Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 3Citation - Scopus: 5Design and Implementation of Spatial Correlation-Based Clustering for Multiuser Miso-Noma Systems(Institute of Electrical and Electronics Engineers Inc., 2021) Göztepe, Caner; Özbek, Berna; Karabulut Kurt, GüneşIn this letter, we propose a novel user clustering algorithm for downlink multiuser multiple-input single-output (MISO) non-orthogonal multiple access (NOMA) systems along with its implementation in a real-time testing environment. The proposed method selects the clusters by considering users' spatial channel properties against the generated orthogonal directions. This is then followed by power allocation and zero-forcing precoding steps to mitigate the interference between the selected clusters. Performance comparisons are provided in terms of both real-time tests and simulations. It is demonstrated that a notable improvement in capacity and reliability can be obtained through the proposed approach in multiuser MISO-NOMA systems with reduced complexity.Article Citation - WoS: 6Citation - Scopus: 6User Selection for Millimeter Wave Non-Uniform Full Dimensional Mimo(IEEE, 2020) Mumtaz, Rao; Gonzalez, Jonathan; Cumalı, İrem; Özbek, BernaThe millimeter wave (mmWave) based full-dimensional (FD) MIMO communication is one of the promising technology to fulfill the demand of high data rate for the sixth generation (6G) services including 6D hologram, haptic and multi-sensory communications. In order to satisfy the requirements of 6G applications, we investigate a non-uniform rectangular array (NURA) structure with FD-MIMO antenna systems for the multiuser mmWave communications. For the dense scenarios where the number of users to be served is high, we propose user selection algorithms for both digital and hybrid transceiver designs in FD-MIMO with NURA for the multiuser mmWave communications. For the digital transceivers, the users are selected based on their channel correlation considering FD-MIMO with NURA structures. For the hybrid transceivers, sequential user and beam selection is performed using the correlation between the beamspace channels in FD-MIMO with NURA case. The superiority of the NURA compared to uniform antenna structure is shown through the performance evaluations in the multiuser mmWave communications. Besides, the sum data rate results and complexity analysis denote the feasibility of the proposed algorithms compared to the joint user and beam selection schemes.Article Citation - WoS: 9Citation - Scopus: 10Radio Resource Management for User-Relay Assisted Ofdma-Based Wireless Networks(Urban und Fischer Verlag GmbH und Co. KG, 2016) Baştürk, İlhan; Özbek, BernaOrthogonal frequency division multiple access (OFDMA) based relay assisted networks are important for current and next-generation wireless networks since they have great potential to provide high data rate to users at anywhere, anytime. Towards that end, fixed relay assisted OFDMA networks are commonly utilized by the operators. However, they require supplementary costly infrastructure. User-relay assisted OFDMA-based networks are promising candidates to fulfill the demanding coverage and capacity requirements of future wireless networks in a cost efficient way. Thus, they have become popular as a complementary solution to fixed relay networks. Generic frame structure that divides the resource allocation frame into two subframes is mostly used in the literature for fixed and user-relay assisted networks in which it is assumed that a user can act as a destination and a relay simultaneously. However, it may be difficult to apply this assumption to practical systems because of the limitations of the current transceiver design. Thus, we propose a novel frame structure for user-relay assisted OFDMA-based wireless networks in order to cope with these drawbacks. The efficient radio resource management algorithms including relay selection and resource allocation are developed in order to exploit the opportunities of the proposed frame structure.