Elektrik - Elektronik Mühendisliği Bölümü Koleksiyonu
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Conference Object Citation Count: 0Alternative Transducer Power Gain Expression in Broadband Matching Network Designs(IEEE, 2016) Şengül, Metin Y.In this paper a reflection coefficient based transducer power gain expression has been derived which is an alternative to the impedance based expression exists in the literature. A broadband double matching problem is solved by using the derived gain expression and the obtained performance has been compared with the performance obtained via the existing expression.Conference Object Citation Count: 1Anomaly Detection in Walking Trajectory(IEEE, 2018) Öğrenci, Arif SelçukAnalysis of the walking trajectory and the detection of anomalies in this trajectory, provide important benefits in the fields of health and security. In this work, two methods to detect anomalies in trajectories, are compared. Firstly, an unsupervised method is used where the conformance among trajectories are taken into consideration. Trajectories that deviate from others are qualified as anomalies. Secondly, the points in the trajectories are considered as a time series. Artifical neural networks performing supervised learning based on the backpropagation algorithm are used. The results are compared, and the points to be enhanced are highlighted.Conference Object Citation Count: 2Anomaly detection in walking trajectory [Yürüyüş yörüngesinde anormallik algılama](Institute of Electrical and Electronics Engineers Inc., 2018) Öğrenci, Arif SelçukAnalysis of the walking trajectory and the detection of anomalies in this trajectory provide important benefits in the fields of health and security. In this work two methods to detect anomalies in trajectories are compared. Firstly an unsupervised method is used where the conformance among trajectories are taken into consideration. Trajectories that deviate from others are qualified as anomalies. Secondly the points in the trajectories are considered as a time series. Artifical neural networks performing supervised learning based on the backpropagation algorithm are used. The results are compared and the points to be enhanced are highlighted.Article Citation Count: 0Broadband Matching via Reflection Coefficient Modeling(AVES YAYINCILIK, 2016) Şengül, Metin Y.[Abstract Not Available]Conference Object Citation Count: 1Busy tone based power control for coordination of IEEE 802.11af and 802.22 system [IEEE 802.11af ve 802.22 Sistemlerinin Uyumlu Çalışmaları için Meşgul Ton Tabanlı Güç Kontrolü](Institute of Electrical and Electronics Engineers Inc., 2017) Baykaş, Tunçer; Erküçük, Serhat; Karatalay, Onur; Baykaş, TunçerIn this paper a new power control algorithm based on busy tone approach has been proposed for the coordination of IEEE 802.22 and IEEE 802.11af systems in TV white space. Different from the earlier studies in addition to both 802.11af access point and clients listening to the busy tone they also adjust their communication power according to the location information and use hopping for communication if needed. Acccordingly interference caused to 802.22 systems has been reduced while the 802.11af systems are still able to communicate. This study quantifies the 802.11af and 802.22 system performances in terms of interfering packet rate and succesful packet transmission rate for different scenarios considering the communication parameters and channel models adapted for the standards. © 2017 IEEE.Conference Object Citation Count: 1Busy Tone Based Power Control for Coordination of IFFY 802.11af and 802.22 System(IEEE, 2017) Baykaş, Tunçer; Erküçük, Serhat; Karatalay, Onur; Baykas, TuncerIn this paper, a new power control algorithm based on busy tone approach has been proposed for the coordination of IEEE 802.22 and IEEE 802.11af systems in TV white space. Different from the earlier studies, in addition to both 802.11af access point and clients listening to the busy tone, they also adjust their communication power according to the location information and use hopping for communication, if needed Acccordingly, interference caused to 802.22 systems has been reduced while the 802.11af systems are still able to communicate. This study quantifies the 802.11af and 802.22 system performances in terms of interfering packet rate and succesful packet transmission rate for different scenarios considering the communication parameters and channel models adapted for the standards.Conference Object Citation Count: 1Busy Tone Implementation for Coexistence of IEEE 802.22 and 802.11 af Systems(IEEE, 2015) Baykaş, Tunçer; Erküçük, Serhat; Baykaş, TunçerIn this paper a new algorithm based on busy tone approach has been proposed for the coexistence of IEEE 802.22 and IEEE 802.11af systems in TV white space. Different from the earlier study in addition to 802.11af access points listening to the busy tone signal their clients also listen to the busy tone and let the access points know once they hear it. Accordingly interference caused to 802.22 systems has been reduced. This study quantifies the improved system performance in terms of interfering packet rate for different hearing regions considering the communication parameters and channel models adapted for the standards.Conference Object Citation Count: 5Comparison of Compressed Sensing Based Algorithms for Sparse Signal Reconstruction(IEEE, 2016) Erküçük, Serhat; Başaran, Mehmet; Erküçük, Serhat; Çırpan, Hakan AliCompressed sensing theory shows that any signal which is defined as sparse in a given domain can be reconstructed using fewer linear projections instead of using all Nyquist-rate samples. In this paper we investigate basis pursuit matching pursuit orthogonal matching pursuit and compressive sampling matching pursuit algorithms which are basic compressed sensing based algorithms and present performance curves in terms of mean squared error for various parameters including signal-tonoise ratio sparsity and number of measurements with regard to mean squared error. In addition accuracy of estimation performances has been supported with theoretical lower bounds (Cramer-Rao lower bound and deterministic lower mean squared error). Considering estimation performances compressive sampling matching pursuit yields the best results unless the signal has a non-sparse structure.Conference Object Citation Count: 0Effect of channel estimation errors on the performance of space time coded systems with antenna selection(IEEE, 2007) Güçlüoğlu, Tansal; Panayırcı, ErdalThis paper presents the effects of channel estimation errors on the performance especially diversity gain of space-time coded systems with antenna selection. We consider maximum signal to noise ratio as the antenna selection criteria. Specifically we first present the effect on the upper bound for pairwise error probability of space-time coded systems with antenna selection over flat fading channels. Moreover we provide simulation results for the antenna selection at the receiver and/or transmitter to show the effect of channel estimation.Conference Object Citation Count: 1The effect of channel resolution on compressed sensing based Ultra-Wideband channel estimation [Kanal çözünürlü?ünün sıkıştırılmış algılama tabanlı ultra geni?ş bantlı kanal kesti?ri?mi?ne etki?si?](2011) Erküçük, Serhat; Erküçük, Serhat; Cirpan, Hakan AliUltra short pulses are transmitted in Ultra-Wideband (UWB) communications. As a result of this pulses at the receiver can be resolved individually due to the sparse structure of the channel. Due to these properties the UWB channel can be estimated by using a compressed sensing based channel estimation method. The performance of channel estimation depends on the sparsity of the channel. In this work the effect of channel resolution which directly affects the sparsity is examined. It is shown that the channel becomes more sparse and the channel estimation performance is improved with increased channel resolution. Also the system performances of practically used selective-Rake receivers with estimated channels are found to be close to the perfect channel estimation case. © 2011 IEEE.Conference Object Citation Count: 0The Effect of Data Augmentation on ADHD Diagnostic Model using Deep Learning(IEEE, 2019) Özmen, Atilla; Özmen, Atilla; Akan, AydinAttention Deficit Hyperactivity Disorder (ADHD) is a neuro-behavioral hyperactivity disorder. It is frequently seen in childhood and youth, and lasts a lifetime unless treated.The ADHD classification model should be objective and robust. Correct diagnosis usually depends on the knowledge and experience of health professionals. In this respect, an automated method to be developed for the ADHD classification model is of great importance for clinicians. In this study, the effect of data augmentation on ADHD classification model with deep learning was investigated. For this purpose, magnetic resonance images were taken from NPIstanbul NeuroPsychiatry Hospital and ADHD-200 database. Since the images were not sufficient in terms of training, data augmentation methods were applied and by convolutional neural network (CNN) architecture, these data were classified and tried to reveal the diagnosis of the disease independently from the non-objective experiences of the health professionals.Conference Object Citation Count: 2The effect of secondary user locations on the cooperative detection performance [İki?nci?l kullanıcı konumlarının i?şbi?rli?kli? algılama yöntemi? performansına etki?si?](IEEE, 2012) Erküçük, Serhat; Erküçük, SerhatIn conventional cooperative detection a fusion center decides on the presence or absence of the primary user by gathering all the information from secondary users and conveys this decision to all users. This approach does not take into account the locations of the secondary users where a user far from the primary user may also have to keep silent. In a recent work there has been a new detection method based on combining received signals from more than two users obtaining decision tables and deciding individually for each user. While the proposed method showed promising results for the secondary users the effect of the user distribution was not investigated. In this study we consider the effect of secondary user location and number on the detection performance. We show that (i) the evaluation of the conventional method in the proposed method is not accurate and (ii) depending on the user location the detection performance may be better or worse compared to the conventional detection. © 2012 IEEE.Conference Object Citation Count: 1Effects of channel models and optional data rates on the IEEE 802.15.4a system performance [Kanal modellerinin ve seçime bağli veri hızlarının IEEE 802.15.4a sistem başarımına etkileri](2010) Erküçük, Serhat; Erküçük, SerhatThe wireless personal area network standard IEEE 802.15.4a uses ultra wideband impulse radios (UWB-IRs) for precise ranging and location and as well as for communications at low data rates (about 1 Mb/s). In addition to low data rates there are optional data rates defined in the standard that can support up to 27 Mb/s. In this paper the IEEE 802.15.4a system performance is studied for optional data rates in addition to considering the effect of channel models at the mandatory data rate. For the considered channel models system performances are evaluated for different numbers of Rake fingers and the error correction capability of channel encoding is tested at various data rates. The results of this study are important for the implementation of the IEEE 802.15.4a standard. ©2010 IEEE.Conference Object Citation Count: 0EM-based joint data detection and channel estimation for uplink MC-CDMA systems over frequency selective channels(IEEE, 2007) Doğan, Hakan; Panayırcı, Erdal; Çırpan, Hakan Ali; Fleury, Bernard HenriThis paper is concerned with joint channel estimation and data detection for uplink multicarrier code-division multiple-access (MC-CDMA) systems in the presence of frequency fading channel. The detection and estimation algorithm implemented at the receiver is based on a version of the expectation maximization (EM) technique which is very suitable for the multicarrier signal formats. Application of the EM-based algorithm to the problem of iterative data detection and channel estimation leads to a receiver structure that also incorporates a partial interference cancelation. Computer simulations show that the proposed algorithm has excellent BER end estimation performance.Conference Object Citation Count: 0Fault estimation of Trakya and Marmara Sea regions using 2D Gabor filtering [2 boyutlu gabor filtre yöntemi uygulayarak Trakya ve Marmara denizindeki fay hatlarının saptanması](2005) Özmen, Atilla; Erdoğan, Didem; Uçan, Osman Nuri; Albora, Ali MuhittinIn this paper we have applied 2D Gabor filtering to gravity and magnetic anomalies in estimation of discontinuities. Gabor filtering is an effective separation method compared to others having steerable and frequency parameter properties. We have found new faults using Gabor filtering for gravity and magnetic anomalies of Marmara Sea. © 2005 IEEE.Conference Object Citation Count: 1Iterative channel estimation for spatial modulation systems over fast fading channels(IEEE, 2014) Acar, Yusuf; Doğan, Hakan; Panayırcı, ErdalSpatial 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 have not been investigated for SM based systems. In this paper it shown that the RLS based receiver has a performance degradation for fast fading channels and a new iterative channel estimation techniques is proposed with the necessary signal model to enhance receiver performance for fast fading channels. Computer simulation results indicate that proposed iterative receiver has a significant performance advantage over the RLS based receiver for time-varying Rayleigh channels.Conference Object Citation Count: 2Iterative channel estimation for spatial modulation systems over fast fading channels [Hızlı sönümlemeli kanallarda uzaysal modülasyon sistemleri için iteratif kanal kestirimi](IEEE Computer Society, 2014) Panayırcı, Erdal; Doğati, Hakan; Panayırcı, ErdalSpatial 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 have not been investigated for SM based systems. In this paper it shown that the RLS based receiver has a performance degradation for fast fading channels and a new iterative channel estimation techniques is proposed with the necessary signal model to enhance receiver performance for fast fading channels. Computer simulation results indicate that proposed iterative receiver has a significant performance advantage over the RLS based receiver for time-varying Rayleigh channels. © 2014 IEEE.Conference Object Citation Count: 0Iterative Receiver for DS-CDMA Systems in the Presence of Time-Varying Channels(IEEE, 2008) Doğan, Hakan; Panayırcı, Erdal; Çırpan, Hakan Ali; Cam, GökhanIn this paper we present an efficient iterative receiver structure of tractable complexity for joint multiuser detection and multichannel estimation (JDE) of direct-sequence code-division multiple-access systems operating in the presence of time-varying flat fading channel. The time-varying channel is assumed to be modeled according to a piece-wise constant channel. An optimality criterion is defined and analytical expressions for the corresponding optimized weight coefficients are given. Monte-Carlo simulations of a synchronous scenario show that the proposed JDE receiver have excellent multiuser efficiency and are robust against errors in the estimation of the channel parameters.Conference Object Citation Count: 0Joint phase noise estimation and source detection [Ortak faz gürültüsü kestirimi ve kaynak sezimlemesi](2010) Şenol, Habib; Şenol, Habib; Panayırcı, ErdalRapidly 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 mean square error (MSE) - signal to noise ratio (SNR) performance of source detector and phase noise estimator is presented for each iteration of the algorithm. Moreover average MSE - pilot spacing performance curves of phase noise estimator are given for various SNR values. ©2010 IEEE.Conference Object Citation Count: 0Linear Combination of Pulses for Coexistence in the IEEE 802.15.4a Standard(IEEE, 2009) Erküçük, Serhat; Kaleli, Burç ArslanThe 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 limited and the notch locations are not flexible due to the limited number of pulses allowed by the standard. We also make some suggestions for increasing the number of notches at desired frequencies.
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