Browsing Elektrik-Elektronik Mühendisliği / Electrical - Electronics Engineering by Title
Now showing items 126-145 of 330
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Generalized LED Index Modulation Optical OFDM for MIMO Visible Light Communications Systems
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Publisher and Date:(IEEE, 2016)In this paper we propose a generalized light emitting diode (LED) index modulation scheme for multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) visible light communications (VLC) systems. The proposed scheme generalizes the LED index modulation concept by using the spatial multiplexing principle to transmit complex OFDM signals through VLC channels by separating these signals into their real-imaginary and positive-negative parts. The maximum a posteriori (MAP) ...
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Genetic algorithm based broadband equalizer design with ripple level control
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Publisher and Date:(IEEE, 2012)In this paper broadband equalizer design with ripple control via genetic algorithm has been studied. The equalizer is defined as a lossless two-port terminated by load impedance and the coefficients of its describing scattering polynomials have been optimized via genetic algorithm. During the optimization process ripple level of the transducer power gain has been controlled. An example has been given to illustrate the utilization of the proposed approach. © 2012 IEEE.
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Growth and shape stability of Cu-Ni core-shell nanoparticles: an atomistic perspective
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Publisher and Date:(Royal Soc Chemistry, 2018)The growth and shape stability of bi-metallic cubic Cu-Ni nanoparticles are studied using atomic-level simulations. Cubic nano-crystals coated with an ultra-thin Cu layer can be readily obtained when Ni cubic nanoparticles are used as the seeds. At elevated temperatures the Cu seed with extending Ni branches preserves its shape compared to the Ni seed with extending Cu branches.
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Guest editorial: special issue on high mobility wireless communications
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Publisher and Date:(2012)
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High-pass/low-pass section design for 0 degrees-360 degrees lumped-element phase shifters via the real frequency technique
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Publisher and Date:(TUBITAK Scientific & Technical Research Council Turkey, 2017)In this paper an algorithm based on the real frequency technique (RFT) is proposed to design high-pass and low-pass sections of a 0 degrees-360 degrees wide range lumped-element phase shifter. The switching process however is not considered in this work. In the algorithm it is enough to define the section type (high-pass or low-pass) and the number of elements in the sections there is no need to select the exact circuit topologies for the high-pass and low-pass sections. This is a natural consequence ...
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High-pass/low-pass section design for 0◦ 360◦ lumped-element phase shifters via the real frequency technique
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Publisher and Date:(Tübitak, 2017)In this paper, an algorithm based on the real frequency technique (RFT) is proposed to design high-pass and low-pass sections of a 0 ◦ –360 ◦ wide range lumped-element phase shifter. The switching process, however, is not considered in this work. In the algorithm, it is enough to define the section type (high-pass or low-pass) and the number of elements in the sections; there is no need to select the exact circuit topologies for the high-pass and low-pass sections. This is a natural consequence ...
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A Hybrid Deep Learning Framework for Unsupervised Anomaly Detection in Multivariate Spatio-Temporal Data
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Publisher and Date:(Mdpi, 2020)Multivariate time-series data with a contextual spatial attribute have extensive use for finding anomalous patterns in a wide variety of application domains such as earth science, hurricane tracking, fraud, and disease outbreak detection. In most settings, spatial context is often expressed in terms of ZIP code or region coordinates such as latitude and longitude. However, traditional anomaly detection techniques cannot handle more than one contextual attribute in a unified way. In this paper, a ...
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A hybrid deep learning framework for unsupervised anomaly detection in multivariate spatio-temporal data
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Publisher and Date:(MDPI AG, 2020)Multivariate time-series data with a contextual spatial attribute have extensive use for finding anomalous patterns in a wide variety of application domains such as earth science, hurricane tracking, fraud, and disease outbreak detection. In most settings, spatial context is often expressed in terms of ZIP code or region coordinates such as latitude and longitude. However, traditional anomaly detection techniques cannot handle more than one contextual attribute in a unified way. In this paper, a ...
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Hybrid MEMS-based Molecular Communication System
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Publisher and Date:(IEEE, 2019)In this paper, we consider a molecular communication link integrated in a micro-electro mechanical system (MEMS) based environment. We apply acoustic tweezing techniques to the molecular communication system to increase communication reliability. We use finite element methods to simulate this hybrid system. By deriving the symbol error rate as the performance metric, we show that the proposed system facilitates reliable communication in the presence of fluid flow and its performance is robust ...
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Hybrid MEMS-Based molecular communication system
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Publisher and Date:(Institute of Electrical and Electronics Engineers Inc., 2019)In this paper, we consider a molecular communication link integrated in a micro-electro mechanical system (MEMS) based environment. We apply acoustic tweezing techniques to the molecular communication system to increase communication reliability. We use finite element methods to simulate this hybrid system. By deriving the symbol error rate as the performance metric, we show that the proposed system facilitates reliable communication in the presence of fluid flow and its performance is robust ...
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IEEE 802.15.4a Based Ultra Wideband Systems for Coexistence with Primary Users
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Publisher and Date:(IEEE, 2015)Peaceful coexistence is a major implementation issue for both cognitive radios and ultra wideband (UWB) systems. Accordingly the UWB impulse radio (UWB-IR) based Wireless Personal Area Network (WPAN) standard IEEE 802.15.4a has suggested using linear combination of pulses to limit interference to coexisting primary systems. In this paper motivated by implementing the IEEE 802.15.4a based UWB-IR systems for peaceful coexistence we consider the implementation of linear combination of pulses as ...
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IEEE 802.15.7r1 Reference Channel Models for Visible Light Communications
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Publisher and Date:(IEEE-Inst Electrical Electronics Engineers Inc, 2017)The IEEE has established the standardization group 802.15.7r1 "Short Range Optical Wireless Communications", which is currently in the process of developing a standard for visible light communication (VLC). As with any other communication system, realistic channel models are of critical importance for VLC system design, performance evaluation, and testing. This article presents the reference channel models that were endorsed by the IEEE 802.15.7r1 Task Group for evaluation of VLC system proposals. ...
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Information Theoretical Performance Analysis and Optimisation of Cooperative Underwater Acoustic Communication Systems
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Publisher and Date:(Inst Engineering Technology-IET, 2016)In this study the authors investigate the information theoretical limits on the performance of single-carrier cooperative underwater acoustic communication systems in the presence of intersymbol interference. The authors assume decode-and-forward relaying and consider orthogonal half-duplex cooperation. Under the assumptions of sparse and frequency-selective Rician fading channel and non-white correlated Gaussian ambient noise the authors derive expressions for bounds on the individual and achievable ...
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Information theoretical performance limits of single-carrier underwater acoustic systems
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Publisher and Date:(Inst Engineering Technology-IET, 2014)In this study the authors investigate the information theoretical limits on the performance of point-to-point single-carrier acoustic systems over frequency-selective underwater channels with intersymbol interference. Under the assumptions of sparse and frequency-selective Rician fading channel and non-white correlated Gaussian ambient noise the authors derive an expression for channel capacity and demonstrate the dependency on channel parameters such as the number location and power delay profile ...
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Interpolation Based Pilot-Aided Channel Estimation for STBC Spatial Modulation and Performance Analysis Under Imperfect CSI
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Publisher and Date:(Inst Engineering Technology-IET, 2016)A combination of space-time block coding and spatial modulation (STBC-SM) has been recently proposed for multiple input-multiple output systems to obtain both spatial diversity gain and more capacity simultaneously while assuming the perfect channel state information (P-CSI) was available at the receiver. However in practical scenarios the CSI is unknown to the receiver and should be estimated in order to detect the transmitted data in a reliable way. Therefore channel estimation (CE) is a major ...
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Iterative channel estimation and decoding of turbo coded SFBC-OFDM systems
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Publisher and Date:(IEEE, 2007)We consider the design of turbo receiver structures for space-frequency block coded orthogonal frequency division multiplexing (SFBC-OFDM) systems in the presence of unknown frequency and time selective fading channels. The Turbo receiver structures for SFBC-OFDM systems under consideration consists of an iterative MAP Expectation/Maximization (EM) channel estimation algorithm soft MMSE-SFBC decoder and a soft MAP outer-channel-code decoder. MAP-EM employs iterative channel estimation and it ...
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Iterative channel estimation for spatial modulation systems over fast fading channels
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Publisher and Date:(IEEE, 2014)Spatial Modulation (SM) based on the use of antenna indices to transmit information in addition to the conventional signal constellations has been recently proposed to solve practical problems encountered in MIMO systems. In the literature estimation of CSI for SM systems is simply investigated by RLS for slow fading channels. However iterative receivers that offer significant performance gains over a non- iterative when the total number of pilot is not sufficient and the channel is fast fading ...
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Iterative channel estimation for spatial modulation systems over fast fading channels [Hızlı sönümlemeli kanallarda uzaysal modülasyon sistemleri için iteratif kanal kestirimi]
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Publisher and Date:(IEEE Computer Society, 2014)Spatial Modulation (SM) based on the use of antenna indices to transmit information in addition to the conventional signal constellations has been recently proposed to solve practical problems encountered in MIMO systems. In the literature estimation of CSI for SM systems is simply investigated by RLS for slow fading channels. However iterative receivers that offer significant performance gains over a non-iterative when the total number of pilot is not sufficient and the channel is fast fading ...
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Iterative channel estimation techniques for uplink MC-CDMA systems
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Publisher and Date:(IEEE, 2007)In this work maximum likelihood (ML) channel estimation for uplink multicarrier code-division multiple-access (MC-CDMA) systems is considered in the presence of frequency fading channel. The expectation-maximization (EM)- and a space-alternating generalized expectation-maximization (SAGE) algorithm are introduced to avoid matrix inversion for the ML channel estimation problem. We compare the both algorithms in terms of the number of used iteration and show that the proposed algorithms converge the ...
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Iterative channel estimation techniques for uplink MC-CDMA systems
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Publisher and Date:(IEEE, 2007)In this work maximum likelihood (ML) channel estimation for uplink multicarrier code-division multiple-access (MC-CDMA) systems is considered in the presence of frequency fading channel. The expectation-maximization (EM)- and a space-alternating generalized expectation-maximization (SAGE) algorithm are introduced to avoid matrix inversion for the ML channel estimation problem. We compare the both algorithms in terms of the number of used iteration and show that the proposed algorithms converge the ...