Дисертації з теми "Mobile signal"
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Athanasiadis, Tasso, and tas atha@bigpond net au. "Signal Processing Techniques for Mobile Multimedia Systems." RMIT University. Electrical and Computer Engineering, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080123.115457.
Повний текст джерелаАнотація:
Recent trends in wireless communication systems show a significant demand for the delivery of multimedia services and applications over mobile networks - mobile multimedia - like video telephony, multimedia messaging, mobile gaming, interactive and streaming video, etc. However, despite the ongoing development of key communication technologies that support these applications, the communication resources and bandwidth available to wireless/mobile radio systems are often severely limited. It is well known, that these bottlenecks are inherently due to the processing capabilities of mobile transmission systems, and the time-varying nature of wireless channel conditions and propagation environments. Therefore, new ways of processing and transmitting multimedia data over mobile radio channels have become essential which is the principal focus of this thesis. In this work, the performance and suitability of various signal processing techniques and transmission strategies in the application of multimedia data over wireless/mobile radio links are investigated. The proposed transmission systems for multimedia communication employ different data encoding schemes which include source coding in the wavelet domain, transmit diversity coding (space-time coding), and adaptive antenna beamforming (eigenbeamforming). By integrating these techniques into a robust communication system, the quality (SNR, etc) of multimedia signals received on mobile devices is maximised while mitigating the fast fading and multi-path effects of mobile channels. To support the transmission of high data-rate multimedia applications, a well known multi-carrier transmission technology known as Orthogonal Frequency Division Multiplexing (OFDM) has been implemented. As shown in this study, this results in significant performance gains when combined with other signal-processing techniques such as spa ce-time block coding (STBC). To optimise signal transmission, a novel unequal adaptive modulation scheme for the communication of multimedia data over MIMO-OFDM systems has been proposed. In this system, discrete wavelet transform/subband coding is used to compress data into their respective low-frequency and high-frequency components. Unlike traditional methods, however, data representing the low-frequency data are processed and modulated separately as they are more sensitive to the distortion effects of mobile radio channels. To make use of a desirable subchannel state, such that the quality (SNR) of the multimedia data recovered at the receiver is optimized, we employ a lookup matrix-adaptive bit and power allocation (LM-ABPA) algorithm. Apart from improving the spectral efficiency of OFDM, the modified LM-ABPA scheme, sorts and allocates subcarriers with the highest SNR to low-frequency data and the remaining to the least important data. To maintain a target system SNR, the LM-ABPA loading scheme assigns appropriate signal constella tion sizes and transmit power levels (modulation type) across all subcarriers and is adapted to the varying channel conditions such that the average system error-rate (SER/BER) is minimised. When configured for a constant data-rate load, simulation results show significant performance gains over non-adaptive systems. In addition to the above studies, the simulation framework developed in this work is applied to investigate the performance of other signal processing techniques for multimedia communication such as blind channel equalization, and to examine the effectiveness of a secure communication system based on a logistic chaotic generator (LCG) for chaos shift-keying (CSK).
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GOMES, RENATO ARREGUI. "RADIO SIGNAL BEHAVIOUR ON MICROCELLULAR MOBILE ENVIRONMENTS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1999. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=7473@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORCom o aumento da demanda pelos serviços celulares se faz necessário estudar e desenvolver técnicas cada vez mais sofisticadas para a melhoria da capacidade e da qualidade dos sistemas celulares. Uma destas é a utilização moderada de microcélulas em regiões urbanas, e em algumas situações em regiões suburbanas. Os maiores problemas da utilização de microcélulas são suas características de propagação, bem diferentes das características das células convencionais. Para melhor compreender as características de propagação de um sinal rádio móvel num ambiente microcelular, este trabalho se propôs a fazer um estudo experimental onde, fenômenos como forma de células, efeitos de sombreamento, multipercurso e outros, foram analisados. Um laboratório móvel foi montado e uma grande campanha de medidas foi realizada em ambientes urbanos de características diferentes. Análises determinísticas e estatísticas, foram realizadas para se determinar parâmetros como o fator de queda do sinal com a distância e o desvio padrão da variabilidade do sinal. Estes resultados são importantes para o cálculo aproximado da cobertura do sinal em regiões semelhantes às estudadas. Especial atenção foi dada ao cálculo do ponto de quebra da dependência do sinal com a distância. Este ponto define a transição entre a região de campo próximo e a região de difração, sendo fundamental para estudos de cobertura. Uma importante contribuição foi na determinação da dependência da cobertura do sinal com a altura da antena transmissora. Os resultados medidos ajudaram a caracterizar a célula e conseqüentemente obter informações para localizações ótimas das altura das antenas, além de definir a melhor cobertura que estas alturas podem oferecer. Uma análise estatística da variabilidade do sinal foi realizada e distribuições de probabilidade foram testados frente aos resultados experimentais. A determinação de parâmetros importantes destas distribuições ajudou na verificação da aderência destes modelos aos resultados medidos. Os resultados são de extrema importância para esclarecer aspectos de propagação do sinal em microcélulas e disponibilizar dados para a elaboração de modelos de predição para o cálculo da cobertura do sinal para o projetista, resultando numa melhoria da qualidade e da capacidade do sistema microcelular.
The ever-increasing demand for cellular services raises the necessity of developing more sophisticated techniques to improve system quality and capacity. One of the techniques is the use of microcells in urban and occasionally suburban regions. However, the major problems facing the microcell deployment are the microcells peculiar propagation characteristics, which are very different from the conventional cellular systems. In order to address this problem, an experimental study of cell shape, shadowing effects and multipath, was carried out. A mobile laboratory was assembled and extensive measurements on different urban environments were performed. Deterministic and statistical analysis were carried out to find the parameters such as path loss versus distance factor, and the standard deviation of signal variability. Special attention was given to the determination of the breaking point, transition between the near field and diffraction regions on line-of-sight path. An important contribution was on the study of the effects of transmitter antenna height on coverage. The measured results will help on cell characterization and on finding the best height for the base station antennas. A statistical analysis of signal variability was performed to determine the best-fit probability distribution function with parameters carefully calculated. The collected results are of extreme importance to clarify propagation aspects of microcellular signal and to make it available a huge data bank for elaboration of better prediction models which will produce better quality and capacity of the microcellular systems.
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Landqvist, Ronnie. "Signal processing techniques in mobile communication systems : signal separation, channel estimation and equalization /." Karlskrona : Blekinge Institute of Technology, 2005. http://www.bth.se/fou/Forskinfo.nsf/allfirst2/98bf8bfb44d67d86c1257099003e2fc1?OpenDocument.
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Holm, Rasmus. "Energy-Efficient Mobile Communication with Cached Signal Maps." Thesis, Linköpings universitet, Programvara och system, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-124607.
Повний текст джерелаАнотація:
Data communication over cellular networks is expensive for the mobile device in terms of energy, especially when the received signal strength (RSS) is low. The mobile device needs to amplify its transmission power to compensate for noise leading to an increased energy consumption. This thesis focuses on developing a RSS map for the third generation cellular technology (3G) which can be stored locally at the mobile device, and can be used for avoiding expensive communication in low RSS areas. The proposed signal map is created by crowdsourced information collected from several mobile devices. An application is used to collect data in the mobile device of the user and the application periodically sends the information back to the server which computes the total signal map. The signal map is composed of three levels of information: RSS information, data rate tests and estimated energy levels. The energy level categorizes the energy consumption of an area into "High", "Medium" or "Low" based on the RSS, data rate test information and an energy model developed from physical power measurements. The coarse categorization provides an estimation of the energy consumption at each location. It is evaluated by collecting data traces on a smartphone at different locations and comparing the measured energy consumption at each location to the energy level categories of the map. The RSS prediction is preliminarily evaluated by collecting new data along a path and comparing how well it correlates to the signal map. The evaluation in this thesis shows that with the current collected data there are not enough observations in the map to properly estimate the RSS. However, we believe that with more observations a more accurate evaluation could be done.
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Sonbas, Buket. "Signal Processing for Sensor Based Navigation of Mobile Robot." Thesis, Högskolan i Gävle, Avdelningen för elektronik, matematik och naturvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-14230.
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A self-navigating, path following and obstacle avoiding mobile robot is difficult to realize especially when its sensors are strongly effected by noise. This MSc thesis is aimed at investigating a realistic scenario of an autonomous mobile robot simulated in the MatLab environment. The robot system is able to follow a given reference path by utilizing its onboard sensors and decision making capabilities to avoid collisions with arbitrarily placed obstacles along its path. A novel navigational algorithm based on modifying the robot’s way-points using the run-time sensory data is developed and used to go around obstacles and then rejoin the original travel path as needed. The thesis work explores the impact of varying noise in the sensory data and ways of improving the navigational accuracy via signal processing. The study is done in two major sections, the first focusing on the navigational aspects of the mobile robot and the second exploring the sensory data analyses issues. The robot considered has a triangular shape with two differentially driven wheels at the rear left and rear right corners for skid steering control and one castor wheel in the front corner for balance purposes. The sensing system of the mobile robot includes infrared range finders with viewing angles of 180 degrees placed on the corners of the robot, which are able to detect obstacles all around the robot allowing effective path planning to be carried out via the special-purpose developed navigational algorithms. A reference path in an obstacle cluttered environment is assumed to be available for the robot to follow while avoiding randomly placed obstacles as the two wheels are driven to navigate the robot along the path using the robot kinematics. For making the navigation mobility of the robot as realistic as possible, practical infrared sensors have been studied experimentally to determine their noise characteristics to include in the simulation studies and the noise levels easily varied to simulate low and high noise levels and assess their effects on the overall navigational precision. Signal processing methods are used to show that improvements in the navigational performance can be achieved when the noise levels are high.
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Prihodko, Nikolajs. "Machine Learning for Forecasting Signal Strength in Mobile Networks." Thesis, Linköpings universitet, Statistik och maskininlärning, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-154466.
Повний текст джерелаАнотація:
In this thesis we forecast the future signal strength of base stations in mobile networks. Better forecasts might improve handover of mobile phones between base stations, thus improving overall user experience. Future values are forecast using a series of past sig- nal strength measurements. We use vector autoregression (VAR), a multilayer perceptron (MLP), and a gated recurrent unit (GRU) network. Hyperparameters, including the set of lags, of these models are optimised using Bayesian optimisation (BO) with Gaussian pro- cess (GP) priors. In addition to BO of the VAR model, we optimise the set of lags in it using a standard bottom-up and top-down heuristic. Both approaches result in similar predictive mean squared error (MSE) for the VAR model, but BO requires fewer model estimations. The GRU model provides the best predictive performance out of the three models. How- ever, none of the models (VAR, MLP, or GRU) achieves the accuracy required for practical applicability of the results. Therefore, we suggest adding more information to the model or reformulating the problem.
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Chitraranjan, Charith Devinda. "Tracking Vehicles from Mobile Phone Received Signal Strength Sequences." Diss., North Dakota State University, 2015. http://hdl.handle.net/10365/25527.
Повний текст джерелаАнотація:
We address the problem of tracking vehicles from received signal strength (RSS) sequences generated by mobile phones carried in them. Our main objectives are to provide travel-time estimates for selected roads and provide personal navigation assistance when GPS is unavailable or undesirable. A mobile phone periodically measures the RSS levels from the associated cell tower and several (six for GSM) strongest neighbor cell towers. Each such measurement is known as an RSS fingerprint. In Chapter 3, we propose local alignment of mobile phone RSS measurements to track vehicles. We use local alignment instead of the traditionally used global alignment to allow for vehicles changing roads. More specifically, we use local dynamic time warping to align the RSS sequence of a phone, to a reference sequence that we had collected for the relevant road. Due to fluctuations in RSS levels and other effects, even at the same location, the set of cell towers reported in a fingerprint and their reported RSS levels vary over time. To model these variations, in Chapter 4.1, we propose a complete observation model for RSS fingerprints that specifies for each gird-location in the area of interest, the distribution of the probability of observing any fingerprint at that location. We then use it with a Dynamic Bayesian Network to track vehicles. Unlike traditional observation models, which model only the variation of the RSS levels, we model the variation of the set of cells reported in fingerprints as well. Accurate estimation of the parameters of either traditional or our complete observation model requires recording fingerprints by driving on the roads of interest, which is tedious and expensive. Therefore, to avoid such driving, we propose unsupervised learning in Chapter 5 to estimate model parameters using RSS sequences of phone calls made by road-users. Experiments with RSS data collected on five roads demonstrate that our proposed algorithms produce lower errors than relevant existing methods. Furthermore, application of our algorithms to real subscriber call traces produced travel-time estimates for a given road segment that were, on average, within 13% - 14% of travel-times computed through license plate recognition.
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Mehta, Mehul. "Power control for a mobile satellite system." Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245306.
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Nordio, Alessandro. "Advanced signal processing algorithms for 3rd generation wireless mobile systems /." [S.l.] : [s.n.], 2002. http://library.epfl.ch/theses/?nr=2550.
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Wong, Hak Lim. "Signal strength-based location estimation in two different mobile networks." HKBU Institutional Repository, 2006. http://repository.hkbu.edu.hk/etd_ra/700.
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Afgani, Mostafa Z. "Exploitation of signal information for mobile speed estimation and anomaly detection." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/4890.
Повний текст джерелаАнотація:
Although the primary purpose of the signal received by amobile handset or smartphone is to enable wireless communication, the information extracted can be reused to provide a number of additional services. Two such services discussed in this thesis are: mobile speed estimation and signal anomaly detection. The proposed algorithms exploit the propagation environment specific information that is already imprinted on the received signal and therefore do not incur any additional signalling overhead. Speed estimation is useful for providing navigation and location based services in areas where global navigation satellite systems (GNSS) based devices are unusable while the proposed anomaly detection algorithms can be used to locate signal faults and aid spectrum sensing in cognitive radio systems. The speed estimation algorithms described within this thesis require a receiver with at least two antenna elements and a wideband radio frequency (RF) signal source. The channel transfer function observed at the antenna elements are compared to yield an estimate of the device speed. The basic algorithm is a one-dimensional and unidirectional two-antenna solution. The speed of the mobile receiver is estimated from a knowledge of the fixed inter-antenna distance and the time it takes for the trailing antenna to sense similar channel conditions previously observed at the leading antenna. A by-product of the algorithm is an environment specific spatial correlation function which may be combined with theoretical models of spatial correlation to extend and improve the accuracy of the algorithm. Results obtained via computer simulations are provided. The anomaly detection algorithms proposed in this thesis highlight unusual signal features while ignoring events that are nominal. When the test signal possesses a periodic frame structure, Kullback-Leibler divergence (KLD) analysis is employed to statistically compare successive signal frames. A method of automatically extracting the required frame period information from the signal is also provided. When the signal under test lacks a periodic frame structure, information content analysis of signal events can be used instead. Clean training data is required by this algorithm to initialise the reference event probabilities. In addition to the results obtained from extensive computer simulations, an architecture for field-programmable gate array (FPGA) based hardware implementations of the KLD based algorithm is provided. Results showing the performance of the algorithms against real test signals captured over the air are also presented. Both sets of algorithms are simple, effective and have low computational complexity – implying that real-time implementations on platforms with limited processing power and energy are feasible. This is an important quality since location based services are expected to be an integral part of next generation cognitive radio handsets.
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Kanso, A. "Novel signal processing techniques for pilot-based SSB mobile radio systems." Thesis, University of Bath, 1985. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.353395.
Повний текст джерелаАнотація:
In the light of increasing spectral congestion in the land mobile radio bands below 1 GHz,a renewed interest in Single Sideband (SSB) modulation has been observed world-wide. In this context, much of the work described in this thesis has been directed towards assessing and developing audio signal processing techniques that enable the spectrum and power efficient SSB systems to acheive a comparable performance with that of existing wideband modulation systems. Statistical properties of the land mobile-radio propagation are presented showing that the received signal can be adversely affected by unwanted random phase and envelope modulations. Their effect upon AM, FM and SSB systems are discussed. A novel space diversity system employing a technique termed as Feedforward Signal Regeneration (FFSR) is presented which simultaneously performs the operation of an equal gain combining and suppression of both the random envelope and phase modulations. In connection with the use of FFSR techniques in SSB systems, a phase-locked Transparent-Tone-In-Band (TTIB) pilot-tone configuration which allows the transmission of a "transparent" pilot-tone, positioned centrally within the audio bandwidth, is discussed. Finally, efficient coherent and non-coherent data transmission in the mobile-radio environment is shown to be possible by the use of the TTIB/FFSR diversity system.
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Papakonstantinou, Konstantinos. "Les applications du traitement du signal statistique à la localisation mobile." Paris, Télécom ParisTech, 2010. http://www.theses.fr/2010ENST0041.
Повний текст джерелаАнотація:
Dans ce travail nous attaquons au problème de l’estimation de la position d’une station mobile (SM) dans un environnement NLoS. Les méthodes de localisation traditionnelles sont des processus en deux étapes: dans la première étape un ensemble de paramètres qui dépendent de la position du MT (LDP) est estimé. Dans la deuxième étape, la position de la SM est estimée en etrouvant la position qui correspondrait le plus aux paramètres LDP. Nous avons développé un algorithme (4D Unitary ESPRIT) d’estimation de LDP des composantes multi-trajets (MPC), à haute résolution et à faible complexité, pour les systèmes MIMO-OFDM. Pour la deuxième étape de localisation, nous avons développé plusieurs méthodes hybrides. En general, le problème de localisation NLoS n’est toujours pas résolu provient de la difficulté à faire correspondre des estimations de LDP à une position du MT unique. C’est pourquoi nous utilisons le modèle à rebond unique (SBM) ou le modèle SBM dynamique. Les deux avantages énormes des méthodes basées sur le (D)SBM sont la possibilité d’identification même lorsque les estimations des LDP ne sont disponibles que pour 2 MPC et la performance remarquable pour les cas où le canal est plus riche. Enfin, nous avons développé une méthode directe d’estimation de position (DLE) pour les systèmes MIMO-OFDM qui opèrent dans les environnements NLoS. Le DLE estime la position de la SM directement à partir du signal reçu. Une meilleure précision est constatée pour des rapports signal sur bruit faibles à moyens et/ou pour un petit nombre d’échantillons, comme le démontrent nos résultatsIn this work we attack the problem of mobile terminal (MT) location estimation in NLoS environments. Traditional localization methods are 2-step processes: In the 1st step a set of location-dependent parameters (LDP) is estimated. In the 2nd step, the MT location is estimated by finding the position that best fits the LDP estimates. For the 1st step we have developed a high-resolution low-complexity LDP estimation algorithm (4D Unitary ESPRIT) for MIMO-OFDM systems, to estimate the angles of arrival (AoA), the angles of departure (AoD), the delays (ToA) and the Doppler shifts (DS) of the multipath components (MPC). As far as the second step of localization is concerned, we developed several hybrid methods applicable to NLoS environments. In the NLoS localization problem, mapping the LDP estimates to the location of the MT is not trivial. To this end, we utilize static and dynamic geometrical channel models (eg. SBM). The 2 great advantages of the SBM-based methods are the identifiability even for cases when LDP estimates are available for only 2 MPC and the remarkable performance for cases when the channel is richer. Due to these great advantages, we consider SBM-based methods to be an appealing solution for the NLoS localization problem. Moreover, we have developed a direct location estimation (DLE) method for MIMO-OFDM systems. In contrast to traditional methods, DLE estimates the MT location directly from the received signal. Its main advantage is the enhanced accuracy at low to medium signal-to-noise ratio (SNR) and/or with small number of data samples, as demonstrated by our results
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Hao, Wu, and Zheng Zhibin. "CDMA SATELLITE MOBILE COMMUNICATION SYSTEM MULTI-SIGNAL RECEIVING AND SOFTWARE IMPLEMENTATION." International Foundation for Telemetering, 2000. http://hdl.handle.net/10150/606499.
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International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, CaliforniaThis paper presents one new type CDMA multi-signal receiving protocol, which is suitable for satellite mobile communication systems. Then it gives the principle analysis and describes the realization of this protocol. Meanwhile, it gives the software protocol implementation scheme. From the long point of view, it will more increase the system flexibility, which is easier to update; and will solve the interoperability and integration application problems. Finally, the simulation results conclude that software implementation of CDMA multi-signal receiving in satellite mobile communication system is feasible, and it may be used in other wireless communication systems.
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Wong, K.-H. H. "Transmission of channel coded speech and data over mobile radio channels." Thesis, University of Southampton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235340.
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Yim, Wan Hung. "All-digital multicarrier demodulators for on-board processing satellites in mobile communication systems." Thesis, University of Surrey, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.290415.
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Brooks, Duncan John. "Adaptive algorithms for low complexity equalizers in mobile communications." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312445.
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Banh, Dennis V. "A ring model for local mobile radio communications with variable packet length." Thesis, Monterey, California: Naval Postgraduate School, 1990. http://hdl.handle.net/10945/27549.
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Approved for public release; distribution unlimited.This thesis presents an analysis of the performance of a local mobile radio communications system utilizing the Aloha random access protocol with variable length packets. The capture phenomenon due to the nearfar effect that enhances the performance of the system is investigated. A tagged packet will capture the base station if its signal-to-interference ratio exceeds a threshold gamma sub zero. Because of the nearfar effect, users near the base station typically have a stronger signal than those farther away. A multiple ring model is used to alleviate this problem. Users in one ring employ different retransmission strategy from those in other rings. A shorter retransmission delay is allocated to users in rings farther from the base station than those closer to the base station in order to achieve approximately the same average delay throughout the network regardless of location.
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Khokhar, Khawar Siddique. "Design and development of mobile channel simulators using digital signal processing techniques." Thesis, Durham University, 2006. http://etheses.dur.ac.uk/2948/.
Повний текст джерелаАнотація:
A mobile channel simulator can be constructed either in the time domain using a tapped delay line filter or in the frequency domain using the time variant transfer function of the channel. Transfer function modelling has many advantages over impulse response modelling. Although the transfer function channel model has been envisaged by several researchers as an alternative to the commonly employed tapped delay line model, so far it has not been implemented. In this work, channel simulators for single carrier and multicarrier OFDM system based on time variant transfer function of the channel have been designed and implemented using DSP techniques in SIMULINK. For a single carrier system, the simulator was based on Bello's transfer function channel model. Bello speculated that about 10Βτ(_MAX) frequency domain branches might result in a very good approximation of the channel (where в is the signal bandwidth and τ(_MAX) is the maximum excess delay of the multi-path channel). The simulation results showed that 10Bτ(_MAX) branches gave close agreement with the tapped delay line model(where Be is the coherence bandwidth). This number is π times higher than the previously speculated 10Bτ(_MAX).For multicarrier OFDM system, the simulator was based on the physical (PHY) layer standard for IEEE 802.16-2004 Wireless Metropolitan Area Network (WirelessMAN) and employed measured channel transfer functions at the 2.5 GHz and 3.5 GHz bands in the simulations. The channel was implemented in the frequency domain by carrying out point wise multiplication of the spectrum of OFDM time The simulator was employed to study BER performance of rate 1/2 and rate 3/4 coded systems with QPSK and 16-QAM constellations under a variety of measured channel transfer functions. The performance over the frequency selective channel mainly depended upon the frequency domain fading and the channel coding rate.
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Maidana, Renan Guedes. "Outdoor localization system for mobile robots based on radio-frequency signal strength." Pontif?cia Universidade Cat?lica do Rio Grande do Sul, 2018. http://tede2.pucrs.br/tede2/handle/tede/8140.
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Na ?rea da Rob?tica M?vel, o problema da localiza??o ? definido como a determina??o da posi??o e orienta??o de um rob? em um espa?o tri-dimensional atrav?s de informa??es de seus sensores. A solu??o mais comum para esse problema ? utilizar um receptor de GPS (doingl?s, Global Positioning System), que reporta posi??o absoluta com rela??o a um sistema de coordenadas fixo e centralizado na Terra. Por?m, o sinal de GPS ? muito afetado por condi??es ambientais e oclus?o de linha de vis?o, por vezes fornecendo estimativas de posi??o de baixa qualidade, se houverem .Com inspira??o nestes problemas, este projeto prop?e um sistema de localiza??o para ser usado por um rob? terrestre em um ambiente externo n?o-controlado, onde h? indisponibilidade de GPS ou que suas medidas s?o de baixa qualidade. Tendo em vista que sensores de baixo custo apresentam medi??es imprecisas devido a fatores ambientais (e.g. terreno acidentado), ? proposta a utiliza??o de pares receptor-transmissor de R?dio-Frequ?ncia, onde a medida do Indicador de Pot?ncia de Sinal Recebido ? usada para estimar as dist?ncias entre receptor e trans- missor, que s?o por sua vez usadas para posicionamento. Essa medida possuia vantagem de ser independente da ilumina??o do ambiente e do estado do terreno, que afetam outros m?todos de localiza??o como Odometria Visual ou por rodas. Um erro m?dio de posiciona- mento de 0.41m foi alcan?ado atrav?s da fus?o de odometria por rodas, velocidade angular de um girosc?pio e pot?ncia de sinal recebido, em um algoritmo de Filtro de Kalman Esten- dido Aumentado, comum a melhoria de 82.66% referente ao erro m?dio de 2.38 m obtido com um sensor GPS comum.
In the field of Mobile Robotics, the localization problem consists on determining a robot?s position and orientation in a three-dimensional space through sensor information. The most common solution to this problem is to employ a Global Positioning System receiver, also known as GPS, which reports absolute position in relation to an Earth-centered fixed coordinate system. However, GPS signals are greatly affected by atmospheric conditions and line-of-sight occlusion, sometimes providing very poor position estimates, if any at all. Inspired by these problems, this project proposes a localization system to be used by a robot in an uncontrolled outdoor environment, where GPS measurements are poor or unavailable. As common sensors provide inaccurate position estimates due to environmental factors (e.g. rough terrain), we propose the use of Radio-Frequency receiver-transmitter pairs, in which the Received Signal Strength Indicator is used for estimating the distances between receiver and transmitter, which in turn are used for positioning. This measurement has the advantage of being independent from lighting conditions or the state of the terrain, factors which affect other localization methods such as visual or wheel odometry. A mean positioning error of 0.41 m was achieved by fusing wheel odometry, angular velocity from a gyroscope and the received signal strength, in an Augmented Extended Kalman Filter algorithm, with an improvement of 82.66% relative to the mean error of 2.38 m obtained with a common GPS sensor.
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Yamashita, Fumihiro. "Study on digital signal processing techniques for high-scalable mobile satellite communications." 京都大学 (Kyoto University), 2006. http://hdl.handle.net/2433/143957.
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Fouladpouri, S. A. A. "An investigation of computerised prediction models for mobile radio propagation over irregular terrain." Thesis, University of Liverpool, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233872.
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Barzaj, Yasmin. "Conception d'une architecture hybride pour l'instrumentation et l'étude du comportement des 2RM." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS119.
Повний текст джерелаАнотація:
La thèse propose un système embarqué hybride pour l'acquisition de données. Le système se compose d'un "Smartphone" couplé à un micro-contrôleur de type MBED doté d'une interface bus CAN et d'une carte mémoire SD. Selon les besoins de la recherche,on peut ajouter des capteurs ad-hoc, installés sur le véhicule par exemple, en plus des capteurs présents dans les "smartphones" récents. Le postulat est que l'on peut bénéficier des capteurs présents dans les "Smartphones" pour réduire la complexité et le coût de l'instrumentation tout en obtenant une précision de mesure acceptable, et ainsi permettre un déploiement à large échelle du système d'instrumentation. Un tel instrument de mesure a pour objectif de permettre des applications variées dans le domaine des transports routiers (étude des comportements de conduite, contrôle des flux, ...). Une méthode a été implémentée pour identification des performances des capteurs embarqués dans divers smartphones. Des travaux ont été conduit pour la détection "en ligne" des défaillances de capteurs, et la reconnaissance "hors ligne" de manœuvres réalisées par le conducteur, l'objectif étant, à terme, de reconnaître automatiquement des manœuvres typiques telles que : la prise de virages, la prise de rond-points; les manœuvres d'évitementIn this thesis, we propose a new technic to identify a hybrid system for Data Acquisition,by using ad-hoc sensors on the vehicle, the sensors in the recent smartphones, MBED and CAN-BUS. The assumption is that the Smartphone's sensors will reduce the complexity and the high cost of these instrumentations. The objective is obtaining acceptable measurement accuracy of the collected trajectories and enable for a large-scale deployment of the system's instrumentation, such as a helpful system in the domain of transport. Weshow in this thesis how to build a hybrid system by depending on the properties of the used sensors in both the smartphones and in the vehicles to identify several situation like a failure sensor, accident situation and Rider's behaviour. This system is tested and evaluated on several real time on line - off- line including the used mode and method
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Hammerschmidt, Joachim S. "Adaptive space and space-time signal processing for high-rate mobile data receivers /." Düsseldorf : VDI-Verl, 2001. http://www.gbv.de/dms/bs/toc/329240056.pdf.
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Frappé, Antoine. "All-digital RF signal generation using delta-sigma modulation for mobile communication terminals." Lille 1, 2007. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2007/50376-2007-Frappe.pdf.
Повний текст джерелаАнотація:
Dans le cadre de la radio logicielle, un transmetteur numérique, basée sur la modulation delta-sigma, est proposé. Son architecture est construite autour de deux modulateurs delta-sigma passe-bas suréchantillonnés du 3ème ordre qui fournissent un signal multiplexé sur 1 bit à haute cadence, qui code directement le signal RF dans le domaine numérique. La séquence de sortie peut ensuite être appliquée à l'entrée d'un amplificateur de puissance commuté ayant une bonne efficacité. Le standard UMTS a été choisi comme exemple d'application et un générateur de signaux RF 1 bit à 7. 8Géch/s a été réalisé dans une technologie 90nm CMOS. Une arithmétique redondante comprenant des signaux complémentaires, une quantification de sortie non exacte et une évaluation anticipée de la sortie ont été implémentées pour parvenir à la cadence désirée. Une logique dynamique différentielle sur 3 phases d'horloge, générées par une DLL, a été utilisée au niveau circuit. Le circuit intégré du transmetteur prototype démontre une fonctionnalité complète jusqu'à une fréquence d'horloge de 4GHz, permettant ainsi d'atteindre une bande passante de 50MHz autour d'une fréquence porteuse de 1GHz. Si la bande image est utilisée, la fréquence d'émission peut être déplacée jusqu'à 3GHz. Avec une fréquence d'horloge de 2. 6GHz et un canal WCDMA de 5MHz modulé autour d'une fréquence porteuse à 650MHz, 53. 6dB d'ACLR sont obtenus pour une puissance de canal en sortie de -3. 9dBm. Pour la bande image (1. 95GHz), l'ACPR est de 44. 3dB pour une puissance maximale du canal en sortie de -15. 8dBm, ce qui rentre dans les spécifications UMTS. L'aire active du circuit est de 0. I5mm² et sa consommation de 69mW sous IV à cette fréquence.
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Shekaramiz, Mohammad. "Sparse Signal Recovery Based on Compressive Sensing and Exploration Using Multiple Mobile Sensors." DigitalCommons@USU, 2018. https://digitalcommons.usu.edu/etd/7384.
Повний текст джерелаАнотація:
The work in this dissertation is focused on two areas within the general discipline of statistical signal processing. First, several new algorithms are developed and exhaustively tested for solving the inverse problem of compressive sensing (CS). CS is a recently developed sub-sampling technique for signal acquisition and reconstruction which is more efficient than the traditional Nyquist sampling method. It provides the possibility of compressed data acquisition approaches to directly acquire just the important information of the signal of interest. Many natural signals are sparse or compressible in some domain such as pixel domain of images, time, frequency and so forth. The notion of compressibility or sparsity here means that many coefficients of the signal of interest are either zero or of low amplitude, in some domain, whereas some are dominating coefficients. Therefore, we may not need to take many direct or indirect samples from the signal or phenomenon to be able to capture the important information of the signal. As a simple example, one can think of a system of linear equations with N unknowns. Traditional methods suggest solving N linearly independent equations to solve for the unknowns. However, if many of the variables are known to be zero or of low amplitude, then intuitively speaking, there will be no need to have N equations. Unfortunately, in many real-world problems, the number of non-zero (effective) variables are unknown. In these cases, CS is capable of solving for the unknowns in an efficient way. In other words, it enables us to collect the important information of the sparse signal with low number of measurements. Then, considering the fact that the signal is sparse, extracting the important information of the signal is the challenge that needs to be addressed. Since most of the existing recovery algorithms in this area need some prior knowledge or parameter tuning, their application to real-world problems to achieve a good performance is difficult. In this dissertation, several new CS algorithms are proposed for the recovery of sparse signals. The proposed algorithms mostly do not require any prior knowledge on the signal or its structure. In fact, these algorithms can learn the underlying structure of the signal based on the collected measurements and successfully reconstruct the signal, with high probability. The other merit of the proposed algorithms is that they are generally flexible in incorporating any prior knowledge on the noise, sparisty level, and so on.
The second part of this study is devoted to deployment of mobile sensors in circumstances that the number of sensors to sample the entire region is inadequate. Therefore, where to deploy the sensors, to both explore new regions while refining knowledge in aleady visited areas is of high importance. Here, a new framework is proposed to decide on the trajectories of sensors as they collect the measurements. The proposed framework has two main stages. The first stage performs interpolation/extrapolation to estimate the phenomenon of interest at unseen loactions, and the second stage decides on the informative trajectory based on the collected and estimated data. This framework can be applied to various problems such as tuning the constellation of sensor-bearing satellites, robotics, or any type of adaptive sensor placement/configuration problem. Depending on the problem, some modifications on the constraints in the framework may be needed. As an application side of this work, the proposed framework is applied to a surrogate problem related to the constellation adjustment of sensor-bearing satellites.
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Guo, Yan. "Perception multimodale pour un robot mobile en milieu marin." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2011. http://tel.archives-ouvertes.fr/tel-00637552.
Повний текст джерелаАнотація:
Dans le domaine de la robotique, les véhicules autonomes de surface en milieu marin jouent un rôle important. Ils permettent de réaliser des opérations dangereuses, comme la surveillance d'environnements marins ou encore des relevés hydrographiques. Avant d'envisager le déplacement d'un véhicule autonome de surface, il est nécessaire d'assurer sa perception de l'environnement. Elle consiste à observer, localiser et éviter les obstacles. A cause des contraintes technologiques, la complexité de l'environnement naturel, et de la diversité des situations rencontrées, il est difficile d'effectuer une plate-forme parfaitement autonome et adaptée à des applications variées. Cette thèse s'inscrit dans le cadre du projet ASAROME (Autonomous SAiling Robot for Oceanographic MEasurements), un projet de réalisation d'un voilier autonome pour des missions de mesures et d'observations de longues durées. Dans un premier temps, nous avons conçu une plate-forme de perception composée de plusieurs types de capteurs : hydrophones, caméra panoramique, centrale inertielle et sonar. A partir des signaux acquis pendant des campagnes de test, nous avons développé des méthodes de traitement du signal. Elles consistent à analyser et traiter des signaux sonores sous-marins et des images panoramiques pour la reconnaissance d'objets, la détection et la localisation d'obstacles. Pour améliorer la perception des obstacles, des méthodes de fusion de données multi-capteurs ont été développées. L'ensemble des algorithmes ont été validés expérimentalement, en lac puis en mer. Ce travail n'est que le premier pas vers la réalisation d'un robot autonome en milieu marin capable de réaliser des missions complexes de longue durée, mais il montre sa faisabilité par le développement de capacités de perception adaptées.
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Kasebzadeh, Parinaz. "Parameter Estimation for Mobile Positioning Applications." Licentiate thesis, Linköpings universitet, Reglerteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-141877.
Повний текст джерелаАнотація:
The availability and reliability of mobile positioning algorithms depend on both the quality of measurements and the environmental characteristics. The positioning systems based on global navigation satellite systems (GNSS), for example, have typically a few meters accuracy but are unavailable in signal denied conditions and unreliable in multipath environments. Other radio network based positioning algorithms have the same drawbacks. This thesis considers a couple of cases where these drawbacks can be mitigated by model-based sensor fusion techniques. The received signal strength (RSS) is commonly used in cellular radio networks for positioning due to its high availability, but its reliability depends heavily on the environment. We have studied how the directional dependence in the antenna gain in the base stations can be compensated for. We propose a semiempirical model for RSS measurements, composed of an empirical log-distance model of the RSS decay rate, and a deterministic antenna gain model that accounts for non-uniform base station antenna radiation. Evaluations and comparisons presented in this study demonstrate an improvement in estimation performance of the joint model compared to the propagation model alone. Inertial navigation systems (INS ) rely on integrating inertial sensor measurements. INS as a standalone system is known to have a cubic drift in the position error, and it needs supporting sensor information, for instance, position fixes from GNSS whenever available. For pedestrians, special tricks such as parametric gait models and step detections can be used to limit the drift. In general, the more accurate gait parameters, the better position estimation accuracy. An improved pedestrian dead reckoning (PDR) algorithm is developed that learns gait parameters in time intervals when direct position measurements (such as GNSS positions) are available. We present a multi-rate filtering solution that leads to improved estimates of both gait parameters and position. To further extend the algorithm to more realistic scenarios, a joint classifier of the user’s motion and the device’s carrying mode is developed. Classification of motion mode (walking, running, standing still) and device mode (hand-held, in pocket, in backpack) provides information that can assist in the gait learning process and hence improve the position estimation. The algorithms are applied to collected data and promising results are reported. Furthermore, one of the most extensive datasets for personal navigation systems using both rigid body motion trackers and smartphones is presented, and this dataset has also been made publicly available.
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Asjadi, Hosein G. "Real-time implementation of low bit-rate speech coders for satellite land-mobile communication systems." Thesis, University of Surrey, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254950.
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Coulton, Paul. "Novel synchronisation and channel estimation techniques using auxiliary decoding information." Thesis, Lancaster University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266675.
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Perry, Russell. "Low complexity adaptive equalisation for wireless applications." Thesis, University of Bristol, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389138.
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Салюк, Руслан Віталійович. "Малогабаритний пригнічувач сигналів мобільного зв'язку". Bachelor's thesis, КПІ ім. Ігоря Сікорського, 2020. https://ela.kpi.ua/handle/123456789/39459.
Повний текст джерелаАнотація:
Даний дипломний проект зроблений для реалізації малогабаритного пригнічувача сигналів мобільного зв’язку. Особливості цього пригнічувача полягають у простій конструкції та працездатності як з антеною, так і без неї – на деяких відстанях.
Мета роботи – побудова та розробка малогабаритного пригнічувача сигналів мобільного зв’язку.
Придушувач випромінюють сигнал у тому ж діапазоні частот, що і пристрій, який ви хочете видалити. Навколо цього пригнічувача створюється поле "білого шуму", в якому губляться сигнали від інших джерел.
Результатом цієї роботи є зроблена модель малогабаритного пригнічувача сигналів мобільного зв'язку.This diploma project is designed for the implementation of a small-sized mobile signal suppressor. The features of this suppressor are simple design and operability both with and without an antenna – at certain distances. The purpose of this work is to develop a small – sized mobile signal suppressor. The suppressor emits a signal in the same frequency range as the device you want to remove. A "white noise" field is created around this suppressor, where signals from other sources are lost. The result of this work is a well-made model of a small-sized mobile signal suppressor.
Данный дипломный проект сделан для реализации малогабаритного подавителя сигналов мобильной связи. Особенности этого подавителя заключаются в простой конструкции и работоспособности как с антенной, так и без нее - на некоторых расстояниях. Цель работы - построение и разработка малогабаритного подавителя сигналов мобильной связи. Придушувач излучают сигнал в том же диапазоне частот, что и устройство, которое вы хотите удалить. Вокруг этого подавителя создается поле "белого шума", в котором теряются сигналы от других источников. Результатом этой работы является совершенная модель малогабаритного подавителя сигналов мобильной связи.
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Thomas, Seimon M. "Signal and neutral processing techniques for the interpretation of mobile robot ultrasonic range data." Thesis, Cardiff University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246116.
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Moretti, Daniela. "Exposure of neuronal networks to GSM mobile phone signals." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-00949371.
Повний текст джерелаАнотація:
The central nervous system is the most likely target of mobile telephony radiofrequency field (RF) exposure in terms of biological effects. Several EEG (electroencephalography) studies have reported variations in the alpha-band power spectrum during and/or after RF exposure, in resting EEG and during sleep. In this context, the observation of the spontaneous electrical activity of neuronal networks under RF exposure can be an efficient tool to detect the occurrence of low-level RF effects on the nervous system. In this thesis research work we developed a dedicated experimental setup in the GHz range for the simultaneous exposure of neuronal networks and monitoring of electrical activity. A transverse electromagnetic (TEM) cell was used to expose the neuronal networks to GSM-1800 signals at a SAR level of 3.2 W/kg. Recording of the neuronal electrical activity and detection of the extracellular spikes and bursts under exposure were performed using Micro Electrode Arrays (MEAs). This work provides the proof of feasibility and preliminary results of the integrated investigation regarding exposure setup, culture of the neuronal network, recording of the electrical activity and analysis of the signals obtained under RF exposure. In the main experiment (16 cultures), there was a 30% reversible decrease in mean firing rate (MFR) and bursting rate (BR) during the 3 min exposures to RF. Additional experiments are needed to further characterize this effect, especially in terms of temperature elevation at the microscopic level.
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Zhou, Junyang. "Enhanced signal propagation models and algorithm selector for providing location estimation services within cellular radio networks." HKBU Institutional Repository, 2007. http://repository.hkbu.edu.hk/etd_ra/776.
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Singh, Kuldeep. "An Investigation of Spam Filter Optimaltiy : based on Signal Detection Theory." Thesis, Norwegian University of Science and Technology, Department of Telematics, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9960.
Повний текст джерелаАнотація:
Unsolicited bulk email, commonly known as spam, represents a significant problem on the Internet. The seriousness of the situation is reflected by the fact that approximately 97% of the total e-mail traffic currently (2009) is spam. To fight this problem, various anti-spam methods have been proposed and are implemented to filter out spam before it gets delivered to recipients, but none of these methods are entirely satisfactory. This thesis analyzes the properties of spam filters from the viewpoint of Signal Detection Theory (SDT). The Bayesian approach of Signal Detection Theory provides a basis for determining the tuning of spam filters from the particular user's point of view and helps in determining the utility which the spam filter provides to the user.
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Campbell, Matthew C. "Design of a Mobile Transceiver for Precision Indoor Location." Digital WPI, 2010. https://digitalcommons.wpi.edu/etd-theses/1116.
Повний текст джерелаАнотація:
"This thesis documents the design and implementation process for the next generation of the WPI Precision Personnel Location (PPL) system hardware. The driving goal of the new hardware was to support a new method of radio frequency location developed at WPI referred to as Transactional Array Reconciliation Tomography (TART). This new method is based on a time of arrival (TOA) technique as opposed to the previous Singular Value Array Reconciliation Tomography (SART), which uses time difference of arrival (TDOA). The use of a TOA method requires additional timing information and necessitates a bidirectional (transmit and receive) multicarrier transaction. The design of the new transceiver that can function as both a mobile locator and a static reference unit is the main focus of this thesis. This redesign also addressed previous hardware issues that have been exposed through extensive use in real world testing."
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Gerzaguet, Robin. "Méthodes de traitement numérique du signal pour l'annulation d'auto-interférences dans un terminal mobile." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GRENT014/document.
Повний текст джерелаАнотація:
Les émetteurs-récepteurs actuels tendent à devenir multi-standards c’est-àdireque plusieurs standards de communication peuvent cohabiter sur la même puce. Lespuces sont donc amenées à traiter des signaux de formes très différentes, et les composantsanalogiques subissent des contraintes de conception de plus en plus fortes associées au supportdes différentes normes. Les auto-interférences, c’est à dire les interférences généréespar le système lui-même, sont donc de plus en plus présentes, et de plus en plus problématiquesdans les architectures actuelles. Ces travaux s’inscrivent dans le paradigmede la « radio sale » qui consiste à accepter une pollution partielle du signal d’intérêtet à réaliser, par l’intermédiaire d’algorithmes, une atténuation de l’impact de ces pollutionsauto-générées. Dans ce manuscrit, on s’intéresse à différentes auto-interférences(phénomène de "spurs", de "Tx leakage", ...) dont on étudie les modèles numériques etpour lesquelles nous proposons des stratégies de compensation. Les algorithmes proposéssont des algorithmes de traitement du signal adaptatif qui peuvent être vus comme des« algorithmes de soustraction de bruit » basés sur des références plus ou moins précises.Nous dérivons analytiquement les performances transitionnelles et asymptotiques théoriquesdes algorithmes proposés. On se propose également d’ajouter à nos systèmes unesur-couche originale qui permet d’accélérer la convergence, tout en maintenant des performancesasymptotiques prédictibles et paramétrables. Nous validons enfin notre approchesur une puce dédiée aux communications cellulaires ainsi que sur une plateforme de radiologicielleRadio frequency transceivers are now massively multi-standards, which meansthat several communication standards can cohabit in the same environment. As a consequence,analog components have to face critical design constraints to match the differentstandards requirements and self-interferences that are directly introduced by the architectureitself are more and more present and detrimental. This work exploits the dirty RFparadigm : we accept the signal to be polluted by self-interferences and we develop digitalsignal processing algorithms to mitigate those aforementioned pollutions and improve signalquality. We study here different self-interferences and propose baseband models anddigital adaptive algorithms for which we derive closed form formulae of both transientand asymptotic performance. We also propose an original adaptive step-size overlay toimprove transient performance of our method. We finally validate our approach on a systemon chip dedicated to cellular communications and on a software defined radio
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Schölling, Björn. "Binaural signal processing for source localization and noise reduction with applications to mobile robotics." Münster Verl.-Haus Monsenstein und Vannerdat, 2009. http://d-nb.info/994281242/04.
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GONCALVES, JULIANA VALIM OLIVER. "SIGNAL VARIABILITY, COHERENCE BANDWIDTH AND DELAY SPREAD ON MOBILE RADIO PROPAGATION ENVIRONMENT AT 3.5GHZ." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2009. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=15393@1.
Повний текст джерелаАнотація:
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
Nesta dissertação, é apresentado estudo realizado sobre a variabilidade do sinal, da banda de coerência e do espalhamento de retardos em um ambiente de rádio propagação móvel, por meio de medição em campo de um sinal WiMAX propagado ao longo do canal rádio móvel. A análise da estatística do sinal capturado é comparada com valores teóricos. O sinal WiMAX utilizado possui a tecnologia OFDM-256, como base da sua camada física, e frequência central de 3,410 GHz. A partir dos dados coletados durante as medições, são realizadas as análises da variabilidade do sinal, taxa de cruzamento de nível, tempo médio de desvanecimento, verificada a banda de coerência do canal e calculado o espalhamento de retardos (delay spread), por meio de fórmulas teóricas, em ambientes de LOS e NLOS. O nível do sinal medido é apresentado na forma de distribuição de probabilidade cumulativa, comparado com as distribuições cumulativas teóricas Rayleigh e m-Nakagami, sendo possível verificar a satisfatória adaptação dos dados às distribuições teóricas. São apresentados gráficos com a informação de taxa de cruzamento de nível e tempo médio de desvanecimento de determinadas subportadoras do sinal capturado, bem como os valores teóricos dos parâmetros supracitados, de acordo com as distribuições Rayleigh e m-Nakagami. Novamente, é possível verificar a satisfatória adaptação entre as informações teóricas e os dados medidos em campo. Por fim, é realizada a correlação entre as subportadoras, com o intuito de averiguar a banda de coerência definida, neste trabalho, para um valor de correlação igual a 0,5. De posse dessa informação, o cálculo do parâmetro de espalhamento de retardos é realizado, com base em fórmulas presentes na literatura.
This work presents a study of signal variability, coherence bandwidth and delay spread of a WiMAX signal transmitted through a mobile radio propagation environment. The statistical analysis of the received signal is compared with theoretical distributions. The transmitted WiMAX signal has its physical layer based on OFDM-256 and 3.4 GHz as central frequency. Based on the signal received during the measurements campaign some analysis are done: signal variability; level crossing rate; average fade duration; coherence bandwidth; and delay spread calculation, based on theoretical formulas, in LOS and NLOS environment. The received signal amplitude is plotted as a function of the cumulative probability and compared to the theoretical Rayleigh and m-Nakagami cumulative distributions. It’s possible to notice a good characterization of the measured data based on those two distributions. Some graphs show the level crossing rate and average fade duration of a specific subcarrier of the received signal. In the same graphs are also plotted the theoretical values of Nakagami-m and Rayleigh distributions for those two parameters and we are able to see the good agreement. The correlation between subcarriers is also calculated in order to find out the correlation bandwidth for a correlation of 0.5. Once that the correlation bandwidth is known, the delay spread is calculated based on theoretical formulas.
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Flutura, Simon [Verfasser], and Elisabeth [Akademischer Betreuer] André. "Mobile social signal interpretation in the wild for wellbeing / Simon Flutura ; Betreuer: Elisabeth André." Augsburg : Universität Augsburg, 2021. http://d-nb.info/1241474370/34.
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Slobodník, Šimon. "Porovnání mapy pokrytí mobilního operátora s reálným pokrytím prostřednictvím GIS." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226597.
Повний текст джерелаАнотація:
The objective of the diploma thesis is to compare the actual signal quality in selected locations with the coverage maps of the mobile operator. The places of interest with reduced level of signal strength are located in Brno and its surroundings. Theoretical part of the thesis discusses the issues of geographical information systems, GNSS technologies, mechanisms of signal propagation and mobile applications useful for surveying purposes. The practical part describes the communication with mobile operators, the process of data collection and processing the project using ArcMap software.
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Ng, Matthew James. "Corridor Navigation for Monocular Vision Mobile Robots." DigitalCommons@CalPoly, 2018. https://digitalcommons.calpoly.edu/theses/1856.
Повний текст джерелаАнотація:
Monocular vision robots use a single camera to process information about its environment. By analyzing this scene, the robot can determine the best navigation direction. Many modern approaches to robot hallway navigation involve using a plethora of sensors to detect certain features in the environment. This can be laser range finders, inertial measurement units, motor encoders, and cameras.
By combining all these sensors, there is unused data which could be useful for navigation. To draw back and develop a baseline approach, this thesis explores the reliability and capability of solely using a camera for navigation. The basic navigation structure begins by taking frames from the camera and breaking them down to find the most prominent lines. The location where these lines intersect determine the forward direction to drive the robot. To improve the accuracy of navigation, algorithm improvements and additional features from the camera frames are used. This includes line intersection weighting to reduce noise from extraneous lines, floor segmentation to improve rotational stability, and person detection.
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Gao, Minqi. "Learning mobile robot control for obstacle avoidance based on motion energy neurons /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?ECED%202009%20GAO.
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Terry, John D. "Blind adaptive array techniques for mobile satellite communications." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/13425.
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Ait, Aider Omar. "Localisation référencée modèle d'un robot mobile d'intérieur." Phd thesis, Université d'Evry-Val d'Essonne, 2002. http://tel.archives-ouvertes.fr/tel-00682235.
Повний текст джерелаАнотація:
Le présent travail porte sur la localisation incrémentale et absolue d'un robot mobile dans un environnement d'intérieur partiellement modélisé en utilisant la vision monoculaire. L'environnement de navigation du robot est à base de primitives géométriques (segments). Il intègre la notion d'occultation grâce à un découpage de l'espace 2-D navigable en Régions d'Invariance Visuelle. Le modèle de caméra à perspective pleine est obtenu grâce au calibrage par la méthode de Zhang. L'approche adoptée est composée de quatre étapes : acquisition d'une image à partir de la position courante du robot, extraction des primitives observées, mise en correspondance des primitives de l'image avec celles du modèle et calcul de la position et de l'orientation de la caméra. Deux méthodes numériques de calcul de la position et de l'orientation de la caméra grâce à des correspondances de droites sont présentées est adaptées au cas spécifique de la robotique mobile. Enfin, un algorithme de mise en correspondance des segments de l'image avec ceux du modèle est défini. Il est basé sur la recherche dans un arbre d'interprétation. Les Régions d'Invariance Visuelle et la configuration du système sont utilisées pour réduire l'espace des correspondances. Des contraintes géométriques d'ordre un et deux sont définies pour assurer l'élagage rapide de l'arbre. Une nouvelle fonction de vérification de la cohérence globale permet de sélectionner l'hypothèse de correspondance la plus cohérente.
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Martin, Cristoff. "Mobile Satellite Broadcast and Multichannel Communications : analysis and design." Doctoral thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-177.
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Balkorkian, Sevag, and Zhang Hao. "Analysis of Internal RF Interferences in Mobile." Thesis, KTH, Microelectronics and Information Technology, IMIT, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3909.
Повний текст джерелаАнотація:
Nowadays, mobile phones have greater functionality; a camera, color LCD screen, wireless LAN, Bluetooth, IrDA and others. In the near future wider variety of new functionalities will be added, from high quality voice, high definition video to high data rate wireless channels. As consumer electronics integrate greater functionality and high operating frequencies, their emissions will exceed the specified limits, most of these emissions will be a result of the internal interferences in the mobile phone. Moreover higher operating frequencies will be required to improve the quality of these functionalities, something that will make it more difficult to control these interferences. Internal or external sources of electromagnetic interference can degrade the performance of sensitive analog/digital circuits inside the mobile phone. Moreover the electronic device must satisfy a host of global regulations that limit it’s susceptibility to these interferences, as well as the interference emitted by the device itself.
Therefore designing a new electronic device to perform new and exciting functions will not be a pleasant task if it can not meet certain specifications and function as required to adhere to certain global regulations.
This thesis project investigates the sources of interference inside a mobile phone; mainly the electromagnetic interferences and its effect on the radio transceiver focusing on the GSM receiver sensitivity. This report is a result of intensive research, an investigation of possible sources of interference, also actual measurements were performed; RSSI, OTA and sniffing measurements; to identify the physical sources of interferences, and their effect on the receiver sensitivity. Finally solutions were recommended and implemented to suppress the interferences due to different sources, mainly through filtering, shielding or proper grounding of signals and components/subsystems in the mobile phone.
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Frank, Florian. "Hybrid analogue & digital access network architectures for the mobile/fixe infrastructure convergence." Phd thesis, Université Paris-Est, 2011. http://tel.archives-ouvertes.fr/tel-00665650.
Повний текст джерелаАнотація:
In order to realize the convergence of the optical infrastructure of fixed and mobile access networks, the objective of this thesis is to study the solutions for distributing native radio carriers through typical optical access networks.The first Part describes the contexts and the main physical properties of the optical and radio access networks: from nowadays deployed Fiber To The Home (FTTH) systems, and their expected evolutions, to the current radio system Universal Mobile Telecommunications System (UMTS) towards the expected requirements of modern mobile radio systems. This allows to settle the optical environment in which the Radio over Fiber(RoF)-functionalities will have to be integrated, and to know on which radio systems'figures of merits to focus on when implementing it. The second Part shows the benefit and possibilities of re-using the optical infrastructure of the fixed access networks for distributed radio systems. Then a review of the analog and digital RoF techniques is proposed, and their feasibility of integration into legacy FTTH systems is discussed. The third part deals with the computing and simulations of an analog RoF-system where the optical link is either passive or optically pre-amplified, and even boosted. The goal is to provide numerical results to the practical lab. results of the second half of the fourth part where the Signal to Noise Ratio (SNR) matters. Therefore successively formal expressions, numerical results for simple 2-tone signals and more realistic UMTS signals are considered. The fourth and last part deals with the obtained practical results. These can be split into two main categories : Error Vector Magnitude (EVM)-oriented results where an Avalanche Photo-Detector (APD) is used for legacy and extended-reach PON architectures using a direction shared Semiconductor Optical Amplifier (SOA) ; and an Adjacent/Alternate Channel power Leakage Ratio (ACLR)-driven part where the focus is seton a very critical figure of merit of radio systems, especially in the downlink. The latter part turned out to be mandatory and prevailing over the initially considered EVM concerns. Hence several RoF architectures, compatible with PONs, are introduced in order to overcome the non-linearities undergone by the RoF-signals, induced by the chromatic dispersion of the PON's fiber and the laser chirp, and degrading the ACLR performances
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Ahmed, Rana [Verfasser], and Joachim [Akademischer Betreuer] Speidel. "Equalization and blind signal combining algorithms for mobile television broadcast reception / Rana Ahmed ; Betreuer: Joachim Speidel." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2016. http://d-nb.info/1118507460/34.
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