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Publication Metadata only From Asia to Europe: Short-Term Traffic Flow Prediction Between Continents(IEEE, 2014) Kaya, Sevgi; Kilic, Necati; Kocak, Taskin; Gungor, Cagri; Swiss Federal Institutes of Technology Domain; ETH Zurich; Bahcesehir UniversityModelling the traffic flow and predicting the near-future traffic status are two challenging problems of the smart transportation on roads. The difficulty is particularly pronounced in forecasting the complex non-linear dynamics of flow. Most of the state-of-the-art work on traffic flow prediction determine the parameters based on the fundamental relationship between flow, density and speed without considering its influence to the consecutive one. However, these approaches tend to fail in real life scenarios due to the negligence of the spatio-temporal dependence of parameters within road segments. In this paper, we propose a new traffic flow model to predict the arterial travel time using probe data. We then evaluate our model under various traffic conditions to determine its feasibility for near-future traffic flow prediction. The proposed method presents promising results by outperforming the state-of-the-art in predicting near-future traffic flow on roads in case of sparse data and high flow density.Publication Metadata only Credit Risk Analysis based on Hybrid Classification: Case Studies on German and Turkish Credit Datasets(IEEE, 2018) Cetiner, Erkan; Kocak, Taskin; Gungor, V. Cagri; Bahcesehir University; Abdullah Gul UniversityIn finance sector, credit risk analysis plays a major role in decision process. Banks and finance institutions gather large amounts of raw data from their customers. Data mining techniques can be employed to obtain useful information from this raw data. Several data mining techniques, such as support-vector machines (SVM), neural networks, naive-bayes, have already been used to classify customers. In this paper, we propose hybrid classification approaches, which try to combine several classifiers and ensemble learners to boost accuracy on classification results. Furthermore, we compare these approaches' performance with respect to their classification accuracy. We work with two diverse datasets, namely, German credit dataset and Turkish bank dataset. The goal of using such diverse dataset is to show generalization capabality of our approaches. Experimental results provide three important consequences. First, feature selection stage has a major role both on result accuracy and calculation complexity. Second, hybrid approaches have better generalability over single classifiers. Third, using SVM-Radial Basis Function (RBF) as the base classifier and a hybrid model member gives the best accuracy and type-1 accuracy results among others.Publication Metadata only Location-aided Multi-user Beamforming for 60 GHz WPAN Systems(IEEE, 2012) Han, Congzheng; Zhu, Xiaoyi; Doufexi, Angela; Kocak, Taskin; University of Bristol; Bahcesehir University60 GHz wireless personal area networks (WPANs) offer multi-Gbps throughput, which will provide for a new wave of high data rate applications. This paper exploits the use of location information to improve the performance and enhance range of 60 GHz multi-user beamforming systems. When the location information is available at the transmitter, the scheduler chooses a set of maximum angularly separated users to share wireless resources simultaneously. If additional feedback of signal-to-interference and noise ratio (SINR) is known, a location-assisted scheduler is employed to increase the system overall performance. Both numerical and simulated results show that significant enhancement can be achieved by the proposed schedulers for 60 GHz WPAN systems.Publication Metadata only A Performance Evaluation of 60 GHz MIMO Systems for IEEE 802.11ad WPANs(IEEE, 2011) Zhu, Xiaoyi; Doufexi, Angela; Kocak, Taskin; University of Bristol; Bahcesehir UniversityThe IEEE 802.11ad task group has published its first draft to cope with the characteristics in 60 GHz millimeter-wave (mmWave) wireless communications. In this paper, three different 2x2 multiple-input multiple-output (MIMO) techniques are considered to enhance the performance of 60 GHz wireless personal networks (WPANs). Packet Error Rate (PER) and link throughput performance are simulated under different channel conditions. In addition, the system throughput over operation range is presented in the paper. Results show that significant enhancements in both coverage and capacity can be achieved by employing space-time block codes (STBC), spatial multiplexing (SM) and three different configurations of beamforming.Publication Metadata only Throughput and Coverage Performance for IEEE 802.11ad Millimeter-Wave WPANs(IEEE, 2011) Zhu, Xiaoyi; Doufexi, Angela; Kocak, Taskin; University of Bristol; Bahcesehir UniversityRecently, the development and requirement for ultra-high data rate wireless communication applications has increased dramatically. The 60 GHz millimeter-wave wireless technology is getting increasing attention, and the IEEE 802.11 Task Group AD is making standardization efforts for multi-gigabit data rate communications on both the physical (PHY) and medium access control (MAC) layers. This paper presents a performance evaluation of the PHY and MAC layers of IEEE 802.11ad. Packet error rate and PHY throughput are presented for different modes, and the theoretical MAC throughput is analyzed for different bit error rates, packet sizes and modes. In addition, 2x2 space-time block coding (STBC) is employed for range extension. The cross layer results show our approach enhance the throughput and coverage compared to the case of single antenna.Publication Metadata only Open Distributed System to Provide Real-Time Communication Service over Web(IEEE, 2017) Armagan, Ozgur; Guner, Huseyin; Keskin, Selcuk; Kocak, Taskin; Netas; Bahcesehir UniversityNowadays, corporate companies use different applications and service providers to take advantage of services such as instant messaging, e-mail, social networks and company-wide calls. These service providers are demanding higher licensing fees for additional features needed by the institutions. For example, the ability to call landlines as well as in-house calls can greatly increase the costs of the corporate companies. Moreover, there is no application in the market that provides ease of use by collecting all these services under one roof. In this work, a system has been designed to ensure that all these shortcomings are eliminated and landlines can be called. The