Sürdürülebilir Yeşil Kampüs Koleksiyonu / Sustainable Green Campus Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7755
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Article Citation - WoS: 3Citation - Scopus: 3Channel and Queue Aware Joint Relay Selection and Resource Allocation for Miso-Ofdma Based User-Relay Assisted Cellular Networks(Springer Verlag, 2018) Baştürk, İlhan; Özbek, BernaUser-relay assisted orthogonal frequency division multiple access (OFDMA) networks are cost-effective solutions to meet the growing capacity and coverage demands of the next generation cellular networks. These networks can be used with multiple antennas technology in order to obtain a diversity gain to combat signal fading and to obtain more capacity gain without increasing the bandwidth or transmit power. Efficient relay selection and resource allocation are crucial in such a multi-user, multi-relay and multi-antenna environment to fully exploit the benefits of the combination of user-relaying and multiple antennas technology. Thus, we propose a channel and queue aware joint relay selection and resource allocation algorithm for multiple-input single-output (MISO)-OFDMA based user-relay assisted downlink cellular networks. Since, the proposed algorithm is not only channel but also queue-aware, the system resources are allocated efficiently among the users. The proposed algorithm for the MISO-OFDMA based user-relay assisted scheme is compared to existing MISO-OFDMA based non-relaying and fixed relay assisted schemes and it is also compared with the existing single-input single-output (SISO)-OFDMA based user-relay assisted scheme. Simulation results revealed that the proposed scheme outperforms the existing schemes in terms of cell-edge users’ total data rate, average backlog and average delay.Conference Object Citation - WoS: 1Citation - Scopus: 1Cell Load Based User Association for Tetra Trunk Systems(Institute of Electrical and Electronics Engineers Inc., 2018) Karataş, Azad; Özbek, Berna; Bardak, Erinç Deniz; Sönmez, İlkerIncreasing traffic in communication systems need efficient new cell selection algorithms to control the distribution of users. For better and seamless transmission, load balancing become critical factors for cell selection algorithms. Un-desired consequents in these situations may cause disasters specifically for the emergency cases in public safety services. In this paper, a cell selection algorithm is proposed for Terrestrial Trunked Radio (TETRA) based Professional Mobile Radio (PMR) systems. The proposed algorithm is designed to provide a fairer distribution of users among cells while keeping the number of received power measurement less. The performances of the proposed algorithm are obtained in urban and rural environment.Conference Object Approximate Best Linear Unbiased Channel Estimation for Multi-Antenna Frequency Selective Channels With Applications To Digital Tv Systems(SPIE, 2004) Özen, Serdar; Pladdy, Christopher; Nerayanuru, Sreenivasa M.; Fimoff, Mark J.; Zoltowski, Michael D.We provide an iterative and a non-iterative channel impulse response (CIR) estimation algorithm for communication receivers with multiple-antenna. Our algorithm is best suited for communication systems which utilize a periodically transmitted training sequence within a continuous stream of information symbols, and the receivers for this particular system are expected work in a severe frequency selective multipath environment with long delay spreads relative to the length of the training sequence. The iterative procedure calculates the (semi-blind) Best Linear Unbiased Estimate (BLUE) of the CIR. The non-iterative version is an approximation to the BLUE CIR estimate, denoted by a-BLUE, achieving almost similar performance, with much lower complexity. Indeed we show that, with reasonable assumptions, a-BLUE channel estimate can be obtained by using a stored copy of a pre-computed matrix in the receiver which enables the use of the initial CIR estimate by the subsequent equalizer tap weight calculator. Simulation results are provided to demonstrate the performance of the novel algorithms for 8-VSB ATSC Digital TV system. We also provide a simulation study of the robustness of the a-BLUE algorithm to timing and carrier phase offsets.Conference Object Yazılım Tabanlı Radyolarda Karşılıklı Kanal Özelliğinin İncelenmesi(Institute of Electrical and Electronics Engineers Inc., 2016) Uslu, Merve; Tuğrel, Halim Bahadır; Karabulut Kurt, Güneş; Özbek, BernaKablosuz haberleşme sistemlerinde, kanal kestirimi çok önemli bir yer tutmaktadır. Bu çalışmada A ve B, iki haberleşme düğümü olduğu varsayıldığında, A düğümünden B düğümüne olan kanal için elde edilen kanal katsayıları ile, B düğümünden A düğümüne olan kanal için elde edilen kanal katsayılarının benzerliği incelenmiştir. Karşılıklı kanal özelliğinden dolayı bu kanalların birbirine benzer çıkmaları beklenmektedir. Bu çalışmada, laboratuvar ortamında yazılım tabanlı radyo kitleri kullanılarak karşılıklı kanal özelliği test ortamında test edilmiş, bu iki kanal katsayılarının genlik ve faz ortalama değerleri karşılaştırılmıştır.Conference Object Citation - Scopus: 2Resource Allocation for User-Relay Assisted Miso-Ofdma Networks(Institute of Electrical and Electronics Engineers Inc., 2015) Baştürk, İlhan; Özbek, BernaThe next generation cellular networks request higher capacity and coverage that user-relay assisted Orthogonal Frequency Division Multiple Access (OFDMA) networks are costeffective solutions to meet these demands. These networks can be enriched with multiple antennas in order to obtain a diversity gain to combat signal fading and to achieve more capacity gain without increasing the bandwidth or transmit power. However, radio resource management (RRM) such as relay selection and resource allocation (RA) is important in such a multi-user, multirelay and multi-antenna environment to fully take advantage of multiple-input single-output (MISO)-OFDMA based user-relay assisted cellular networks. Thus, we propose a RA algorithm for these networks to reveal the benefits of the combination of userrelaying and multiple antennas technologies and compare the proposed scheme with existing schemes in terms of percentage of satisfied users and cell-edge users' data rate.Article Citation - WoS: 11Citation - Scopus: 11Calibration of Double Stripe 3d Laser Scanner Systems Using Planarity and Orthogonality Constraints(Elsevier Ltd., 2014) Ozan, Şükrü; Gümüştekin, ŞevketIn this study, 3D scanning systems that utilize a pair of laser stripes are studied. Three types of scanning systems are implemented to scan environments, rough surfaces of near planar objects and small 3D objects. These scanners make use of double laser stripes to minimize the undesired effect of occlusions. Calibration of these scanning systems is crucially important for the alignment of 3D points which are reconstructed from different stripes. In this paper, the main focus is on the calibration problem, following a treatment on the pre-processing of stripe projections using dynamic programming and localization of 2D image points with sub-pixel accuracy. The 3D points corresponding to laser stripes are used in an optimization procedure that imposes geometrical constraints such as coplanarities and orthogonalities. It is shown that, calibration procedure proposed here, significantly improves the alignment of 3D points scanned using two laser stripes.Conference Object Active Eye-Glasses With Local Dimming(Institute of Electrical and Electronics Engineers Inc., 2011) Özvural, Görkem; Gümüştekin, ŞevketThe sense of sight provides the most reliable information about the environment. Although the human eye has a wide dynamic range for brightness adaptation, direct exposure to relatively bright light sources wipes out the total visual perception. The most remarkable example of this situation is driving a car at night, while the other cars are coming from the opposite lane with headlights on. In this work, we have proposed and developed a set of LCD equipped active glasses to solve this light adaptation problem. First, the location of the light sources are determined using an on board camera which is assembled in front of the glasses. After processing image data, the locations of the bright light sources are darkened and the disturbing effect of intense light sources is reduced. © 2011 Chamber of Turkish Electric.Article Citation - WoS: 86Citation - Scopus: 101A Comparative Study of Glottal Source Estimation Techniques(Elsevier Ltd., 2012) Drugman, Thomas; Bozkurt, Barış; Dutoit, ThierryAbstract: Source-tract decomposition (or glottal flow estimation) is one of the basic problems of speech processing. For this, several techniques have been proposed in the literature. However, studies comparing different approaches are almost nonexistent. Besides, experiments have been systematically performed either on synthetic speech or on sustained vowels. In this study we compare three of the main representative state-of-the-art methods of glottal flow estimation: closed-phase inverse filtering, iterative and adaptive inverse filtering, and mixed-phase decomposition. These techniques are first submitted to an objective assessment test on synthetic speech signals. Their sensitivity to various factors affecting the estimation quality, as well as their robustness to noise are studied. In a second experiment, their ability to label voice quality (tensed, modal, soft) is studied on a large corpus of real connected speech. It is shown that changes of voice quality are reflected by significant modifications in glottal feature distributions. Techniques based on the mixed-phase decomposition and on a closed-phase inverse filtering process turn out to give the best results on both clean synthetic and real speech signals. On the other hand, iterative and adaptive inverse filtering is recommended in noisy environments for its high robustness. © 2011 Elsevier Ltd. All rights reserved.Article Citation - WoS: 28Citation - Scopus: 30Optical Fiber Sensor System for Remote and Multi-Point Refractive Index Measurement(Elsevier Ltd., 2016) Yüksel, KıvılcımA Fresnel-reflection-based RI sensor using SMF fiber tips as sensing points interrogated by multi-wavelength OTDR from a distant location (up to several tens of kilometers) has been reported. The advantage of the system compared to previous work is that the distance between sensor points is not limited by the spatial resolution of OTDR. Experimental work demonstrated that the proposed sensor is capable of measuring refractive index of liquid chemicals with a precision of 1.7 × 10−4. This sensor prototype have strong conveniences (simple installation requirements, fast response and reliability in harsh environment) compared to previous Fresnel-based RI sensors which makes it a very good option for environmental monitoring systems. © 2016 Elsevier B.V.Conference Object Citation - Scopus: 1Implementation of Partial Synchronization of Different Chaotic Systems by Field Programmable Gate Array(Institute of Electrical and Electronics Engineers Inc., 2009) Eroğlu, Can; Savacı, Ferit AcarIn this study, the synchronization of the master-slave systems has been achieved and implemented on Field Programmable Gate Array (FPGA). In this paper, the master system and the slave system have been chosen as Lorenz and Rossler systems, respectively. The feedback control rule has been derived by feedback linearization method. By feedback linearization, the coordinate transformation has been achieved then the control command for synchronization has been obtained. In order to implement designed synchronized system, Matlab Simulink design of the system has been translated to Xilinx System Generator design to generate Very-High-Speed Integrated Circuits Hardware Description Language (VHDL) code which is used to produce bitstream file. By Xilinx Integrated Software Environment (ISE) program, VHDL code is converted to bitstream file which has been embedded into FPGA by Field Upgradeable Systems Environment (FUSE). Finally, the designed synchronized system has been observed on the HP 54540C oscilloscope.