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1
Chu, Alice Pin-Chen. "High-Rate Space-Time Block Codes in Frequency-Selective Fading Channels". Thesis, University of Canterbury. Electrical and Computer Engineering, 2012. http://hdl.handle.net/10092/10360.
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The growing popularity of wireless communications networks has resulted in greater bandwidth contention and therefore spectrally efficient transmission schemes are highly sought after by designers.
Space-time block codes (STBCs) in multiple-input, multiple-output (MIMO) systems are able to increase channel capacity as well as reduce error rate. A general linear space-time structure known as linear dispersion codes (LDCs) can be designed to achieve high-data rates and has been researched extensively for flat fading channels. However, very little research has been done on frequency-selective fading channels. The combination of ISI, signal interference from other transmitters and noise at the receiver mean that maximum likelihood sequence estimation (MLSE) requires high computational complexity. Detection schemes that can mitigate the signal interference can significantly reduce the complexity and allow intersymbol interference (ISI) equalization to be performed by a Viterbi decoder.
In this thesis, detection of LDCs on frequency-selective channels is investigated. Two predominant detection schemes are investigated, namely linear processing and zero forcing (ZF). Linear processing depends on code orthogonality and is only suited for short channels and small modulation schemes. ZF cancels interfering signals when a sufficient number of receive antennas is deployed. However, this number increases with the channel length. Channel decay profiles are investigated for high-rate LDCs to ameliorate this limitation. Performance improves when the equalizer assumes a shorter channel than the actual length provided the truncated taps carry only a small portion of the total channel power.
The LDC is also extended to a multiuser scenario where two independent users cooperate over half-duplex frequency-selective channels to achieve cooperative gain. The cooperative scheme transmits over three successive block intervals. Linear and zero-forcing detection are considered.
2
Lee, King F. "Space-time and space-frequency coded orthogonal frequency division multiplexing transmitter diversity techniques". Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/14981.
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3
Zheng, Changqing 1979. "Optimum spreading bandwidth for DS-CDMA on time and frequency fading channels". Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/16870.
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Thesis (M.Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (p. 69-70).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
by Changqing Zheng.
M.Eng.and S.B.
4
Shang, Lei, i lei shang@ieee org. "Modelling of Mobile Fading Channels with Fading Mitigation Techniques". RMIT University. Electrical and Computer Engineering, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20061222.113303.
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This thesis aims to contribute to the developments of wireless communication systems. The work generally consists of three parts: the first part is a discussion on general digital communication systems, the second part focuses on wireless channel modelling and fading mitigation techniques, and in the third part we discuss the possible application of advanced digital signal processing, especially time-frequency representation and blind source separation, to wireless communication systems. The first part considers general digital communication systems which will be incorporated in later parts. Today's wireless communication system is a subbranch of a general digital communication system that employs various techniques of A/D (Analog to Digital) conversion, source coding, error correction, coding, modulation, and synchronization, signal detection in noise, channel estimation, and equalization. We study and develop the digital communication algorithms to enhance the performance of wireless communication systems. In the Second Part we focus on wireless channel modelling and fading mitigation techniques. A modified Jakes' method is developed for Rayleigh fading channels. We investigate the level-crossing rate (LCR), the average duration of fades (ADF), the probability density function (PDF), the cumulative distribution function (CDF) and the autocorrelation functions (ACF) of this model. The simulated results are verified against the analytical Clarke's channel model. We also construct frequency-selective geometrical-based hyperbolically distributed scatterers (GBHDS) for a macro-cell mobile environment with the proper statistical characteristics. The modified Clarke's model and the GBHDS model may be readily expanded to a MIMO channel model thus we study the MIMO fading channel, specifically we model the MIMO channel in the angular domain. A detailed analysis of Gauss-Markov approximation of the fading channel is also given. Two fading mitigation techniques are investigated: Orthogonal Frequency Division Multiplexing (OFDM) and spatial diversity. In the Third Part, we devote ourselves to the exciting fields of Time-Frequency Analysis and Blind Source Separation and investigate the application of these powerful Digital Signal Processing (DSP) tools to improve the performance of wireless communication systems.
5
Wavegedara, Kapila Chandika B. "Advanced receivers for space-time block-coded single-carrier transmissions over frequency-selective fading channels". Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/620.
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In recent years, space-time block coding (STBC) has emerged as an effective transmit-diversity technique to combat the detrimental effects of channel fading. In addition to STBC, high-order modulation schemes will be used in future wireless communication systems aiming to provide ubiquitous-broadband wireless access. Hence, advanced receiver schemes are necessary to achieve high performance. In this thesis, advanced and computationally-efficient receiver schemes are investigated and developed for single-carrier space-time (ST) block-coded transmissions over frequency-selective fading (FSF) channels.
First, we develop an MMSE-based turbo equalization scheme for Alamouti ST block-coded systems. A semi-analytical method to estimate the bit error rate (BER) is devised. Our results show that the proposed turbo equalization scheme offers significant performance improvements over one-pass equalization. Second, we analyze the convergence behavior of the proposed turbo equalization scheme for Alamouti ST block-coded systems using the extrinsic information transfer (EXIT)-band chart technique.
Third, burst-wise (BW)-STBC is applied for uplink transmission over FSF channels in block-spread-CDMA systems with multiuser interference-free reception. The performances of different decision feedback sequence estimation (DFSE) schemes are investigated. A new scheme combining frequency-domain (FD) linear equalization and modified unwhitened-DFSE is proposed. The proposed scheme is very promising as the error-floor behavior observed in the existing unwhitened DFSE schemes is eliminated.
Fourth, we develop a FD-MMSE-based turbo equalization scheme for the downlink of ST block-coded CDMA systems. We adopt BW-STBC instead of Alamouti symbol-wise (SW)-STBC considered for WCDMA systems and demonstrate its superior performance in FSF channels. Block spreading is shown to be more desirable than conventional spreading to improve performance using turbo equalization. We also devise approximate implementations (AprxImpls) that offer better trade-offs between performance and complexity. Semi-analytical upper bounds on the BER are derived.
Fifth, turbo multicode detection is investigated for ST block-coded downlink transmission in DS-CDMA systems. We propose symbol-by-symbol and chip-by-chip FD-MMSE-based multicode detectors. An iterative channel estimation scheme is also proposed. The proposed turbo multicode detection scheme offers significant performance improvements compared with non-iterative multicode detection. Finally, the impact of channel estimation errors on the performance of MMSE-based turbo equalization in ST block-coded CDMA systems is investigated.
6
Gong, Yi. "Space-time coding for high data-rate wireless communications over space and frequency selective fading channels /". View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202002%20GONG.
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Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2002.Includes bibliographical references (leaves 105-114). Also available in electronic version. Access restricted to campus users.
7
Nguyen, Linh Trung. "Estimation and separation of linear frequency- modulated signals in wireless communications using time - frequency signal processing". Queensland University of Technology, 2004. http://eprints.qut.edu.au/15984/.
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Signal processing has been playing a key role in providing solutions to key problems encountered in communications, in general, and in wireless communications, in particular. Time-Frequency Signal Processing (TFSP) provides eective tools for analyzing nonstationary signals where the frequency content of signals varies in time as well as for analyzing linear time-varying systems. This research aimed at exploiting the advantages of TFSP, in dealing with nonstationary signals, into the fundamental issues of signal processing, namely the signal estimation and signal separation. In particular, it has investigated the problems of (i) the Instantaneous Frequency (IF) estimation of Linear Frequency-Modulated (LFM) signals corrupted in complex-valued zero-mean Multiplicative Noise (MN), and (ii) the Underdetermined Blind Source Separation (UBSS) of LFM signals, while focusing onto the fast-growing area of Wireless Communications (WCom). A common problem in the issue of signal estimation is the estimation of the frequency of Frequency-Modulated signals which are seen in many engineering and real-life applications. Accurate frequency estimation leads to accurate recovery of the true information. In some applications, the random amplitude modulation shows up when the medium is dispersive and/or when the assumption of point target is not valid; the original signal is considered to be corrupted by an MN process thus seriously aecting the recovery of the information-bearing frequency. The IF estimation of nonstationary signals corrupted by complex-valued zero-mean MN was investigated in this research. We have proposed a Second-Order Statistics approach, rather than a Higher-Order Statistics approach, for IF estimation using Time-Frequency Distributions (TFDs). The main assumption was that the autocorrelation function of the MN is real-valued but not necessarily positive (i.e. the spectrum of the MN is symmetric but does not necessary has the highest peak at zero frequency). The estimation performance was analyzed in terms of bias and variance, and compared between four dierent TFDs: Wigner-Ville Distribution, Spectrogram, Choi-Williams Distribution and Modified B Distribution. To further improve the estimation, we proposed to use the Multiple Signal Classification algorithm and showed its better performance. It was shown that the Modified B Distribution performance was the best for Signal-to-Noise Ratio less than 10dB. In the issue of signal separation, a new research direction called Blind Source Separation (BSS) has emerged over the last decade. BSS is a fundamental technique in array signal processing aiming at recovering unobserved signals or sources from observed mixtures exploiting only the assumption of mutual independence between the signals. The term "blind" indicates that neither the structure of the mixtures nor the source signals are known to the receivers. Applications of BSS are seen in, for example, radar and sonar, communications, speech processing, biomedical signal processing. In the case of nonstationary signals, a TF structure forcing approach was introduced by Belouchrani and Amin by defining the Spatial Time- Frequency Distribution (STFD), which combines both TF diversity and spatial diversity. The benefit of STFD in an environment of nonstationary signals is the direct exploitation of the information brought by the nonstationarity of the signals. A drawback of most BSS algorithms is that they fail to separate sources in situations where there are more sources than sensors, referred to as UBSS. The UBSS of nonstationary signals was investigated in this research. We have presented a new approach for blind separation of nonstationary sources using their TFDs. The separation algorithm is based on a vector clustering procedure that estimates the source TFDs by grouping together the TF points corresponding to "closely spaced" spatial directions. Simulations illustrate the performances of the proposed method for the underdetermined blind separation of FM signals. The method developed in this research represents a new research direction for solving the UBSS problem. The successful results obtained in the research development of the above two problems has led to a conclusion that TFSP is useful for WCom. Future research directions were also proposed.
8
Nguyen, Linh-Trung. "Estimation and separation of linear frequency- modulated signals in wireless communications using time - frequency signal processing". Thesis, Queensland University of Technology, 2004. https://eprints.qut.edu.au/15984/1/Nguyen_Linh-Trung_Thesis.pdf.
Pełny tekst źródłaStreszczenie:
Signal processing has been playing a key role in providing solutions to key problems encountered in communications, in general, and in wireless communications, in particular. Time-Frequency Signal Processing (TFSP) provides eective tools
for analyzing nonstationary signals where the frequency content of signals varies in time as well as for analyzing linear time-varying systems. This research aimed at exploiting the advantages of TFSP, in dealing with nonstationary signals, into the fundamental issues of signal processing, namely the signal estimation and signal separation. In particular, it has investigated the problems of (i) the Instantaneous Frequency (IF) estimation of Linear Frequency-Modulated (LFM) signals corrupted in complex-valued zero-mean Multiplicative Noise (MN), and (ii) the Underdetermined Blind Source Separation (UBSS) of LFM signals, while focusing onto the fast-growing area of Wireless Communications (WCom).
A common problem in the issue of signal estimation is the estimation of the frequency of Frequency-Modulated signals which are seen in many engineering and real-life applications. Accurate frequency estimation leads to accurate recovery of the true information. In some applications, the random amplitude modulation
shows up when the medium is dispersive and/or when the assumption of point target is not valid; the original signal is considered to be corrupted by an MN process thus seriously aecting the recovery of the information-bearing frequency. The IF estimation of nonstationary signals corrupted by complex-valued zero-mean MN
was investigated in this research. We have proposed a Second-Order Statistics approach,
rather than a Higher-Order Statistics approach, for IF estimation using Time-Frequency Distributions (TFDs). The main assumption was that the autocorrelation function of the MN is real-valued but not necessarily positive (i.e. the spectrum of the MN is symmetric but does not necessary has the highest peak at zero frequency). The estimation performance was analyzed in terms of bias and variance, and compared between four dierent TFDs: Wigner-Ville Distribution, Spectrogram, Choi-Williams Distribution and Modified B Distribution. To further improve the estimation, we proposed to use the Multiple Signal Classification algorithm
and showed its better performance. It was shown that the Modified B Distribution performance was the best for Signal-to-Noise Ratio less than 10dB.
In the issue of signal separation, a new research direction called Blind Source Separation (BSS) has emerged over the last decade. BSS is a fundamental technique in array signal processing aiming at recovering unobserved signals or sources from observed mixtures exploiting only the assumption of mutual independence between the signals. The term "blind" indicates that neither the structure of the mixtures nor the source signals are known to the receivers. Applications of BSS are seen in, for example, radar and sonar, communications, speech processing, biomedical signal processing. In the case of nonstationary signals, a TF structure forcing
approach was introduced by Belouchrani and Amin by defining the Spatial Time- Frequency Distribution (STFD), which combines both TF diversity and spatial diversity. The benefit of STFD in an environment of nonstationary signals is the direct exploitation of the information brought by the nonstationarity of the signals.
A drawback of most BSS algorithms is that they fail to separate sources in situations where there are more sources than sensors, referred to as UBSS. The UBSS of nonstationary signals was investigated in this research. We have presented a new approach for blind separation of nonstationary sources using their TFDs. The
separation algorithm is based on a vector clustering procedure that estimates the
source TFDs by grouping together the TF points corresponding to "closely spaced"
spatial directions. Simulations illustrate the performances of the proposed method for the underdetermined blind separation of FM signals. The method developed in this research represents a new research direction for solving the UBSS problem.
The successful results obtained in the research development of the above two problems has led to a conclusion that TFSP is useful for WCom. Future research directions were also proposed.
9
Chi, Xuan. "The Impact of Channel Estimation Error on Space-Time Block and Trellis Codes in Flat and Frequency Selective Channels". Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/33963.
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Recently multiple antenna systems have received significant attention from researchers as a means to improve the energy and spectral efficiency of wireless systems. Among many classes of schemes, Space-Time Block codes (STBC) and Space-Time Trellis codes (STTC) have been the subject of many investigations.Both techniques provide a means for combatting the effects of multipath fading without adding much complexity to the receiver. This is especially useful in the downlink of wireless systems. In this thesis we investigate the impact of channel estimation error on the performance of both STBC and STTC.
Channel estimation is especially important to consider in multiple antenna systems since (A) for coherent systems there are more channels to estimate due to multiple antennas and (B) the decoupling of data streams relies on correct channel estimation. The latter effect is due to the intentional cross-talk introduced into STBC.
Master of Science
10
Sokoya, Oludare Ayodeji. "Performance analysis of channel codes in multiple antenna OFDM systems". Thesis, University of Pretoria, 2012. http://hdl.handle.net/2263/25431.
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Multiple antenna techniques are used to increase the robustness and performance of wireless networks. Multiple antenna techniques can achieve diversity and increase bandwidth efficiency when specially designed channel codes are used at the scheme’s transmitter. These channel codes can be designed in the space, time and frequency domain. These specially designed channel codes in the space and time domain are actually designed for flat fading channels and in frequency selective fading channel, their performance may be degraded. To counteract this possible performance degradation in frequency selective fading channel, two main approaches can be applied to mitigate the effect of the symbol interference due to the frequency selective fading channel. These approaches are multichannel equalisation and orthogonal frequency division multiplexing (OFDM). In this thesis, a multichannel equalisation technique and OFDM were applied to channel codes specially designed for multiple antenna systems. An optimum receiver was proposed for super-orthogonal space-time trellis codes in a multichannel equalised frequency selective environment. Although the proposed receiver had increased complexity, the diversity order is still the same as compared to the code in a flat fading channel. To take advantage of the multipath diversity possible in a frequency selective fading channel, super-orthogonal block codes were employed in an OFDM environment. A new kind of super-orthogonal block code was proposed in this thesis. Super-orthogonal space-frequency trellis-coded OFDM was proposed to take advantage of not only the possible multipath diversity but also the spatial diversity for coded OFDM schemes. Based on simulation results in this thesis, the proposed coded OFDM scheme performs better than all other coded OFDM schemes (i.e. space time trellis-coded OFDM, space-time block coded OFDM, space-frequency block coded OFDM and super-orthogonal space-time trellis-coded OFDM). A simplified channel estimation algorithm was proposed for two of the coded OFDM schemes, which form a broad-based classification of coded OFDM schemes, i.e. trelliscoded schemes and block-coded schemes. Finally in this thesis performance analysis using the Gauss Chebychev quadrature technique as a way of validating simulation results was done for super-orthogonal block coded OFDM schemes when channel state information is known and when it is estimated. The results obtained show that results obtained via simulation and analysis are asymptotic and therefore the proposed analysis technique can be use to obtain error rate values for different SNR region instead of time consuming simulation.Thesis (PhD)--University of Pretoria, 2012.
Electrical, Electronic and Computer Engineering
unrestricted
11
Cavalcante, Lucas Costa Pereira. "Avalia??o de desempenho da codifica??o wavelet em canais seletivos em frequ?ncia". Universidade Federal do Rio Grande do Norte, 2014. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15497.
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Previous issue date: 2014-02-14Wavelet coding has emerged as an alternative coding technique to minimize the fading effects of wireless channels. This work evaluates the performance of wavelet coding, in terms of bit error probability, over time-varying, frequency-selective multipath Rayleigh fading channels. The adopted propagation model follows the COST207 norm, main international standards reference for GSM, UMTS, and EDGE applications. The results show the wavelet coding s efficiency against the inter symbolic interference which characterizes these communication scenarios. This robustness of the presented technique enables its usage in different environments, bringing it one step closer to be applied in practical wireless communication systems
A codifica??o wavelet surgiu como uma t?cnica de codifica??o de canal alternativa para minimizar os efeitos destrutivos dos canais de comunica??o sem fio caracterizados pelo desvanecimento. Esse trabalho avalia o desempenho de sistemas com codifica??o wavelet, em termos de probabilidade de erro de bit, sobre canais de comunica??o com desvanecimento Rayleigh variante no tempo e m?ltiplos percursos seletivos em frequ?ncia. O modelo de propaga??o adotado segue a norma COST207, principal refer?ncia dos padr?es internacionais para aplica??es GSM, UMTS e EDGE. Os resultados demonstram a efici?ncia da t?cnica no combate a interfer?ncia inter-simb?lica, caracter?stica desses cen?rios de comunica??o. Essa robustez habilita o uso da t?cnica em diferentes ambientes, trazendo-a um passo ainda mais pr?ximo de ser aplicada em sistemas pr?ticos de comunica??o sem fio
12
Krémé, Ama Marina. "Modification locale et consistance globale dans le plan temps-fréquence". Electronic Thesis or Diss., Aix-Marseille, 2021. http://www.theses.fr/2021AIXM0340.
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Aujourd'hui, il est devenu facile de retoucher des images, par exemple de flouter une région, ou de la modifier pour faire disparaître ou apparaître un objet, une personne, etc. La retouche d'images fait partie des outils de base de la plupart des logiciels d'édition d'images. Dans le cadre des signaux audio, il est souvent plus naturel d'effectuer de telles retouches dans un domaine transformé, en particulier le domaine temps-fréquence. Là encore, c'est une pratique assez courante, mais qui ne repose pas nécessairement sur des arguments théoriques solides. Des cas d'applications incluent la restauration de régions du plan temps-fréquence où une information a été perdue (par exemple l'information de phase), la reconstruction d'un signal dégradé par une perturbation additive bien localisée dans le plan temps-fréquence, ou encore la séparation de signaux localisés dans différentes régions du plan temps-fréquence. Dans cette thèse, nous proposons et développons des méthodes théoriques et algorithmiques pour résoudre ce type de problème. Nous les abordons dans un premier temps comme un problème de reconstruction de données manquantes dans lequel il manque certaines phases des coefficients temps-fréquence. Nous formulons mathématiquement le problème, puis nous proposons trois méthodes pour le résoudre. Dans un second temps, nous proposons une approche qui consiste à atténuer une source de dégradation avec l'hypothèse que celle-ci est bien localisée dans une région spécifique du plan temps-fréquence. Nous obtenons la solution exacte du problème qui fait intervenir des opérateurs appelés multiplicateurs de GaborNowadays, it has become easy to edit images, such as blurring an area, or changing it to hide or add an object, a person, etc. Image editing is one of the basic tools of most image processing software. In the context of audio signals, it is often more natural to perform such an editing in a transformed domain, in particular the time-frequency domain. Again, this is a fairly common practice, but not necessarily based on sound theoretical arguments. Application cases include the restoration of regions of the time-frequency plane where information has been lost (e.g. phase information), the reconstruction of a degraded signal by an additive perturbation well localized in the time-frequency plane, or the separation of signals localized in different regions of the time-frequency plane. In this thesis, we propose and develop theoretical and algorithmic methods to solve this issue. We first formulate the problem as a missing data reconstruction problem in which the missing data are only the phases of the time-frequency coefficients. We formulate it mathematically, then we propose three methods to solve it. Secondly, we propose an approach that consists in attenuating a source of degradation with the assumption that it is localized in a specific region of the time-frequency plane. We consider the case where the signal of interest is perturbed by an additive signal and has an energy that is more widely spread in the time-frequency plane. We formulate it as an optimization problem designed to attenuate the perturbation with precise control of the level of attenuation. We obtain the exact solution of the problem which involves operators called Gabor multipliers
13
Menon, Rekha. "Impact of Channel Estimation Errors on Space Time Trellis Codes". Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/36490.
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Space Time Trellis Coding (STTC) is a unique technique that combines the use of multiple transmit antennas with channel coding. This scheme provides capacity benefits in fading channels, and helps in improving the data rate and reliability of wireless communication. STTC schemes have been primarily designed assuming perfect channel estimates to be available at the receiver. However, in practical wireless systems, this is never the case. The noisy wireless channel precludes an exact characterization of channel coefficients. Even near-perfect channel estimates can necessitate huge overhead in terms of processing or spectral efficiency. This practical concern motivates the study of the impact of channel estimation errors on the design and performance of STTC.
The design criteria for STTC are validated in the absence of perfect channel estimates at the receiver. Analytical results are presented that model the performance of STTC systems in the presence of channel estimation errors. Training based channel estimation schemes are the most popular choice for STTC systems. The amount of training however, increases with the number of transmit antennas used, the number of multi-path components in the channel and a decrease in the channel coherence time. This dependence is shown to decrease the performance gain obtained when increasing the number of transmit antennas in STTC systems, especially in channels with a large Doppler spread (low channel coherence time). In frequency selective channels, the training overhead associated with increasing the number of antennas can be so large that no benefit is shown to be obtained by using STTC.
The amount of performance degradation due to channel estimation errors is shown to be influenced by system parameters such as the specific STTC code employed and the number of transmit and receive antennas in the system in addition to the magnitude of the estimation error. Hence inappropriate choice of system parameters is shown to significantly alter the performance pattern of STTC.
The viability of STTC in practical wireless systems is thus addressed and it is shown that that channel estimation could offset benefits derived from this scheme.
Master of Science
14
Marques, Julian Marcell Enzveiler. "Uma comparação entre metodologias para cálculo da vida em fadiga no domínio do tempo e da frequência com aplicação na simulação dinâmica de implementos rodoviários". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/163899.
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Atualmente, a exigência da indústria na construção de estruturas complexas é consequência da acirrada concorrência, principalmente, entre empresas dos segmentos rodoviários. Com o auxílio de ferramentas computacionais, baseadas no Método de Elementos Finitos, é possível dimensionar essas estruturas submetidas a solicitações aleatórias variando no tempo. Nesse caso, é comum a realização de simulações dinâmicas no domínio do tempo que se empregue um modelo de Elementos Finitos de placa ou viga e, assim, obter as tensões nos locais críticos de interesse. Porém, análises no domínio do tempo capturam tensões e deformações com boa precisão, mas costumam ser caras computacionalmente. Na maioria dos casos estudados, a vida em fadiga é fundamental para prever falhas estruturais de elevadas proporções, como o colapso da viga principal da estrutura chassi de um implemento rodoviário. Diante disso, são de interesse tecnológico e industrial as análises no domínio da frequência, a fim de diminuir o custo computacional de simulação dinâmica independente do modelo de Elementos Finitos. Com esse propósito, o presente trabalho propõe uma comparação entre metodologias capazes em estimar a vida em fadiga no domínio do tempo e da frequência, de um caso simples e um segundo caso, mais complexo, que é o da indústria. Os diferentes modelos de Elementos Finitos e métodos de cálculos da vida em fadiga no domínio da frequência são comparados e discutidos, usando-se como referência o método clássico de cálculo da vida em fadiga, domínio do tempo. A metodologia leva em conta os diferentes Elementos Finitos empregados, as simplificações dos modelos estruturais usados e potenciais restrições cinemáticas aplicadas ao modelo. A comparação é feita com a ajuda de ferramentas comerciais que executam as análises modais, harmônicas, transientes, espectrais e rotinas de cálculos. Assim, o analista pode selecionar malhas com quantidade viável de graus de liberdade tornando possível as simulações dinâmicas e, além disso, prever a vida em fadiga no domínio do tempo para modelos simples e complexos. A partir dos resultados, verificou-se que as análises de estimativa da vida em fadiga no domínio da frequência, para modelos complexos, ainda não apresentam resultados confiáveis e, assim, são sugeridas recomendações.Currently, the industry demand for the construction of complex structures is a consequence of the fierce competition, mainly between companies from semi-trailers segments. With the support of computational tools, based on the Finite Element Method, it is possible to size these structures submitted to random requests varying in time. In this case, it is common to perform dynamic simulations in the time domain to use a Finite Element model of plate or beam and thus obtain the stresses at the critical sites of interest. However, time domain analyses capture tensions and deformations with good accuracy, but they are often computationally expensive. In most of the studied cases, fatigue life is fundamental to predict structural failures of high proportions, such as main beam collapse of the chassis structure of a semi-trailer. Therefore, the semi-trailer industry segments is interested in the frequency domain, in order to reduce the computational cost of dynamic simulation no matter of the Finite Element model. With this purpose, the present work proposes a comparison between methodologies which are able to estimate the fatigue life in time domain and frequency, of a simple and second case, more complex, that of the industry. The different Finite Element models and methods of calculating fatigue life in frequency domain are compared and discussed using the classic time domain fatigue life calculation method as reference. The methodology takes into account the different Finite Elements are used, the simplifications of the structural models used and potential kinematic constraints applied to the model. The comparison is made with not only the following analyses: modal, harmonic, transient, spectral, but also computational routines. Thus, the analyst can select meshes with a viable amount of degrees of freedom making dynamic simulations possible, in addition, to its predict the fatigue life in time domain for simple and complex models. Based on the results, it was verified that the fatigue life estimates in frequency domain, for complex models, do not present reliable results yet. Therefore, recommendations are suggested.
15
Chen, Harry Zhi Bing. "Space-time coding for frequency-selective fading channels". Thesis, 2003. http://hdl.handle.net/2429/15161.
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This thesis studies space-time coded transmissions over frequency-selective channels. For
this, the performance of maximum likelihood sequence estimation (MLSE) decoding is
analyzed, taking into account channel estimation errors. Furthermore, reduced complexity
suboptimum decoding schemes are investigated.
To analyze MLSE decoding performance, three lower bounds, namely, the matched
filter bound (MFB), the improved MFB (IMFB), and the IMFB I, are derived. The MFB
assumes no intersymbol interference (ISI) in the received symbols, while IMFB takes into
account the effect of ISI of neighboring symbols, and thus provides a tighter bound. IMFB JL,
which is the tightest lower bound for time-reversal and space-time block coding (TR-STBC),
in addition, considers the decoupling errors of the symbols from the other transmit antenna.
Our numerical results for delay diversity (DD), TR-STBC, and maximum ratio combining
(MRC) show that the IMFB, and especially the IMFB JL, match well with simulation results.
For reduced complexity decoding, we present three different decision-feedback sequence
estimation (DFSE) schemes for TR-STBC and' DD. The first scheme, called unwhitened
DFSE (U-DFSE), performs reduced-state sequence estimation based on the output of the
spatial-temporal matched filter (MF) typically employed in TR-STBC. The second approach
improves upon U-DFSE by subtracting a bias term caused by anti-causal interference
from the U-DFSE metric. In the third scheme, the noise component in the output of the
spatial-temporal MF is first whitened using a prediction-error filter that can be efficiently computed using the Levinson-Durbin algorithm. Subsequently, whitened DFSE (W-DFSE)
is performed. Our results show that for binary modulation, U-DFSE and its improved version
can approach the performance of W-DFSE for the full range of delay spreads relevant
for the global system of mobile communication (GSM) and enhanced data rates for GSM
evolution (EDGE). On the other hand, for high-level modulation, only W-DFSE gives a
satisfactory performance.
16
YEN, YU-SHUN, i 顏于舜. "Orthogonal Frequency/Time-Multiplexed Amplitude Modulations in Flat Fading Channel". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/74378408194468502678.
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碩士逢甲大學
通訊工程學系
103
In this paper, we research on orthogonal time-domain multiplexed modulation and orthogonal frequency-domain multiplexed modulation in flat fading channel. The bit error rate performances of OTMOAM in flat fading channel is simulated and compared with OMOAM. Peak-to-average ratio performances of OTMOAM in flat fading channel is simulated and compared with OMOAM. We show through simulation that performance of OTMOAM is better than OMOAM.
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Hau, Shiu Juin, i 許君豪. "A deterministic simulation model for time and frequency selective fading channel". Thesis, 2003. http://ndltd.ncl.edu.tw/handle/57351557762935642683.
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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
The research and simulation modeling on wireless fading channel is very important to analyze and evaluate the performance for mobile communication. For this important need, this thesis concerns how to use sum of sinusoids, which how different magnitude, different Doppler frequency (or excess delay time) and random phase, to synthesis a color Gaussian random process. The simulated fading channel needs to meet the statistical properties about the time selective and frequency selective fading channel. Furthermore, the table look up technique will be used to develop a wireless high-speed channel simulation modeling for increasing the simulation efficiency. Finally, the high -speed simulated fading channel for frequency selective statistics is used to evaluate the performance of OFDM system under the different environment parameters.
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Shih-Chuan, Chou. "Space-Time Code Scheme for CPFSK Modulation over Frequency-Selective Fading Channel". 2006. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0016-1303200709315226.
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Wu, Jian-Jhong, i 吳建中. "Blind Decoding of Serially Concatenated Space-Time Codes in Frequency-Selective Fading". Thesis, 2002. http://ndltd.ncl.edu.tw/handle/82242430447692209899.
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碩士國立交通大學
電信工程系
90
Space-time (ST) codes arrange the transmitted coded symbols in both time and spatial domains in such ways so as to achieve high coding gain while taking full advantage of the transmit and receive diversity. This thesis proposes decoder structures for ST block codes and ST trellis codes. The decoders use the turbo principle to decode the "equivalent" serially-concatenated ST codes, assuming a frequency selective fading environment. We first examine a serially concatenated ST block coded system. It consists of a nonrecursive convolutional code as the outer code and a ST block codes as the inner codes with an interleaver inserted in between them. The second system is a ST trellis coded scheme. The receiver regards the received samples as if they are serially-concatenated coded with a ST trellis codes as the outer code and the equivalent frequency selective FIR channel model as the inner codes with an interleaver placed at the output of the ST encoder. The performance of both systems under perfect channel state information is examined first. We then consider the more practical case issue when channel state has to be estimated. To begin with, we discuss the scenario when pilot symbols are available. Pseudo-maximum-likelihood (PML) and block least mean square (BLMS) methods are used to derive proper solutions. In order to increase bandwidth eciency, i.e., reduce the length of transmitted pilot symbols, Viterbi algorithm (VA) will be associated with them for channel estimation. The second scenario is the blind case where there is no pilot symbols. We make use of the concept of tree search together with a branch and bound algorithm to reduce the complexity and make the overall algorithm practical. Numerical system performance for various receiver structures is obtained and compared via computer simulation. We show that a multiple-antenna system does deliver diversity gain it promises and iterative decoding procedure of (equivalent) serially-concatenated codes results in performance improvement. Numerical results also indicate that all our proposed detector structures are efficient and practical.
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Cheng, Chih-Chung, i 鄭志崇. "Space-Time Code Design for CPFSK Modulation over Frequency-Nonselective Fading Channels". Thesis, 2005. http://ndltd.ncl.edu.tw/handle/84051705758262284423.
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博士國立清華大學
電機工程學系
93
In this thesis, we derive a novel space-time code design criterion for continuous phase frequency shift keying (CPFSK) over frequency-nonselective fading channels. Our derivation is based on a specific matrix that is related to the input symbols of the CPFSK modulators. With this code design criterion, we propose a simple interleaved space-time encoding scheme for CPFSK modulation over frequency-nonselective correlated fading channels to exploit potential temporal and spatial diversity advantages. Such an encoding scheme consists of a ring convolutional encoder and a spatial encoder between which a convolutional interleaver is placed. A decoding algorithm that generates symbol metrics for the Viterbi decoder of convolutional codes from the spatial modulation trellis is examined. Simulation results confirm that the advantages of combination of the interleaved convolutional encoding (for temporal diversity) and the spatial encoding (for spatial diversity) are promising for various system parameters.
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Cheng, Hung-Yi, i 鄭宏毅. "Space-Time Code Design over Frequency-Nonselective Fading Channels by Division Algebras". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/70591553601622639459.
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碩士國立清華大學
電機工程學系
97
In this thesis, we derive a new space-time code design criterion for linear modulation over frequency-nonselective fading channels. In order to achieve maximum transmit spatial diversity, we first adopt a method in the literature to use division algebras to design an inner space-time code length equal to the number of transmit antennas. Then this short inner space-time code in concatenated with a ring systematic convolutional encoder to encode a space-time code of full length to achieve the maximum transmit diversity. For practical channels, we place an interleaver between convolutional encoder and the mini space-time encoder to combat the correlated fading. Both theoretical analytic and simulation results show that our proposed coding scheme is very effective.
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Chou, Shih-Chuan, i 周世權. "Space-Time Code Scheme for CPFSK Modulation over Frequency-Selective Fading Channel". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/80202323909069846694.
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碩士國立清華大學
電機工程學系
94
In this thesis, we derive a space-time code design criterion for continuous phase frequency shift keying (CPFSK) over frequency-selective fading channels. Our derivation is based on a speci¯c matrix that is related to the input symbols of the CPFSK modulators. With this code design criterion, we propose a simple interleaved space-time encoding scheme for CPFSK modulation over frequency-selective correlated fading channels to exploit potential temporal, spatial and multipath diversity advantages. Such an encoding scheme consists of a ring convolutional encoder followed by a spatial encoder between which a convolutional interleaver and cascaded with an extender is placed. A decoding algorithm that generates symbol metrics for the Viterbi decoder of convolutional codes from the spatial modulation trellis is examined.
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Shih, Min-Chi, i 施旻奇. "Space-Time Code Design for QPSK Modulation over Frequency-Nonselective Fading Channels". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/99351375178113141964.
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碩士國立清華大學
通訊工程研究所
95
In this thesis, we proposed a new space-time encoding scheme for QPSK modulation over frequency-nonselective fading channels. This scheme alleviates the tradeoff between the diversity and the rate of space-time coding by increasing decoding complexity. We derived the space-time code design criteria over fast fading channels. This scheme consists of a systematic convolutional encoder over a ring and a spatial encoder, and in addition, an interleaver to combat with correlated fading. Simulation results have confirmed the excellent performance of our proposed scheme.
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Li, Chi-Ming, i 李啟銘. "Space-Time Code Design for Linear Modulation over Frequency-Selective Fading Channels". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/3n9t57.
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碩士國立清華大學
電機工程學系所
105
In this thesis, we derived the rank design criterion of a space-time code scheme for linear modulation over frequency-selective fast fading channels with oversampling technique. With an optimal convolutional temporal encoder and an optimal spatial encoder achieving the full transmit spatial diversity, the overall diversity gain is at least Lr(L*ECL*L) if L<=l and Lr(Lt*ECL*l+L-l) if L >l, where Lr is the number of receive antennas, Lt the number of transmit antennas, ECL the effective code length of the convolutional encoder, l the oversampling factor and L the number of taps in the equivalent tapped-delay-line channel model. We have devised an finite-state machine for a Viterbi decoder which implements the maximum likelihood sequential detection of the received signal.Simulation results have confirmed that this coding scheme is very effective.
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Tang, Xin. "Adaptive DS-CDMA multiuser detection for time variant frequency selective Rayleigh fading channel". Thesis, 2002. http://library1.njit.edu/etd/fromwebvoyage.cfm?id=njit-etd2002-075.
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Chou, Yung-Chun, i 周永濬. "Iterative Decoding of Space-Time Code Design for CPFSK Modulation over Frequency-Nonselective Fading Channels". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/38713118619399293095.
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Xu, Di-Lan, i 許迪嵐. "Direct-sequence spread-spectrum paralell acquisition in a time selective frequency nonselective rayleigh fading channel". Thesis, 1993. http://ndltd.ncl.edu.tw/handle/79015258442134241061.
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Tsai, Jih-Lin, i 蔡季霖. "Performance Analysis of Space-Time Block Code and Space-Frequency Block Code over Wireless Fading Channel". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/61053280341956313881.
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碩士國立中興大學
通訊工程研究所
96
Space-time coding had improved the performance of wireless transmission. And this technology had been implemented into many wireless transmission standards. The reason that we choose this subject as our research field is because of the WiMAX technol-ogy. We take the STBC and OFDM system to simulate the performance results of both STBC only and STBC-OFDM system. The environment is using the European standard COST 207 as the channel to transmit datas. First, we will take the STBC schemes proposed by Alamouti and Tarokh to transmit through the flat-fading channel to see the system performance. Then implying the OFDM system to substitute the transmission in time domain to transmission in fre- quency domain. Later on, we will simulate the system transmission without OFDM and with OFDM over multipath fading channel, to see the improvement of the performance.
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Yang, Chieh-Chih, i 楊傑智. "On Frequency-Domain Equalization with Training-Based Channel Estimation for Orthogonal Space-Time Block Coded System via MIMO Frequency-Selective Fading Channels". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/02950626224237711536.
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碩士國立交通大學
電機與控制工程系所
95
We propose an instructive derivation for the generalized block-level orthogonal space-time block encoder, capable of achieving full spatial diversity via frequency- selective fading environment provided that channel order is known. Instead of dealing with special case and then extending the results intuitively, we provide an alternative by starting with the general signal model with multiple transmit and multiple receive antennas, from which a general form of block-level orthogonality is established. In particular, transmit diversity with more than two transmit antennas can be achieved without compromise by means of frequency-domain equalization, in contrast to the QO-STBC-based approach. Pairwise error probability analysis is derived, under certain assumption which is numerically supported by simulation results, for analytical verifications of our claim on full diversity, inclusive of transmit-receive diversity and the multipath one. Moreover, the encoder structure enables us to generalize a training-based channel estimation technique, originally proposed for flat-fading scenario, to the frequency-selective fading scenario. Surprisingly we even obtain similar optimality criteria for optimal training block design which in our case, the signal block are fixed as OSTBC-based and the design derivation reduces to derive optimal power constraint over the training blocks. The optimality criteria for the training blocks are easy to satisfy when randomness of signal constellation is not a concern. Simulation results validate our discussion of the behaviors of the least-squares and linear MMSE channel estimates.
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Lai, Wei-yu, i 賴威諭. "Iterative Multiuser Detection for Single Carrier Space-Time Block-Coded CDMA transmission Over Frequency-Selective Fading Channel". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/qks43r.
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碩士國立臺灣科技大學
電機工程系
94
In this thesis, we combine single carrier space-time blocked transmission with multi-user CDMA system, in the meanwhile, we adopt low complexity iterative multi-user detection and consider frequency selective fading channel. Besides, in order to increase data rate, we use super-orthogonal codes to extension. In transmitter, for combination of super-orthogonal codes, CDMA system and single carrier transmission, we propose a new space-time block codes structure. Take two transmitter antennas as an example, this structure need to have two spreading sequence to distinguish different user. Utilization of MTCM, we can increase data rate and apply this structure to multi-user system. The receiver, based on these user-specific sequences, intends to differentiate the active users by invoking the “turbo principle” decoding due to the serially concatenated framework. A soft-input soft-output (SISO) interference suppressor for each user is first derived by minimum mean-square error sense to provide the reliability estimates of coded bits, assuming the channel state information is known precisely at the receiver. The resulting extrinsic information for coded bit streams is passed through a bank of single-user decoders after being de-interleaved. Simulation results demonstrate system performance in terms of bit error probability with variant ratio of the number of users to spreading length for the receiver equipped with multi-antennas. Besides, the performance comparison with conventional coded DS-CDMA systems is also manifested under the constraint of identical power and bandwidth efficiencies.
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Lin, Chi-Lin, i 林奇霖. "Performance Analysis of Multi-Carrier DS-CDMA Wireless Systems Using Frequency-Time Spreading Codes in Fading Channels". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/20414969088822420624.
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碩士國立中興大學
電機工程學系所
94
In this thesis, we focus on the improvement of the coding schemes in multicarrier direct-sequence code-division multiple-access (MC/DS-CDMA) systems. While two-dimensional (2-D) orthogonal variable spreading factor (OVSF) codes with good auto- and cross-correlation properties were proposed for the MC/DS-CDMA systems in order to eliminate multiple-access interference, the number of orthogonal code sequence is restricted by the code length. Therefore, 2-D frequency-time spreading (FTS) code was proposed to increase the number of orthogonal code sequences by sacrificing some performance. To further improve the code cardinality and system performance, we here propose a modified 2-D FTS code. The new coding scheme uses Walsh code for frequency hopping, but a modified Barker code for time spreading. The new code is obtained by special permutations of Walsh code onto the time slots of the modified Barker code. To keep the cross-correlation functions as low as possible, the permutation is algebraic controlled by prime sequences over Galois field of a prime number. Finally, we evaluate the performance of the modified 2-D FTS code in the MC/DS-CDMA system over a non-fading AWGN, Rayleigh fading, and Rician fading channel, and compare with those of the 2-D OVSF and original FTS codes.
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Li, Wei-Jhen, i 李瑋真. "A Study of Diversity-Multiplexing Tradeoff of a Space-Time Code Design over Frequency-Nonselective Fading Channels". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/4ht8ve.
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碩士國立清華大學
電機工程學系所
106
In this thesis, we derived a simple diversity-multiplexing tradeoff of a space-time coding scheme for linear modulation over frequency-nonselective fading channels. With an optimal convolutional temporal encoder and the Golden spatial code, which achieves the full transmit spatial diversity, the maximum overall diversity gain is Lr*Lt*ECL over fast fading channels, where Lr is the number of receive antennas, Lt the number of transmit antennas, ECL the effective code length of the convolutional encoder. With the Viterbi decoder, simulation results demonstrate the theoretical analysis and justify the effectiveness of our coding scheme.
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Emad, Amin. "Effects of interference on carrier tracking in fading and symbol synchronization". Master's thesis, 2009. http://hdl.handle.net/10048/720.
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Thesis (M. Sc.)--University of Alberta, 2009.Title from PDF file main screen (viewed on Dec. 14, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science, Department of Electrical and Computer Engineering, University of Alberta." Includes bibliographical references.
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Liu, Che-Chih, i 劉哲誌. "A Study of Diversity-Multiplexing Tradeoff of a Space-Time Code Design over Multiple Access Frequency-Nonselective Fading Channels". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/gqup58.
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碩士國立清華大學
電機工程學系所
106
In this thesis, we derived the rank design criterion of a space-time coding scheme for linear modulation over multiple access frequency-nonselective fast fading channels and gave a simple code construction for multiple access channels. We also evaluated the diversity and multiplexing tradeoffs under both single and multiple users cases. We observed that the diversity gain of our space-time coding scheme is greater than that of the uncoded optimal one in low multiplexing gain, but is smaller in high multiplexing gain.
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Χριστοδούλου, Κωνσταντίνος. "Δέκτες χωροχρονικής κωδικοποίησης για συχνοτικά επιλεκτικά συστήματα". Thesis, 2010. http://nemertes.lis.upatras.gr/jspui/handle/10889/3669.
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Η χωροχρονική μπλοκ κωδικοποίηση (STBC) αποτελεί μία αποδοτική και ευρέως διαδεδομένη τεχνική διαφορετικότητας μετάδοσης για την αντιμετώπιση του φαινομένου της εξασθένησης στις ασύρματες επικοινωνίες. Χαρακτηριστικό παράδειγμα είναι ο ορθογώνιος κώδικας του σχήματος Alamouti, ο οποίος με δύο κεραίες μετάδοσης επιτυγχάνει τη μέγιστη χωρική διαφορετικότητα στο μέγιστο δυνατό ρυθμό μετάδοσης, για οποιονδήποτε (πραγματικό ή μιγαδικό) αστερισμό συμβόλων. Ωστόσο, το σχήμα Alamouti έχει σχεδιαστεί για συχνοτικά επίπεδα κανάλια. Στην παρούσα εργασία μελετούμε την εφαρμογή STBC σε κανάλια συχνοτικά επιλεκτικής εξασθένησης. Εστιάζουμε κυρίως στο συνδυασμό του σχήματος Alamouti με τεχνικές εξάλειψης της διασυμβολικής παρεμβολής, εξετάζοντας τα σχήματα OFDM-STBC, FDE-STBC και TR-STBC, που έχουν προταθεί στη βιβλιογραφία. Επιπρόσθετα των συμβατικών δεκτών, για τα δύο τελευταία σχήματα περιγράφουμε και προσαρμοστικούς δέκτες, οι οποίοι παρακολουθούν τις μεταβολές του καναλιού, χωρίς να απαιτούν την ακριβή εκτίμησή του. Η έρευνα πάνω στα προηγούμενα σχήματα οδήγησε σε ορισμένα αξιόλογα αποτελέσματα. Κατ’ αρχήν, αποδεικνύουμε ότι τα σχήματα FDE-STBC και TR-STBC είναι ισοδύναμα, μολονότι καθένα εφαρμόζει διαφορετική κωδικοποίηση στα μεταδιδόμενα δεδομένα. Επίσης, σχεδιάζουμε έναν νέο δέκτη για το σχήμα TR-STBC, τον οποίο αναπτύσσουμε και σε προσαρμοστική μορφή. Βασικό πλεονέκτημα του προτεινόμενου δέκτη είναι ότι εκμεταλλεύεται τους κυκλικούς πίνακες συνέλιξης για τη μείωση της πολυπλοκότητας αποκωδικοποίησης. Τέλος, η απόδοση κάθε σχήματος και δέκτη αξιολογείται σε διάφορες συνθήκες εξασθένησης μέσω προσομοιώσεων σε υπολογιστικό περιβάλλον.Space-time block coding (STBC) is an effective and widely used transmit diversity technique to combat multipath fading in wireless communication systems. A prominent example of STBC is the orthogonal code of Alamouti scheme, which achieves full spatial diversity at full transmission rate for two transmit antennas and any (real or complex) signal constellation. However, Alamouti scheme has been designed only for frequency-flat channels. In this thesis we study the application of STBC in frequency-selective channels. We mainly focus on combining Alamouti scheme with techniques for mitigating intersymbol interference, by studying several schemes (OFDM-STBC, FDE-STBC and TR-STBC) that have been proposed in literature. In addition to the conventional receivers, for FDE-STBC and TR-STBC we describe adaptive receivers too, which have the ability of tracking channel variations, without requiring explicit channel estimation. Research made upon the above schemes has come to some remarkable results. First, we prove that TR-STBC and FDE-STBC are equivalent, although each one encodes differently the transmitted data. Then, we design a new receiver for TR-STBC, which exploits the circulant convolution matrices, in order to reduce decoding complexity and we, also, develop an adaptive structure for the proposed receiver. At last, we evaluate the performance of all the described schemes and receivers in different fading conditions, by using computer simulations.