Yüksek Lisans Tezleri

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Analysis and performance measurements of MIMO OFDM techniques for LTE
(Çankaya Üniversitesi, 2018) İbişoğlu, İsmail
Nowadays, the demand towards mobile phones that require high data rates applications has rapidly increased. In mobile networks, the Third Generation Partnership Project (3GPP) to meet the increasing demand developed long-term evolution (LTE) standard. Today, on February 28th, 2017[1], 790 operators have commercially launched LTE in 201 countries, according to data released this week by GSA (Global mobile Suppliers Association) in its latest update of the Evolution to LTE report. This study has analyzed LTE network structure which is based 3GPP standards, Version 7, 8, 9, 10, 11 and 12, and defined LTE technology properties. Afterwards, information is offered about different methods for capacity and coverage area calculations. This study also tested whether Shannon Capacity Equality or using software (like ATOLL) tools are preferred by today operators on sample.
Designing a patch antenna for 5G communication system
(Çankaya Üniversitesi, 2017) Yıldıran, Orçun
This thesis includes the design and analyzes of rectangular, circular and hexagonal type patch antennas for the next generation (5G) mobile networks. Both the microstrip feed line and coaxial feed techniques are used to feed the patch antenna. The best feed point location for both techniques is found to achieve the highest performance. The high frequency structural simulator (HFSS 12.1) is used to simulate the antenna and find out the characteristics. The antenna performance characteristics such as VSWR, return loss, radiation pattern are obtained. Moreover, a MATLAB Graphical User Interface (GUI) is designed to calculate the antenna parameters for rectangular and circular patch antennas with different feeding methods.
Effect of sliding windows techniques over a performance of TCP/IP networks
(Çankaya Üniversitesi, 2018) Abedi, Abbas Fadhil Abdulabbas
The communication channels have a variety of features in the communication system and networks, particularly wireless channels. It is used in transmissions between two nodes and deals with high error rates. Such errors that occur frequently which are not easy to be avoided, have the greatest effect on the performance of a network. So, it must be concluded that error rates are for different network conditions with use of different types of sliding windows techniques. In this thesis, error correcting techniques have been investigated based on a retransmission technique they used. One of the famous retransmission techniques is sliding windows technique, which it has three sub-algorithms called: stop and wait, selective repeat, and go back N. In this work, selective repeat and go back N algorithms were taken into account, but a stop and wait algorithm was not considered since it doesn't use any window structure in their retransmissions. Also, it always has a high delay amount with less performance compared to the selective repeat and go back N techniques. For this purpose, sliding window techniques have been implemented on Multi-Protocol Label Switching (MPLS) network platform which is simulated in MATLAB with all its details. In the simulation, all nodes running over a TCP/IP on MPLS network and nodes randomly send a number of data packets to any random node over the same network, which uses a path determined by the shortest path routing algorithm. Finally, the sliding window techniques have been studied and analyzed for their performances on the MPLS for the different traffic conditions, in terms of delay, throughput and packet loss rates. Indeed, the best sliding window technique was determined and suggested for different traffic types of the MPLS networks.
Lane keeping control for self-driving vehicles
(Çankaya Üniversitesi, 2018) Saraçoğlu, Kıvanç
Intelligent Transportation Systems including Lane Keeping Systems (LKS) aim at providing comfort to drivers, preventing congestion, decreasing gas and CO2 emissions and the number of traffic accidents. LKSs will be widely employed in the automobile industry in the near future as an essential part of modern vehicles including cars, buses and trucks. When realizing a LKS, it is necessary to decide about the required signal measurements and to implement control algorithms that are suitable for different vehicle speeds, road curvatures and can be adapted to different types of vehicles such as passenger vehicles, buses and trucks. The main aim of this thesis is to evaluate and compare different lane keeping algorithms. These lane keeping algorithms are applied to a vehicle model, whose longitudinal motion is decoupled from the lateral motion. Four lane keeping control algorithms are investigated. The first two control algorithms measure the yaw rate and the displacement error at a pre-view distance to compute the necessary rate of change of the steering angle for following a road. The first control algorithms uses a linear controller transfer function, whereas the second control algorithm uses sliding mode control. The third control algorithm also measures the yaw rate and the displacement error at a pre-view distance but directly computes the required steering angle for lane keeping. The fourth control algorithm measures the yaw rate, the heading error and the displacement of the center of gravity (COG). These algorithms are evaluated using simulation experiments with given displacement errors and road profiles. The main outcomes of the thesis are as follows. As the first contribution, the thesis shows that the measurement of the displacement error at a pre-view distance increases the robustness of lane keeping control algorithms. On the downside, since the displacement error at the pre-view distance is controlled, the displacement error at the COG can become large at high velocities. As the second contribution, the thesis concludes that it is beneficial to combine measurements of the yaw rate, the displacement errors at the preview-distance and the COG as well as a prediction of the road curvature to obtain an efficient control algorithm. Such control algorithm is proposed in the thesis and its superior performance is shown by simulation experiments.
Spectral analysis of ECG signals for pre-diagnosis of heart diseases
(Çankaya Üniversitesi, 2018) Al-Jada, Omar Saad Abdulqader
In this thesis we used the three cases for diagnosis of the heart attacks. The first case is healthy persons, second case is non healthy persons and the last one is unknown persons. For detection of them we used the correlation and auto correlation between the cases. For the simulation results we used the MATLAB programming languages. For diagnosis we used two statistical method. The first one is to take only one dice (assuming that this selected dice is a perfect representative of the remaining dice) and throw it many times (multiplying the time axis, to get time average). The second is to throw all dice or some of the dice at the same time (multiplying the event axis, to get ensemble average). The question is how many times should the experiment be repeated along time axis in the first case and how many dice thrown at a time in the second case so that we arrive at a result well approximated to the ones to get a result within 98 % confidence interval the minimum number that an experiment should be performed

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