Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

Browse

Filters

2015 - 201922020 - 20222

Settings

Subject: search.filters.subject.Wireless networks

Search Results

Now showing 1 - 4 of 4
  • Master Thesis
    Wirelless Mesh Network Throughput Analysis Using Petri Nets
    (Izmir Institute of Technology, 2022) Oğuzer, Lütfü Melih Buğra; Tuğlular, Tuğkan; Belli, Fevzi
    Evolving technology has made the understanding of quality perception in software processes more difficult. Unlike other sectors, rapid adaptation and software development processes have become a critical issue. This issue can especially be observed in the service, telecommunication, and high technology sectors. User demands and competition are quite high and with this competition, the need to subject the customized or developed software to rapid testing processes has formed. Undoubtedly, this process implies a great responsibility for the "quality assurance" teams. This responsibility has reached a level that can only be handled by the quality assurance departments that automate the testing cycles. However, it is also important that these cycles are very efficient. Our research is concerned with modeling test processes with Petri nets and creating test scenarios based on this modeling to make automation processes in the telecommunications industry more efficient. In this research, the performance analysis of wireless mesh networks is executed through place/transition petri-net modeling. Through this modeling, reusable test scenarios which were compared and analyzed with traditional automation processes were created for performance tests. The research also addresses another topic which is the shortening of the modeling processes created with Petri nets and how to make them more efficient. In this context, a tool has been developed in order to shorten the modeling process and analyze the reusable test scenarios. Finally, ten test engineers were interviewed about reusable test processes. In these interviews, feedback was provided on reusable test scenarios in test automation processes.
  • Master Thesis
    Wireless Physical Layer Network Coding for Multiple Antenna Systems
    (01. Izmir Institute of Technology, 2020) İlgüy, Mert; Özbek, Berna
    Wireless networks are prone to interference due to their broadcast nature. In the design of most of the traditional networks, this broadcast nature is perceived as a performance-degrading factor. However, physical layer network coding (PNC) exploits this broadcast nature by enabling simultaneous transmissions from different sources and facilitates an increase in the spectral efficiency of the wireless networks. Besides, the massive multiple input multiple output (MIMO) is considered as one of key technologies to improve the spectral efficiency for wireless communication systems. The combination of PNC and multi-user massive MIMO in the sixth generation (6G) networks can increase further the spectral efficiency. In this thesis, PNC based systems are examined via bit error rate (BER) and coverage probability by focusing on the BER of the network coded symbol (NCS). Hence, PNC based systems are compared with network coding (NC) and conventional schemes. The influence of the signal-to-noise ratio (SNR) differences of the users are examined on the BER performances. Thereby, an alternative method to estimate NCS is proposed for the MIMO-PNC systems without using log likelihood ratio (LLR). We derive a closed form expression for the coverage probability in PNC based multi-user massive MIMO systems by employing zero forcing (ZF) equalization. The non-orthogonal multiple access (NOMA) based PNC system is proposed. We show the applicability of the PNC in the NOMA based MIMO systems by giving the the BER performance results.
  • Master Thesis
    Offloading Strategies for Heterogeneous Wireless Networks
    (Izmir Institute of Technology, 2016) Tuna, Evren; Özbek, Berna
    There has been a tremendous increase in the usage of multimedia services with the rapid penetration of mobile devices. In parallel to the technological developments in hardware and software of communication devices, users demand to have higher quality and more reliable services. The developments in network technologies are towards forming a converged structure that mobile, fixed and internet access technologies are able to operate together. Heterogeneous wireless networks have a critical role in order to meet dramatically increasing traffic demand. As a result of better operation of the systems with the help of heterogeneous wireless networks, it is possible to serve subscribers with higher performance with the help of offloading which transfer the traffic load from a network to another one. Various strategies are used in order to offload traffic between different wireless communication technologies. The main objective of this thesis is to examine offloading strategies which provides operation of different wireless communication technologies efficiently in heterogeneous wireless networks. The performance evaluations of different offloading strategies in various scenarios are implemented. The comparisons of strategies which are user initiated and network initiated are provided by considering their overhead load.
  • Master Thesis
    Interference Management Techniques for Femtocell Networks
    (Izmir Institute of Technology, 2015) Bayrak, Uğur; Özbek, Berna
    The need for high capacity and data rate increases with the growing demand for wireless communication. In order to meet this demand, one of the most effective ways of improving capacity and data rate is deployment of femtocell networks which are considered to be a promising technique for future wireless networks. However, mass deployment of these low-power base stations brings many challenges. Interference management will be one of the major challenges for the dense deployment scenarios of femtocells in coverage of the macro base stations. To cope with interference problem, there are many interference management techniques. In this thesis, power control and beamforming techniques are implemented separately and jointly in order to deal with cross-tier downlink interference which occurs between macro base station and users of femtocell. In this two-tier network system involving femtocell and macrocell layers, power control problem, first, is investigated. Feasible transmission power region for femtocell is determined with respect to the user locations so that targeted signal-to-interference-plus-noise-ratio (SINR) values are satisfied. Secondly, beamforming technique is applied using partial zero-forcing method. In this method, beamforming vectors are designed to remove cross-tier interference. It is observed that SINR of macro base station’s user does not undergoes any degradation in the nearfield region of femtocell. Finally, we apply these two techniques jointly. Since both interference suppression and power-efficiency is provided, joint technique seems to be a viable and environment-friendly solution for femtocell networks.