Browsing Elektrik-Elektronik Mühendisliği / Electrical - Electronics Engineering by Title
Now showing items 74-93 of 330
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Data Detection Based Iterative Channel Estimation for Coded SM-OFDM Systems
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Publisher and Date:(IEEE, 2016)The combination of spatial modulation (SM) and orthogonal frequency division multiplexing (OFDM) as SM-OFDM is a recently proposed efficient modulation scheme with exploiting the index of transmit antenna to convey information bits for multiple-input multiple-output (MIMO) wireless communication systems due to its low complexity feature. The pioneering works assume that the perfect channel state information (P-CSI) or pilot symbols aided channel estimation (PSA-CE) is available at the receiver. ...
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Data-Aided Autoregressive Sparse Channel Tracking for OFDM Systems
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Publisher and Date:(IEEE, 2016)In order to meet future communication system requirements channel estimation over fast fading and frequency selective channels is crucial. In this paper Space Alternated Generalized Expectation Maximization Maximum a Posteriori (SAGE-MAP) based channel estimation algorithm is proposed for Orthogonal Frequency Division Multiplexing (OFDM) systems for Autoregressive (AR) modeled time-varying sparse channels. Also an initialization algorithm has been developed from the widely used sparse approximation ...
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Design and implementation of a negative feedback oscillator circuit based on a Cellular Neural Network with an Opposite Sign Template
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Publisher and Date:(2010)In this paper explicit amplitude and frequency expressions for a Cellular Neural Network with an Opposite-Sign Template (CNN-OST) under oscillation condition are derived and a novel inductorless oscillator circuit with negative feedbacks based on this simple structure is designed and implemented. The system is capable of generating quasi-sine signals with tuneable amplitude and frequency which can't be provided at the same time in the classical oscillator circuits.
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Design and performance analysis of a novel trellis coded space-time-frequency OFDM transmission scheme
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Publisher and Date:(Wiley-Blackwell, 2008)In this paper a new transmit diversity technique is proposed for wireless communications over frequency selective fading channels. The proposed technique utilises orthogonal frequency division multiplexing (OFDM) to transform a frequency selective fading channel into multiple flat fading subchannels on which first space-frequency coding and then additional space-time coding are applied resulting in a space-time-frequency OFDM (STF-OFDM) scheme. This scheme provides a quasi-orthogonal 4 x 4 ...
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Design of broadband microwave amplifiers with mixed-elements via reflectance data modeling
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Publisher and Date:(Elsevier GMBH Urban & Fischer Verlag, 2008)A practical method is introduced to design single-stage broadband microwave amplifiers with mixed lumped and distributed elements via modeling the reflectance data obtained from lumped-element input and output matching network prototypes. The same transducer power gain level is obtained by using less number of lumped-elements in the mixed-element amplifier than that of the lumped-element amplifier prototype. A mixed-element amplifier design is presented to exhibit the utilization of the method. ...
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Design of broadband single matching networks
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Publisher and Date:(Elsevier GMBH Urban & Fischer Verlag, 2009)In general commercially available software tools are preferred to design broadband matching networks for wireless communication systems. But they need a properly selected matching network topology with good initial element values. Therefore in this paper a new real frequency technique is presented to generate broadband single matching networks with suitable initial element values. In the proposed method load impedance is written in terms of ABCD-parameters of the desired matching network and the ...
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Design of distributed-element RF filters via reflectance data modeling
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Publisher and Date:(Elsevier GMBH Urban & Fischer Verlag, 2008)A reflectance-based modeling method is presented to obtain the distributed-element counterpart of a lumped-element network which is described by measured or computed reflectance data at a set of frequencies. Numerical generation of the scattering parameters forms the basis of this modeling tool. It is not necessary to select a circuit topology for the distributed-element model which is the natural consequence of the modeling process. Our approach supplements the known interpolation methods by a ...
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Design of impedance matching network for B&K 8104 hydrophone via Direct Computational Technique for underwater communication
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Publisher and Date:(2010)Underwater acoustic communication is a rapidly growing field of applied research and is a technique of sending and receiving message below water. There are several ways of doing such communication but the most common one is realized by using transducers. In underwater acoustic communication one of the most important problems is driving the transducers with matched network. In this study design of impedance matching network for B&K 8104 hydrophone that can be used for underwater communication was ...
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Design of low-pass ladder networks with mixed lumped and distributed elements by means of artificial neural networks
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Publisher and Date:(AVES YAYINCILIK, 2003)In this paper, calculation of parameters of low-pass ladder networks with mixed lumped and distributed elements by means of artificial neural networks is given. The results of ANN are compared with the values that are desired. It has been observed that the calculated and the desired values are extremely close to each other. So this algorith can be used to obtain the parameters that will be used to synthesize such circuits.
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Design of mixed-element networks via modeling
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Publisher and Date:(IEEE, 2008)A new method is introduced to design mixed lumped and distributed element network
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Design of Phase Shifters with Ladder Stubs Via Real Frequency Technique
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Publisher and Date:(World Scientific, 2020)Generally at high frequencies, lumped-elements are not preferred because of their limited range of values. Therefore, in this work, a kind of phase shifter formed with ladder stubs is studied and a new approach to design phase shifter's low pass and high pass sections which are composed of series or shunt connected open-ended or short-ended stubs is proposed. In the approach, since the main focus is to form low pass and high pass two-port sections, switching process is not considered. First, the ...
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Design of practical broadband matching networks with commensurate transmission lines
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Publisher and Date:(Elsevier GMBH Urban & Fischer Verlag, 2013)To design broadband matching networks for microwave communication systems commercially available computer aided design (CAD) tools are always preferred. But these tools need proper matching network topology and element values. Therefore in this paper a practical method is proposed to generate distributed-element matching networks with good initial element values. Then the gain performance of the designed matching network can be optimized employing these tools. The utilization of the proposed method ...
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Design of Practical Broadband Matching Networks With Lumped Elements
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Publisher and Date:(IEEE-INST Electrical Electronics Engineers Inc, 2013)It is always preferable to use commercially available software tools to design broadband matching networks for microwave communication systems. However for these tools the matching network topology and element values must be selected properly. Therefore in this paper a practical method is presented to generate matching networks with good initial element values. Eventually the performance of the designed matching network is optimized by employing the commercially available computer-aided design ...
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Design of Practical Broadband Matching Networks With Mixed Lumped and Distributed Elements
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Publisher and Date:(IEEE-INST Electrical Electronics Engineers Inc, 2014)Computer-aided design (CAD) tools are always preferred for designing broadband matching networks. However these tools give excellent results when the suitable matching network topology and initial element values are provided. Therefore in this brief a new initialization algorithm is proposed to get suitable network topology and element values for CAD tools. Then the power transfer capability of the matching network can be improved by using any CAD tool. It is clear from the example studied that ...
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Design of practical matching networks with lumped elements via modeling
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Publisher and Date:(IEEE, 2007)It is a common practice to utilize commercially available software tools to design matching networks for wireless communication systems. Most of these tools require a properly selected matching network topology with good initial element values. Therefore in this paper a practical method is presented to generate matching networks with initial element values. In the implementation process of the proposed method first the driving point immitance data for the matching network is obtained in a straight ...
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Design table formation of stepped impedance prototype filters
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Publisher and Date:(Istanbul University, 2010)In literature there exist some tables containing normalized element values to design low-pass lumped-element prototype filters with several different responses like maximally flat or equal-ripple. In this work an algorithm is presented to form such tables for stepped impedance prototype filters. By using the proposed algorithm a table for 0.5 dB equal-ripple stepped impedance prototype filter is formed. Then a design example is given to show the utilization of the formed table.
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Design table formation of stepped impedance prototype filters
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Publisher and Date:(AVES YAYINCILIK, 2010)In literature, there exist some tables containing normalized element values, to design low-pass lumped-element prototype filters with several different responses like maximally flat or equal-ripple. In this work, an algorithm is presented, to form such tables for stepped impedance prototype filters. By using the proposed algorithm, a table for 0.5 dB equal-ripple stepped impedance prototype filter is formed. Then a design example is given, to show the utilization of the formed table.
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Detection of interdependent primary systems using wideband cognitive radios
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Publisher and Date:(Elsevier GMBH Urban & Fischer Verlag, 2013)Cognitive radios (CRs) may be sharing multiple frequency bands with primary systems if the CR is a wideband or an ultra wideband (UWB) system. In that case the CR should ensure all the coexisting primary systems in these bands are detected before it can start data transmission. In this work we study the primary system detection performance of a wideband CR assuming that there are multiple coexisting primary systems and that these primary systems may be jointly active. Accordingly we consider the ...
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Detection of jointly active primary systems
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Publisher and Date:(IEEE, 2012)Recent studies in cognitive radios consider the detection of multiple bands for a better utilization of the spectrum. If the cognitive radio (CR) is an ultra wideband (UWB) or a wideband system then the CR should ensure all the coexisting primary systems in these bands are detected before the CR can start data transmission. In this work we study the primary system detection performance of a wideband CR assuming that there are multiple coexisting primary systems and that these primary systems may ...
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Detection of Multiple Primary Systems Using DAA UWB-IRs
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Publisher and Date:(IEEE, 2009)Underlay ultra wideband (UWB) systems have to be able to detect the presence of primary systems operating in the same band for detect-and-avoid (DAA) operation. In this paper the performances of joint and independent detection of multiple primary systems are investigated assuming that the primary systems are potentially dependent (e.g. frequency division duplex uplink-downlink communications). Joint detection is performed based on generating the maximum a posteriori (MAP) decision variables at the ...