Sürdürülebilir Yeşil Kampüs Koleksiyonu / Sustainable Green Campus Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7755
Browse
6 results
Search Results
Article Citation - WoS: 3Citation - Scopus: 3Channel and Queue Aware Joint Relay Selection and Resource Allocation for Miso-Ofdma Based User-Relay Assisted Cellular Networks(Springer Verlag, 2018) Baştürk, İlhan; Özbek, BernaUser-relay assisted orthogonal frequency division multiple access (OFDMA) networks are cost-effective solutions to meet the growing capacity and coverage demands of the next generation cellular networks. These networks can be used with multiple antennas technology in order to obtain a diversity gain to combat signal fading and to obtain more capacity gain without increasing the bandwidth or transmit power. Efficient relay selection and resource allocation are crucial in such a multi-user, multi-relay and multi-antenna environment to fully exploit the benefits of the combination of user-relaying and multiple antennas technology. Thus, we propose a channel and queue aware joint relay selection and resource allocation algorithm for multiple-input single-output (MISO)-OFDMA based user-relay assisted downlink cellular networks. Since, the proposed algorithm is not only channel but also queue-aware, the system resources are allocated efficiently among the users. The proposed algorithm for the MISO-OFDMA based user-relay assisted scheme is compared to existing MISO-OFDMA based non-relaying and fixed relay assisted schemes and it is also compared with the existing single-input single-output (SISO)-OFDMA based user-relay assisted scheme. Simulation results revealed that the proposed scheme outperforms the existing schemes in terms of cell-edge users’ total data rate, average backlog and average delay.Conference Object Citation - WoS: 1Citation - Scopus: 1Cell Load Based User Association for Tetra Trunk Systems(Institute of Electrical and Electronics Engineers Inc., 2018) Karataş, Azad; Özbek, Berna; Bardak, Erinç Deniz; Sönmez, İlkerIncreasing traffic in communication systems need efficient new cell selection algorithms to control the distribution of users. For better and seamless transmission, load balancing become critical factors for cell selection algorithms. Un-desired consequents in these situations may cause disasters specifically for the emergency cases in public safety services. In this paper, a cell selection algorithm is proposed for Terrestrial Trunked Radio (TETRA) based Professional Mobile Radio (PMR) systems. The proposed algorithm is designed to provide a fairer distribution of users among cells while keeping the number of received power measurement less. The performances of the proposed algorithm are obtained in urban and rural environment.Master Thesis Cell Selection Algorithms for Conventional Narrow Band Wireless Systems(Izmir Institute of Technology, 2017) Yılmaz, Saadet Simay; Özbek, BernaPublic safety organizations provide a stable and secure environment for the society. Wireless communication between public safety officers is very important to transmit voice or data during an emergency crisis. When the public communication networks can not provide service during crisis, disaster and high traffic cases, Professional Mobile Radio systems (PMR) such as conventional Association of Public Safety Communications Officials (APCO25) and trunked Digital Mobile Radio (DMR) systems are needed to improve the service quality and to provide uninterrupted service provided to the users. While providing continuous voice and data service, it is very important to efficiently select the base station to be served and to ensure that a mobile user can seamlessly attach from one base station to another base station while moving within a cell. In this sense, it is critical to determine the base station to be served by efficient cell selection algorithms. Cell selection is the process of deciding the base station which provides services to the users. Cell selection plays an important role in balancing the system load and thus overall system performance. By means of efficient cell selection algorithms, it is aimed to reduce the waiting time and to connect a base station as soon as possible while establishing reliable transmission link for PMR systems in emergencies.Conference Object Yazılım Tabanlı Radyolarda Karşılıklı Kanal Özelliğinin İncelenmesi(Institute of Electrical and Electronics Engineers Inc., 2016) Uslu, Merve; Tuğrel, Halim Bahadır; Karabulut Kurt, Güneş; Özbek, BernaKablosuz haberleşme sistemlerinde, kanal kestirimi çok önemli bir yer tutmaktadır. Bu çalışmada A ve B, iki haberleşme düğümü olduğu varsayıldığında, A düğümünden B düğümüne olan kanal için elde edilen kanal katsayıları ile, B düğümünden A düğümüne olan kanal için elde edilen kanal katsayılarının benzerliği incelenmiştir. Karşılıklı kanal özelliğinden dolayı bu kanalların birbirine benzer çıkmaları beklenmektedir. Bu çalışmada, laboratuvar ortamında yazılım tabanlı radyo kitleri kullanılarak karşılıklı kanal özelliği test ortamında test edilmiş, bu iki kanal katsayılarının genlik ve faz ortalama değerleri karşılaştırılmıştır.Conference Object Citation - Scopus: 2Resource Allocation for User-Relay Assisted Miso-Ofdma Networks(Institute of Electrical and Electronics Engineers Inc., 2015) Baştürk, İlhan; Özbek, BernaThe next generation cellular networks request higher capacity and coverage that user-relay assisted Orthogonal Frequency Division Multiple Access (OFDMA) networks are costeffective solutions to meet these demands. These networks can be enriched with multiple antennas in order to obtain a diversity gain to combat signal fading and to achieve more capacity gain without increasing the bandwidth or transmit power. However, radio resource management (RRM) such as relay selection and resource allocation (RA) is important in such a multi-user, multirelay and multi-antenna environment to fully take advantage of multiple-input single-output (MISO)-OFDMA based user-relay assisted cellular networks. Thus, we propose a RA algorithm for these networks to reveal the benefits of the combination of userrelaying and multiple antennas technologies and compare the proposed scheme with existing schemes in terms of percentage of satisfied users and cell-edge users' data rate.Master Thesis Interference Management Techniques for Femtocell Networks(Izmir Institute of Technology, 2015) Bayrak, Uğur; Özbek, BernaThe 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.