Dissertations / Theses on the topic 'Constant Modulus Algorithm'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 30 dissertations / theses for your research on the topic 'Constant Modulus Algorithm.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
Schumacher, Robert G. Jr. "An Efficient FPGA Implementation of a Constant Modulus Algorithm Equalizer for Wireless Telemetry." University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1417738709.
Full textBatra, Anuj. "Extensions of the constant modulus algorithm and the phase-locked loop for blind multiuser detection." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/15360.
Full textLuo, Yuhui. "A mixed cross-correlation and constant modulus adaptive algorithm for joint blind equalisation and source separation." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270380.
Full textTaiwo, Peter, and Itie Serge Kone Dossongui. "Towards Real-Time CMA Equalization by using FFT for Signal Blocks transmitted over an Aeronautical channel." International Foundation for Telemetering, 2016. http://hdl.handle.net/10150/624260.
Full textJauhar, Ahmad Shujauddin. "A CMA-FRESH Whitening Filter for Blind Interference Rejection." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/85389.
Full textMaster of Science
Wireless communication is complicated by the fact that multiple radios may be attempting to transmit at the same frequency, time and location concurrently. This scenario may be a due to malicious intent by certain radios (jamming), or mere confusion due to a lack of knowledge that another radio is transmitting in the same channel. The latter scenario is more common due to congested wireless spectrum, as the number of devices increases exponentially. In either case, interference results. We present a novel interference rejection method in this work, one that is blind to the properties of the interferer and adapts to cancel it. It follows the philosophy of property restoration as extolled by the constant modulus algorithm (CMA) and is a frequency shift (FRESH) filter, hence the name. The process of restoring the wireless spectrum to white noise is what makes it a whitening filter, and is also how it adapts to cancel interference. Such a filter has myriad possible uses, and we examine the use case of rejecting interference to detect or recover the signal-of-interest (SOI) that we are attempting to receive. We present performance results in both cases and compare with conventional time-invariant filters and state of the art FRESH filters.
Xingwen, Ding, Zhai Wantao, Chang Hongyu, and Chen Ming. "CMA BLIND EQUALIZER FOR AERONAUTICAL TELEMETRY." International Foundation for Telemetering, 2016. http://hdl.handle.net/10150/624262.
Full textFilho, João Mendes. "Algoritmos eficientes para equalização autodidata de sinais QAM." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/3/3142/tde-15032012-122010/.
Full textIn this work, we propose efficient blind algorithms for equalization of communication channels, considering the transmission of QAM (quadrature amplitude modulation) signals. Their error functions are constructed in order to make the estimation error equal to zero at the coordinates of the constellation symbols. This characteristic enables the proposed algorithms to have a similar performance to that of a supervised equalization algorithm as the NLMS (normalized least mean-square), independently of the QAM order. Under some favorable conditions, we verify analytically that the coefficient vector of the proposed algorithms are collinear with the Wiener solution. Furthermore, using the information of the symbol estimate in conjunction with its neighborhood, we propose schemes of low computational cost in order to improve their convergence rate. The divergence of the constant-modulus based algorithm is avoided by using a mechanism, which disregards nonconsistent estimates of the transmitted symbols. Additionally, we present a tracking analysis in which we obtain analytical expressions for the excess mean-square error in stationary and nonstationary environments. From these expressions, we verify that using a fractionally-spaced equalizer in a noiseless stationary environment, the proposed algorithms can achieve perfect equalization, independently of the QAM order. The algorithms are extended to jointly adapt the feedforward and feedback filters of the decision feedback equalizer, taking into account a mechanism to avoid degenerative solutions. Simulation results suggest that the proposed schemes may be advantageously used to recover QAM signals and make the switching to the decision direct mode unnecessary.
Fernandes, Carlos Alexandre Rolim. "EqualizaÃÃo adaptativa e autodidata de canais lineares e nÃo-lineares utilizando o algoritmo do mÃdulo constante." Universidade Federal do CearÃ, 2005. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=2041.
Full textEste trabalho trata da proposiÃÃo de algoritmos para equalizaÃÃo cega de canais lineares e nÃao-lineares inspirados no Algoritmo do MÃdulo Constante (CMA). O CMA funciona de maneira bastante eficiente com constelaÃÃes nas quais todos os pontos possuem a mesma amplitude, como em modulaÃÃes do tipo Phase Shift Keying (PSK). Entretanto, quando os pontos da constelaÃÃo podem assumir diferentes valores de amplitudes, como em modulaÃÃes do tipo Quadrature Amplitude Modulation (QAM), o CMA e seus derivados muitas vezes nÃo funcionam de forma satisfatÃria. Desta forma, as tÃcnicas aqui propostas sÃo projetadas para melhorar a performance do CMA em termos de velocidade de convergÃncia e precisÃo, quando operando em sinais transmitidos com diversos mÃdulos, em particular para a modulaÃÃo QAM. Assim como o CMA, para possuir um bom apelo prÃtico, essas tÃcnicas devem apresentar bom compromisso entre complexidade, robustez e desempenho. Para tanto, as tÃcnicas propostas utilizam o Ãltimo sÃmbolo decidido para definir uma estimaÃÃo de raio de referÃncia para a saÃda do equalizador. De fato, esses algoritmos podem ser vistos como generalizaÃÃes do CMA e de alguns derivados do CMA para constelaÃÃes com mÃltiplos raios. A proposiÃÃo de algoritmos do tipo gradiente estocÃstico à concluÃda com o desenvolvimento de tÃcnicas originais, baseadas no CMA, para equalizaÃÃo de canais do tipo Wiener, que consiste em um filtro linear com memÃria, seguido por um filtro nÃo-linear sem memÃria. As expressÃes para a adaptaÃÃo do equalizador sÃo encontradas com o auxÃlio de uma notaÃÃo unificada para trÃs diferentes estruturas: i) um filtro de Hammerstein; ii) um filtro de Volterra diagonal; e iii) um filtro de Volterra completo. Um estudo teÃrico acerca do comportamento do principal algoritmo proposto, o Decision Directed Modulus Algorithm (DDMA) à realizado. SÃo analisadas a convergÃncia e a estabilidade do algoritmo atravÃs de uma anÃlise dos pontos de mÃnimo de sua funÃÃo custo. Outro objetivo à encontrar o valor teÃrico do Erro MÃdio QuadrÃtico MÃdio em Excesso - Excess Mean Square Error (EMSE) fornecido pelo DDMA considerando-se o caso sem ruÃdo. Ao final, à feito um estudo em que se constata que o algoritmo DDMA possui fortes ligaÃÃes com a soluÃÃo de Wiener e com o CMA. VersÃes normalizadas, bem como versÃes do tipo Recursive Least Squares (RLS), dos algoritmos do tipo gradiente estocÃstico estudados sÃo tambÃm desenvolvidas. Cada famÃlia de algoritmos estudada fie composta por quatro algoritmos com algumas propriedades interessantes e vantagens sobre as tÃcnicas clÃssicas, especialmente quando operando em sinais QAM de ordem elevada. TambÃm sÃo desenvolvidas versÃes normalizadas e do tipo RLS dos algoritmos do tipo CMA estudados para equalizaÃÃo de canais nÃo-lineares. O comportamento de todas as famÃlias de algoritmos desenvolvidos à testado atravÃs de simulaÃÃes computacionais, em que à verificado que as tÃcnicas propostas fornecem ganhos significativos em desempenho, em termos de velocidade de convergÃncia e erro residual, em relaÃÃo Ãs tÃcnicas clÃssicas.
This work studies and proposes algorithms to perform blind equalization of linear and nonlinear channels inspired on the Constant Modulus Algorithm (CMA). The CMA works very well for modulations in which all points of the signal constellation have the same radius, like in Phase Shift Keying (PSK) modulations. However, when the constellation points are characterized by multiple radii, like in Quadrature Amplitude Modulation (QAM) signals, the CMA does not work properly in many situations. Thus, the techniques proposed here are designed to improve the performance of the CMA, in terms of speed of convergence and residual error, when working with signals transmitted with multiple magnitude, in particular with QAM signals. As well as for the CMA, these techniques should have a good compromise among performance, complexity and robustness. To do so, the techniques use the last decided symbol to estimate reference radius to the output of the equalizer. In fact, they can be seen as modifications of the CMA and of some of its derivatives for constellations with multiple radii. The proposition of stochastic gradient algorithms is concluded with the development of new adaptive blind techniques to equalize channels with a Wiener structure. A Wiener filter consists of a linear block with memory followed by a memoryless nonlinearity, by using the CMA. We develop expressions for the adaptation of the equalizer using a unified notation for three different equalizer filter structures: i) a Hammerstein filter, ii) a diagonal Volterra filter and iii) a Volterra filter. A theoretical analysis of the main proposed technique, the Decision Directed Modulus Algorithm (DDMA), is also done. We study the convergence and the stability of the DDMA by means of an analysis of the minima of the DDM cost function. We also develop an analytic expression for the Excess Mean Square Error (EMSE) provided by the DDMA in the noiseless case. Then, we nd some interesting relationships among the DDM, the CM and the Wiener cost functions. We also develop a class of normalized algorithms and a class of Recursive Least Squares (RLS)-type algorithms for blind equalization inspired on the CMA-based techniques studied. Each family is composed of four algorithms with desirable properties and advantages over the original CM algorithms, specially when working with high-level QAM signals. Normalized and RLS techniques for equalization of Wiener channels are also developed. The behavior of the proposed classes of algorithms discussed is tested by computational simulations. We verify that the proposed techniques provide significative gains in performance, in terms of speed of convergence and residual error, when compared to the classical algorithms.
Santos, Samuel Batista dos. "Estudo de algoritmos adaptativos aplicados a redes de sensores sem fio : caso supervisionado e não supervisionado." reponame:Repositório Institucional da UFABC, 2014.
Find full textDissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia da Informação, 2014.
Redes de sensores sem o (WSN - Wireless Sensor Networks) têm sido usadas na observação de fenômenos, identicação de sistemas, equalização de canais, além de aplicações nas mais diversas áreas. Considerando o caso de redes homogêneas com protocolo ponto a ponto, nas quais os sensores são capazes de processar suas informações e se comunicar com sensores vizinhos, diversos algoritmos adaptativos vêm sendo aplicados no processamento dos dados medidos. Estes algoritmos podem ser supervisionados ou não supervisionados. Buscando estimar parâmetros comuns através de um processamento distribuído, a topologia da rede passa a ser uma característica importante e precisa ser levada em conta nos algoritmos utilizados. Tais algoritmos operam em modo de difusão, considerando a troca de informações entre sensores vizinhos na atualização dos coecientes dos ltros adaptativos de cada sensor. O mapeamento da topologia da rede é feito de forma matricial através das chamadas matrizes de combinação. Neste trabalho, estudamos o impacto da escolha da matriz de combinação no desempenho dos algoritmos supervisionados. No caso de algoritmos não supervisionados, como a única proposta encontrada na literatura considerava um caso bastante restrito em que o algoritmo só poderia ser aplicado a uma rede com topologia em anel e comunicação unidirecional entre os nós, propomos um novo algoritmo capaz de operar em modo de difusão em qualquer topologia, baseado no clássico critério do módulo constante. O algoritmo proposto é simulado em diversas situações, sempre apresentando vantagens em relação a uma rede sem cooperação entre os nós.
Wireless sensor networks (WSN) have been used in the observation of several phenomena, system identication, channel equalization, and others. Considering the case of homogeneous networks with point to point protocol, in which the sensors are able to process their information and communicate with neighbors, various adaptive algorithms have been applied in the processing of measured data. These algorithms can be supervised or unsupervised. Seeking to estimate common parameters across a distributed processing, network topology becomes an important feature and must be taken into account in the algorithms used. Such algorithms operate in diusion mode, that is, considering the exchange of information between sensors to update the coecients of the adaptive lters. Thenetwork topology is mapped through the use of a matrix, denoted combination matrix. In this work, we study the impact of the choice of the combination matrix on the performance of supervised algorithms. In the case of blind methods, the only technique found in the literature was applied to the specic case of a network with ring topology and unidirectional communication between nodes. Thus, we propose a new algorithm capable of operating in diusion mode on any topology, based on the classical constant modulus criterion. The proposed algorithm is simulated in several scenarios, always presenting advantages over a network without cooperation between nodes.
Silva, Daniela Brasil. "Restauração cega de imagens: soluções baseadas em algoritmos adaptativos." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/3/3142/tde-27082018-143938/.
Full textThe goal of blind image deconvolution is to restore a degraded image without using information from the actual image or from the point spread function. The mapping of the gray levels of an image into a communication signal enables the use of blind equalization techniques for image restoration. In this work, we use a blind image deconvolution scheme based on the convex combination of a blind equalizer with an equalizer in the decision-directed mode. The combination is also blindly adapted, which enables automatic switching between the component filters. Thus, the proposed scheme is able to achieve the performance of a supervised adaptive filtering algorithm without prior knowledge of the original image. The performance of the combination is illustrated by simulations, which show the efficiency of this scheme when compared to other solutions in the literature.
Assis, Fábio Ferreira de. "Algoritmos set-membership para equalização autodidata aplicados a redes de sensores sem fio." reponame:Repositório Institucional da UFABC, 2018.
Find full textDissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia da Informação, Santo André, 2018.
Este trabalho dedica-se ao estudo de algoritmos de filtragem adaptativa autodidata no modo difusão, com aplicações em redes de sensores sem fio (RSSF). No modo difusão, os nós sensores da rede possuem poder de processamento local e trocam informações com seus vizinhos. Neste trabalho, propomos dois algoritmos utilizando como base o algoritmo CMA no modo Difusão (CMAD), com duas abordagens distintas da técnica Set-Membership. O primeiro baseia-se no algoritmo Set-Membership Least Mean Squares (SM-LMS), desenvolvido também no modo difusão. Estendemos o algoritmo para o contexto não supervisionado, denotando por Algoritmo Set-Membership CMA no modo Difusão (SM-CMAD). Mostramos que este algoritmo apresenta desempenho melhor ou similar ao CMAD, em termos de velocidade de convergência, patamar de interferência intersimbólica (IIS) e possuindo a importante vantagem de reduzir as trocas de informações entre os nós, economizando energia e recursos da rede. O segundo algoritmo proposto se baseia no Set-Membership do Módulo Constante (SM-CM), o qual estendemos para o contexto de redes de sensores sem fio no modo difusão. Tal algoritmo é denotado por Algoritmo Set-membership CMA no modo Difusão Square-root Gamma (SM-CMAD-SG). Novamente o algoritmo apresenta um bom desempenho quando comparado com o CMAD e, quando comparado ao SM-CMAD, vemos que sua principal vantagem está na economia em termos de atualizações dos coeficientes do filtro, que chega a valores acima de 70% em diversos cenários de simulação, sem grandes perdas de desempenho economizando energia.
This work is devoted to the study of unsupervised adaptive filtering algorithms in diffusion mode, with applications in wireless sensor networks (WSNs). In diffusion mode, network sensing nodes have local processing power and exchange information with their neighbors. In this work, we propose two algorithms based on the CMA algorithm in Diffusion mode (CMAD), with two different approaches to the Set-Membership technique. The first one is based on the Set-Membership Least Mean Squares (SM-LMS) algorithm, also developed in the diffusion mode. We extend the algorithm to the unsupervised context, denoting by Set-Membership CMA in Diffusion mode (SM-CMAD). We show that this algorithm presents better or similar performance to CMAD, in terms of convergence speed, intersymbol interference threshold (IIS), and has the important advantage of reducing the exchange of information between nodes, saving energy and network resources. The second proposed algorithm is based on the Set-Membership of the Constant Modulus (SM-CM), which we extend to the context of wireless sensor networks in the diffusion mode. This algorithm is denoted by the Set-membership CMA in Diffusion mode Square-root Gamma (SM-CMAD-SG). This algorithm performs well when compared to CMAD and, when compared to SM-CMAD, we see that its main advantage lies in the economy in terms of the update of the filter coefficients, which reaches values above 70% in several scenarios without loss of performance, saving energy.
Dabeer, Onkar. "Convergence analysis of the LMS and the constant modulus algorithms /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2002. http://wwwlib.umi.com/cr/ucsd/fullcit?p3055781.
Full textNeville, Katrina Lee, and katrina neville@rmit edu au. "Channel Compensation for Speaker Recognition Systems." RMIT University. Electrical and Computer Engineering, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080514.093453.
Full textAl-Hasani, Firas Ali Jawad. "Multiple Constant Multiplication Optimization Using Common Subexpression Elimination and Redundant Numbers." Thesis, University of Canterbury. Electrical and Computer Engineering, 2014. http://hdl.handle.net/10092/9054.
Full textVestin, Albin, and Gustav Strandberg. "Evaluation of Target Tracking Using Multiple Sensors and Non-Causal Algorithms." Thesis, Linköpings universitet, Reglerteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-160020.
Full textDe, Villiers Johan Pieter. "Blind multi-user cancellation using the constant modulus algorithm." Diss., 2003. http://hdl.handle.net/2263/28080.
Full textDissertation (M Eng (Electronic Engineering))--University of Pretoria, 2006.
Electrical, Electronic and Computer Engineering
unrestricted
Chen, Tsan-Lin, and 陳燦琳. "Blind Equalization Using Constant Modulus Algorithm for Cable DVB System." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/99135981610746576622.
Full text國立交通大學
電子工程系
90
Blind equalizers have long been employed to recover the distorted signal over ISI channel with AWGN noise. Among the many blind algorithms, constant modulus algorithm (CMA) is the most frequently employed adaptation algorithm in blind equalizers. In this thesis, we consider the applicability of such equalizers to the EN300429 DVB system using QAM modulation technique. Specifically, the effects of several algorithms for blind equalization are discussed and compared. Computer simulation results indicate that the performances of blind equalizers using SGA algorithm, one variant of the CMA, is the best approach for improving convergence speed and reducing steady state error. Also, the blind equalizers for DPASK modulation scheme can achieve similar convergence behaviors, if it is employed in DVB systems.
Wang, Hong-Bin, and 王宏彬. "A 5Gb/s Blind Feed-Forward Equalizer Based on Constant Modulus Algorithm." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/73544624038699329284.
Full text國立臺灣科技大學
電機工程系
101
In high-speed wireline communications, to reduce frequency-dependent channel loss is an important issue. The equalizer is an effective solution to resolve the frequency- dependent signal attenuation. This thesis proposed an on-chip constant-modulus-algorithm (CMA) -based Feed-Forward equalizer (FFE) to overcome this problem. Since CMA is a blind equalization method that does not need training sequence, the adaptive mechanism can be completely implemented on chip. This thesis proposed a constant-modulus-algorithm-based Feed-Forward equalizer that compensates the cable loss for 5 Gb/s USB 3.0 application. The CMA-based FFE chip was realized in TSMC 90 nm CMOS process. The power consumption of equalizer is 10.45 mW under 1.2 V supply voltage. The total chip area is 0.45 mm2 with pads, and the core area is 0.043 mm2. In post layout simulations, the proposed equalizer has the ability to compensate the cable loss for USB 3.0. In this thesis, we assumed a 1.8-meter and a 3-meter cable lines in simulations. The compensated cable loss are 11 dB (for the 1.8 m cable) and 16 dB (for the 3 m cable) at Nyquist frequency, respectively. After simulating a transmission of three hundred thousand bits, we show that the equalizer can improve BER from 3.3e-6 to 0 for the 1.8-meter USB 3.0 cable line; for the 3-meter USB 3.0 cable, it can improve the BER from 0.5 to 0.
Yang, Yu-Sheng, and 楊育盛. "A 3.125 Gb/s Blind Decision Feedback Equalizer Based on Constant Modulus Algorithm." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/06138478603911017218.
Full text國立臺灣科技大學
電機工程系
101
In high speed wireline communications, the frequency-dependent channel loss is an important issue. The equalizer is an effective method to resolve the frequency- dependent signal attenuation problem in wireline communications. This thesis realizes an on-chip constant-modulus-algorithm(CMA)-based decision feedback equalizer (DFE) to overcome the problem. The CMA is a blind equalization method, so it does not need a training sequence. Thus, the adaptive mechanism can be completely implemented on chip. The wireline we consider in this thesis is the RG58A/U coaxial cable for 3.125 Gb/s Ethernet application. The CMA-based DFE chip was realized in TSMC 0.18 μm CMOS process. The equalizer consumed 42 mW power at 1.8 V supply. The chip area is 1.25 mm2. In post layout simulations, the proposed equalizer can compensate for a 12.23-dB channel loss at Nyquist frequency for a 15-meter RG58A/U cable with 5.6667e-5 BER. For a 20-meter RG58A/U cable with 16.75 dB loss at Nyquist frequency, the equalizer can improve the BER from 2.3871e-1 down to 1.6633e-3.
Chung, Jen-hao, and 鍾仁豪. "A 5 Gb/s Blind Feed-Forward Equalizer Based on the Constant Modulus Algorithm." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/24338108735124171964.
Full text國立臺灣科技大學
電機工程系
102
In high-speed wireline communications, to reduce frequency-dependent channel loss is an important issue. The equalizer is an effective solution to resolve the frequency- dependent signal attenuation. This thesis proposed an on-chip constant-modulus-algorithm (CMA) -based Feed-Forward equalizer (FFE) to overcome this problem. Since CMA is a blind equalization method that does not need training sequence, the adaptive mechanism can be completely implemented on chip. This thesis proposed the constant-modulus-algorithm-based Feed-Forward equalizer that compensates the cable loss for 5 Gb/s USB 3.0 application. The CMA-based FFE chip was realized in TSMC 90 nm CMOS process. The power consumption of equalizer is 14.4 mW under 1.2 V supply voltage. The total chip area is 0.59 mm2 with pads, and the core area is 0.058 mm2. In post layout simulations, the proposed equalizer has the ability to compensate the cable loss for USB 3.0. In this thesis, we assumed a 3-meter lines in simulations. The compensated cable loss are 16 dB for the 3 m cable at Nyquist frequency, respectively. After simulating a transmission of three hundred thousand bits, we show that the equalizer can improve BER from 0.5 to 0 for the 3-meter USB 3.0 cable. In fact, the equalizer can not improve the BER from 0.5 down to 0.
Liu, Hsiao-Chen, and 劉肖真. "Wavelet-Based Multiuser MC-CDMA Receiver with Linearly Constrained Constant Modulus Inverse QRD-RLS Algorithm." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/96196497378870289632.
Full text國立中山大學
電機工程學系研究所
90
In this thesis, the problem of multiple access interference (MAI) suppression for the multi-carrier (MC) code division multiple access (CDMA) system, based on the wavelet-based (WB) multi-carrier modulation, associated with the combining process is investigated for Rayleigh fading channel. The main concern of this thesis is to derive a new scheme, based on the linearly constrained constant modulus (LCCM) criterion with the robust inverse QR decomposition (IQRD) recursive least squares (RLS) algorithm to improve the performance of the conventional MC-CDMA system with combining process. To verify the merits of the new algorithm, the effect due to imperfect channel parameters estimation and frequency offset are investigated. We show that the proposed robust LCCM IQRD-RLS algorithm outperforms the conventional LCCM-gradient algorithm [6], in terms of output SINR, improvement percentage index (IPI), and bit error rate (BER) for MAI suppression under channel mismatch environment. Also, the performance of the WB MC-CDMA system is superior to the one with conventional MC-CDMA system. It is more robust to the channel mismatch and frequency offset. Moreover, the WB MC-CDMA system with robust LCCM IQRD-RLS algorithm does have better performance over other conventional approaches, such as the LCCM-gradient algorithm, maximum ratio combining (MRC), blind adaptation algorithm and partitioned linear interference canceller (PLIC) approach with LMS algorithm, in terms of the capability of MAI suppression and bit error rate (BER).
Yu, Chih-Kai, and 游智凱. "Estimation of Four Transmitting Antennas Space-Time Block Code by Modified Constant Modulus Algorithm (MCMA)." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/70276974012202400689.
Full text中原大學
電子工程研究所
98
Twin-QPSK is a four transmitting antennas space-time coding system with the features of orthogonal, full diversity, and full code rate. Here, the blind equalization at the receiver is proceeded by using the Modified Constant Modulus Algorithm (MCMA) which can estimate the transmitting signal without the training sequence in the system. The simulation results show that the original transmitted signals can be estimated efficiently. Compared with semi-blind algorithm, this approach not only increases the efficiency of using bandwidth, but also reduces the complexity of the system.
Yu, Hung-ming, and 尤宏明. "Linearly Constrained Constant Modulus Inverse QRD-RLS Algorithm for Modified Gaussian Wavelet-Based MC-CDMA Receiver." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/2a3m84.
Full text國立中山大學
電機工程學系研究所
95
In this thesis, the problem of multiple access interference (MAI) suppression for the multi-carrier (MC) code division multiple access (CDMA) system, based on the multi-carrier modulation with modified Gaussian wavelet, associated with the combining process is investigated for Rayleigh fading channel. The main concern of this thesis is to derive a new scheme, based on the linearly constrained constant modulus (LCCM) criterion with the robust inverse QR decomposition (IQRD) recursive least squares (RLS) algorithm to improve the performance of the wavelet-based MC-CDMA system with combining process. To verify the merits of the new algorithm, the effect due to imperfect channel parameters estimation and near-far effect are investigated. We show that the proposed robust LCCM IQRD-RLS algorithm outperforms the conventional LCCM-gradient algorithm, in terms of output SINR, for MAI suppression under channel mismatch environment. Also, the performance of the modified Gaussian wavelet-based MC-CDMA system is superior to the one with wavelet-based MC-CDMA system. It is more robust to the channel mismatch and near-far effect. Moreover, the modified Gaussian wavelet-based MC-CDMA system with robust LCCM IQRD-RLS algorithm does have better performance over other conventional approaches, such as the LCCM-gradient algorithm, maximum ratio combining (MRC), and blind adaptation algorithm, in terms of the capability of MAI suppression and bit error rate (BER).
Luo, Yin-chen, and 羅尹辰. "New Blind Constant Modulus Sliding Windows GSC-RLS Algorithm for DS-CDMA Receiver with Min/Max Criterion." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/n3d35d.
Full text國立中山大學
電機工程學系研究所
95
The code division multiple access (CDMA) system implemented by the direct-sequence (DS) spread spectrum (SS) technique is one of the most promising multiplexing technologies for the wireless communications services. The SS communication adopts a technique of using much wider bandwidth necessary to transmit the information over the channel, and has been proposed for third generation broadband wireless access. The capacity and performance of the DS-CDMA system are mainly limited by the multiple access interference (MAI) and the inter-symbol-interference (ISI) caused by the multipath-fading channel. To circumvent the above-mentioned problems many adaptive multiuser detectors, for instance the minimum mean square error (MMSE) and the minimum output energy (MOE) criteria, subject to certain constraints, have been proposed. Since the LCMV criterion is the linearly constrained (LC) version of MOE, it is high sensitivity to the channel mismatch caused by the unreliable estimation. In order to deal with this problem, the LC constant modulus (LCCM) criterion was considered to avoid capturing the interfering user instead of the desired user when the power of interfering user is much higher than the desired user. In this thesis, based on the Min/Max criterion we propose a novel blind LCCM recursive least-square (RLS) algorithm, with the generalized side-lobe canceller (GSC) structure, named as the CM GSC-RLS algorithm, to effectively alleviate the effect of MAI and ISI for DS-CDMA receiver, for time-varying channel. Due to the variation of channel at the receiver, the desired user amplitude or power is not available and has to be estimated. To solve this problem, we propose a simple scheme to estimate the parameter of constant modulus, adaptively, associated with the CM GSC-RLS algorithm. With the new proposed algorithm, the amplitude variation of desired user, due to changing characteristics of channel, can be tracked, effectively. Thus, better performance achievement, in terms of output signal-to-interference-plus-noise ratio (SINR) and bit error rate (BER), over the conventional GSC-RLS algorithms can be expected.
Cheng, Ming-Kai, and 鄭名凱. "Novel Blind ST-BC MIMO-CDMA Receiver with Adaptive Constant Modulus-GSC-RLS Algorithm in Multipath Channel." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/14565483379461059601.
Full text國立中山大學
電機工程學系研究所
97
In this thesis, we present a new hybrid pre-coded direct-sequence code division multiple access (DS-CDMA) system framework that use the multiple-input multiple-output (MIMO) antennas along with Alamouti’s space-time block code (ST-BC). In the transmitter, the idea of hybrid pre-coded is exploited. It not only used to counteract the inter-symbol interference (ISI) introduced by the channel fading duo to multipath propagation but also very useful for exacting the phase of channel by appropriate design, which is not adopted in the conventional blind receiver. Under this structure, we propose a new blind adaptive MIMO-CDMA receiver based on the linearly constrained constant modulus (LCCM) criterion. To reduce the complexity of receiver design, framework of the generalized sidelobe canceller (GSC) associated with the recursive least square (RLS) algorithm is adopted for implementing the LCCM MIMO-CDMA receiver, and use gradient method to track the desired user’s amplitude, simultaneously. Via computer simulations, advantages of the proposed scheme will be verified. Compared to the conventional blind Capon receiver, we will show that the performance of the proposed scheme is more robust against inaccuracies in the acquisition of the desired user’s timing.
Wang, Sheng-Meng, and 王勝盟. "Adaptive Linearly Constrained Constant Modulus Conjugate Gradient Algorithm with Applications to Multiuser DS-CDMA Detector for Multipath Fading Channel." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/94377267081327148403.
Full text國立中山大學
電機工程學系研究所
91
The direct-sequence code division multiple access (DS-CDMA) is one of the significant techniques for wireless communication systems with multiple simultaneous transmissions. The main concern of this thesis is to propose a new linearly constrained constant modulus modified conjugate gradient (LCCM-MCG) adaptive filtering algorithm to deal with problem of channel mismatch associated with the multiple access interference (MAI) in DS-CDMA system over multipath fading channel. In fact, the adaptive filtering algorithm based on the CM criterion is known to be very attractive for the case when the channel parameters are not estimated perfectly. The proposed LCCM-MCG algorithm is derived based on the so-called generalized sidelobe canceller (GSC). It has the advantage of having better stability and less computational complexity compared with conventional recursive least-squares (RLS) algorithm, and can be used to achieve desired performance for multiuser RAKE receiver. Moreover, with the MCG algorithm it requires only one recursive iteration per incoming sample data for updating the weight vector, but still maintains performance comparable to the RLS algorithm. From computer simulation results, we show that the proposed LCCM-MCG algorithm has fast convergence rate and could be used to circumvent the effect due to channel mismatch. Also, the performance, in terms of bit error rate (BER), is quite close to the LCCM-RLS algorithm suggested in [18], and is superior to the stochastic gradient descent (SGD) algorithm proposed in [7].
Chang, Shih-chi, and 張世奇. "Blind Adaptive DS-CDMA Receivers with Sliding Window Constant Modulus GSC-RLS Algorithm Based on Min/Max Criterion for Time-Variant Channels." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/88347590504212626430.
Full text國立中山大學
電機工程學系研究所
94
The code division multiple access (CDMA) system implemented by the direct-sequence (DS) spread spectrum (SS) technique is one of the most promising multiplexing technologies for wireless communications services. The SS communication adopts a technique of using much wider bandwidth necessary to transmit the information over the channel. In the DS-CDMA system, due to the inherent structure interference, referred to as the multiple access interference (MAI), the system performance might degrade. Next, for DS-CDMA systems over frequency-selective fading channels, the effect of inter symbol interference (ISI) will exist, such that a multiuser RAKE receiver has to be employed to combat the ISI as well as MAI. Since, in practical wireless communication environment, there may have several communication systems operated in the same area at the same time. In this thesis, we consider the environment of DS-CDMA systems, where the asynchronous narrow band interference (NBI) due to other systems is joined suddenly to the CDMA system. In general, when a system works in a stable state with adaptive detectors, a suddenly joined NBI signal will cause the system performance to be crash down. Under such circumstance, the existing conventional adaptive RAKE detectors may not be able to track well for the rapidly sudden changing NBI associated with the problems of ISI and MAI. It is known that the adaptive filtering algorithms, based on the sliding window linear constrained recursive least squares (SW LC-RLS), is very attractive to a violent changing environment. The main concern of this thesis is to propose a novel sliding window constant modulus RLS (SW CM-RLS) algorithm, based on the Min/max criterion, to deal with the NBI for DS-CDMA system over multipath channels. For simplicity and having less system complexity the generalized side-lobe canceller (GSC) structure is employed, and is referred to as the SW CM-GSC-RLS algorithm. The aim of the SW CM-GSC-RLS algorithm is used to alleviate the effect of NBI. It has the advantages of having faster convergence property and tracking ability, and can be applied to the environment in which the NBI is suddenly joined to the system under the effect of channel mismatch to achieve desired performance. At the end of this thesis, we extend the idea of the proposed algorithm to the space-time DS-CDMA RAKE receiver, in which the adaptive beamformer with temporal domain DS-CDMA receiver is employed. Via computer simulation results, we show that our new proposed schemes outperform the conventional CM GSC-RLS algorithm as well as the GSC-RLS algorithm (the so-called LCMV approach), in terms of mean square error of estimating channel impulse response, output signal to interference plus noise ratio and bit-error-rate.
Wang, Shiue-Ru, and 王學儒. "Channel Tracking in MIMO OFDM Systems by Utilizing Constant Modulus Algorithms." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/37077845311215753094.
Full text國立中央大學
通訊工程研究所
97
The combination of multiple input and multiple output (MIMO) technology and orthogonal frequency division multiplexing (OFDM) to combat multipath and mobile channels is widely used in wireless communications. For example, in wireless network applications with limited number of pilots, channel tracking is an important scheme to deal with time-varying channels. Here, the Alamouti space-time block code is applied to a two-by-two MIMO OFDM system in which we explore a new channel tracking algorithm that can alternatively operate between the constant modulus algorithm (CMA) and the decision feedback algorithm based on the proposed mechanism. The proposed algorithm is also further verified in an intercarrier interference cancellation algorithm that can solve the time-varying channel with changed status even between two consecutive OFDM symbols. Simulation results show that the proposed algorithm can achieve better performance than the method employing only the CMA method or the decision feedback method.
Samarasinghe, Devanarayanage Pradeepa. "Efficient methodologies for real-time image restoration." Phd thesis, 2011. http://hdl.handle.net/1885/9859.
Full textWu, Ping-Chen, and 吳品正. "A Constraint-Based Genetic Algorithm for the Scheduling of Module Operations in TFT-LCD Manufacturing." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/73432246267269173416.
Full text明新科技大學
工程管理研究所
92
This paper develops an operational strategy for the production scheduling of the module factory in thin film transistor liquid crystal display (TFT-LCD) manufacturing, where the module process involves a mass-customized production environment that depends on the availability of the key parts or components. How to meet a variety of designated materials requested by customers and how to cope with the quick response for confirmed orders will gradually become important issues for TFT-LCD industry. Basically, the traditional MRP (Material requirement planning) is such a planning approach based on preliminary assumptions of unlimited-capacity and fixed lead time, in which a capacity-adjusted effort is needed to meet the capacity constraints after MRP executed. Therefore, a constraint-based genetic algorithm (CBGA) simultaneously taking the designated material and available capacity constraints into account is developed for the purpose of minimizing earliness, tardiness, makespan, and flow time. Herein a factorial experiment design is used to evaluate the performance differences between the CBGA with two traditional dispatching rules, FS/EDD and BS/LDD. It has been shown that the performance obtained by CBGA is superior to those heuristics.