Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği
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Conference Object Adaptive Limited Feedback Scheme for Stream Selection Based Interference Alignment in Heterogeneous Networks(IEEE, 2016) Beyazıt, Esra Aycan; Özbek, Berna; Le Ruyet,D.This paper presents a stream selection based interference alignment approach with imperfect channel state information for heterogeneous networks. The proposed algorithm performs the selection of a stream sequence among a predetermined set of sequences. Those selected sequences are the ones that mostly contribute to the sum rate when performing the exhaustive search. These stream sequences form a regular structure where the first stream is associated to a pico user. The effect of imperfect channel state information on the proposed algorithm is analyzed and a bit allocation scheme is proposed by deriving an upper bound on the rate loss due to quantization. © 2016 IEEE.Conference Object Kırpılmış ortalamalı gürbüz konum kestiriminde yeni sonuçlar(IEEE, 2014) Altınkaya, Mustafa AzizWhen there are more than necessary distance measurements in localization by distance measurements with closed form estimators, forming smaller subgroups of measurements and averaging the location estimates obtained with these subgroups of measurements makes it possible to eliminate outlier measurements if they are present. In order to eliminate these outlier results, the nearest estimate to the geometric median of estimates is proposed as a reference in this work. Conducted simulation studies show that significant gains can be obtained using geometric median in place of arithmetic average in robust averaging methods.Conference Object Citation - Scopus: 2Model-Free Expectation Maximization for Divisive Hierarchical Clustering of Multicolor Flow Cytometry Data(IEEE, 2014) Köktürk, Başak Esin; Karaçalı, BilgeThis paper proposes a new method for automated clustering of high dimensional datasets. The method is based on a recursive binary division strategy that successively divides an original dataset into distinct clusters. Each binary division is carried out using a model-free expectation maximization scheme that exploits the posterior probability computation capability of the quasi-supervised learning algorithm. The divisions are carried out until a division cost exceeds an adaptively determined limit. Experiment results on synthetic as well as real multi-color flow cytometry datasets showed that the proposed method can accurately capture the prominent clusters without requiring any knowledge on the number of clusters or their distribution models.Conference Object Citation - WoS: 2Citation - Scopus: 3Heterojen ağlarda iyileştirilmiş veri katarı seçimi ile girişim hizalama(IEEE, 2015) Le Ruyet, Didier; Aycan, Esra; Özbek, BernaIn this article, interference that occurs in heterogeneous networks is studied and a new stream selection approach with an interference alignment solution is presented. In the proposed algorithm, stream selection starts with the streams that belongs to the pico cell users and continues to select the strongest streams that increase the total sum rate. The power of each stream with the precoding and the postcoding vectors are calculated by performing singular value decomposition (SVD). Virtual channels that belong to the selected stream are calculated by using precoding and postcoding vectors. After the selection procedure, the interferences between the selected stream and the remaining streams are mitigated by orthogonally projecting the channel matrices of the remaining streams to the virtual channels of the selected stream.Conference Object Enzimatik Reaksiyonların Kimyasal Langevin-levy Denklemiyle Modellenmesi(IEEE, 2012) Altınkaya, Mustafa Aziz; Kuruoğlu, Ercan EnginChemical Langevin Equation (CLE) describes a useful approximation in stochastic modeling of chemical reactions. CLE-based ?-leaping algoritm updates the quantities of every molecule in a reaction system with a period of ?, firing every reaction in the system so many times that the concentration of each molecule can be assumed to remain in the current concentration state. Substituting the Brownian motion in the CLE with a Levy flight, one might expect the CLE to converge more rapidly. This work shows that alpha (Levy)-stable increments can be used in ?-leaping, demonstrating it with the example of a detailed kinetic model describing the enzymatic transgalactosylation reaction during lactulose hydrolysis. © 2012 IEEE.Conference Object Citation - Scopus: 1Kablosuz Ağlarda Hücre Seçim Algoritmalarının Başarımı(IEEE, 2012) Aycan, Esra; Özbek, BernaIn this paper, the performance of signal to interference and noise ratio (SINR) and distance based cell selection algorithms for wireless systems are examined considering different cells. The performance results are obtained by assuming the users are not moving within a setup includes macrocell, picocell and femtocells. The comparisons of the obtained results are shown in terms of SINR and load in the cells. © 2012 IEEE.Conference Object Citation - Scopus: 1Dijital Sitolojide Kanser Tanıma için Analitik ve Öngörüsel Yarı-güdümlü Öğrenme(IEEE, 2012) Karaçalı, BilgeIn this work, cancer recognition in digital cytology data was carried out using quasi-supervised learning. The data subject to recognition contained ground-truth data only in the form of a labeled set of cancer-free samples and the cancerous samples were provided along with cancer-free samples in an unlabeled mixed dataset. In this framework, a predictive method was derived to label future samples as cancerous or cancer-free based on this data at hand together with an analytical method to label the cancerous samples in the mixed dataset. In the experiments, the methods based on the quasi-supervised learning algorithm achieved higher recognition performance in both cases than the alternative approaches based on supervised support vector machine classifiers. These results indicate that the quasi-supervised learning is the only valid approach in both analytical and predictive recognition when only labeled cancer-free samples are available for statistical learning. © 2012 IEEE.Conference Object Citation - Scopus: 1Elektroensefalografi Verilerinin Yarı-güdümlü Öğrenme ile Otomatik Olarak İşaretlenmesi(IEEE, 2012) Köktürk, Başak Esin; Karaçalı, BilgeIn this study, the separation of the stimulus effects from the baseline was investigated in electroencephalography data recorded under different visual stimuli using quasi-supervised learning. The data feature vectors were constructed using independent component analysis and wavelet transform, and then, these feature vectors were separated using quasi-supervised learning. Experiment results showed that the EEG data of the stimuli can be separated using quasi-supervised learning. © 2012 IEEE.Conference Object Citation - Scopus: 1Avrupa Karasal Sayısal Televizyon Standartlarının Tbgg Kanalı Etkisindeki Performans Karşılaştırması(IEEE, 2012) Karakuş, Oktay; Özen, SerdarIn this study, a general simulation of the European Digital Terrestrial Television Broadcasting standards which are known as "Digital Video Broadcasting - Terrestrial (DVB-T)" and "Second Generation Digital Video Broadcasting - Terrestrial (DVB-T2)" are implemented. The both of the standards are simulated under the effects of Additive White Gaussian Noise (AWGN) Channel and the acquired results are compared according to the Target Bit Error Rate (BER) value which is stated in standards. These results show that DVB-T2 standard outperforms DVB-T standard under AWGN Channel and achieves nearly from four to seven decibels power gain according to code rate and modulation parameters. © 2012 IEEE.Conference Object Entropi Tabanlı Öznitelikler ile Müzik Enstrümanlarının Sınıflandırılması(IEEE, 2011) Özbek, Mehmet ErdalBy using the entropy values computed in temporal and spectral domain, the variations of musical signals can also be followed. In this study, the normalized entropy values computed in both domains are proposed to be used as features. These entropy based features are compared with similar features like temporal and spectral centroid, spectral flatness, and spectral spread. Then, their performances are investigated for classification of musical instruments. © 2011 IEEE.