Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/15956

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2014 - 20155

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Department: search.filters.department.Çankaya Üniversitesi, Fen Bilimleri Enstitüsü, Elektronik ve Haberleşme Mühendisliği BölümüSubject: search.filters.subject.Yinelemeli Çözüm

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Now showing 1 - 5 of 5
  • Master Thesis
    The use of convolutional product codes in cooperative communication systems
    (2014) Hadi, Ali
    In this thesis work, the performances of cooperative communication systems employing convolutional product codes (CPCs) and serially concatenated convolution codes (SCCCs) are inspected in detail and compared to each other. Different combining methods at destination are proposed. One of these methods is based on the combination of bit probabilities on the other hand other method focuses combining the signals considering their signal to noise rations (SNRs). The effect of relay number on the system performance is inspected. Reduced complexity cooperative communication systems utilizing convolutional product codes are considered. The proposed systems are all iteratively parallel decodable and have low latency
  • Master Thesis
    Design of a photovoltaic power converter for driving and controlling ac motors
    (2014) Soodi, Hamed Atyia
    The availability of renewable energy sources is of increasing importance on the market. In order to use renewable energy efficiently, suitable power processing equipment is needed to support different applications such as energy storage, feeding energy to the grid or driving AC motors. The subject of this thesis is the power processing for the speed control of AC motors, whereby photovoltaic (PV) modules are considered as the renewable energy source. In the classical design, this task is performed in two stages. First, the low DC voltage provided by the PV module is boosted to a higher voltage level that is suitable for driving the AC motor using a DC-DC converter. Second, the resulting DC link voltage is converted to a 3- phase AC voltage that is used for driving the AC motor by the help of a voltage source inverter (VSI). The frequency of this AC can be changed in order to change the motor speed. In contrast, this thesis proposes to employ a Z-source inverter (ZSI) as an AC motor drive. The ZSI combines the DC voltage boost and the AC voltage generation in a single stage by using a special capacitor/inductor network. The thesis first provides the model of the ZSI and discusses the working principle of voltage boost. Then, the generation of a variable frequency AC voltage based on the spacevector the pulse width modulation is elaborated. Together, a complete design of a VSI for driving AC motors is obtained. The suitability of the design is evaluated by a simulation study in Matlab/Simulink. It shows that the designed VSI can be optimized for AC motors with different characteristics. In addition, it is verified that the same VSI can be used for different AC motors by simply adjusting the voltage boost, that is, without changing any hardware components
  • Master Thesis
    Joint source channel coding using trellis coded quantization
    (2015) Al-Sammarrie, Samir H. Salih
    Trellis coded quantization is inspired from trellis coded modulation for better bit efficient quantizer design. In this thesis study we proposed joint communication systems, involving trellis coded quantization, space time block codes, and recursive systematic convolutional codes. The proposed joint communicatios structures are novel and they are iteratively processable. Using the RSC(1,5/7)octal state transition diagram we proposed a new trellis coded quantization approach and integrated the proposed structure with space time block codes and the performance of the joint system is obtained via computer simulation. From simulation results it is seen that the proposed system shows better performance that the classical TCQ integrated with space time block codes and in addition the proposed system has lower distortion when compared to its classical counterparts.
  • Master Thesis
    Joint structures involving pdsccs, tcm and space time codes
    (2015) Saeed Al-Kattan, Ahmed Ameer
    In this thesis we propose new concatenated joint communication structures involving convolutional product codes, space time codes and trellis coded modulation. The first structure consists of convolutional product codes and space time codes. The second one includes convolutional product codes and trellis coded modulation. The proposed structures are all parallel decodable due to the structure of convolutional product codes and have low decoding latencies, which are the main advantages of these proposed structures considering their classical counterparts constructed using serially concatenated convolutional codes, space time codes and trellis coded modulation. The use of multi-antennas at the proposed structures increases the spectral efficiency.
  • Master Thesis
    Performance of space time block coded bit interleaved coded modulation systems for mobile communication channels
    (2014) Ismaeil, Omar Khaza’al
    In this thesis concatenated systems involving bit interleaved coded modulation (BICM) and space time codes (STC) are inspected in detail. Space time block codes (STBCs) are used while forming the joint structures. Performance of the joint structures involving BICM and STCs for additive white Gaussian and mobile fading channels are measured via computer simulations. Iterative decoding logic is applied for the decoding of these joint structures. An alternative feedback path for the iterative decoding of BICM-STBC joint structures is proposed and simulation results showed that the proposed path result in better bit error rate performance. Concatenated BICM-STBCs are also used in cooperative communication structures. A signal combination method based on the linear combination of the signal probabilities coming from the relays is proposed and it is seen that proper choosing of the coefficients for the linear combination of the probabilities is an important criteria for the performance of the cooperated systems.