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1
Kane, Roma. "Multiuser TDMA channel estimation". Diss., Columbia, Mo. : University of Missouri-Columbia, 2004. http://hdl.handle.net/10355/5810.
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Thesis (M.S.)--University of Missouri-Columbia, 2004.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (June 30, 2006) Vita. Includes bibliographical references.
2
Song, Limeng. "ATSC DTV Channel Estimation". Thesis, Université Laval, 2009. http://www.theses.ulaval.ca/2009/26235/26235.pdf.
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Shiao, Fu-Sheng. "Combined Channel Estimation and Turbo Equalization for Wireless Channels". Thesis, University of Canterbury. Electrical and Computer Engineering, 2007. http://hdl.handle.net/10092/1189.
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Single-carrier linear modulation techniques combined with frequency-domain equalization provide a viable alternative to multicarrier techniques for combating multipath fading in channels with large delay spread. Such modulations tolerate frequency offset and have well controlled peak to average power ratio. They have comparable complexity to orthogonal frequency division multiplexing (OFDM) systems, and are more robust to synchronization errors. If error correction coding is used, then information can be iteratively passed between the equalizer and the decoder to improve performance. This is referred to as turbo equalization. To date, several turbo equalization schemes have been proposed, but little work has been done to address the problem of channel estimation for the turbo equalization process. The work in this thesis considers frequency-domain turbo equalization with imperfect channel state information (CSI) at the receiver for different wireless channels. A receiver structure incorporating joint frequency-domain turbo equalization and time- domain channel estimation is developed. The novelty of this scheme lies in the combination of time-domain channel estimation and frequency-domain turbo equalization, and in its extension to high level modulation formats. The performance of the system is investigated by a combination of analysis and computer simulation. It is found that the system performs well over a range of dispersive channels.
4
Potter, Chris. "Modeling Channel Estimation Error in Continuously Varying MIMO Channels". International Foundation for Telemetering, 2007. http://hdl.handle.net/10150/604490.
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ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, NevadaThe accuracy of channel estimation plays a crucial role in the demodulation of data symbols sent across an unknown wireless medium. In this work a new analytical expression for the channel estimation error of a multiple input multiple output (MIMO) system is obtained when the wireless medium is continuously changing in the temporal domain. Numerical examples are provided to illustrate our findings.
5
Khan, Anwer Ali. "Iterative Decoding and Channel Estimation over Hidden Markov Fading Channels". Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/32470.
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Since the 1950s, hidden Markov models (HMMS) have seen widespread use in electrical engineering. Foremost has been their use in speech processing, pattern recognition, artificial intelligence, queuing theory, and communications theory. However, recent years have witnessed a renaissance in the application of HMMs to the analysis and simulation of digital communication systems. Typical applications have included signal estimation, frequency tracking, equalization, burst error characterization, and transmit power control. Of special significance to this thesis, however, has been the use of HMMs to model fading channels typical of wireless communications. This variegated use of HMMs is fueled by their ability to model time-varying systems with memory, their ability to yield closed form solutions to otherwise intractable analytic problems, and their ability to help facilitate simple hardware and/or software based implementations of simulation test-beds.
The aim of this thesis is to employ and exploit hidden Markov fading models within an iterative (turbo) decoding framework. Of particular importance is the problem of channel estimation, which is vital for realizing the large coding gains inherent in turbo coded schemes. This thesis shows that a Markov fading channel (MFC) can be conceptualized as a trellis, and that the transmission of a sequence over a MFC can be viewed as a trellis encoding process much like convolutional encoding. The thesis demonstrates that either maximum likelihood sequence estimation (MLSE) algorithms or maximum a posteriori (MAP) algorithms operating over the trellis defined by the MFC can be used for channel estimation. Furthermore, the thesis illustrates sequential and decision-directed techniques for using the aforementioned trellis based channel estimators en masse with an iterative decoder.
Master of Science
6
Dessalermos, Spyridon. "Undersea acoustic propagation channel estimation". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Jun%5FDessalermos.pdf.
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Thesis (M.S. in Electrical Engineering and M.S. in Applied Physics)--Naval Postgraduate School, June 2005.Thesis Advisor(s): Joseph Rice, Roberto Cristi. Includes bibliographical references (p. 117-119). Also available online.
7
Gurel, Ilker. "Channel Estimation For Ofdm Systems". Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606940/index.pdf.
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In this thesis, various pilot symbol aided channel estimation and tracking methods are investigated and their performances are compared for an OFDM system with packet based communication on HF channel. For the HF channel, Watterson HF channel model is used. The compared methods are least squares (LS) channel estimation, linear minimum mean square error (LMMSE) channel estimation, least mean squares (LMS) channel tracking, recursive least squares (RLS) channel tracking, constant position model based Kalman filter channel tracking, and constant velocity model based Kalman filter channel tracking. For LMS and RLS methods some adaptive approaches are also investigated.
8
Richter, Andreas. "Estimation of radio channel parameters". Ilmenau : ISLE, 2005. http://deposit.d-nb.de/cgi-bin/dokserv?idn=981051421.
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Carroll, Brian Michael. "Analysis of Sparse Channel Estimation". The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1244045602.
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10
Ho, Kenneth T. "Uplink channel estimation in WiMAX". College Park, Md. : University of Maryland, 2008. http://hdl.handle.net/1903/8214.
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Thesis (M.S.) -- University of Maryland, College Park, 2008.Thesis research directed by: Dept. of Electrical and Computer Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
11
Lu, Biao. "Wireline channel estimation and equalization /". Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p3004324.
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Zeydan, Engin. "Channel Phase And Data Estimation In Slowly Fading Frequency Nonselective Channels". Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607419/index.pdf.
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In coherent receivers, the effect of the multipath fading channel on the transmitted signal must be estimated to recover the transmitted data. In this thesis, the channel
phase and data estimation problems are investigated in a transmitted data sequence when the channel is modeled as slowly fading, frequency non-selective channel.
Channel phase estimation in a transmitted data sequence is investigated and data estimation is obtained in a symbol-by-symbol MAP receiver that is designed for minimum symbol error probability criterion.
The channel phase is quantized in an interval of interest, the trellis diagram is constructed and Viterbi decoding algorithm is applied that uses the phase transition and observation models for channel phase estimation. The optimum coherent and noncoherent detectors for binary orthogonal and PSK signals are derived and the modulated signals in a sequence are detected in symbol-by-symbol MAP receivers.Simulation results have shown that the performance of the receiver with phase estimation is between the performance of the optimum coherent and noncoherent
receiver.
13
Mongol, Bayarpurev, Takaya Yamazato, Hiraku Okada i Masaaki Katayama. "Channel Estimation for BFDM/OQAM System in Dispersive Time-Varying Channels". IEEE, 2006. http://hdl.handle.net/2237/7762.
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14
Song, Xuegui. "Channel estimation techniques for OFDM systems in dispersive time-varying channels". Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/8897.
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Coherent modulation is more effective than differential modulation for orthogonal frequency division multiplexing (OFDM) systems requiring high data rate and spectral efficiency. Channel estimation is therefore an integral part of the receiver design. In this thesis, two iterative maximum likelihood based channel estimation algorithms are proposed for an OFDM system in dispersive time-varying channels. A multipath channel model is proposed for OFDM uplink transmission in macrocellular systems. The multipath fading channel is modeled such that the channel state can be determined by estimating the unknown channel parameters. A second-order Taylor series expansion is adopted to simplify the channel estimation problem. Based on the system model, an iterative maximum likelihood based algorithm is first proposed to estimate the discrete-time channel parameters. The mean square error performance of the proposed algorithm is analyzed using a small perturbation technique. Based on a convergence rate analysis, an improved iterative maximum likelihood based channel estimation algorithm is presented using a successive overrelaxation method. Numerical experiments are performed to confirm the theoretical analyses and show the improvement in convergence rate of the improved algorithm.
15
Wang, Yi. "Joint OFDM symbol detection and channel estimation over doubly selective channels". Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=121486.
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Orthogonal Frequency Division Multiplexing (OFDM) is a promising technique for high data rate transmission, that is widely used in modern wireless communication systems because of its good performance over frequency selective channels. However OFDM systems are sensitive to channel time variation resulting in Inter-Carrier Interference (ICI), that without suitable detection methods can degrade performance. Channel State Information (CSI) is essential to various OFDM data detection schemes and its acquisition is a critical factor, in particular over time-varying channels. This work considers a technique for integrating the Kalman filter channel estimation with a version of Sphere Decoding (SD) adapted to OFDM detection. By modelling the OFDM system in frequency domain as a Multiple Input Multiple Output (MIMO) system, we derive a powerful SD technique for data detection. By approximating the channel matrix as banded, we are able to maintain a feasible complexity for SD and deliver competitive performance when compared to other existing scheme. For acquisition of CSI, the Basis Expansion (BE) method is used to model the time-varying channels and a Kalman filter is constructed for tracking. The Kalman filter employs decision-feedback from the SD, requiring only a low pilot symbol density, and hence improves bandwidth efficiency. The performance of this scheme is evaluated by Monte-Carlo computer simulations. Results show that compared with competing algorithm, this scheme provides performance gains. When it is used over moderate time-varying LTE channels, this scheme shows good performance even in the presence of carrier phase noise.Le multiplexage par répartition en fréquence orthogonale (OFDM, pour Orthogonal Frequency Division Multiplexing) est une technique prometteuse pour la transmission de données à haut débit. Il est largement utilisé dans les systèmes de communication sans fil actuels en raison de ses bonnes performances sur les canaux sélectifs en fréquence. Toutefois, les systèmes reposant sur l'OFDM sont sensibles aux variations de temps de voie, qui entraînent un brouillage inter-porteuses (ICI, pour Inter-Carrier Interference). En l'absence de méthodes de détection appropriée, ce brouillage peut réduire les performances. Les informations d'état de canal (CSI, pour Channel State Information) constituent un élément essentiel des divers systèmes de détection de données basés sur l'OFDM et leur acquisition est un facteur crucial, surtout sur les canaux variables en temps. La présente examine une technique permettant d'intégrer l'évaluation de canaux reposant sur un filtre de Kalman à une variante du décodage par sphères (SD, pour Sphere Decoding) adaptée à la détection OFDM. En modélisant le système d'OFDM dans le domaine fréquentiel comme un système « entrées multiples, sorties multiples » (MIMO, pour Multiple Input Multiple Output), nous obtenons une puissante technique de SD pour la détection des données. En tenant pour acquis que la matrice de canal est une matrice bande, il est possible de maintenir une complexité recelant le potentiel pour une implantation réelle du SD et d'obtenir des performances concurrentielles comparativement à d'autres systèmes existants. En ce qui a trait à l'acquisition des CSI, on utilise la méthode de l'« expansion de base » (BE, pour Basis Expansion) pour modéliser les canaux variables en temps et on crée un filtre de Kalman pour le suivi des variations de temps des canaux. Le filtre de Kalman utilise les retours de décisions tirés du SD. Il ne nécessite ainsi qu'une faible densité de symboles pilotes, ce qui accroît l'optimisation de la bande passante. Les performances de ce système sont évaluées à l'aide de simulations informatiques reposant sur la méthode de Monte-Carlo. Les résultats montrent que par rapport à l'algorithme mis en concurrence, ce système permet des gains de performance. Quand il est utilisé sur des canaux LTE (Long Term Evolution) modérément variables en temps, ce système atteint une bonne performance, même en présence de brouillage de la phase des porteuses.
16
Jain, Payal. "On the Impact of Channel and Channel Quality Estimation on Adaptive Modulation". Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/36072.
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The rapid growth in wireless communications has given rise to an increasing demand for channel capacity using limited bandwidth. Wireless channels vary over time due to fading and changing interference conditions. Typical wireless systems are designed by choosing a modulation scheme to meet worst case conditions and thus rely on power control to adapt to changing channel conditions. Adaptive modulation, however, exploits these channel variations to improve the spectral efficiency of wireless communications by intelligently changing the modulation scheme based on channel conditions. Necessarily, among the modulation schemes used are spectrally efficient modulation schemes such as quadrature amplitude modulation (QAM) techniques.
QAM yields the high spectral efficiency due to its use of amplitude as well as phase modulation and therefore is an effective technique for achieving high channel capacity. The main drawbacks of QAM modulation are its reduced energy efficiency (as compared to standard QPSK) and its sensitivity to channel amplitude variations. Adaptive modulation attempts to address the first drawback by using more energy efficient schemes in low SNR conditions are reserving the use of QAM for high SNR conditions. The second drawback leads to a requirement of high quality channel estimation. Many researchers have studied pilot symbol assisted modulation for compensating the effects of fading at the receiver. A main contribution of this thesis is the investigation of different channel estimation techniques (along with the effect of pilot symbol spacing and Doppler spread) on the performance of adaptive modulation.
Another important parameter affecting adaptive modulation is the signal-to-noise ratio. In order to adapt modulation efficiently, it is essential to have accurate knowledge of the channel signal-to-noise ratio. The performance of adaptive modulation depends directly on how well the channel SNR is estimated. The more accurate the estimation of the channel SNR is, the better the choice of modulation scheme becomes, and the better the ability to exploit the variations in the wireless channel is. The second main contribution
of this thesis is the investigation of the impact of SNR estimation techniques on the performance and spectral efficiency of adaptive modulation. Further, we investigate the impact of various channel conditions on SNR estimation and the resulting impact on the performance of adaptive modulation. Finally, we investigate long term SNR estimation, its use in adaptive modulation and present a comparison between the two approachesMaster of Science
17
Patel, Chirag S. "Wireless channel modeling, simulation, and estimation". Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-03282006-200818/.
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Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2006.Andrew, Alfred, Committee Member ; Durgin, Gregory, Committee Member ; Li, Geoffrey, Committee Member ; Ingram, Mary Ann, Committee Member ; Stuber, Gordon, Committee Chair.
18
Xinzhu, Jin. "Channel Estimation Techniques of SC-FDMA". Thesis, Karlstad University, Faculty of Technology and Science, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-1262.
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Abstract
This master thesis investigates several di®erent channel estimation techniques in an SC-
FDMA (Single Carrier Frequency Division Multiple Access) system with parameters set
according to the standards of 3GPP LTE (3rd Generation Partnership Project Long Term
Evolution). 3GPP LTE is the name given to a project within the 3GPP to improve the
mobile phone standard to cope with future requirements. In this thesis, we ¯rst introduce
the SC-FDMA system, which is a transmission technique that utilizes single carrier mod-
ulation, then ¯ve types of estimators are investigated. Essential to all channel estimatiors
is the use of pilot symbols. In the last part we compare the performance of the channel
estimation techniques with each other in di®erent environments by analysing their symbol
error rates. All simulations are done in a Matlab environment.
19
Kim, JoonBeom. "Iterative Channel Estimation for Wireless Communications". Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14064.
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The main objective of this dissertation is to present the structural design, performance evaluation, and complexity reduction of iterative joint channel estimation and data detection receivers. One of the main technical challenges in advanced wireless communications stems from the characteristics of a wireless channel, e.g., time selectivity of a channel, mobility of users, and multipath propagation. Channel estimation is essential for achieving reliable information transmission for practical wireless communication applications. Numerous channel estimation structures have been developed for different underlying channels using pilot-symbol assisted modulation (PSAM) approaches. However, since pilot symbols carry no data information, the time and the power spent on pilot symbols degrades the efficiency and the throughput of the system. Therefore, it is necessary to minimize the pilot insertion ratio without degrading the error performance. This motivates our research on iterative joint channel estimation and data detection receivers with full- and reduced- or low-complexity.
In this thesis, we first propose an iterative channel estimator (ICE), based on a maximum a posteriori (MAP) algorithm, for single-carrier systems with PSAM structures. In contrast to existing MAP channel estimators, the proposed channel estimator has a lower computational complexity, which increases linearly with the modulation alphabet size. The computational complexity is reduced by exploiting a survivor in an efficient manner, while achieving comparable error performance to a full complexity receiver. For orthogonal frequency division multiplexing (OFDM) systems, we also propose novel signal constellations to facilitate channel estimation without pilot symbol transmission, and analyze the bit error rate for the proposed constellations. We also develop a suitable joint channel estimation and data detector with full- and low-complexity for the proposed constellations. This low-complexity ICE achieves an error performance comparable to the ICE with full-complexity. Finally, for vertical Bell Laboratories layered space-time OFDM systems, we propose an ICE based on a PSAM structure for time-varying multipath fading channels. By exploiting the statistical properties of a wireless channel, we also develop a method to suppress intercarrier interference due to the channel time selectivity, and propose a low-complexity ICE that exploits a priori information in an efficient manner.
20
Avan, Muhammet. "Joint Frequency Offset And Channel Estimation". Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/2/12610149/index.pdf.
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In this thesis study, joint frequency offset and channel estimation methods for
single-input single-output (SISO) systems are examined. The performance of
maximum likelihood estimate of the parameters are studied for different training
sequences. Conventionally training sequences are designed solely for the channel
estimation purpose. We present a numerical comparison of different training
sequences for the joint estimation problem. The performance comparisons are made
in terms of mean square estimation error (MSE) versus SNR and MSE versus the
total training energy metrics. A novel estimation scheme using complementary
sequences have been proposed and compared with existing schemes. The proposed
scheme presents a lower estimation error than the others in almost all numerical
simulations. The thesis also includes an extension for the joint channel-frequency
offset estimation problem to the multi-input multi-output systems and a brief
discussion for multiple frequency offset case is also given.
21
Ahmed, Mohsin Niaz. "LTE Uplink Modeling and Channel Estimation". Thesis, Linköpings universitet, Datorteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-69571.
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This master thesis investigates the uplink transmition from User Equipment (UE) to base station in LET (Long Term Evolution) and channel estimation using pilot symbols with parameter defined in 3GPP (3rd Generation Partnership Project) specifications. The purpose of the thesis was to implement a simulator which can generate uplink signal as it is generated by UE. The Third Generation (3G) mobile system was given the name LTE. This thesis focus on the uplink of LTE where single carrier frequency division multiple access (SC-FDMA) is utilized as a multiple access technique. The advantage over the orthogonal frequency division multiple access (OFDMA), which is used in downlink is to get better peak power characteristics. Because in uplink communication better peak power characteristic is necessary for better power efficiency in mobile terminals. To access the performance of uplink transmition realistic channel model for wireless communication system is essential. Channel models used are proposed by International Telecommunication Union (ITU) and the correct knowledge of these models is important for testing, optimization and performance improvements of signal processing algorithms. The channel estimation techniques used are Least Square (LS) and Least Minimum Mean Square Error (LMMSE) for different channel models. Performance of these algorithms has been measured in term of Bit Error Rate (BER) and Signal to Noise Ratio (SNR).
22
Alli, Idd Pazi. "Channel estimation in mobile wireless systems". Thesis, KTH, Signalbehandling, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-98754.
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The demands of multimedia services from mobile user equipment (UE) for achieving high data rate, high capacity and reliable communication in modern mobile wireless systems are continually ever-growing. As a consequence, several technologies, such as the Universal Mobile Telecommunications System (UMTS) and the 3rd Generation Partnership Project (3GPP), have been used to meet these challenges. However, due to the channel fading and the Doppler shifts caused by user mobility, a common problem in wireless systems, additional technologies are needed to combat multipath propagation fading and Doppler shifts. Time-variant channel estimation is one such crucial technique used to improve the performance of the modern wireless systems with Doppler spread and multipath spread. One of vital parts of the mobile wireless channel is channel estimation, which is a method used to significantly improve the performance of the system, especially for 4G and Long Term Evolution (LTE) systems. Channel estimation is done by estimating the time-varying channel frequency response for the OFDM symbols. Time-variant channel estimation using Discrete Prolate Spheroidal Sequences (DPSS) technique is a useful channel estimation technique in mobile wireless communication for accurately estimating transmitted information. The main advantage of DPSS or Slepian basis expansion is allowing more accurate representation of high mobility mobile wireless channels with low complexity. Systems such as the fourth generation cellular wireless standards (4G), which was recently introduced in Sweden and other countries together with the Long Term Evolution, can use channel estimation techniques for providing the high data rate in modern mobile wireless communication systems. The main goal of this thesis is to test the recently proposed method, time-variant channel estimation using Discrete Prolate Spheroidal Sequences (DPSS) to model the WINNER phase II channel model. The time-variant sub-carrier coefficients are expanded in terms of orthogonal DPS sequences, referred to as Slepian basis expansions. Both Slepian basis expansions and DPS sequences span the low-dimensional subspace of time-limited and band-limited sequences as Slepian showed. Testing is done by using just two system parameters, the maximum Doppler frequency Dmax v and K, the number of basis functions of length N = 256. The main focus of this thesis is to investigate the Power spectrum and channel gain caused by Doppler spread of the WINNER II channel model together with linear fitting of curves for both the Slepian and Fourier basis expansion models. In addition, it investigates the Mean Square Error (MSE) using the Least Squares (LS) method. The investigation was carried out by simulation in Matlab, which shows that the spectrum of the maximum velocity of the user in mobile wireless channel is upper bounded by the maximum normalized one-sided Doppler frequency. Matlab simulations support the values of the results. The value of maximum Doppler bandwidth vDmax of the WINNER model is exactly the same value as DPS sequences. In addition to the Power spectrum of the WINNER model, the fitting of Slepian basis expansion performs better in the WINNER model than that of the Fourier basis expansion.
23
Yi, Na. "Channel estimation for linear block transmissions". Thesis, University of Liverpool, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426104.
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Mai, Huiheng. "Iterative channel estimation for wireless communications". Thesis, University of York, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433681.
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Lindén, Erik. "Iterative Channel Estimation in LTE Uplink". Thesis, KTH, Kommunikationsteori, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-147128.
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An algorithm for iterative channel estimation using soft feedback for LTE uplink is proposed. The algorithm has low complexity compared to MMSE estimation and does not require knowledge of the channel statistics. A simple polynomial model is used for noise suppression across OFDM symbols and a DCT-based filter is used for noise suppression across subcarriers. The algorithm has been tested on several channel models and has been shown to provide a gain of about 0:5 dB with two estimation stages, compared to the no-feedback case. Further, the algorithm has been applied to a MIMO case. A comparison has been made between the proposed algorithm and turbo equalization.En algoritm for iterativ kanalestimering i LTE-upplank foreslas. Algoritmen harlag komplexitet jamfort med MMSE-estimering. En enkel polynomiell modellanvands for att undertrycka brus over OFDM-symboler och ett DCT-baseratlter anvands for att undertrycka brus over sub-barvagor.Algoritmen har testats med era kanalmodeller och visats ge en vinst pa cirka0:5 dB med tva estimeringsitrationer, jamfort med en icke-iterativ mottagare.Algoritmen har ocksa applicerats till en MIMO-situation.En jamforelse mellan den foreslagna algoritmen och turboutjamning hargjorts.
26
Hogstrom, Christopher. "SPARSE CHANNEL ESTIMATION FOR AERONAUTICAL TELEMETRY". International Foundation for Telemetering, 2016. http://hdl.handle.net/10150/624251.
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This paper applies a compressed sensing (CS) algorithm to SOQPSK-TG waveform samples to
reconstruct a sparse channel. The mean squared error (MSE) is computed between the estimated
channel and the true channel. The estimated channel is then used in an equalized system and a
bit error rate (BER) curve is calculated. The results are then compared to a Maximum Likelihood
(ML) estimator. The CS estimate does not produce significant gains but it doesn’t break anything either.
27
Kleynhans, Waldo. "On channel estimation for mobile WiMAX". Diss., Pretoria : [s.n.], 2008. http://upetd.up.ac.za/thesis/available/etd-01262009-102433/.
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Abd, El-Sallam Amar. "Low order channel estimation for CDMA systems". Thesis, Curtin University, 2005. http://hdl.handle.net/20.500.11937/2420.
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New approaches and algorithms are developed for the identification and estimation of low order models that represent multipath channel effects in Code Division Multiple Access (CDMA) communication systems. Based on these parsimonious channel models, low complexity receivers such as RAKE receivers are considered to exploit these propagation effects and enhance the system performance. We consider the scenario where multipath is frequency selective slowly fading and where the channel components including delays and attenuation coefficients are assumed to be constant over one or few signalling intervals. We model the channel as a long FIR-like filter (or a tapped delay line filter) with the number of taps related to the ratio between the channel delay-spread and the chip duration. Due to the high data rate of new CDMA systems, the channel length in terms of the chip duration will be very large. With classical channel estimation techniques this will result in poor estimates of many of the channel parameters where most of them are zero leading to a reduction in the system performance. Unlike classical techniques which estimate directly the channel response given the number of taps or given an estimate of the channel length, the proposed techniques in this work will firstly identify the significant multipath parameters using model selection techniques, then estimate these identified parameters. Statistical tests are proposed to determine whether or not each individual parameter is significant. A low complexity RAKE receiver is then considered based on estimates of these identified parameters only. The level of significance with which we will make this assertion will be controlled based on statistical tests such as multiple hypothesis tests. Frequency and time domain based approaches and model selection techniques are proposed to achieve the above proposed objectives.The frequency domain approach for parsimonious channel estimation results in an efficient implementation of RAKE receivers in DS-CDMA systems. In this approach, we consider a training based strategy and estimate the channel delays and attenuation using the averaged periodogram and modified time delay estimation techniques. We then use model selection techniques such as the sphericity test and multiple hypotheses tests based on F-Statistics to identify the model order and select the significant channel paths. Simulations show that for a pre-defined level of significance, the proposed technique correctly identifies the significant channel parameters and the parsimonious RAKE receiver shows improved statistical as well as computational performance over classical methods. The time domain approach is based on the Bootstrap which is appropriate for the case when the distribution of the test statistics required by the multiple hypothesis tests is unknown. In this approach we also use short training data and model the channel response as an FIR filter with unknown length. Model parameters are then estimated using low complexity algorithms in the time domain. Based on these estimates, bootstrap based multiple hypotheses tests are applied to identify the non-zero coefficients of the FIR filter. Simulation results demonstrate the power of this technique for RAKE receivers in unknown noise environments. Finally we propose adaptive blind channel estimation algorithms for CDMA systems. Using only the spreading code of the user of interest and the received data sequence, four different adaptive blind estimation algorithms are proposed to estimate the impulse response of frequency selective and frequency non-selective fading channels. Also the idea is based on minimum variance receiver techniques. Tracking of a frequency selective varying fading channel is also considered.A blind based hierarchical MDL model selection method is also proposed to select non-zero parameters of the channel response. Simulation results show that the proposed algorithms perform better than previously proposed algorithms. They have lower complexity and have a faster convergence rate. The proposed algorithms can also be applied to the design of adaptive blind channel estimation based RAKE receivers.
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Saad, Haea. "Enhanced Channel Estimation for MIMO-OFDM in 5G NR : or an analysis of the channel estimation performance". Thesis, Karlstads universitet, Institutionen för matematik och datavetenskap (from 2013), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-85070.
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Song, Liying Tugnait Jitendra K. "Channel estimation and equalization for doubly-selective channels using basis expansion models". Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SPRING/Electrical_and_Computer_Engineering/Dissertation/Song_Liying_29.pdf.
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Holm, Henrik. "Adaptive Coded Modulation Performance and Channel Estimation Tools for Flat Fading Channels". Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elektronikk og telekommunikasjon, 2002. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-2150.
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The need for spectrally efficient transmission on mobile and wireless channels is prevalent. A promising scheme for such transmission is adaptive coded modulation. In this thesis, techniques for assessing the performance of such systems are presented. One of the vulnerable points of such systems is the need for a reliable feedback channel. Channel prediction is proposed as a technique to combat the harmful effects of feedback delay. The Nakagami distribution is often employed in a model for the fading envelope of a wireless channel; this leads to a gamma-distributed signal-to-noise ratio. Nakagami (1960) provides expressions for the probability density function (PDF) of the product, sum, and ratio of two correlated gamma-distributed random variables (RVs). However, such an expression for the difference between two such RVs has not been provided by Nakagami. Anew expression for this PDF is provided in this dissertation, and it is shown that it is closely related to a distribution first described by McKay (1932). Applications of the new PDF include outage probability calculation in an environment with self-interference and assessment of the quality of certain channel estimation techniques.
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Aktas, Emre. "Channel estimation and equalization for wireless communication systems in frequency selective channels /". The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486546889382902.
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Abd, El-Sallam Amar. "Low order channel estimation for CDMA systems". Curtin University of Technology, Department of Electrical and Computer Engineering, 2005. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=16299.
Pełny tekst źródłaStreszczenie:
New approaches and algorithms are developed for the identification and estimation of low order models that represent multipath channel effects in Code Division Multiple Access (CDMA) communication systems. Based on these parsimonious channel models, low complexity receivers such as RAKE receivers are considered to exploit these propagation effects and enhance the system performance. We consider the scenario where multipath is frequency selective slowly fading and where the channel components including delays and attenuation coefficients are assumed to be constant over one or few signalling intervals. We model the channel as a long FIR-like filter (or a tapped delay line filter) with the number of taps related to the ratio between the channel delay-spread and the chip duration. Due to the high data rate of new CDMA systems, the channel length in terms of the chip duration will be very large. With classical channel estimation techniques this will result in poor estimates of many of the channel parameters where most of them are zero leading to a reduction in the system performance. Unlike classical techniques which estimate directly the channel response given the number of taps or given an estimate of the channel length, the proposed techniques in this work will firstly identify the significant multipath parameters using model selection techniques, then estimate these identified parameters. Statistical tests are proposed to determine whether or not each individual parameter is significant. A low complexity RAKE receiver is then considered based on estimates of these identified parameters only. The level of significance with which we will make this assertion will be controlled based on statistical tests such as multiple hypothesis tests. Frequency and time domain based approaches and model selection techniques are proposed to achieve the above proposed objectives.The frequency domain approach for parsimonious channel estimation results in an efficient implementation of RAKE receivers in DS-CDMA systems. In this approach, we consider a training based strategy and estimate the channel delays and attenuation using the averaged periodogram and modified time delay estimation techniques. We then use model selection techniques such as the sphericity test and multiple hypotheses tests based on F-Statistics to identify the model order and select the significant channel paths. Simulations show that for a pre-defined level of significance, the proposed technique correctly identifies the significant channel parameters and the parsimonious RAKE receiver shows improved statistical as well as computational performance over classical methods. The time domain approach is based on the Bootstrap which is appropriate for the case when the distribution of the test statistics required by the multiple hypothesis tests is unknown. In this approach we also use short training data and model the channel response as an FIR filter with unknown length. Model parameters are then estimated using low complexity algorithms in the time domain. Based on these estimates, bootstrap based multiple hypotheses tests are applied to identify the non-zero coefficients of the FIR filter. Simulation results demonstrate the power of this technique for RAKE receivers in unknown noise environments. Finally we propose adaptive blind channel estimation algorithms for CDMA systems. Using only the spreading code of the user of interest and the received data sequence, four different adaptive blind estimation algorithms are proposed to estimate the impulse response of frequency selective and frequency non-selective fading channels. Also the idea is based on minimum variance receiver techniques. Tracking of a frequency selective varying fading channel is also considered.
A blind based hierarchical MDL model selection method is also proposed to select non-zero parameters of the channel response. Simulation results show that the proposed algorithms perform better than previously proposed algorithms. They have lower complexity and have a faster convergence rate. The proposed algorithms can also be applied to the design of adaptive blind channel estimation based RAKE receivers.
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Yao, Ning. "Iterative algorithms for channel estimation and equalization /". View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202005%20YAO.
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Mheidat, Hakam. "Channel Estimation and Equalization for Cooperative Communication". Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/2852.
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The revolutionary concept of space-time coding introduced in the last decade has demonstrated that the deployment of multiple antennas at the transmitter allows for simultaneous increase in throughput and reliability because of the additional degrees of freedom offered by the spatial dimension of the wireless channel. However, the use of antenna arrays is not practical for deployment in some practical scenarios, e. g. , sensor networks, due to space and power limitations. A new form of realizing transmit diversity has been recently introduced under the name of user cooperation or cooperative diversity. The basic idea behind cooperative diversity rests on the observation that in a wireless environment, the signal transmitted by the source node is overheard by other nodes, which can be defined as "partners" or "relays". The source and its partners can jointly process and transmit their information, creating a "virtual antenna array" and therefore emulating transmit diversity.
Most of the ongoing research efforts in cooperative diversity assume frequency flat channels with perfect channel knowledge. However, in practical scenarios, e. g. broadband wireless networks, these assumptions do not apply. Frequency-selective fading and imperfect channel knowledge should be considered as a more realistic channel model. The development of equalization and channel estimation algorithms play a crucial element in the design of digital receivers as their accuracy determine the overall performance.
This dissertation creates a framework for designing and analyzing various time and frequency domain equalization schemes, i. e. distributed time reversal (D-TR) STBC, distributed single carrier frequency domain (D-SC-FDE) STBC, and distributed orthogonal frequency division multiplexing (D-OFDM) STBC schemes, for broadband cooperative communication systems. Exploiting the orthogonally embedded in D-STBCs, we were able to maintain low-decoding complexity for all underlying schemes, thus, making them excellent candidates for practical scenarios, such as multi-media broadband communication systems.
Furthermore, we propose and analyze various non-coherent and channel estimation algorithms to improve the quality and reliability of wireless communication networks. Specifically, we derive a non-coherent decoding rule which can be implemented in practice by a Viterbi-type algorithm. We demonstrate through the derivation of a pairwise error probability expression that the proposed non-coherent detector guarantees full diversity. Although this decoding rule has been derived assuming quasi-static channels, its inherent channel tracking capability allows its deployment over time-varying channels with a promising performance as a sub-optimal solution. As a possible alternative to non-coherent detection, we also investigate the performance of mismatched-coherent receiver, i. e. , coherent detection with imperfect channel estimation. Our performance analysis demonstrates that the mismatched-coherent receiver is able to collect the full diversity as its non-coherent competitor over quasi-static channels.
Finally, we investigate and analyze the effect of multiple antennas deployment at the cooperating terminals assuming different relaying techniques. We derive pairwise error probability expressions quantifying analytically the impact of multiple antenna deployment at the source, relay and/or destination terminals on the diversity order for each of the relaying methods under consideration.
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Reyaz, Tarannum. "Iterative channel estimation for CDMA wireless systems". Thesis, University of York, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485135.
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Code Division Multiple Access, a common platform on which 3G technologies are built, provide higher capacity for voice and data communications and allow more subscribers to connect at any given time. The first stage in the CDMA signal processing receiver comprises the estimation of complex channel coefficients. This channel estimation plays a major role in the successful detection of the user's signals and in this thesis we analyse some existing channel estimation techniques, as well as proposing a new scheme based on the APPA method. This thesis describ~s the WCDMA uplink physical layer in detail and explains the single user transmitter and receiver architecture. One of the main features of CDMA is the use of rake receivers, which incorporates maximal ratio combining techniques to mitigate the effects of fading caused by the multipath channel. A conventional rake receiver has been implemented and its perfonnance analysed in different channel conditions. The perfonnance of the rake receiver improved with an increase in diversity and when the paths that arrived were· separated by more than one chip duration. To estimate the channel parameters, that are needed to correct th.e phase rotations and attenuations caused by the fading channel, a Wiener filter was employed which produced estimates in agreement with the actual channel parameters. The perfonnance .of various spreading codes were also analysed which showed that codes with long spreading gain perfonned better than those with short gains due to the high cross correlation between the short code lengths. An iterative channel estimator based on Expectation Maxim~ation (EM) algorithm is iJ:lplemented and analysed in flat fading and frequency selective fading channels for S1S0 and MIMO systems. Turbo codes well known as powerful error control codes and capable of achieving Shannon bound for channel capacity produce extrinsic information during the decoding process whiCh is used to improve the decoding iteratively; This extrinsic information is exploited in the EM channel estimation process where the estimation operates iteratively and jointly with the turbo decoding thereby providing reliable channel estimates. The iterative channel estimator is found to perfonn significantly better than the non-iterative estimator. A major contribution of the thesis is the development of a new channel estimation algorithm based on the APPA scheme which is also based on the turbo princfpie. The algorithm involves derivation of the log-likelihood function and then the approximation of this function in order to derive maximum-likelihood estimates of the channel amplitude and phase. The log-likelihood function of the APPA scheme consists of the log of the expected likelihood function rather than the expected value of the log-' likelihood function as in the EM scheme. It' is shown to perfonn better than the EM algorithm in flat fading channel conditions for a BPSK turbo coded 'system. Its performance is measured by comparing the mean square estimation error with the Cramer-Rao bound and overall BERperformance against SNRs. A new technique was developed to estimate the phase of the carrier using join~ turbodecoding and carrier phase estimation for differentially encoded OQPSK system. This was done in order to show the benefits of including the turbo decoder in the iterative estimation process. The differentially encoded OQPSK modulation scheme has been adopted by numerous wireless communication systems especially satellite communication systems.
37
Ye, Diliao. "Indoor Positioning based on Wireless Channel Estimation". Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-187440.
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Kaats, Adrian. "Estimation of biological ion channel permeation properties". Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110344.
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Methods are presented for improving the accuracy of the value of the diffusion coefficient used in continuum theory based simulation of ion channel permeation. A mathematical framework is derived for computing the diffusion coefficient of a spherical species undergoing diffusion confined within an arbitrarily defined container. Methods for standardizing the coordinates of the atoms constituting biological ion channels are presented. From its standardized coordinates, a method is described for rendering the channel's pore lining surface. This surface representation is used as the definition of the container in application of the mathematical framework for diffusion coefficient estimation within the channel's pore. These methods are applied to Gramicidin A (GA). Results for the value of the diffusion coefficient computed in pore of GA via these methods are comparable to those produced from much more complex and costly molecular dynamics simulations. Predictions about the nature of diffusion in highly confined geometries based on the mathematical framework for computing the diffusion coefficient are presented. Their implications for design with ion channels are discussed.Cette thèse présente des méthodes pour évaluer plus précisément le coefficient de diffusion utilisé dans les simulations fondées sur la théorie du continuum de la perméation des canaux ioniques. On établit tout d'abord un cadre mathématique pour le calcul des coefficients de diffusion d'espèces sphériques lors d'une diffusion restreinte à un contenant arbitrairement délimité. On présente ensuite des méthodes pour standardiser les coordonnées d'atomes formant des canaux ioniques biologiques. En utilisant ces coordonnées standardisées, on démontre comment on peut représenter la surface d'un pore intérieur d'un canal ionique. On utilise alors cette représentation comme contenant ainsi que le cadre mathématique présenté précédemment afin d'évaluer le coefficient de diffusion dans le pore du canal. On applique ensuite ces méthodes à la gramicidine A (GA) pour calculer le coefficient de diffusion du pore de la GA, avec des résultats comparables à ceux obtenus par des simulations de dynamique moléculaire beaucoup plus complexes et coûteuses. Finalement, à l'aide du cadre mathématique servant à calculer le coefficient de diffusion, on formule des prévisions à propos de la diffusion dans des espaces très restreints, et on considère leur incidence sur la conception appliquée aux canaux ioniques.
39
Stirling, Iain G. "On multipath channel estimation for CDMA systems". Thesis, University of Strathclyde, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415361.
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COSTA, RENATA BRAZ FALCAO DA. "CHANNEL ESTIMATION OVER POWER LINE COMMUNICATIONS SYSTEMS". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2007. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=11480@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORA utilização das linhas de potência para fins de comunicação vem recebendo grande atenção nos últimos anos, principalmente devido a grande demanda por serviços de telecomunicações. A grande virtude é que as linhas de potência para comunicação apresentam uma solução sem a necessidade de nova fiação. Além disso, apresentam saída de potência disponível em todos os cômodos de uma residência, onde o terminal de comunicação possa ser usado, são de fácil instalação e acima de tudo apresentam custo reduzido. Sendo assim a comunicação através de linhas de potência vem se mostrando uma solução viável na oferta de serviços de telecomunicações. Esta tese investigou os sistemas PLC no que diz respeito à estimação do canal. Foi desenvolvido um método paramétrico de estimação do canal PLC baseado no algoritmo EM (Expectation Maximization). Foi feita a avaliação de desempenho combinando modulação OFDM (Orthogonal Frequency Division Multiplexing), estimação do canal PLC e equalização, sendo utilizado como referencias os equalizadores ZF (Zero Forcing) e MMSE (Minimum Mean Square Error).
The powerline communications systems have been receiving increasing attention in last few years. Power line communications presents a no new wires solution with the additional advantages of ubiquitous node availability, easy installation, and cost effectiveness. This thesis investigation the powerline estimation channel. It was presented parametric channel estimation method using EM (Expectation Maximization) algorithm. The performance using OFDM (Orthogonal Frequency Division Multiplexing), PLC Channel estimation and equalization was availability. The performance was studied using two equalization techniques Zero- Forcing and Minimum Mean Square Error.
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Beek, Jaap van de. "Synchronization and channel estimation in OFDM systems". Doctoral thesis, Luleå tekniska universitet, Signaler och system, 1998. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-18017.
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This thesis addresses synchronization and channel estimation in OFDM communication systems. The joint maximum likliehood estimator of symbol time and carrier frequency offsets for OFDM systems using a cyclic prefix is presented. This estimator exploits the redundancy introduced by the prefix and does not require extra pilot information. Signal models, accounting for pulse shaping, channel dispersion, or slowly changing synchronization errors and the associated maximum likliehood estimators are presented. Tracking synchronization of a multiuser OFDM system, which often has been questioned, is feasible using a scheme incorporating the above estimator concept. Furthermore, this thesis analyzes channel estimators based on the discrete Fourier transform. The symbol error rate of systems employing these estimators may experience an irreducible error floor. A novel channel estimation concept using singular-value decomposition of the channel attenuations is presented. These channel estimators, designed with suitably chosen fixed design parameters, combine low-complexity and high performance.Godkänd; 1998; 20061122 (haneit)
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Trepkowski, Rose E. "Channel Estimation Strategies for Coded MIMO Systems". Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/10062.
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High transmission data rate, spectral efficiency, and reliability are necessary for future wireless communications systems. In a multipath-rich wireless channel, deploying multiple antennas at both the transmitter and receiver achieves high data rate, without increasing the total transmission power or bandwidth. When perfect knowledge of the wireless channel conditions is available at the receiver, the capacity has been shown to grow linearly with the number of antennas. However, the channel conditions must be estimated since perfect channel knowledge is never known a priori. In practice, the channel estimation procedure can be aided by transmitting pilot symbols that are known at the receiver. System performance depends on the quality of channel estimate, and the number of pilot symbols. It is desirable to limit the number of transmitted pilot symbols because pilot symbols reduce spectral efficiency.
This thesis analyzes the system performance of coded multiple-input multiple-output (MIMO) systems for the quasi-static fading channel. The assumption that perfect channel knowledge is available at the receiver must be removed, in order to more accurately examine the system performance. Emphasis is placed on developing channel estimation strategies for an iterative Vertical Bell-Labs Layered Space Time (V-BLAST) architecture. The channel estimate can be sequentially improved between successive iterations of the iterative V-BLAST algorithm. For both the coded and uncoded systems, at high signal to noise ratio only a minimum number of pilot symbols per transmit antenna are required to achieve perfect channel knowledge performance.Master of Science
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Wang, Fei. "Pilot-Based Channel Estimation in OFDM System". University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1302129482.
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Berna, Gedik. "Channel estimation for Amplify and Forward Channels". Thesis, 2008. http://hdl.handle.net/10012/3688.
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Cooperative diversity has been proposed as a powerful means to enhance the performance of high-rate communications over wireless fading channels. It realizes spatial diversity advantages in a distributed manner where two or more nodes share their antennas to mimic a virtual antenna array.
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Kao, Chen-Wei, i 高禎唯. "Nearby Channel V.S. Blind Channel Estimation". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/48584281818353785127.
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碩士國立臺灣海洋大學
通訊與導航工程學系
104
With advancing technology, almost everyone has a mobile phone. Consider a simple and static environment: user A is communicating with base station through channel A by mobile phone and nearby, user B is not using phone. In [13], we know that if a transmitted signal pass through two similar channels, the power distribution of received signals in frequency domain are also similar. Therefore, we hope to abstract some information from user B to support user A. In this paper, we assume the following situation. We estimate channel A by a Blind Subspace Method and obtain channel B information by a Pilot-Assisted Channel Estimation Method. We apply channel B’s information (channel B’s coefficient) to a Blind Subspace Method. The simulation results show that if correlation coefficient is 0.9, i.e. channel A is very similar to channel B, then the converging rates of the Subspace Method is faster. However, while correlation coefficients are 0.6 and 0.1, channel B’s information cannot provide any benefit to channel A because of these are different channels.
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Wan, Ping. "Channel estimation for OFDM in fast fading channels". Thesis, 2011. http://hdl.handle.net/1828/3413.
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The increasing demand for high data rate transmission over broadband
radio channels has imposed significant challenges in wireless
communications. Accurate channel estimation has a major impact on
the whole system performance. Specifically, reliable estimate of the
channel state information (CSI) is more challenging for orthogonal
frequency division multiplexing (OFDM) systems in doubly selective
fading channels than for the slower fading channels over which OFDM
has been deployed traditionally. With the help of a basis expansion
model (BEM), a novel multivariate autoregressive (AR) process is
developed to model the time evolution of the fast fading channel.
Relying on pilot symbol aided modulation (PSAM), a novel Kalman
smoothing algorithm based on a second-order dynamic model is
exploited, where the mean square error (MSE) of the channel
estimator is near to that of the optimal Wiener filter. To further
improve the performance of channel estimation, a novel
low-complexity iterative joint channel estimation and symbol
detection procedure is developed for fast fading channels with a
small number of pilots and low pilot power to achieve the bit error
rate (BER) performance close to when the CSI is known perfectly. The
new channel estimation symbol detection technique is robust to
variations of the radio channel from the design values and
applicable to multiple modulation and coding types. By use of the
extrinsic information transfer (EXIT) chart, we investigate the
convergence behavior of the new algorithm and analyze the
modulation, pilot density, and error correction code selection for
good system performance for a given power level. The algorithms
developed in this thesis improve the performance of the whole system
requiring only low ratios of pilot to data for excellent performance
in fast fading channels.Graduate
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"ATSC DTV Channel Estimation". Thesis, Université Laval, 2009. http://www.theses.ulaval.ca/2009/26235/26235.pdf.
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Liao, Jing-Luen, i 廖經倫. "The Impact of Estimation Error on Channel Estimation-Based Equalizer for UWA Channel". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/68785692990239570269.
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碩士國立臺灣大學
電信工程學研究所
99
Underwater acoustic channels are generally recognized as one of the most difficult communication media in use today. The ocean is a time and spatially varying propagation environment. The underwater acoustic propagation is best supported at low frequencies, and the bandwidth available for communication is extremely limited. The underwater acoustic communication differ from RF communication in two aspects: One is the long multipath delay time that containing ten to hundreds of symbols, and the other is the rapid time variation of underwater acoustic channel. The receiver structure that has been found useful in many applications is a decision-feedback equalizer(DFE). Due to the nature of the propagation channel, the required signal processing is often prohibitively complex, to reduce computational complexity of signal processing, the receiver structures that are matched to the physical channel characteristics are investigates. A channel estimation-based equalization which relies on an adaptive channel estimation to compute its parameters, this estimation is used to cancel the post-cursor ISI before the linear equalization. The impact of estimation error on the channel estimation-based equalizer are investigated.
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Jin, Jinghua. "Diversity receiver design and channel statistic estimation in fading channels /". 2006.
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Guo-Jiun, shiau, i 蕭國濬. "Kalman Channel Estimation for MIMO Systems in Flat Fading Channels". Thesis, 2003. http://ndltd.ncl.edu.tw/handle/77170985239996814402.
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碩士國立臺北科技大學
電腦通訊與控制研究所
91
Recently, a wireless communication architecture known as Vertical BLAST (Bell Laboratories layered Space-Time) or V-BLAST could achieve high spectral efficiency by using multiple transmit and receive antennas. Unfortunately, the channel estimation error results in the poor performance in a V-BLAST system. A modified nulling vector which minimizes the power of various terms generated by the channel estimation errors has been also proposed. However, it still assumes that the channels are fixed during a data block (quasi-static). In this paper, we use Kalman filter to estimate the time-varying channel coefficients within a data block and perform the V-BLAST nulling and modified nulling. We consider the channel-variation in a data block, which is more practical environment. Via simulations, we show the performance improvement of the proposed system.