
We first proposed a single input and two outputs of the CNNs to simultaneously estimate both heart rate and breathing rate. This network utilises the inner relationship between heart rate and respiration rate of the channel state information (CSI). Therefore, heart rate and respiration rate should be jointly estimated because they are related to each other. We leverage the amplitude and phase information of CSI collected by a pair of WiFi devices as an input for the neural network. We then train the network to predict the heart rate and breathing rate without the traditional complex feature-selection algorithms. For algorithms using sub-carrier selection strategy, the network may not be able to achieve its optimal performance, as it uses CSI partially. Therefore, we utilise the CNN model to improve accuracy and reduce computational complexity. Our WiFi-based approach solves the problems of privacy issues and the environmental factors. Using the generalisation ability of the CNN, one can easily adapt to different environments and avoid the unreliability of the analysis method due to environmental changes. For this system, in the real environment, the estimation error of breathing rate is 0.2 beats per minute, and heart rate is 0.6042 beats per minute. The overall accuracy of this system can achieve 99.109% and 98.581%, respectively.
In addition, we design and compare two neural networks based on deep learning for categorising four types of sleep stages, including wake, rapid eye movement (REM) sleep, non-rapid eye movement (NREM) light sleep and NREM deep sleep. The first neural network uses the data calculated by the cardiopulmonary coupling (CPC) algorithm as an input. For the second network, the input data is the CSI matrix without further processing. By comparing two neural-network classification approaches, we find that the WiFi sleep-stage neural network performs better because the CSI is influenced not just by large-scale movement (body movement) but also by tiny-scale movement (chest movement). Human body-movement data, respiration data and heart rate during sleep were already included in the CSI data. This also explains why we do not use the motion-sensing module in our system. We directly use the CSI matrix without further processing as input for classification. The overall accuracy of the method based on WiFi can achieve 95.925%. The accuracy for using the CPC algorithm is 90.15%.
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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.
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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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Payaró, Llisterri Miquel. "IMPACT OF CHANNEL STATE INFORMATION ON THE ANALYSIS AND DESIGN OF MULTIANTENNA COMMUNICATION SYSTEMS." Doctoral thesis, Universitat Politècnica de Catalunya, 2007. http://hdl.handle.net/10803/6900.
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Al llarg d'aquesta última dècada, s'ha produit un creixement constant en la demanda d'elevades taxes de transmissió de dades que han de suportar les aplicacions sobre comunicacions sense fils. Entre les diferents solucions ideades per la comunitat recercaire per tal de fer front a aquesta nova demanda, la utilització de múltiples antenes s'erigeix com una de les millors candidates degut al fet que proporciona simultàniament una millora en les taxes de transmissió i en la fiabilitat en la recepció de les dades. L'ús d'antenes múltiples en un dels extrems de la comunicació data de la dècada dels seixanta, nogensmenys ha estat en aquests últims anys quan s'ha pogut provar, tant en els camps teòric com pràctic, tot el potencial que possibilita la presència de múltiples antenes en ambdós extrems de la comunicació.El disseny adequat de sistemes de comunicació amb múltiples antenes per satisfer aquesta demanda no només depèn de la funció de mèrit (o de la mètrica de rendiment) escollida, sinó que també es veu afectat per la quantitat i la qualitat de la informació de l'estat del canal que es troba disponible als extrems de la comunicació. Aquesta tesi tracta sobre l'anàlisi i el disseny d'arquitectures per sistemes de comunicació amb múltiples antenes i amb diferents nivells de quantitat i qualitat de la informació de l'estat del canal. La secció d'anàlisi es centra en l'estudi de la capacitat i les taxes de transmissió assolibles per aquests tipus de sistemes de comunicació i la part de disseny queda més encarada a la síntesi de sistemes de comunicació pràctics amb l'objectiu de maximitzar el rendiment d'acord amb la mètrica de rendiment escollida.
Primerament, l'atenció es centra en sistemes de comunicació amb múltiples antenes per a un únic usuari amb informació perfecte de l'estat del canal, que suposa una idealització dels sistemes pràctics que s'empren en la realitat. En aquest context, es revisen resultats de capacitat que són ben coneguts, i es caracteritza, a més, un transmissor lineal dissenyat per tal de maximitzar la fiabilitat de l'enllaç sense fils amb múltiples antenes. Addicionalment, s'apunten una sèrie d'analogies entre el disseny del transmissor lineal òptim i la teoria de construcció de constel.lacions de símbols.
En segon lloc, es roman en un escenari de comunicacions amb un únic usuari i es considera el cas on la informació sobre l'estat del canal és incompleta. En aquest cas, es presenta un anàlisi detallat sobre la capacitat a través de les formulacions ergòdica i composta (compound), les quals prenen significat depenent del model utilitzat per caracteritzar el canal. Mentres que en canals ràpidament variants la capacitat ergòdica és la mesura clau de les taxes de transmissió assolibles per qualsevol sistema de comunicació, en canals fixos o de variació lenta, és la capacitat composta, la que mesura la mínima taxa de transmissió assolible de forma sostinguda durant la transmissió del missatge.
Seguidament, es considera el cas on la informació disponible sobre l'estat del canal és imperfecta. Precisament, es discorre sobre un sistema de comunicació pràctic anomentat Precodificador Espacial de Tomlinson i Harashima i s'estudien les seves potencialitats en termes de taxes de transmissió assolibles. Gràcies a l'arquitectura versàtil del Precodificador Espacial de Tomlinson i Harashima l'esmentat estudi es duu a terme tant per escenaris amb un únic usuari com per escenaris amb múltiples usuaris. Per aquests dos casos, es presenta així doncs un disseny que és robust a les incerteses de la informació de l'estat del canal i que té per objectiu minimitzar les pèrdues de taxa de transmissió d'informació.
Finalment, restant en un escenari amb múltiples usuaris amb coneixement imperfecte de l'estat del canal, es presenta una arquitectura de transmissió que és robusta a les incerteses de la informació sobre l'estat del canal disponible tant en el transmisor com en el receptor. La variable per al disseny robust és la distribució de potència entre els símbols d'informació destinats a cada usuari, i el criteri d'optimització és minimitzar la potència total transmesa, tot garantint una determinada qualitat de servei per cada usuari i per qualsevol possible realització del canal que sigui compatible amb la informació disponible sobre l'estat del canal.
During the last decade, there has been a steady increase in the demand of high data rates that are to be supported by wireless communication applications. Among the different solutions that have been proposed by the research community to cope with this new demand, the utilization of multiple antennas arises as one of the best candidates due to the fact that it provides both an increase in reliability and also in information transmission rate. Although the use of multiple antennas at the receiver side dates back from the sixties, the full potential of multiple antennas at both communication ends has been both theoretically and practically recognized in the last few years.
The design of proper multi-antenna communication systems to satisfy the high data rates demand depends not only on the chosen figure of merit or performance metric, but also on the quantity and the quality of the channel state information that is available at the communication ends. In this dissertation we deal with the analysis and design of different architectures for multiple-antenna communication systems for various degrees of quality and quantity of channel state information. The analysis section is devoted to the study of capacity and achievable rates and the part that deals with design is aimed at the synthesis of practical communication systems that maximize a certain performance measure.
Firstly, we focus our attention on multiple antenna single-user communication systems with perfect channel state information, which is an idealization of actual practical systems. In this context, we review well known capacity results and deal with the practical characterization of a linear transmitter that is designed to maximize the reliability of the wireless multi-antenna link. Some analogies between the optimal linear transmitter design and the theory of constellation construction are also pointed out.
Secondly, we stay in a single-user scenario and we move onto the case where the channel state information is incomplete. In this case, a detailed capacity analysis is presented dealing with the ergodic and compound capacity formulations, which arise depending on the model utilized to characterize the channel. While in rapidly varying channels the ergodic capacity is a key measure of the rates that can be achieved by any communication system, in slow varying or fixed channels the compound capacity measures the minimum transmission rate that can be sustained during the transmission of the message.
Next, we shift to the case where the available channel state information is imperfect. Precisely, we deal with a practical communication system called spatial Tomlinson-Harashima precoder and study its achievable rate capabilities. Due to the versatile architecture of the spatial Tomlinson-Harashima precoder we are able to perform the study for the single and multi-user scenarios. For both cases, a design is presented which is robust to the uncertainties of the channel state information and which is aimed at maximizing the transmission rate.
Finally, staying in the multi-user scenario with imperfect channel state information, we present a transmission architecture that is robust to the uncertainties of the side information that is available at both the transmitter and the receiver. The robustness criterion is to minimize the transmitted power while guaranteeing a certain quality of service per user for every possible realization of the channel that is compatible with the available channel state information.
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Buzuverov, Alexey [Verfasser], Anja [Akademischer Betreuer] Klein, and Bruno [Akademischer Betreuer] Clerckx. "Multi-User Networks with Outdated Channel State Information / Alexey Buzuverov ; Anja Klein, Bruno Clerckx." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2019. http://d-nb.info/1183911513/34.
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Engelmann, Sabrina. "Beamforming and Protection Strategies in Gaussian MISO Wiretap Systems with Partial Channel State Information." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-172869.
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Within this thesis, we investigate the possibilities of physical layer secrecy for two special system models. In detail, we study beamforming and protection strategies in the Multiple-Input Single-Output (MISO) Gaussian Wiretap Channel (WTC) and the Gaussian two-hop relay WTC with multiple antennas at transmitter and receiver. In both system models, we examine the influence of partial Channel State Information (CSI) on the link to the eavesdropper and compare the achievable secrecy rates with the case of full CSI. We show for the MISO WTC that in the fast fading scenario the Beamforming Vector (BV) can be optimized such that the ergodic secrecy rate is maximized with regard to the degree of channel knowledge. Further we show that the ergodic secrecy rate can be significantly increased by usage of Artificial Noise (AN), if applied in a smart way. This means that the degree of channel knowledge on the link to the eavesdropper influences the portion of power that is spent for AN at the transmitter as well as the direction, in which the AN signal is sent. In addition, we apply the same beamforming and protection strategies to the slow fading scenario and find that these techniques also reduce the secrecy outage probability. For the two-hop relay WTC, we introduce Information Leakage Neutralization (IN) as a new protection strategy. If applied to a system model, where the transmitter has full CSI, the instantaneous secrecy rate performs almost as well as the instantaneous capacity of the peaceful system without an eavesdropper. The IN protected scheme outperforms the AN protected approach and performs much better than any beamforming scheme without additional protection mechanism. Another positive aspect of the IN protected scheme in the case of full CSI is that conventional channel codes can be applied instead of wiretap codes. For the case of partial CSI, where the transmitter has only an outdated estimate on the channel between relay and the eavesdropper, we show that the IN protected scheme can also be applied. Here, it strongly depends on the channel realizations and the delay of the estimate, whether the IN or the AN protection scheme should be appliedIn dieser Arbeit wird das Leistungsvermögen der Sicherheit auf der physikalischen Schicht anhand von zwei speziellen Systemmodellen untersucht. Im Detail werden Beamforming- und Absicherungsstrategien im gaußschen Multiple-Input Single-Output (MISO) Wiretap Channel (WTC) und dem gaußschen Two-hop Relay WTC mit mehreren Antennen am Sender und Empfänger studiert. In beiden Systemmodellen wird der Einfluss von partieller Kanalkenntnis zum Abhörer betrachtet und die so erreichbaren Sicherheitsraten mit denen verglichen, die bei voller Kanalkenntnis erreichbar sind. Für den MISO WTC kann gezeigt werden, dass für Kanäle mit schnellem Schwund der Beamforming-Vektor in Hinblick auf die ergodische Sicherheitsrate unter Berücksichtigung des Grades der Kanalkenntnis optimiert werden kann. Zudem kann durch die intelligente Verwendung von künstlichem Rauschen (Artificial Noise, AN) die ergodische Sicherheitsrate signifikant erhöht werden. Hierbei nimmt der Grad der Kanalkenntnis direkt Einfluss auf die Aufteilung der Leistung zwischen Daten- und AN-Signal am Sender sowie auch auf die Richtung, in der das AN-Signal gesendet wird. Zudem kann gezeigt werden, dass dieselben Beamforming- und Absicherungsstrategien ebenfalls die Sicherheitsausfallwahrscheinlichkeit für Kanäle mit langsamem Schwund minimieren. Im gaußschen Two-hop Relay WTC wird Information Leakage Neutralization (IN) als neuartige Absicherungsstrategie eingeführt. Diese Absicherungsstrategie erreicht nahezu dieselben instantanen Raten wie ein friedvolles System ohne Abhörer, wenn es bei voller Kanalkenntnis am Sender eingesetzt wird. Weiterhin sind durch die IN-Absicherungsstrategie höhere Raten erreichbar als durch den Einsatz von AN. Zusätzlich kann im Fall von voller Kanalkenntnis auf den Einsatz von Wiretap-Codes verzichtet werden. Auch im Fall partieller Kanalkenntnis, wo der Sender nur eine veraltete Schätzung des Kanals zwischen Relay und Abhörer besitzt, kann gezeigt werden, dass die IN-Absicherungsstrategie angewendet werden kann. Hierbei hängt es jedoch stark von den Kanalrealisierungen und dem Alter der Kanalschätzung ab, ob die IN- oder die AN-Absicherungsstrategie bessere Ergebnisse bringt und daher angewandt werden sollte
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Ding, Minhua. "Multiple-input multiple-output wireless system designs with imperfect channel knowledge." Thesis, Kingston, Ont. : [s.n.], 2008. http://hdl.handle.net/1974/1335.
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Tran, Tuyen X. "Achievable Rate and Capacity of Amplify-and-Forward Multi-Relay Networks with Channel State Information." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1376743091.
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Zhao, Bo [Verfasser], and Andreas [Akademischer Betreuer] Czylwik. "Limited Feedback of Channel State Information in Wireless Communication Systems / Bo Zhao ; Betreuer: Andreas Czylwik." Duisburg, 2021. http://d-nb.info/1239048777/34.
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Cooper, Reginald Larenzo. "Sensing and Learning Channel State Information in a Dynamic Wireless Environment with Cognitive Radios and Networks." Research Showcase @ CMU, 2012. http://repository.cmu.edu/dissertations/211.
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Sensing and learning channel state information CSI in a dynamic wireless environment DWE has not been a focus of the cognitive radio and network research. The focus has been on obtaining spectral resource information about the spectrum availability i.e. spectrum sensing for dynamic spectrum access or how to adapt radios and networks in a way that improves the effectiveness of the radio networks, for example rate adaptation. In most of these cases it is assume that the CSI is already known or it is obtained from a method that directly measures the spectrum of interest through channel estimation, fading prediction or forecasting, blind estimation, and many others. In DWEs the wireless channel may change at high rates (i.e. fast fading), and methods that directly measure the channel will not provide accurate and timely CSI needed for a cognitive radio or network.
In this thesis a counterintuitive method is presented, indirect channel measurements. Indirect channel measuring is a technique used to determine the transfer function of a desired part of the RF spectrum, which spans several coherence bandwidths, without directly sending a signal through the spectrum of interest, but indirectly through adjacent spectrum. The indirect measuring of the channel has the ability to improve the timeliness and accuracy associated with the obtainment of the CSI in DWEs when using cognitive radios and networks.
This thesis will explain the indirect channel measurements ICM research and how it can be used in cognitive radio networks for SISO rate adaptation in dynamic wireless environments. Included will be an analytical and empirical analysis of the performance of the ICM technique and other comparable and contrasting techniques. This thesis will also show which technique is best suited for a particular set of parameters for a given dynamic wireless environment. A contextual explanation will also be given to provide a visual picture of a cognitive radio network that will be able to implement the ICM technique using rate adaptation, and its ability to be implemented in hardware.
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Yu, Zehao. "Towards location-awareness in next generation wireless networks : a new approach based on channel state information." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127117.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, May, 2020Cataloged from the official PDF of thesis.
Includes bibliographical references (pages 69-78).
Location-awareness in next generation wireless networks will be a key enabler for numerous emerging applications. Recently, a novel approach to localization based on soft information (SI), exploiting all positional information inherent in measurement and contextual data, has been proposed. This thesis further develops SI-based localization by establishing a new approach relying on channel state information (CSI) measurements. In particular, we design an efficient joint message-passing (MP) localization algorithm, which consists of two layers: the transformation layer and the estimation layer. The transformation layer extracts SI of the channel impulse response (CIR) from CSI measurements using a sparsity promoting prior model, which addresses the difficulty of unknown number of multipath in estimating the CIR. The estimation layer infers node positions based on the SI of the CIR using a delay-origin uncertainty model, which describes the conditional distribution of the delays in the CIR given node positions. Simulation results using QuaDriGa channel simulator show that our localization algorithm achieves decimeter-level localization accuracy for both Wi-Fi and mmWave signals, which outperforms conventional algorithms.
by Zehao Yu.
S.M.
S.M. Massachusetts Institute of Technology, Department of Aeronautics and Astronautics
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Rey, Micolau Francesc. "Feedback-Channel and adaptative mimo coded-modulations." Doctoral thesis, Universitat Politècnica de Catalunya, 2006. http://hdl.handle.net/10803/6899.
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En els sistemes de comunicacions on el transmissor disposa de certa informació sobre l'estat del canal (CSI), es possible dissenyar esquemes lineals de precodificació que assignin la potència de manera òptima induint guanys considerables, sigui en termes de capacitat, sigui en termes de la fiabilitat de l'enllaç de comunicacions. A la pràctica, aquest coneixement del canal mai és perfecte i, per tant, el senyal transmès es veurà degradat degut al desajust entre la informació que el transmissor disposi del canal i el seu estat real.En aquest context, aquesta tesi estudia dos problemes diferents però alhora estretament relacionats: el disseny d'un esquema pràctic de seguiment del canal en transmissió per canals variants en temps, i el disseny d'esquemes lineals de precodificació que siguin robustos a la incertesa del canal.
La primera part de la tesi proposa el disseny d'un esquema de seguiment de canal que, mitjançant un enllaç de retorn de baixa capacitat, proporcioni al transmissor una informació acurada sobre el seu estat. Històricament, aquest tipus d'esquemes han rebut fortes crítiques degut a la gran quantitat d'informació que és necessari transmetre des del receptor cap el transmissor. Aquesta tesi, doncs, posa especial èmfasi en el disseny d'aquest canal de retorn. La solució que es proposa, basada en el filtre de Kalman, utilitza un esquema que recorda al transmissor DPCM. Les variacions del canal són tractades mitjançant dos predictors lineals idèntics situats en el transmissor i en el receptor, i un canal de retorn que assisteix el transmissor amb l'error de predicció. L'interès d'aquest esquema diferencial és que permet seguir les variacions del canal amb només dos o quatre bits per coeficient complex, fins i tot en canals ràpidament variants.
La resta de la tesi cobreix el segon objectiu, l'estudi de diferents esquemes d'assignació de potències quan el coneixement del canal en transmissió no és perfecte. El problema es planteja per a un sistema MIMO OFDM com a formulació més general, incloent els casos d'una sola antena, de l'esquema beamforming i del canal multiplicatiu com a casos particulars.
Primerament s'ha plantejat l'optimització dels criteris de mínim error quadràtic mig (MMSE) i mínima BER sense codificar. La innovació en el treball presentat a la tesi, respecte a altres treballs que segueixen els mateixos criteris de disseny, ha estat la formulació Bayesiana del problema per al disseny dels algoritmes robustos.
La tesi continua amb el plantejament d'estratègies robustes d'assignació de potència destinades a minimitzar la BER codificada. Per aquesta tasca s'han utilitzat criteris de teoria de la informació. Possiblement una de les principals contribucions d'aquesta tesi ha estat el plantejament del cut-off rate com a paràmetre de disseny. Aquest criteri s'introdueix com alternativa a la capacitat de canal o a la informació mutual per al disseny del transmissor quan s'inclou codificació de canal.
La ultima part de la tesi proposa un interleaver adaptatiu de baixa complexitat que, utilitzant el coneixement del canal disponible en el transmissor, assigna estratègicament els bits no només per combatre les ràfegues d'errors, sinó també per lluitar contra els esvaïments que puguin presentar les diferents portadores del canal per a una realització concreta. El disseny d'aquest interleaver, anomenat "interleaver RCPC" està basat en els codis Rate-Compatible Punctured Convolutional Codes. Com s'il·lustra a partir del resultats numèrics, l'ús d'aquest interleaver millora les prestacions dels algoritmes quan es comparen amb les que s'obtindrien si s'utilitzes un interleaver de bloc o un interleaver pseudo-aleatori.
When the transmitter of a communication system disposes of some Channel State Information (CSI), it is possible to design linear precoders that optimally allocate the power inducing high gains either in terms of capacity or in terms of reliable communications. In practical scenarios, this channel knowledge is not perfect and thus the transmitted signal suffers from the mismatch between the CSI at the transmitter and the real channel.
In that context, this thesis deals with two different, but related, topics: the design of a feasible transmitter channel tracker for time varying channels, and the design of optimal linear precoders robust to imperfect channel estimates.
The first part of the thesis proposes the design of a channel tracker that provides an accurate CSI at the transmitter by means of a low capacity feedback link. Historically, those schemes have been criticized because of the large amount of information to be transmitted from the receiver to the transmitter. This thesis focuses, thus, the attention in an accurate design of the return link. The proposed solution is based on the Kalman filter and follows a scheme that reminds the well known DPCM transmitter. The channel variability is processed by two identical linear predictors located at the transmitter and at the receiver, and a feedback link that assists the transmitter with the prediction error. The interest of this differential scheme is that allows to track the channel variations with only two or four bits per complex channel coefficient even in fast time-varying channels.
The rest of the thesis covers the second topic, studying different robust power allocation algorithms when the CSI is not perfectly known at the transmitter. For the sake of generality, the problem is formulated for the general MIMO OFDM case, encompassing the single antenna transmission, the beamforming schemes and the frequency-flat fading channels as particular cases.
First, the minimum MSE and the minimum uncoded BER parameters are chosen to be optimized, evaluating the performance of the algorithms in terms of uncoded BER. The basic novelty with respect to previous works that considers the same strategies of design is the proposal of a Bayesian approach for the design of the robust algorithms.
Next the study is extended by proposing robust power allocation strategies focused on the minimization of the coded BER. For this purpose, information-theoretic criteria are used. Probably, one of the main contributions in the thesis is the proposal of the cut-off rate as a parameter of design whose maximization is directly related to the coded BER. This criterion is introduced as an alternative to the channel capacity and the mutual information for the design of optimal transceivers in the presence of any channel coding stage.
The last part of the thesis proposes a low complexity adaptive interleaver that, making use of the CSI available at the transmitter, reallocates the bits not only to combat the bursty channel errors but also to combat the specific distribution of the faded subcarriers as a function of the channel response. The design of this interleaver, named as "RCPC interleaver", is based on the Rate-Compatible Punctured Convolutional Codes. As shown by numerical results, the use of this interleaver improves the performance of the algorithms when they are compared with the classical block interleavers and pseudo-random interleavers.
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Duong, Duc Van. "Analysis and optimization of pilot-aided adaptive coded modulation under noisy channel state information and antenna diversity." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Information Technology, Mathematics and Electrical Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-987.
Full textAbstract:
The thesis is largely built on a collection of published and submitted papers where the main focus is to analyze and optimize single-carrier adaptive coded modulation systems with and without antenna diversity. Multidimensional trellis codes are used as component codes. The majority of the analysis is done with both estimation and prediction errors being incorporated. Both channel estimation and prediction are performed using a pilot-symbol-assisted modulation scheme. Thus, known pilot symbols (overhead information) must be transmitted; which consumes power and also degrades system spectral efficiency. Both power consumption and pilot insertion frequency are optimized such that they are kept at necessary values to maximize system throughput without sacrificing the error rate performance. The results show that efficient and reliable system performance can be achieved over a wide range of the considered average channel quality. Going from a single-input single-output system to both spatially uncorrelated and correlated single-input multiple-ouput (SIMO) systems, and further to an uncorrelated multiple-input multiple-output (MIMO) diversity system, is the evolution of the thesis. In the SIMO case, maximum ratio combining is used to combine the incoming signals, whereas the signals are space-time combined in the MIMO diversity system. The multiple-input single-output system comes out as a special case of a MIMO system. Besides the spatially uncorrelated antenna array, the effect of spatial correlation is also considered in the SIMO case. In this case, only prediction error is considered and channel estimation is assumed to be perfect. At first, the impact of spatial correlation in a predicted system originally designed to operate on uncorrelated channels is quanitifed. Then, a maximum a posteriori (MAP)-optimal “space-time predictor” is derived to take spatial correlation into account. As expected, the results show that the throughput is still lower than the uncorrelated system, but the degradation is decreased when the MAP-optimal space-time predictor is used. Thus, by exploiting the correlation properly, the degradation can be reduced. By numerical examples, we demonstrate the potential effect of limiting the predictor complexity, of fixing the pilot spacing, as well as of assuming perfect estimation. The two first simplifications imply lower system complexity and feedback rate, whereas the last assumption is usually made to ease the mathematical analysis. The numerical examples indicate that all the simplifications can be done without serious impact on the predicted system performance.
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Chiang, Hsiao-Lan [Verfasser], Gerhard [Gutachter] Fettweis, and Volker [Gutachter] Kühn. "Millimeter-Wave Hybrid Beamforming Based on Implicit Channel State Information / Hsiao-Lan Chiang ; Gutachter: Gerhard Fettweis, Volker Kühn." Dresden : Technische Universität Dresden, 2019. http://d-nb.info/1230578064/34.
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Xie, Yongzhe. "On adaptive transmission, signal detection and channel estimation for multiple antenna systems." Diss., Texas A&M University, 2004. http://hdl.handle.net/1969.1/1058.
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This research concerns analysis of system capacity, development of adaptive transmission schemes with known channel state information at the transmitter (CSIT) and design of new signal detection and channel estimation schemes with low complexity in some multiple antenna systems. We first analyze the sum-rate capacity of the downlink of a cellular system with multiple transmit antennas and multiple receive antennas assuming perfect CSIT. We evaluate the ergodic sum-rate capacity and show how the sum-rate capacity increases as the number of users and the number of receive antennas increases. We develop upper and lower bounds on the sum-rate capacity and study various adaptive MIMO schemes to achieve, or approach, the sum-rate capacity. Next, we study the minimum outage probability transmission schemes in a multiple-input-single-output (MISO) flat fading channel assuming partial CSIT. Considering two special cases: the mean feedback and the covariance feedback, we derive the optimum spatial transmission directions and show that the associated optimum power allocation scheme, which minimizes the outage probability, is closely related to the target rate and the accuracy of the CSIT. Since CSIT is obtained at the cost of feedback bandwidth, we also consider optimal allocation of bandwidth between the data channel and the feedback channel in order to maximize the average throughput of the data channel in MISO, flat fading, frequency division duplex (FDD) systems. We show that beamforming based on feedback CSI can achieve an average rate larger than the capacity without CSIT under a wide range of mobility conditions. We next study a SAGE-aided List-BLAST detection scheme for MIMO systems which can achieve performance close to that of the maximum-likelihood detector with low complexity. Finally, we apply the EM and SAGE algorithms in channel estimation for OFDM systems with multiple transmit antennas and compare them with a recently proposed least-squares based estimation algorithm. The EM and SAGE algorithms partition the problem of estimating a multi-input channel into independent channel estimation for each transmit-receive antenna pair, therefore avoiding the matrix inversion encountered in the joint least-squares estimation.
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Giese, Jochen. "Constellation Design under Channel Uncertainty." Doctoral thesis, KTH, School of Electrical Engineering (EES), 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-454.
Full textAbstract:
The topic of this thesis is signaling design for data transmission through wireless channels between a transmitter and a receiver that can both be equipped with one or more antennas. In particular, the focus is on channels where the propagation coefficients between each transmitter--receiver antenna pair are only partially known or completetly unknown to the receiver and unknown to the transmitter.
A standard signal design approach for this scenario is based on separate training for the acquisition of channel knowledge at the receiver and subsequent error-control coding for data detection over channels that are known or at least approximately known at the receiver. If the number of parameters to estimate in the acquisition phase is high as, e.g., in a frequency-selective multiple-input multiple-output channel, the required amount of training symbols can be substantial. It is therefore of interest to study signaling schemes that minimize the overhead of training or avoid a training sequence altogether.
Several approaches for the design of such schemes are considered in this thesis. Two different design methods are investigated based on a signal representation in the time domain. In the first approach, the symbol alphabet is preselected, the design problem is formulated as an integer optimization problem and solutions are found using simulated annealing. The second design method is targeted towards general complex-valued signaling and applies a constrained gradient-search algorithm. Both approaches result in signaling schemes with excellent detection performance, albeit at the cost of significant complexity requirements.
A third approach is based on a signal representation in the frequency domain. A low-complexity signaling scheme performing differential space--frequency modulation and detection is described, analyzed in detail and evaluated by simulation examples.
The mentioned design approaches assumed that the receiver has no knowledge about the value of the channel coefficients. However, we also investigate a scenario where the receiver has access to an estimate of the channel coefficients with known error statistics. In the case of a frequency-flat fading channel, a design criterion allowing for a smooth transition between the corresponding criteria for known and unknown channel is derived and used to design signaling schemes matched to the quality of the channel estimate. In particular, a constellation design is proposed that offers a high level of flexibility to accomodate various levels of channel knowledge at the receiver.
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Juntti, J. (Juhani). "Performance analysis of suboptimal soft decision DS/BPSK receivers in pulsed noise and CW jamming utilizing jammer state information." Doctoral thesis, University of Oulu, 2004. http://urn.fi/urn:isbn:9514273869.
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Abstract
The problem of receiving direct sequence (DS) spread spectrum, binary phase shift keyed (BPSK) information in pulsed noise and continuous wave (CW) jamming is studied in additive white noise. An automatic gain control is not modelled. The general system theory of receiver analysis is first presented and previous literature is reviewed. The study treats the problem of decision making after matched filter or integrate and dump demodulation. The decision methods have a great effect on system performance with pulsed jamming. The following receivers are compared: hard, soft, quantized soft, signal level based erasure, and chip combiner receivers. The analysis is done using a channel parameter D, and bit error upper bound. Simulations were done in original papers using a convolutionally coded DS/BPSK system. The simulations confirm that analytical results are valid. Final conclusions are based on analytical results.
The analysis is done using a Chernoff upper bound and a union bound. The analysis is presented with pulsed noise and CW jamming. The same kinds of methods can also be used to analyse other jamming signals. The receivers are compared under pulsed noise and CW jamming along with white gaussian noise. The results show that noise jamming is more harmful than CW jamming and that a jammer should use a high pulse duty factor. If the jammer cannot optimise a pulse duty factor, a good robust choice is to use continuous time jamming.
The best performance was achieved by the use of the chip combiner receiver. Just slightly worse was the quantized soft and signal level based erasure receivers. The hard decision receiver was clearly worse. The soft decision receiver without jammer state information was shown to be the most vulnerable to pulsed jamming. The chip combiner receiver is 3 dB worse than an optimum receiver (the soft decision receiver with perfect channel state information).
If a simple implementation is required, the hard decision receiver should be used. If moderate complex implementation is allowed, the quantized soft decision receiver should be used. The signal level based erasure receiver does not give any remarkable improvement, so that it is not worth using, because it is more complex to implement. If receiver complexity is not limiting factor, the chip combiner receiver should be used.
Uncoded DS/BPSK systems are vulnerable to jamming and a channel coding is an essential part of antijam communication system. Detecting the jamming and erasing jammed symbols in a channel decoder can remove the effect of pulsed jamming. The realization of erasure receivers is rather easy using current integrated circuit technology.
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Chari, Shreya Krishnama. "Link blockage modelling for channel state prediction in high-frequencies using deep learning." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-287458.
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With the accessibility to generous spectrum and development of high gain antenna arrays, wireless communication in higher frequency bands providing multi-gigabit short range wireless access has become a reality. The directional antennas have proven to reduce losses due to interfering signals but are still exposed to blockage events. These events impede the overall user connectivity and throughput. A mobile blocker such as a moving vehicle amplifies the blockage effect. Modelling the blockage effects helps in understanding these events in depth and in maintaining the user connectivity. This thesis proposes the use of a four state channel model to describe blockage events in high-frequency communication. Two deep learning architectures are then designed and evaluated for two possible tasks, the prediction of the signal strength and the classification of the channel state. The evaluations based on simulated traces show high accuracy, and suggest that the proposed models have the potential to be extended for deployment in real systems.Med tillgängligheten till generöst spektrum och utveckling av antennmatriser med hög förstärkning har trådlös kommunikation i högre frekvensband som ger multi-gigabit kortdistans trådlös åtkomst blivit verklighet. Riktningsantennerna har visat sig minska förluster på grund av störande signaler men är fortfarande utsatta för blockeringshändelser. Dessa händelser hindrar den övergripande användaranslutningen och genomströmningen. En mobil blockerare såsom ett fordon i rörelse förstärker blockeringseffekten. Modellering av blockeringseffekter hjälper till att förstå dessa händelser på djupet och bibehålla användaranslutningen. Denna avhandling föreslår användning av en fyrstatskanalmodell för att beskriva blockeringshändelser i högfrekvent kommunikation. Två djupinlärningsarkitekturer designas och utvärderas för två möjliga uppgifter, förutsägelsen av signalstyrkan och klassificeringen av kanalstatusen. Utvärderingarna baserade på simulerade spår visar hög noggrannhet och föreslår att de föreslagna modellerna har potential att utökas för distribution i verkliga system.
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Ngo, Minh Hanh. "Cross-layer adaptive transmission scheduling in wireless networks." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/432.
Full textAbstract:
A new promising approach for wireless network optimization is from a cross-layer perspective. This thesis focuses on exploiting channel state information (CSI) from the physical layer for optimal transmission scheduling at the medium access control (MAC) layer. The first part of the thesis considers exploiting CSI via a distributed channel-aware MAC protocol. The MAC protocol is analysed using a centralized design approach and a non-cooperative game theoretic approach. Structural results are obtained and provably convergent stochastic approximation algorithms that can estimate the optimal transmission policies are proposed. Especially, in the game theoretic MAC formulation, it is proved that the best response transmission policies are threshold in the channel state and there exists a Nash equilibrium at which every user deploys a threshold transmission policy. This threshold result leads to a particularly efficient stochastic-approximation-based adaptive learning algorithm and a simple distributed implementation of the MAC protocol. Simulations show that the channel-aware MAC protocols result in system throughputs that increase with the number of users.
The thesis also considers opportunistic transmission scheduling from the perspective of a single user using Markov Decision Process (MDP) approaches. Both channel state in-formation and channel memory are exploited for opportunistic transmission. First, a finite horizon MDP transmission scheduling problem is considered. The finite horizon formulation is suitable for short-term delay constraints. It is proved for the finite horizon opportunistic transmission scheduling problem that the optimal transmission policy is threshold in the buffer occupancy state and the transmission time. This two-dimensional threshold structure substantially reduces the computational complexity required to compute and implement the optimal policy. Second, the opportunistic transmission scheduling problem is formulated as an infinite horizon average cost MDP with a constraint on the average waiting cost. An advantage of the infinite horizon formulation is that the optimal policy is stationary. Using the Lagrange dynamic programming theory and the super modularity method, it is proved that the stationary optimal transmission scheduling policy is a randomized mixture of two policies that are threshold in the buffer occupancy state. A stochastic approximation algorithm and a Q-learning based algorithm that can adaptively estimate the optimal transmission scheduling policies are then proposed.
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Bothenna, Hasitha Imantha. "Approximation of Information Rates in Non-Coherent MISO wireless channels with finite input signals." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1516369758012866.
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German, Gus Ryan. "A Ray-Based Investigation of the Statistical Characteristics and Efficient Representation of Multi-Antenna Communication Channels." BYU ScholarsArchive, 2004. https://scholarsarchive.byu.edu/etd/145.
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Multi-antenna communication systems are attracting research interest as a means to increase the information capacity, reliability, and spectral efficiency of wireless information transfer. Ray-tracing methods predict the behavior of wireless channels using a model of the propagation environment and are a low-cost alternative to direct measurements. We use ray tracing simulations to validate the statistical time and angle of arrival characteristics of an indoor multipath channel and compare model parameter estimates with estimates derived from channel sounding measurements. Ray tracing predicts the time and angle clustering of multipaths observed in the measurements and provides model parameter estimates which are closely correlated with measured estimates. The ray tracing parameters relating to power characteristics show more deviation from measurements than the time and angle related parameters. Our results also indicate that the description of reflective scatterers in the propagation environment is more important to the quality of the predicted statistical behavior than the description of bulk materials. We use a ray synthesis model to investigate means of efficiently representing the channel for feedback information to the transmitter as a means to increase the information capacity. Several methods of selecting the ray-model feedback information are demonstrated with results from simulated and measured channels. These results indicate that an ESPRIT algorithm coupled with ad hoc transmit/receive pairing can yield better than 90% of the ideal waterfilling capacity when adequate training-based channel estimates are available. Additionally, we investigate a covariance feedback method for providing channel feedback for increased capacity. Both the ray-based and covariance-based feedback methods yield their highest capacity improvements when the signal to noise ratio is low. This results because of the larger benefit of focusing transmit power into the most advantageous eigenmodes of the channel when fewer eigenmodes have power allocated to them by the waterfilling capacity solution. In higher signal to noise ratio cases, more eigenmodes of the channel receive power when waterfilling, and the capacity improvement from feedback information decreases relative to a uniform power allocation. In general, ray model feedback methods are preferable because the covariance feedback quickly requires higher computational effort as the array sizes increase and typically results in lower capacity for a given amount of feedback information.
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Zhang, Lili. "Interference Channel with State Information." Thesis, 2012. http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11427.
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In this dissertation, we study the state-dependent two-user interference channel, where the state information is non-causally known at both transmitters but unknown to either of the receivers. We first propose two coding schemes for the discrete memoryless case: simultaneous encoding for the sub-messages in the first one and super-position encoding in the second one, both with rate splitting and Gel'fand-Pinsker coding. The corresponding achievable rate regions are established. Moreover, for the Gaussian case, we focus on the simultaneous encoding scheme and propose an active interference cancellation mechanism, which is a generalized dirty-paper coding technique, to partially eliminate the state effect at the receivers. The corresponding achievable rate region is then derived. We also propose several heuristic schemes for some special cases: the strong interference case, the mixed interference case, and the weak interference case. For the strong and mixed interference case, numerical results are provided to show that active interference cancellation significantly enlarges the achievable rate region. For the weak interference case, flexible power splitting instead of active interference cancellation improves the performance significantly.
Moreover, we focus on the simplest symmetric case, where both direct link gains are the same with each other, and both interfering link gains are the same with each other. We apply the above coding scheme with different dirty paper coding parameters. When the state is additive and symmetric at both receivers, we study both strong and weak interference scenarios and characterize the theoretical gap between the achievable symmetric rate and the upper bound, which is shown to be less than 1/4 bit for the strong interference case and less than 3/4 bit for the weak interference case. Then we provide numerical evaluations of the achievable rates against the upper bound, which validates the theoretical analysis for both strong and weak interference scenarios. Finally, we define the generalized degrees of freedom for the symmetric Gaussian case, and compare the lower bounds against the upper bounds for both strong and weak interference cases. We also show that our achievable schemes can obtain the exact optimal values of the generalized degrees of freedom, i.e., the lower bounds meet the upper bounds for both strong and weak interference cases.
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Aubry, Augusto. "MIMO Multiple Access Channels with Partial Channel State Information." Tesi di dottorato, 2010. http://www.fedoa.unina.it/8135/1/Aubry_Augusto_23.pdf.
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The increasing demand for wireless communication systems has been the starting point for many
research activities and discussions about the best way to make a cleaver usage of the available spectrum
and the available power, in order to satisfy the requirements of the users. In these systems there are
several issues which have to be taken in to account for the evaluation of their Shannon-Capacity, i.e. the
maximum amount of information that can be reliably delivered: the mobility of the users, the presence
of time varying obstacles, power and bandwidth limitations. A lot of efforts have been conducted for
the Information-Theoretic characterization of wireless communication systems with the assumption of
perfect channel state information (CSI) at the receiver side.
In this Thesis an Information-Theoretic analysis of a Gaussian multiple-input multiple-output multiple
access channel (MIMO MAC), with partial channel knowledge at the receiver, is provided. In particular
an inner and an outer bound for the rate region of a MIMO MAC with partial CSI when the inputs
are Gaussian, are derived. Moreover, the behavior of the gaps between the upper and lower bounds of
the mutual information terms, which define the achievable rate region, is analyzed as function of: i) the
number of the users, ii) the number of the receiving antennas, and iii) the signal to noise ratio. The
problem of finding the precodings that attempt to maximize the lower bound to the sum-rate is also
considered. Furthermore, the low-SNR and high-SNR regime for a MIMO MAC with partial CSI at the
receiver are described. For the former, the attention is focused on the minimum energy per bit and on
the multiaccess slope region, while for the latter on the high-SNR slope.
The aforementioned framework turns out to be useful to describe the performance limits of two relevant
scenarios of MAC systems in which only a partial CSI can be used at the receiver: Cooperative MIMO
Networks and Training Based Systems.
The performed analysis shows that the rates achievable over a MIMO MAC channel with partial CSI at
the receiver side can be interpreted in terms of a coherent MIMO MAC channel with an increased noise
level.
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Perera, Ranjana. "On capacity of fading channels with no channel state information." Phd thesis, 2006. http://hdl.handle.net/1885/10354.
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The rapid development of communication systems with mobile receivers at higher data rates has lead to the importance of studies on information transfer over highly time varying channels. Under such circumstances, the channel variations become fast and the receiver is unable to track the channel during the predefined block length. Here existing results for the channel capacity and the optimal input distribution, under the assumption of knowledge of the channel state information (CSI) are no longer valid. In reality the capacity is significantly reduced in the absence of the CSI at both the transmitter and the receiver. Furthermore, finding the optimal input distribution with no CSI is considered an important problem in information theory.
This thesis first considers the important case of Gaussian signalling in both single input single output (SISO) and multiple input multiple output (MIMO) fading channels with no CSI. For such a signalling scheme we develop closed form solutions for the mutual information at any signal to noise ratio (SNR) for any number of antennas. Furthermore, we use these new expressions to identify the bounds at high SNR and particularly the use of optimal antennas at both ends of a communication system.
To overcome the existing di±culties in calculating the optimal input and the capacity, a novel approach is shown to identify the key characteristics of the optimal input in non-coherent Rayleigh fading MIMO channels. Unlike most work in the literature, this leads to a capacity upper bound which can be obtained without extensive simulations for any antenna number at any SNR. Furthermore, the capacity is shown numerically, deriving the optimal input distribution for any antenna number using a scaler channel model. In particular, some key properties of the optimal input distribution at low SNR is investigated studying the loss in information transfer due to unknown CSI in MIMO wireless communication systems.
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Huang, Kaibin. "MIMO networking with imperfect channel state information." Thesis, 2008. http://hdl.handle.net/2152/4007.
Full textAbstract:
The shortage of radio spectrum has become the bottleneck of achieving broadband wire-less access. Overcoming this bottleneck in next-generation wireless networks hinges on successful implementation of multiple-input-multiple-output (MIMO) technologies, which use antenna arrays rather than additional bandwidth for multiplying data rates. The most efficient MIMO techniques require channel state information (CSI). In practice, such information is usually inaccurate due to overhead constraints on CSI acquisition as well as mobility and delay. CSI inaccuracy can potentially reduce the performance gains provided by MIMO. This dissertation investigates the impact of CSI inaccuracy on the performance of increasing complex MIMO networks, starting with a point-to-point link, continuing to a multiuser MIMO system, and ending at a mobile ad hoc network. Furthermore, this dissertation contributes algorithms for efficient CSI acquisition, and its integration with beamforming and scheduling in multiuser MIMO, and with interference cancelation in ad hoc networks. First, this dissertation presents a design of a finite-rate CSI feedback link for point-to-point beamforming over a temporally correlated channel. We address various important design issues omitted in prior work, including the feedback delay, protocol, bit rate, and compression in time. System parameters such as the feedback bit rate are derived as functions of channel coherence time based on Markov chain theory. In particular, the capacity gain due to beamforming is proved to decrease with feedback delay at least at an exponential rate, which depends on channel coherence time. This work provides an efficient way of implementing beamforming in practice for increasing transmission range and throughput. Second, several algorithms for multiuser MIMO systems are proposed, including CSI quantization, joint beamforming and scheduling, and distributed feedback scheduling. These algorithms enable spatial multiple access and multiuser diversity in a cellular system under the practical constraint of finite-rate multiuser CSI feedback. Moreover, this dissertation shows analytically that the throughput of the MIMO uplink and downlink using the proposed algorithms scales optimally as the number of users increases. Finally, the transmission capacity of a MIMO ad hoc network is analyzed for the case where spatial interference cancelation is applied at receivers. Most important, this dissertation shows that this MIMO technique contributes significant network capacity gains even if the required CSI is inaccurate. In addition, opportunistic CSI estimation is shown to provide a tradeoff between channel training overhead and CSI accuracy.text
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CHEN, LI-YONG, and 陳力永. "Compressing Channel State Feedback Information Using Autoencoder." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/996z7t.
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碩士國立臺北科技大學
電子工程系
107
Channel State Information (CSI) refers to the property of the wireless communication link. CSI can be used to know the effect of the overall fading procedure of the signal from the transmitter to the receiver. In the traditional wireless communication, CSI obtained by the channel estimation is used to restore the distortion of the signal amplitude and phase caused by the channel fading. Nowadays, the application of CSI is becoming more and more diverse, such as: communication scenario identification, user behavior identification, adaptive transmission, channel selection, etc. However, if CSI is directly transmitted back to the base station, a large amount of transmission resources will be consumed. Therefore, how to efficiently transmit CSI to the base station is an important issue. This paper will use deep learning autoencoder to effectively compress and restore the CSI. To verify the effects of autoencoder, this paper use real measurement data from the Software Defined Radio (SDR) device and simulation data from MATLAB, and we will use four different channel state feedback information autoencoder. The result shows that the channel state feedback information can be ffectively compressed and restored by autoencoder. The NMSE of the LOS scenario is as low as 0.0027. The result also shows that the same autoencoder can be used by multiple points. Besides, compared to codebook,the signal strength autoencoder’s NMSE is smaller ,and it can save 30% of the transmission data.
46
Khoshnevis, Behrouz. "Multiple-antenna Communications with Limited Channel State Information." Thesis, 2011. http://hdl.handle.net/1807/30036.
Full textAbstract:
Due to its significant advantage in spectral efficiency, multiple-antenna communication technology will undoubtedly be a major component in future wireless system implementations. However, the full exploitation of this technology also requires perfect feedback of channel state information (CSI) to the transmitter-- something that is not practically feasible. This motivates the study of limited feedback systems, where CSI feedback is rate limited. This thesis focuses on the optimal design of limited feedback systems for three types of communication channels: the relay channel, the single-user point-to-point channel, and the multiuser broadcast channel. For the relay channel, we prove the efficiency of the Grassmannian codebooks as the source and relay beamforming codebooks, and propose a method for CSI exchange between the relay and the destination when global CSI is not available at destination. For the single-user point-to-point channel, we study the joint power control and beamforming problem and address the channel magnitude and direction quantization codebook design problem. It is shown that uniform quantization of the channel magnitude (in dB scale) is asymptotically optimal regardless of the channel distribution. The analysis further derives the optimal split of feedback bandwidth between the magnitude and direction quantization codebooks. For the multiuser broadcast channel, we first prove the sufficiency of a product magnitude-direction quantization codebook for managing the multiuser interference. We then derive the optimal split of feedback bandwidth across the users and their magnitude and direction codebooks. The optimization results reveal an inherent structural difference between the single-user and multiuser quantization codebooks: a multiuser codebook should have a finer direction quantization resolution as compared to a single-user codebook. It is further shown that the users expecting higher rates and requiring more reliable communication should provide a finer quantization of their CSI. Finally, we determine the minimum required total feedback rate based on users' quality-of-service constraints and derive the scaling of the system performance with the total feedback rate.
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Yazdan, Panah Ali. "Relay-aided communications with partial channel state information." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-08-4264.
Full textAbstract:
Modern wireless communication systems strive to enable communications at high data rates, over wide geographical areas, and to multiple users. Unfortunately, this can be a daunting task in practice, as natural laws governing the wireless medium may hinder point-to-point transmissions. Communications over large distances (path loss), and physical obstructions in line-of-sight signals (shadowing) are prime examples of such impediments. One promising solution is to deploy intermediary terminals to help reestablish such broken point-to-point communication links. Such terminals are called relay nodes, and the corresponding systems are referred to as being relay-aided.
As in the case of point-to-point communication, design of efficient transmission and reception techniques in relay-aided systems depends on the availability of propagational channel state information. In practice, such information is only accurate to a certain degree which is governed by overhead constraints, feedback delay, and channel fluctuations due to mobility. Understanding the impacts of such partial channel state information, and devising transmission and reception methods based on such understandings, is the main topic of this dissertation.
The transmission protocol classifies relays as either one-way, where the relay receives signals from one terminal, or two-way, where the relay receives signals from more than one terminal. Designs and solutions for both one- and two-way relaying systems are presented in this dissertation. Emphasis is placed on two-way relaying systems given their superior efficiency in utilizing channel resources.
For one-way relaying this dissertation presents power loading strategies for multiuser-multicast systems derived based on the availability of full or partial channel state information at the terminals.
In the case of two-way relaying, both single and multi-user systems are analyzed. For single-user two-way relaying, this dissertation presents optimal methods of acquiring partial channel state information via pilot-aided channel estimation methods. This includes an analysis of the effects of channel estimation upon the system sum-rate. Also, the design of channel equalizers exhibiting robustness to partial channel state information is proposed. For multi-user two-way relaying, this dissertation presents several precoding strategies at the relay terminal(s) to combat the effects co-channel interference in light of the existence of self-interference inherent to two-way relaying operations.text
48
Buzuverov, Alexey. "Multi-User Networks with Outdated Channel State Information." Phd thesis, 2019. http://tuprints.ulb.tu-darmstadt.de/8571/1/2019_01_21_Buzuverov_Alexey.pdf.
Full textAbstract:
The spread of ubiquitous high-speed mobile communication has changed our daily life and society significantly. Using multiple antennas at transmitters and receivers, known as multiple-input and multiple-output (MIMO) technology, is one of the key developments which allowed new advances in mobile communication. Accurate and up-to-date channel state information at the transmitter (CSIT) is a necessary requirement for achieving the multiplexing gains, referred to in the literature also as degrees of freedom (DoF). Maintaining up-to-date CSIT however may become exhausting in terms of the number of resources. In case the CSIT is completely outdated, no channel time correlation can be exploited. Nevertheless, even completely outdated CSIT can be very useful for achieving DoF greater than that with completely absent CSIT. The key idea is to apply a multi-phase transmission, where in each phase, the interference terms overheard in the previous phases are retransmitted. On one hand, such terms provide the transmitters with new information about the desired symbols. On the other hand, such terms can be cancelled at the receivers which previously overheard them. In such a way, the amount of the produced interference in each consecutive phase is reduced, where in the last phase, an interference-free transmission is achieved. In this thesis, we design new transmission schemes to achieve more DoF in a variety of communication networks with completely outdated or simply delayed CSIT.
Firstly, a network with two transmitters and two receivers is considered, where each transmitter desires to deliver a message to each receiver. Such network is referred to in the literature as the X-channel (XC). We consider a MIMO setting, in which the transmitters have M_1 and M_2 antennas and the receivers have N_1 and N_2 antennas. In the XC, each receiver receives a superposition of two interference signals originating from different transmitters, hence the interference in its plain form cannot be reconstructed using delayed CSIT. By applying redundancy transmission (RT), each transmitter can be forced to span only a fraction of the signal space of each receiver. Then, by applying partial interference nulling (PIN), each receiver can subtract the signal of one of the interferers, where the remaining interference signal can be reconstructed at the transmitter using delayed CSIT. In case min{M_1, M_2}>min{N_1, N_2}, a more effective multi-part transmission, known as interference sensing and redundancy transmission (IS-RT), can be performed, where the interference overheard in the first part comprises the redundancy transmitted in the second part. In this thesis, we perform decodability analysis of the state-of-the-art transmission scheme for the MIMO XC with delayed CSIT which relies on IS-RT-PIN. Our analysis shows, that despite the fact that the receivers obtain a sufficient number of linear combinations, the transmitted information symbols are not always decodable, which is due to a linear dependence of the linear combinations. To address the identified decodability problem, a novel transmission scheme is proposed, where the parameters of the scheme are carefully selected to maximize the number of the transmitted information symbols while ensuring linear independence. The proposed transmission scheme achieves a number of DoF greater than that of the state-of-the-art transmission scheme in which the number of the transmitted information symbols is reduced to the number of the decodable ones.
Secondly, a network with three transmitters and three receivers is considered, where each transmitter wants to deliver a message to its corresponding partner receiver. Such network is referred to in the literature as the three-user interference channel (IC). We consider a symmetric MIMO setting, in which each transmitter has M antennas and each receiver has N antennas. For the three-user MIMO IC with delayed CSIT, two novel transmission schemes for M
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Li-YuanChen and 陳立遠. "Channel State Information (CSI) Reductionfor Cooperative OFDM Systems." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/z43kje.
Full textAbstract:
碩士國立成功大學
電腦與通信工程研究所
104
In recent years, cooperative communications have received much attention. The concept of cooperative communications is to let un-used mobile units help the transmission of other users. Through the neighbor nodes, the transmitted signal can be relayed to the destination. Cooperative communications can reinforce the point-to-point transmission channel. Based on the cooperative communications, we attain a scenario that is like there are several transmit antennas at the transmitter, and this achieves the effect of multiple-input multiple-output (MIMO) system. In fact, the transmitter needs the forward channel state information (CSI) to improve the performance of system. Sometimes, the transmitter needs to estimate the channel responses (CRs) and/or channel amplitude, and forward these CRs to the receiver, and this increases the forward load. In order to efficiently forward the CSI, we propose an efficient method that forward the estimated channel responses (CRs) to the receiver based on the Karhunen-Loève Expansion (KLE). The coefficients of the KLE are used as the parameters for rebuilding the CRs. The number of coefficients of the KLE is much fewer than the size of the original block of CRs, and the KLE leads to efficient compression. These coefficients are Gaussian distribution and nearly uncorrelated. To efficiently forward the coefficients for the cooperative OFDM system, we use the Gaussian quantization (GQ) to reduce the quantization error. The simulation results show that the proposed algorithms can attain good error performance for the cooperative OFDM systems with low forward load in time-varying and frequency-selective channels.
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Liu, Chi-Tang, and 劉啟堂. "Exploiting Decentralized Channel State Information for Slotted ALOHA." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/56388979156402692810.
Full textAbstract:
碩士國立臺灣大學
電信工程學研究所
99
Conventional Slotted ALOHA is a random access protocol designed for collision channels. In this thesis, we consider a cross layer design that exploits decentralized channel state information (D-CSI) for the Medium Access Control (MAC) layer protocol such as slotted ALOHA under the SINR capture model. In view of the inferior performance of the threshold based transmission, we first propose a single-region based channel aware ALOHA strategy that can reduce the multiple access interference (MAI). The system throughput is analyzed and optimized for a wireless network with homogeneous fading. We then propose a two-region extension. Both strategies have a significant gain over other common used protocols. We conclude that the Single-Region strategy is preferable when the SINR capture ratio is smaller than one and the Two-Region strategy is better when the SINR capture ratio is large than one.