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Yayın Cluster based sensors scheduling in a target tracking application with particle filter method(Işık Üniversitesi, 2006) Özfidan, Özgür; Bayazıt, Uluğ; Işık Üniversitesi, Fen Bilimleri Enstitüsü, Elektronik Mühendisliği Yüksek Lisans ProgramıIn multisensor applications, management of sensors is neccessary for the classification of data they produce and for the efficient use of sensors as well. One of the most important aspects in sensor management is the sensor scheduling. By scheduling the sensors, serious redictions can be achieved in the cost of bandwith, power and computation. In this thesis, a simple solution for the problem of sensor scheduling in a multi-sensor target tracking application is presented. Proposed method is called sensor grouping. Due to non-linearity and non-gaussianity of the problem itself, proposed solution is presented in the framework of non-linear Bayesian Estimation. For this purpose a detailedtheoretical background of the theory of Bayesian Tracking and Particle Filtering algorithm is given.Yayın Video quality assessment using subjective and objective metrics(Işık Üniversitesi, 2013-05-22) Gaurav, Rahul; Ateş, Hasan Fehmi; Işık Üniversitesi, Fen Bilimleri Enstitüsü, Elektronik Mühendisliği Yüksek Lisans ProgramıSince past few years, quality assessment of digital videos has acquired a lot of attention in the video processing community, leading to the growth of different 2D and 3D objective metrics for images and videos. Some of these metrics correlate quite well with the Human Visual System (HVS), while some do not. Most of the popular objective metrics do not perfectly correlate with the HVS. This correlation can be measured by the opinion scores based on observations of human subjects. In this thesis, we extensively study about Video Quality Assessment and complexity of HVS by proposing a method which helps us to find the best correlation between HVS and the objective metrics. The motive behind this work is to to introduce an objective metric that is adequate to predict the MOS (Mean Opinion Score) of distorted video sequences based on the FR (Full Reference) method, keeping in mind the benchmark set by the Video Quality Expert Group (VQEG). Subjective quality evaluation experiments using the human observers were performed, that is, a group of non-experts viewing the video sequences in original and distorted forms, as it is the human perception method which is evidently the most reliable one. Thereafter, objective test results, including the introduced metric, called PQM (Perceptual Quality Metric), and several other state-of-art metrics, are compared with MOS provided by human subjects. These comparisons elucidate the level of correlation between tested objective metrics and MOS. As an ultimate objective, we show the accuracy and monotonicity of various quality metrics, including PQM. The results obtained show that the PQM is better correlated with the human subjective judgement.Yayın Optimization of integer-pel motion estimation for H.264 video encoding on tms 320c6416t digital signal processor(Işık Üniversitesi, 2007-12-03) Yazıcı, Muhammet; Ateş, Hasan Fehmi; Işık Üniversitesi, Fen Bilimleri Enstitüsü, Elektronik Mühendisliği Yüksek Lisans ProgramıVideo processing is used in many applications such as broadcast television and home entertainments. Video applications have been revolutionized by the advent of digital TV and DVD-video players. The standardization of video compression technology is essential for many video applications. Today the state-of-the-art compression standard is the H.264 standard. In this thesis, an H.264 encoder implementation is optimized on Texas Instruments TMS320C6416T board for real-time processing. C6416 is a high performance and a low cost digital signal processor (DSP) chip that can achieve real time implementation of the algorithm. Thus, we choose C6416 because of based on our analysis of performance and cost. In this thesis, hierarchal motion estimation module is implemented for the H.264 encoder. First of all algorithm code was written in C language. Then performance critical parts are written in assembly. The resulting code is an optimized implementation on the Texas Instruments TMS320C6416T DSP. Simulations on TMS320C6416T reveal that the encoder processes 39-65 CIF frames per second, which satisfies 25 fps requirement for real-time applications.Yayın Energy and data cooperation in energy harvesting multiple access channels(Işık Üniversitesi, 2016) Şişman, Berrak; Kaya, Onur; Işık Üniversitesi, Fen Bilimleri Enstitüsü, Elektronik Mühendisliği Yüksek Lisans ProgramıA typical wireless device is limited by its nite battery, and energy limitation is as a critical bottleneck on wireless network performance. In addition to the EM radiation caused by high power wireless devices, the batteries used in those devices need to be recharged frequently, causing fast depletion of earth's resources; and are discarded after a while, causing environmental pollution. Moreover, in some scenarios, such as sensor networks deployed in rural areas, it is simply not feasible to replace the batteries of the wireless nodes, hence using nodes which can replenish their energy is of paramount importance in prolonging the network lifetime. As a result, the concept of green communication and the idea of designing communication protocols based on energy harvesting constraints of individual nodes have recently received tremendous attention. With this motivation in mind, this thesis is devoted to designing cooperation and transmit scheduling techniquesfor networks powered soleley by harvested energy. We study energy cooperation in a two user multiple access channel and a two user cooperative multiple access channel with and without battery limitations. We characterize, and optimize the departure region for a two user multiple access channel, under six di erent models, with varying levels of cooperation and energy storage capabilities. We aim to nd the optimum energy management policies of the transmitters to maximize the achievable departure region over a fi nite transmission duration.Yayın Compression of the mammography images using quadtree based energy and pattern blocks(Işık Üniversitesi, 2017-01-16) Nahavandi Gargari, Sepideh; Güz, Ümit; Işık Üniversitesi, Fen Bilimleri Enstitüsü, Elektronik Mühendisliği Yüksek Lisans ProgramıMedical images, like any other digital data, require compression in order to reduce disk space needed for storage and time needed for transmission. This thesis offers , a novel image compression method based on generation of the so-called classified energy and pattern blocks (CEPB) is introduced and evaluation results are presented. The CEPB is constructed using the training images and then located at both the transmitter and receiver sides of the communication system. Then the energy and pattern blocks of input images to be reconstructed are determined by the same way in the construction of the CEPB. This process is also associated with a matching procedure to determine the index numbers of the classified energy and pattern blocks in the CEPB which best represents (matches) the energy and pattern blocks of the input images. Encoding parameters are block scaling coeffcient and index numbers of energy and pattern blocks determined for each block of the input images. These parameters are sent from the transmitter part to the receiver part and the classified energy and pattern blocks associated with the index numbers are pulled from the CEPB. Moreover, in the second part of our method we used Quadtree too. By this way, all CEPB from quadtree results determined for each block of the input images too. input image is reconstructed block by block in the receiver part using a mathematical model that is proposed by 2 different method: Reconstruct Based on one block size Reconstruct Based on Quadtree Evaluation results show that the method provides considerable image compression ratios and image quality even at low bit rates. Test result have shown that Compression ratio and PSNR results is acceptable, moreover, Quadtree method gives better results that fix based block size.Yayın Biometric recognition using bio-signals(Işık Üniversitesi, 2017-04-14) Dursun, Ceren; Gürkan, Hakan; Güz, Ümit; Işık Üniversitesi, Fen Bilimleri Enstitüsü, Elektronik Mühendisliği Yüksek Lisans ProgramıThe main objective of the project is to increase the recognition rate by establishing a multimodal biometric recognition system that uses two di_erent biometric characteristics, as bio-signals. Today, institutions use biometric recognition systems quite often to provide security for many areas such as information security and physical security. The importance of these systems increases day by day in the direction of technological development and increasing demand. Recognition systems based on biometric characteristics are more reliable, because of the possibility of forgetting or losing knowledge in the recognition systems based on knowledge (eg: password) and the possibility of being stolen or guessed by third persons in the biometric recognition based on possessed (eg: card). However, the fraud techniques are also developing in the direction of technological developments and biometric characteristics cannot be renewed in case of imitation, hence the use of multiple biometrics recognition system may be a solution to this problem. At the same time, the use of multiple biometrics increases in the security of systems. In this thesis, a biometric recognition system, which uses the lectrocardiogram (ECG) and speech signals of the person, was created. Since there was not enough time and possibility, an arti_cial database was generated with obtaining these signals from various sources. First, the MIT-BIH Arrhythmia Database was used for ECG signals. This database consists of 48 ECG signals, which belong to 22 females and 26 males. In ccordance with this database, a database was created for the speech signals, which were obtained from the website, given in [1]. The features of the biometric signals were extracted by AC / DCT (Autocorrelation/ Discrete Cosine Transform) method for ECG signals and by Mel Frequency Cepstrum Coe_cients (MFCCs) method for speech signals. The data, which were obtained from the feature extraction, were then classi_ed by the Gaussian Mixture Model (GMM) method. The scores, which were obtained from the classi_cation process, were fused as a single individual's data, and the decision-making step was passed. Recognition rates were obtained in the decision making step. The recognition rate for the ECG signal was %87.50 and 42 persons were matched correctly. The recognition rate for 2 seconds speech signals was %58.33 and 28 persons were matched correctly. Normalization was applied before the fusion of these two datasets. The recognition rate after the fusion was %70.83 and 34 persons were matched correctly. However, when the recognition rates are considered, it has been observed that the recognition rate, which obtained after the fusion, is lower than recognition rate of the ECG signals. Therefore, instead of 2 seconds speech signals, 10 seconds speech signals were used. In this case, the recognition rate of the speech signals was %97.9 and 47 persons were matched correctly. Then, normalization was applied again and two datasets were fused. After the fusion, the rate of recognition reached %95.8 and 46 persons were matched correctly.Yayın Implementation of cooperative diversity in space frequency coded OFDM system(Işık Üniversitesi, 2007) Yiğit, Can; Kaya, Onur; Işık Üniversitesi, Fen Bilimleri Enstitüsü, Elektronik Mühendisliği Yüksek Lisans ProgramıWireless technology is becoming an important part of our daily life. Although earlier wireless technologies were developed to provide voice transmission which did not require large amount of bandwidth, we are now equipped with intelligent mobiles, PDAs and laptop computers each having various applications connecting us to multimedia services that requires high bandwidth utilization. Technology world is converging to IP based systems where reliability and capacity plays an important role. For example the delay periods which can be neglected in voice transmissions can be crucial in services like on demand TV where data transmission have to be smooth. High performance and high reliability requires the bounds of capacity and coding structures to be increased. In this thesis we consider strong coding algorithms and diversity techniques in broadband channels. Space frequency codes which have been proven to achieve high performance in MIMO systems have been employed to single antenna systems by using cooperative diversity where deployment of multiple antennas is difficult. By constructing such a structure we target to achieve available diversities in the channel to improve the performance.Yayın Partner selection and resource allocation in single-cell, multi-cell and cognitive cooperative multiple access channels(Işık Üniversitesi, 2013-06-06) Bakşi, Saygın; Kaya, Onur; Işık Üniversitesi, Fen Bilimleri Enstitüsü, Elektronik Mühendisliği Yüksek Lisans ProgramıWireless communication has been widely used across the globe for several years. As the technology advances and gains popularity, more people start using it and more throughput is needed. For that reason, several techniques are being researched such as MIMO systems and cooperative networks. Wireless cooperative networks make use of the natural property of radiation of electromagnetic waves. Since the waves emitted by a user in the network can be heard by all users in the network, one cooperating partner uses this overheard information to increase throughput. However, to maximize the throughput of a system, cooperating partners must be selected intelligently. In this dissertation, first, we will summarize cooperative communication basics, techniques we used in convex optimization and graph theory. Then, we will show how these concepts can be used together to optimally maximize system throughput and propose lower complexity yet nearly-optimal partner selection algorithm will be proposed. Under the light of the results of this work, in the next chapters, we will introduce a novel fractional frequency reuse scheme which encourages users to cooperate and allow system to support more users. In the last chapter, a cognitive scenario will be used for one cell and we will present the optimal partner selection scheme for system throughput maximization.Yayın Artifact reduction in occluded regions for motion compensated frame interpolation(Işık Üniversitesi, 2008) Yazgan, Rıfat; Ateş, Hasan Fehmi; Işık Üniversitesi, Fen Bilimleri Enstitüsü, Elektronik Mühendisliği Yüksek Lisans ProgramıIn this paper, we propose a new method to be used in occluded regions for motion compensated frame interpolation. Frame rate up conversion is becoming much more important when usage of digital video systems increase. Standard conversion techniques are not effective in increasing the temporal resolution of video without any degradation. Therefore, motion compensated post processing techniques are developed to obtain the best possible image at the receiver. Specifying the correct or reliable motion vectors is the most important issue to be able to prevent the artifacts and deformed structures in the interpolated frame. There are many methods in literature developed for that purpose. However, these methods generally create annoying artifacts in interpolated frames. Significantly, they can not provide acceptable results for covered and uncovered regions. In our work, we build upon the successful multi-stage post processing method which is used to obtain the correct vector for motion compensated frame interpolation. According to our analysis, all these post processing stages are effective to specify the reliable motion vectors, but they are not sufficient to solve the problem in covered and uncovered regions. In thesis, we suggest methods to be able to solve the problem occurring in these regions. In most of adaptive methods, either past or future frames are used for interpolation in covered/uncovered region respectively, but in our proposals we interpolate the new frame by using a weighted combination of the four neighboring frames to minimize the sharp blocking aircrafts that occur because of unidirectional interpolation in occluded areas, and reduces the sharp artifacts in the interpolated frame for covered and uncovered regions, and provides better picture quality.Yayın Ground plane detection using and rgb-d camera for quadcopter landing(Işık Üniversitesi, 2013-06-04) Kırcalı, Doğan; Tek, Faik Boray; Işık Üniversitesi, Fen Bilimleri Enstitüsü, Elektronik Mühendisliği Yüksek Lisans ProgramıThe purpose of this study is to build an autonomous quadcopter which is capable of automated detection of landing zones and landing. To ensure this there are important steps linked together. The first step is to build a quadcopter that can fly. We have used a commercially available quadcopter platform and an Ardu Pilot Mega control card to build a low cost, easy to implement, and stable platform. An open source firmware, named Arducopter, is used for the control card. This system can take-off, land, hover, and follow a given flight path. In order to detect of landing zones and safe landing, we propose to use an RGB-D camera as a sensor and a small onboard pc as the computing engine. Hence, we have modified the acquired quadcopter frame to integrate additional components. In this thesis, we propose a novel and robust ground plane and obstacle detec»tion algorithm based on depth information using RGB-D camera. Moreover, our method was compared with V-disparity algorithm from the literature. It has been shown that our algorithm performs better than V-disparity method and produces useful ground plane-obstacle segmentations, even for difficult cases. The method is able to work in highly dynamic platforms. This algorithm is generic in the sense that it can be used for different forward-facing RGB-D placements, for example in ground vehicles or robots. Moreover, we developed a pre-process to allow the use of the method for down- facing sensor view positions as the core method is inadequate for landing zone detection. The proposed method compensates the movements of the camera caused by the air vehicle, and detects the ground plane obstacles successfully. It has been shown that the use of RGB-D camera allows ground plane and landing zone detection even in no-light conditions. All necessary components in this thesis were financed by FMV Işık University internal research funds BAP-10B302 project.
