Browsing Elektrik-Elektronik Mühendisliği / Electrical - Electronics Engineering by Title
Now showing items 190-209 of 330
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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
Authors:
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 ...
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Optical spatial modulation design
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Publisher and Date:(Royal Soc, 2020)Visible light communication (VLC) systems are inherently signal-to-noise ratio (SNR) limited due to link budget constraints. One favourable method to overcome this limitation is to focus on the pre-log factors of the channel capacity. Multiple-input multiple-output (MIMO) techniques are therefore a promising avenue of research. However, inter-channel interference in MIMO limits the achievable capacity. Spatial modulation (SM) avoids this limitation. Furthermore, the performance of MIMO systems in ...
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Optical Spatial Modulation OFDM System Design
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Publisher and Date:(IEEE, 2016)In this paper a new optical orthogonal frequency division multiplexing (OFDM) method is proposed for multiple-input multiple-output (MIMO) visible light communications (VLC) systems. In the new scheme non-DC biased optical OFDM (NDC-OFDM) and optical spatial modulation (OSM) methods are combined to obtain a novel optical OFDM scheme which has a better error performance. The new scheme is named as non-DC biased optical spatial modulation OFDM (NDC-OSM-OFDM). It is shown via computer simulations ...
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Optical Spatial Modulation OFDM System Design [Optik Uzaysal Modülasyonlu OFDM Sistem Tasarımı]
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Publisher and Date:(Institute of Electrical and Electronics Engineers Inc., 2016)In this paper a new optical orthogonal frequency division multiplexing (OFDM) method is proposed for multiple-input multiple-output (MIMO) visible light communications (VLC) systems. In the new scheme non-DC biased optical OFDM (NDC-OFDM) and optical spatial modulation (OSM) methods are combined to obtain a novel optical OFDM scheme which has a better error performance. The new scheme is named as non-DC biased optical spatial modulation OFDM (NDC-OSM-OFDM). It is shown via computer simulations ...
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Orthogonal Frequency Division Multiplexing With Index Modulation
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Publisher and Date:(IEEE-INST Electrical Electronics Engineers Inc, 2013)In this paper a novel orthogonal frequency division multiplexing (OFDM) scheme called OFDM with index modulation (OFDM-IM) is proposed for operation over frequency-selective and rapidly time-varying fading channels. In this scheme the information is conveyed not only by M-ary signal constellations as in classical OFDM but also by the indices of the subcarriers which are activated according to the incoming bit stream. Different low complexity transceiver structures based on maximum likelihood ...
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Orthogonal frequency division multiplexing with index modulation
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Publisher and Date:(IEEE, 2012)In this paper a novel orthogonal frequency division multiplexing (OFDM) scheme which is called OFDM with index modulation (OFDM-IM) is proposed for frequency-selective fading channels. In this scheme inspiring from the recently introduced spatial modulation concept for multiple-input multiple-output (MIMO) channels the information is conveyed not only by M-ary signal constellations as in classical OFDM but also by the indices of the subcarriers which are activated according to the incoming bit ...
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Orthogonal Frequency Division Multiplexing with Index Modulation in the Presence of High Mobility
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Publisher and Date:(IEEE, 2013)In this paper a novel orthogonal frequency division multiplexing (OFDM) scheme which is called OFDM with index modulation (OFDM-IM) is proposed for frequency-selective fading channels in the presence of high mobility. In this scheme inspiring from the recently introduced spatial modulation concept for multiple-input multiple-output (MIMO) channels the information is conveyed not only by M-ary signal constellations as in classical OFDM but also by the indices of the subcarriers which are activated ...
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Orthogonal frequency division multiplexing with index modulation in the presence of high mobility
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Publisher and Date:(2013)In this paper a novel orthogonal frequency division multiplexing (OFDM) scheme which is called OFDM with index modulation (OFDM-IM) is proposed for frequency-selective fading channels in the presence of high mobility. In this scheme inspiring from the recently introduced spatial modulation concept for multiple-input multiple-output (MIMO) channels the information is conveyed not only by M-ary signal constellations as in classical OFDM but also by the indices of the subcarriers which are activated ...
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Outage Probability of a Cooperative Maximum Ratio Transmission
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Publisher and Date:(IEEE, 2014)In this paper we present a cooperative communication system employing maximum ratio transmission technique and its outage probability performance over Rayleigh fading channels. Since maximum ratio transmission can achieve full diversity when used at tranmitters having multiple antennas while requiring no complexity increase at the receiver the proposed system can be a preferable structure to be used both at the source and amplify-forward type relays of wireless networks to provide high speed and ...
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Outage probability of a cooperative maximum ratio transmission [İşbirlikli maksimum oranlı iletimin kesinti olasılığı]
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Publisher and Date:(IEEE Computer Society, 2014)In this paper we present a cooperative communication system employing maximum ratio transmission technique and its outage probability performance over Rayleigh fading channels. Since maximum ratio transmission can achieve full diversity when used at tranmitters having multiple antennas while requiring no complexity increase at the receiver the proposed system can be a preferable structure to be used both at the source and amplify-forward type relays of wireless networks to provide high speed and ...
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Parameter quantization effects in Gaussian potential function neural networks
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Publisher and Date:(World Scientific and Engineering Academy and Society, 2001)In hardware implementations of Gaussian Potential Function Neural Networks (GPFNN) deviation from ideal network parameters is inevitable because of the techniques used for parameter storage and implementation of the functions electronically resulting in loss of accuracy. This loss in accuracy can be represented by quantization of the network parameters. In order to predict this effect theoretical approaches are proposed. One-input one-output GPFNN with one hidden layer have been trained as function ...
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Partial Power and Rate Adaptation for MQAM/OFDM Systems under CFO
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Publisher and Date:(IEEE, 2014)In this paper a new partial power and rate adaptation scheme for orthogonal frequency division multiplexing (OFDM) systems is proposed in the presence of carrier frequency offset (CFO). The conventional adaptive scheme is shown to be a special case of the partially adaptive scheme technique which enables the resulting non-convex optimization problem solved in a feasible way. It leads to a solution for optimal power adaptation that maximizes the spectral efficiency of an OFDM system using M-ary ...
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Partial power and rate adaptation for MQAM/OFDM systems under CFO
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Publisher and Date:(Institute of Electrical and Electronics Engineers Inc., 2014)In this paper a new partial power and rate adaptation scheme for orthogonal frequency division multiplexing (OFDM) systems is proposed in the presence of carrier frequency offset (CFO). The conventional adaptive scheme is shown to be a special case of the partially adaptive scheme technique which enables the resulting non-convex optimization problem solved in a feasible way. It leads to a solution for optimal power adaptation that maximizes the spectral efficiency of an OFDM system using M-ary ...