Browsing Elektrik-Elektronik Mühendisliği / Electrical - Electronics Engineering by Title
Now showing items 178-197 of 330
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Near field parameter estimation of moving sources with recursive expectation maximization algorithm
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Publisher and Date:(IEEE, 2006)In this paper maximum likelihood (ML) estimator is proposed for the joint estimation of the direction of arrival (DOA) and range parameters of moving sources in the near-field of the antenna array. ML estimation algorithm is presented for deterministic signal model. Recursive form of the expectation maximization (REM) algoritm is suggested for the estimation of the near-field parameters because there is not closed form solutions for the maximum likelihood functions. Moreover simulation results of ...
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Near field parameter estimation of moving sources with recursive expectation maximization algorithm [Yinelemeli beklenti/en büyükleme algoritması ile hareketli kaynakların yakın-alan parametrelerinin kestirimi]
Authors:
Publisher and Date:(2006)In this paper maximum likelihood (ML) estimator is proposed for the joint estimation of the direction of arrival (DOA) and range parameters of moving sources in the near-field of the antenna array. ML estimation algorithm is presented for deterministic signal model. Recursive form of the expectation maximization (REM) algoritm is suggested for the estimation of the near-field parameters because there is not closed form solutions for the maximum likelihood functions. Moreover simulation results of ...
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Neural Network Design for the Recurrence Prediction of Post-Operative Non-Metastatic Kidney Cancer Patients
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Publisher and Date:(Institute of Electrical and Electronics Engineers Inc., 2016)In this paper various post-operative recurrence estimation models called nomograms for the kidney cancer patients without any metastates are introduced and novel systems based on a Multilayer Perceptron Neural Network are designed to simplify and integrate the mentioned techniques which is believed to ease the physician' s post-operative follow up procedures. The parameters effecting the recurrence are the TNM stage tumor size and nuclear (Fuhrman) grade the existance of necrosis and vascular ...
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Neural Network Design for the Recurrence Prediction of Post-Operative Non-Metastatic Kidney Cancer Patients
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Publisher and Date:(IEEE, 2015)In this paper various post-operative recurrence estimation models called nomograms for the kidney cancer patients without any metastates are introduced and novel systems based on a Multilayer Perceptron Neural Network are designed to simplify and integrate the mentioned techniques which is believed to ease the physician's post-operative follow up procedures. The parameters effecting the recurrence are the TNM stage tumor size and nuclear (Fuhrman) grade the existance of necrosis and vascular ...
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A New Approach for Coexistence of IEEE 802.11af and IEEE 802.22 Systems
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Publisher and Date:(2018)In this paper, various algorithms are proposed to help IEEE 802.11af and IEEE 802.22 wireless systems to coexist in TV white space by considering multiple techniques. By using busy tone, power control and multihop communication techniques, improvements have been made compared to prior approaches. With this approach, while IEEE 802.22 systems are protected from intra-network interference, IEEE 802.11af systems are still able to continue transmitting packets. Considering the communication parameters ...
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New channel estimation techniques for cooperative underwater acoustic OFDM systems
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Publisher and Date:Cooperative underwater acoustic communication systems come into prominence in recent years. Since underwater channels are sparse and additive noise entering the system is colored Gaussian noise it is very difficult to estimate the underwater channels and theoretically makes it interesting. in the first part of the thesis the transmission from source to the target recipient is realized by means of a relay system. Orthogonal frequency division multiplexing (OFDM)-based channel estimation problem is ...
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New Trellis Code Design for Spatial Modulation
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Publisher and Date:(IEEE-INST Electrical Electronics Engineers Inc, 2011)Spatial modulation (SM) in which multiple antennas are used to convey information besides the conventional M-ary signal constellations is a new multiple-input multiple-output (MIMO) transmission technique which has recently been proposed as an alternative to V-BLAST (vertical Bell Labs layered space-time). In this paper a novel MIMO transmission scheme called spatial modulation with trellis coding (SM-TC) is proposed. Similar to the conventional trellis coded modulation (TCM) in this scheme a ...
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Noncoherent Ultra Wideband Wireless Sensor Networks for Primary User Detection
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Publisher and Date:(IEEE, 2016)As a result of increasing demand for new technologies unlicensed usage of available spectrum has become very essential to provide an efficient usage of spectrum. For that reason sensor networks may be a reliable option to decide on the absence/presence of licensed users and to communicate without causing much interference as a secondary user network. These networks consist of two communication links for primary user detection. One link is between the primary user and the sensors and the other link ...
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Noncoherent Ultra Wideband Wireless Sensor Networks for Primary User Detection
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Publisher and Date:(IEEE Computer Society, 2016)As a result of increasing demand for new technologies unlicensed usage of available spectrum has become very essential to provide an efficient usage of spectrum. For that reason sensor networks may be a reliable option to decide on the absence/presence of licensed users and to communicate without causing much interference as a secondary user network. These networks consist of two communication links for primary user detection. One link is between the primary user and the sensors and the other link ...
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Nondata-aided joint channel estimation and equalization for OFDM systems in very rapidly varying mobile channels
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Publisher and Date:(IEEE-INST Electrical Electronics Engineers Inc, 2012)This paper is concerned with the challenging and timely problem of joint channel estimation and equalization for 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-maximum a posteriori probability (SAGE-MAP) technique which is particularly well suited to multicarrier signal formats. The algorithm is implemented in the ...
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Novel Channel Models For Visible Light Communications
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Publisher and Date:(Spie-Int Soc Optical Engineering, 2015)In this paper we investigate channel modeling for visible light communications (VLC) using non-sequential ray tracing simulation tools. We create three dimensional realistic simulation environments to depict indoor scenarios specifying the geometry of the environment the objects inside the reflection characteristics of the surface materials as well as the characteristics of the transmitter and receivers i.e. LED sources and photodioes. Through ray tracing simulations we compute the received optical ...
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A Novel Transmit Array Structure for Optical Spatial Modulation
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Publisher and Date:(IEEE, 2019)The performance of multiple input single output (MISO) and multiple input multiple output (MIMO) systems is limited by spatial channel correlation. This limitation becomes particularly severe in light lidelity (LiFi) systems, which use intensity modulation/direct detection (IM/DD) for data transmission, because light emitting diodes (LEDs) can only emit incoherent light. This paper proposes a novel transmitter structure that provides spatially separated channels and enables optical MISO/MIMO spatial ...
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OFDM with transmit and receive antenna selection based on subcarrier groups
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Publisher and Date:(IEEE, 2012)In this paper the performance of coded OFDM transmission over multiple antennas is explored when joint transmit and receive antenna selection is employed. The channel is assumed as Rayleigh frequency selective fading channel and only receiver is assumed to have perfect channel state information (CSI). The performance of MIMO OFDM system using pragmatic coding techniques such as convolutional coding (CC) and space-time block coding (STBC) with antenna selection based on subcarrier groups and other ...
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OFDM with transmit and receive antenna selection based on subcarrier groups
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Publisher and Date:(IEEE, 2012)In this paper the performance of coded OFDM transmission over multiple antennas is explored when joint transmit and receive antenna selection is employed. The channel is assumed as Rayleigh frequency selective fading channel and only receiver is assumed to have perfect channel state information (CSI). The performance of MIMO OFDM system using pragmatic coding techniques such as convolutional coding (CC) and space-time block coding (STBC) with antenna selection based on subcarrier groups and other ...
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On channel estimation for spatial modulated systems over time-varying channels
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Publisher and Date:(Academic Press Inc Elsevier Science, 2015)Spatial Modulation (SM) has been proposed recently for multiple-input multiple-output (MIMO) systems to cope with the interchannel interference and to reduce the detection complexity as compared to the conventional MIMO systems. In SM system the data symbols are transmitted by a randomly selected active antenna of a MIMO transmitter to the receiver through a wireless channel. The information is carried both by the data symbol from any signal constellation such as M-ary phase shift keying (M-PSK) ...
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On Channel Estimation in DC Biased Optical OFDM Systems Over VLC Channels
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Publisher and Date:(IEEE, 2016)Visible Light Communication(VLC) has been considered as a potential access option for 5G wireless systems to solve performance limitation due to bandwidth shortage at radio frequency (RF) band. In (VLC) system illumination infrastructure has dual usage at the same time namely illumination and wireless data transmission. DC Biased optical (DCO)-OFDM has been proposed for VLC systems to provide optically power efficient solution and easy implementation. Wireless communication systems generally require ...
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On Channel Estimation in DC Biased Optical OFDM Systems Over VLC Channels
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Publisher and Date:(IEEE Computer Society, 2016)Visible Light Communication(VLC) has been considered as a potential access option for 5G wireless systems to solve performance limitation due to bandwidth shortage at radio frequency (RF) band. In (VLC) system illumination infrastructure has dual usage at the same time namely illumination and wireless data transmission. DC Biased optical (DCO)-OFDM has been proposed for VLC systems to provide optically power efficient solution and easy implementation. Wireless communication systems generally require ...
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Optical MIMO-OFDM With Generalized LED Index Modulation
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Publisher and Date:(IEEE-INST Electrical Electronics Engineers Inc, 2017)Visible light communications (VLC) is a promising and uncharted new technology for the next generation of wireless communication systems. This paper proposes a novel generalized light emitting diode (LED) index modulation method for multiple-input-multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM)-based VLC systems. The proposed scheme avoids the typical spectrum efficiency losses incurred by time- and frequency-domain shaping in OFDM signals. This is achieved by exploiting ...
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Optical OFDM with index modulation for visible light communications
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Publisher and Date:(Institute of Electrical and Electronics Engineers Inc., 2015)In this paper we propose optical orthogonal frequency division multiplexing with index modulation (O-OFDM-IM) for visible light communications (VLC) systems employing light emitting diodes (LEDs) and photodetectors (PDs). The proposed scheme uses the indices of the active subcarriers of an optical OFDM system to transmit additional information bits. In the proposed scheme the bipolar signals are asymmetrically clipped or DC biased and a log-likelihood ratio (LLR) calculation based detector is used ...
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Optical OFDM with Index Modulation for Visible Light Communications
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Publisher and Date:(IEEE, 2015)In this paper we propose optical orthogonal frequency division multiplexing with index modulation (O-OFDM-IM) for visible light communications (VLC) systems employing light emitting diodes (LEDs) and photodetectors (PDs). The proposed scheme uses the indices of the active subcarriers of an optical OFDM system to transmit additional information bits. In the proposed scheme the bipolar signals are asymmetrically clipped or DC biased and a log-likelihood ratio (LLR) calculation based detector is used ...