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The Global ETD Search service is a free service for researchers
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Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
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Showing 71 to 80 of 81 (0.05 seconds)Spelling suggestions: "subject:"hannel capacity"" "subject:"achannel capacity""
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Revitalizace vybraného úseku toku Hartmanického potoka / Revitalization of the selected section of river "Hartmanický potok"Samková, Aneta January 2017 (has links)
Diploma thesis deal with revitalization Hartmanice river in district Svitavy. Section of interest is on 0,400 – 1,234 of river km. Part of this thesis is also rating current condition of stream and his vegetation accompaniment. Rating was made on base of reconnaissance terrain, my own measurement and photo documentation. In diploma thesis was design some revitalization steps: stabilization sink with wooden sills and stabilization slopes by using willow fences and similar precautions. There was designed total change of flow trend. Rating of current condition and condition of modified stream was made in software HEC-RAS.
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Návrh PPO na toku ve správě Povodí Moravy, s.p. / Proposal of flood protection on the river in the basin of the MoravaSalingerová, Lucie January 2017 (has links)
The main aim of the thesis is an appraisal of the stream Oslava which belongs to the Náměšť nad Oslavou region with the focus on flood control of the town. The thesis asseses current state of the stream with respect to the state of riverbed, bulwark of the stream and evaluation of the capacity of the stream channel. Calculation water surface profiles have been made by usage of the 1D mathematical model HEC-RAS for selected N-year flows. The capacity of flows and objects in the given period has been detected. There is also a map of the water runoffs included and possible solutions of how to protect the area surrounding the stream are proposed. The thesis was complemented with hydroecological monitoring of the stream channel - the HEM analysis 2014.
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Generalized belief propagation based TDMR detector and decoderMatcha, Chaitanya Kumar, Bahrami, Mohsen, Roy, Shounak, Srinivasa, Shayan Garani, Vasic, Bane 07 1900 (has links)
Two dimensional magnetic recording (TDMR) achieves high areal densities by reducing the size of a bit comparable to the size of the magnetic grains resulting in two dimensional (2D) inter symbol interference (ISI) and very high media noise. Therefore, it is critical to handle the media noise along with the 2D ISI detection. In this paper, we tune the generalized belief propagation (GBP) algorithm to handle the media noise seen in TDMR. We also provide an intuition into the nature of hard decisions provided by the GBP algorithm. The performance of the GBP algorithm is evaluated over a Voronoi based TDMR channel model where the soft outputs from the GBP algorithm are used by a belief propagation (BP) algorithm to decode low-density parity check (LDPC) codes.
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Διερεύνηση των τεχνικών παραμέτρων για την μεγιστοποίηση της ποιότητας των παρεχομένων υπηρεσιών στα συστήματα MIMOΦραγκιαδάκης, Αλέξανδρος 01 February 2013 (has links)
Στην παρούσα διπλωματική εργασία μελετάμε τα πλεονεκτήματα που επιφέρει η χρήση πολλαπλών κεραιών στον πομπό και στον δέκτη, κατά την μετάδοση, με στόχο την βελτίωση των παρεχομένων υπηρεσιών στο χρήστη. Στο Κεφάλαιο 1, γίνεται μια ιστορική αναδρομή των ασύρματων επικοινωνιών καθώς των σύγχρονων ασύρματων τεχνολογιών και κεραιών που χρησιμοποιούνται. Στη συνέχεια γίνεται μια αναφορά στις έννοιες του διαφορισμού, του κέρδους διάταξης και της χωρικής πολυπλεξίας οι οποίες συνδέονται άρρηκτα με τα συστήματα MIMO. Στο Κεφάλαιο 2, αναφερόμαστε σε όλα εκείνα τα χαρακτηριστικά που περιγράφουν το ασύρματο κανάλι και εξάγουμε την γραμμική σχέση εισόδου-εξόδου του ασύρματου καναλιού. Στην συνέχεια γίνεται μια ανάλυση των στοχαστικών μοντέλων περιγραφής του ασύρματου διαύλου διαλείψεων και πιο συγκεκριμένα των μοντέλων Rayleigh και Rice. Στο Κεφάλαιο 3 εξετάζουμε την αξιοπιστία διαφόρων τύπων κεραιοσυστημάτων, ως προς τον ρυθμό των ρυθμό των λανθασμένων συμβόλων στον δέκτη. Πιο συγκεκριμένα εξετάζεται η τεχνική Maximal Ratio Combining για τα συστήματα SIMO καθώς και του σχήματος Alamouti για τα συστήματα ΜISO. Συνεχίζοντας στα MIMO συστήματα αναλύουμε τις μεθόδους ισοστάθμισης για την ανάκτηση των δεδομένων, και πιο συγκεκριμένα τις τεχνικές Zero Forcing, Minimum Mean Square Error,V-Blast και καθώς και την βέλτιστη τεχνική Maximum Likelihood. Στο τελευταίο μέρος της εργασίας αναλύουμε τα πλεονεκτήματα των MIMO συστημάτων, ως προς την χωρητικότητα που προσφέρουν, σε στοχαστικά κανάλια διαλείψεων.Στη συνέχεια, γίνεται αναφορά στην μέθοδο SVD και στην αναπαράσταση του MIMO καναλιού από έναν αριθμό ανεξάρτητων SISO διαύλων. Κλείνοντας αναφέρουμε την μέθοδο βέλτιστης κατανομής ισχύος στις κεραίες του πομπού Water-filling, και στην περαιτέρω αύξηση της χωρητικότητας του διαύλου που προσφέρει. / In this diploma thesis we are investigating the benefits of using Multiple Input and Multiple Output antennas in information transmission, with final goal to improve Quality of Service. The first Chapter, includes a historical background of the wireless communications but also is a reference to the modern wireless and antenna technologies. Moreover, we introduce the definition of new concepts, such as diversity and array gain and also spatial multiplexing, which are closely connected with MIMO technology. In the second chapter, we introduce the characteristics which they are describe the wireless channel, while simultaneously we mention the linear input-output relationship of the wireless channel. Additionally, we analyze the stochastic wireless channel models, namely the Rayleigh and the Rician fading models. In the third chapter, we investigate the reliability of different types of antenna topologies, regarding the pace of the invalid symbols in the transmitter. More specifically, we examine the Maximal Ratio Combining and Alamouti technique, for SIMO and MISO systems respectively. The next step is to analyze the equalization methods, which are used in MIMO antennas, and more specifically are, Zero Forcing, Minimum Mean Square Error and V-Blast receivers, but also the optimal Maximum Likelihood equalizer. In the last part of this Thesis, we investigate the benefits of MIMO systems regarding the Capacity, in random channels. Also, a reference to the SVD method has been made,which we use to analyze the MIMO channel, in a number of parallel SISO channels. Lastly, we use the water-filling method to allocate, with the optimal way, the given power in the transmit antennas, a fact that leads to even greater Capacity gain.
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Posouzení možností revitalizace vodního toku Osoblaha – úsek II / Assessment of the Possibilities The Revitalization of a Watercourse Osoblaha – reach IIVysloužilová, Lucie January 2015 (has links)
This thesis deals with examining the possibility of revitalizing the watercourse Osoblaha. It flows through the cadastral territories of municipalities Bohušov, Osoblaha and Kašnice u Bohušova. In this thesis there will be proposed a measure to increase biodiversity of the flow. The trough will be loosened in appropriate segments, oxbow lakes and ponds will be designed. Also the bank shelters for fish stock will be suggested. For slope stabilization will be used reinforcement of fresh willow fences. Impermeable shoots or disintegrating oxbow lakes will be projected in the straight sections of the flow.
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In-home and low-voltage channel characterization of non-cooperative and cooperative power line communicationValencia-Payán, Juan David 27 March 2014 (has links)
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Previous issue date: 2014-03-27 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Esta contribuição descreve uma caracterização estatística da rede de baixa tensão
Brasileira residencial como meio de comunicação. As discussões são baseadas em canais
estimados obtidos em uma campanha de medição realizada em quatro apartamentos
diferentes, com tamanhos que variam de 50 até 90 metros quadrados. Os parâmetros
considerados para esta análise são o Root Mean Square Delay Spread, o ganho médio
do canal e a capacidade do canal. Para efeitos de comparação com a rede de potencia
dos Estados Unidos, a banda de frequência utilizada foi de 1:705 até 30 MHz. A análise
relatada mostra que o Root Mean Square Delay Spread e o ganho médio do canal não
podem ser modelados como variáveis log-normal. Os resultados obtidos geram dúvidas
em relação aos atuais encontrados na literatura, em que se afirma que tanto o Root
Mean Square Delay Spread quanto o ganho médio do canal seguem uma distribuição
log-normal. Foram medidos também a impedância de acesso e o ruído do canal de
comunicação via rede elétrica. Além disso, os conceitos de cooperação para melhorar
o desempenho dos sistemas de comunicação via rede elétrica foram analisados, mais
especificamente na rede de baixa tensão Brasileira residencial. Para isso, foram analisados
a performance dos protocolos de Amplify-and-Forward e Decode-and-Forward, em
conjunto com as técnicas de combinação Equal-Gain Combining, Selection-Combining
e Maximal-Ratio Combining. A análise sobre os dados medidos cobriram uma faixa
de frequência de 1:705 a 100 MHz. Os dados medidos abordam quatro cenários para
possíveis localizações do nó Relay. Os resultados obtidos mostram que o Amplify-and-
Forward é de aplicabilidade limitada no contexto de comunicação via rede elétrica e o
oposto é válido para o protocolo de Decode-and-Forward, principalmente se a probabilidade
de erro de detecção de símbolos no nó Relay tende a zero. / This thesis outlines a statistical characterization of the Brazilian In-Home Low-Voltage
Electric Power Grid as a communication medium. The discussions are based on estimated
channels obtained in a measurement campaign carried out in four different
apartments with sizes ranging from 50 up to 90 square meters. The parameters considered
for this analysis are the Root Mean Square Delay Spread, the average channel
gain, and the channel capacity. For the sake of comparison with the Electric Power
Grid in United States, the frequency band ranging from 1:705 up to 30 MHz was set.
The reported analysis shows that the Root Mean Square Delay Spread and the average
channel gain cannot be modeled as log-normal variables, this cast doubt the current
results found in the literature, in which is stated that both the Root Mean Square
Delay Spread and the average channel gain follow a log-normal distribution. This was
followed by the Power Line Communication access impedance and noise measurements
in the In-Home Low-Voltage Electric Power Grid. Additionally, the suitability of cooperation
concepts for improving the performance of Power Line Communication systems
was analyzed, more specifically in the Brazilian In-Home Low-Voltage Electric Power
Grid. For this purpose, the performance of the Amplify-and-Forward and Decode-and-
Forward protocols, together with the Equal-Gain Combining, Selection Combining,
and Maximal-Ratio Combining techniques were analyzed. The analysis was carried
out on the measured data covering a frequency band from 1:705 up to 100 MHz. The
measured data addresses four scenarios for possible relay node locations. The attained
results show that the Amplify-and-Forward is of limited applicability in the Power Line
Communication context and the opposite is valid to the Decode-and-Forward protocol,
mainly if the error probability of detecting symbols at the relay node is zero.
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Studie možností revitalizačních opatření příměstského vodního toku / Study of river restoration measures of suburban watercourseŠebesta, Radek January 2013 (has links)
This diploma thesis deals with the problem of river restoration. Selected watercourse, which was inappropriately technically modified, had been mapped in detail and land use map was compiled. The watercourse was divided into sections, which were described in detail and assessed for suitability for restoration action. The new nature-friendly channel was designed on the selected section of the watercourse. Technical graphic documentation was designed.
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Revitalizace malého vodního toku / The Revitalization of a Small WatercourseSvědínková, Renáta January 2013 (has links)
My diploma thesis deals with the issue revitalization of a small stream. Assessment and design of revitalization is done on Kuřimka stream which flows through the cadastral territory of the Moravian Knínice - Chudčice - Kníničky. In the diploma thesis were designed several of revitalization measures: stabilization of longitudinal tilt with the use of stone steps in the bottom and wooden thresholds, sedimentation reservoir for capturing sediment and slope stabilization using willow fences and gabions. Proposal of revitalization measures does not deteriorate runoff conditions.
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Modelling of Mobile Fading Channels with Fading Mitigation Techniques.Shang, Lei, lei.shang@ieee.org January 2006 (has links)
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.
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Channel Probing for an Indoor Wireless Communications ChannelHunter, Brandon 13 March 2003 (has links) (PDF)
The statistics of the amplitude, time and angle of arrival of multipaths in an indoor environment are all necessary components of multipath models used to simulate the performance of spatial diversity in receive antenna configurations. The model presented by Saleh and Valenzuela, was added to by Spencer et. al., and included all three of these parameters for a 7 GHz channel. A system was built to measure these multipath parameters at 2.4 GHz for multiple locations in an indoor environment. Another system was built to measure the angle of transmission for a 6 GHz channel. The addition of this parameter allows spatial diversity at the transmitter along with the receiver to be simulated. The process of going from raw measurement data to discrete arrivals and then to clustered arrivals is analyzed. Many possible errors associated with discrete arrival processing are discussed along with possible solutions. Four clustering methods are compared and their relative strengths and weaknesses are pointed out. The effects that errors in the clustering process have on parameter estimation and model performance are also simulated.
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