Browsing Elektrik-Elektronik Mühendisliği / Electrical - Electronics Engineering by Title
Now showing items 149-168 of 330
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Joint Channel Estimation and Equalization for OFDM based Broadband Communications in Rapidly Varying Mobile Channels
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Publisher and Date:(IEEE, 2010)This paper is concerned with the challenging and timely problem of channel estimation for orthogonal frequency division multiplexing (OFDM) systems in the presence of frequency selective and very rapidly time varying channels. In OFDM systems operating over rapidly time-varying channels the orthogonality between subcarriers is destroyed leading to inter-carrier interference (ICI) and resulting in an irreducible error floor. The band-limited discrete cosine serial expansion of low-dimensionality ...
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Joint Channel Estimation Equalization and Data Detection for OFDM Systems in the Presence of Very High Mobility
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Publisher and Date:(IEEE-INST Electrical Electronics Engineers Inc, 2010)This paper is concerned with the challenging and timely problem of joint channel estimation equalization and data detection for uplink orthogonal frequency division multiplexing (OFDM) systems in the presence of frequency selective and very rapidly time varying channels. The resulting algorithm is based on the space alternating generalized expectation maximization (SAGE) technique which is particularly well suited to multicarrier signal formats leading to a receiver structure that also incorporates ...
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Joint Communication and Computing Resource Allocation in 5G Cloud Radio Access Networks
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Publisher and Date:(IEEE-Inst Electrical Electronics Engineers Inc, 2019)Cloud-radio access network (C-RAN) is regarded as a promising solution to manage heterogeneity and scalability of future wireless networks. The centralized cooperative resource allocation and interference cancellation methods in C-RAN significantly reduce the interference levels to provide high data rates. However, the centralized solution is not scalable due to the dense deployment of small cells with fractional frequency reuse, causing severe inter-tier and inter-cell interference turning the ...
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Joint data detection and channel estimation for uplink MC-CDMA systems over frequency selective channels
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Publisher and Date:(Springer, 2007)This paper is concerned with joint channel estimation and data detection for uplink multicarrier code-division multiple-access (MC-CDMA) systems ill the presence of frequency fading channel. The detection and estimation implemented at the receiver are based on a version of the expectation maximization (EM) algorithm which is very suitable for the the multicarrier signal formats. Application of the EM-based algorithm to the problem of iterative data detection and channel estimation leads to a ...
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Joint Detection of Primary Systems Using UWB Impulse Radios
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Publisher and Date:(IEEE-INST Electrical Electronics Engineers Inc, 2011)Regulation in Europe and Japan requires the implementation of detect-and-avoid (DAA) techniques in some bands for the coexistence of licensed primary systems and secondary ultra wideband (UWB) systems. In a typical coexistence scenario a primary system may have potentially interdependent uplink-downlink communication channels (e. g. simultaneous uplink-downlink communications in a frequency division duplex system) overlapping with the frequency band of a UWB system. If such interdependencies of ...
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Joint Optimization of Wireless Network Energy Consumption and Control System Performance in Wireless Networked Control Systems
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Publisher and Date:(IEEE-INST Electrical Electronics Engineers Inc, 2017)Communication system design for wireless networked control systems requires satisfying the high reliability and strict delay constraints of control systems for guaranteed stability with the limited battery resources of sensor nodes despite the wireless networking induced non-idealities. These include non-zero packet error probability caused by the unreliability of wireless transmissions and non-zero delay resulting from packet transmission and shared wireless medium. In this paper we study the ...
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Joint phase noise estimation and source detection [Ortak faz gürültüsü kestirimi ve kaynak sezimlemesi]
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Publisher and Date:(2010)Rapidly time-varying and random disturbing effects on the phase of a signal waveform are known as phase noise. In this paper we consider the problem of joint detection of continuous-valued information source output and estimation of a phase noise by using expectation maximization (EM) algorithm. In order to estimate phase noise initial phase noise values are determined by cubic interpolation that utilizes pilot symbols. Computer simulations are performed for the proposed algorithm and the average ...
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Joint Wavelet-Based Spectrum Sensing and FBMC Modulation for Cognitive mmWave Small Cell Networks
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Publisher and Date:(Inst Engineering Technology-IET, 2016)Millimetre-wave (mmWave) 5G communications is an emerging technology to enhance the capacity of existing systems by thousand-fold improvement. Heterogeneous networks employing densely distributed small cells can optimise the available coverage and throughput of 5G systems. Efficiently utilising the spectrum bands by small cells is one of the approaches that will considerably increase the available data rate and capacity of the heterogeneous networks. This challenging task can be achieved by spectrum ...
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Linear Combination of Pulses for Coexistence in the IEEE 802.15.4a Standard
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Publisher and Date:(IEEE, 2009)The low data rate accurate location ranging Wireless Personal Area Network zWPAN standard IEEE which is based on ultra wideband zUWBg impulse radios suggests using linear combination of pulses to reduce interference to coexisting primary systems. In this paper we consider possible implementations of linear combination of pulses as suggested in the standard and study the generated notches in the resulting code spectrum. Using the zy transform approach we show that the number of these notches is ...
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Linear expansions for frequency selective channels in OFDM
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Publisher and Date:(Elsevier GMBH Urban & Fischer Verlag, 2006)Modeling the frequency selective fading channels as random processes we employ a linear expansion based on the Karhumen-Loeve (KL) series representation involving a complete set of orthogonal deterministic vectors with a corresponding uncorrelated random coefficients. Focusing on OFDM transmissions through frequency selective fading this paper pursues a computationally efficient pilot-aided linear minimum mean square error (MMSE) uncorrelated KL series expansion coefficients estimation algorithm. ...
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Liquid-liquid equilibria of water+propionic acid+solvent ternaries at 298.2 K
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Publisher and Date:(2006)(Liquid + liquid) equilibrium (LLE) data for (water + propionic acid + solvent) were measured at T= 298.2 K and atmospheric pressure. The solvents were methyl isoamyl ketone (5-methyl-2-hexanone) and diisobutyl ketone. The tie-line data were predicted by the UNIFAC method. A comparison of the extracting capabilities of the solvents was made with respect to distribution coefficients separation factors and solvent free selectivity bases.
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Low-complexity joint data detection and channel equalisation for highly mobile orthogonal frequency division multiplexing systems
Authors:
Publisher and Date:(2010)This study is concerned with the challenging and timely problem of channel equalisation and data detection for orthogonal frequency division multiplexing (OFDM) systems in the presence of frequency-selective and very rapidly time-varying channels. The algorithm is based on the space alternating generalised expectation-maximisation (SAGE) technique which is particularly well suited to multicarrier signal formats and can be easily extended to multi-input multi-output-OFDM systems. In fast fading ...
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Low-Complexity MAP-Based Successive Data Detection for Coded OFDM Systems Over Highly Mobile Wireless Channels
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Publisher and Date:(IEEE-INST Electrical Electronics Engineers Inc, 2011)This paper is concerned with the challenging and timely problem of data detection for coded orthogonal frequency-division multiplexing (OFDM) systems in the presence of frequency-selective and very rapidly time varying channels. New low-complexity maximum a posteriori probability (MAP) data detection algorithms are proposed based on sequential detection with optimal ordering (SDOO) and sequential detection with successive cancellation (SDSC). The received signal vector is optimally decomposed into ...
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Lower lower-critical spin-glass dimension from quenched mixed-spatial-dimensional spin glasses
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Publisher and Date:(Amer Physical Soc., 2018)By quenched-randomly mixing local units of different spatial dimensionalities we have studied Ising spin-glass systems on hierarchical lattices continuously in dimensionalities 1 <= d <= 3. The global phase diagram in temperature antiferromagnetic bond concentration and spatial dimensionality is calculated. We find that as dimension is lowered the spin-glass phase disappears to zero temperature at the lower-critical dimension d(c) = 2.431. Our system being a physically realizable system this sets ...
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MAP channel-estimation-based PIC receiver for downlink MC-CDMA systems
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Publisher and Date:(Hindawi Publishing Corporation, 2008)We propose a joint MAP channel estimation and data detection technique based on the expectation maximization (EM) method with paralel interference cancelation (PIC) for downlink multicarrier (MC) code division multiple access (CDMA) systems in the presence of frequency selective channels. The quality of multiple access interference (MAI) which can be improved by using channel estimation and data estimation of all active users affects considerably the performance of PIC detector. Therefore data and ...
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Mathematical Characterization of Thermo-reversible Phase Transitions of Agarose Gels
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Publisher and Date:(Taylor & Francis Inc, 2018)The thermal phase transition temperatures of high (HMP) and low melting point (LMP) agarose gels were investigated by using UV-vis spectroscopy techniques. Transmitted light intensities from the gel samples with different agarose concentrations were monitored during the heating (gel-sol) and cooling (sol-gel) processes. It was observed that the transition temperatures T-m defined as the location of the maximum of the first derivative of the sigmoidal transition paths obtained from the UV-vis ...
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Mathematical models for phase transitions in biogels
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Publisher and Date:(World Scientific Publ Co Pte Ltd, 2019)It has been shown that reversible and irreversible phase transitions of biogels can be represented by epidemic models. The irreversible chemical sol-gel transitions are modeled by the Susceptible-Exposed-Infected-Removed (SEIR) or Susceptible-Infected-Removed (SIR) epidemic systems whereas reversible physical gels are modeled by a modification of the Susceptible-Infected-Susceptible (SIS) system. Measured sol-gel and gel-sol transition data have been fitted to the solutions of the epidemic models, ...
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Maximally random discrete-spin systems with symmetric and asymmetric interactions and maximally degenerate ordering
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Publisher and Date:(Amer Physical Soc., 2018)Discrete-spin systems with maximally random nearest-neighbor interactions that can be symmetric or asymmetric ferromagnetic or antiferromagnetic including off-diagonal disorder are studied for the number of states q = 34 in d dimensions. We use renormalization-group theory that is exact for hierarchical lattices and approximate (Migdal-Kadanoff) for hypercubic lattices. For all d > 1 and all nonmfimte temperatures the system eventually renormalizes to a random single state thus signaling q x q ...
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Metastable reverse-phase droplets within ordered phases: Renormalization-group calculation of field and temperature dependence of limiting size
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Publisher and Date:(AMER PHYSICAL SOC, 2020)Metastable reverse-phase droplets are calculated by renormalization-group theory by evaluating the magnetization of a droplet under magnetic field, matching the boundary condition with the reverse phase and noting whether the reverse-phase magnetization sustains. The maximal metastable droplet size and the discontinuity across the droplet boundary are thus calculated as a function of temperature and magnetic field for the Ising model in three dimensions. The method also yields hysteresis loops for ...
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Minimum Length Scheduling for Discrete Rate Based Full Duplex Wireless Powered Communication Networks
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Publisher and Date:(Springer, 2019)In this study, we consider a wireless powered communication network where multiple users with radio frequency energy harvesting capabilities communicate to a hybrid energy and information access point in full duplex mode. We characterize an optimization framework for minimum length scheduling to determine the optimal rate adaptation and transmission scheduling subject to energy causality and traffic demand constraints of the users considering discrete-rate transmission model. We first formulate ...