Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/11

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Access type: Open accessSubject: search.filters.subject.Multiuser MIMO

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  • Article
    Citation - WoS: 3
    Citation - Scopus: 5
    Design and Implementation of Spatial Correlation-Based Clustering for Multiuser Miso-Noma Systems
    (Institute of Electrical and Electronics Engineers Inc., 2021) Göztepe, Caner; Özbek, Berna; Özbek, Berna; Karabulut Kurt, Güneş; 03.05. Department of Electrical and Electronics Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    In 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: 3
    Citation - Scopus: 3
    Secure Multiuser Mimo Communication Systems With Imperfect Channel State Information
    (Elsevier Ltd., 2019) Özbek, Berna; Özbek, Berna; Özdoğan Şenol, Özgecan; Karabulut Kurt, Güneş; 03.05. Department of Electrical and Electronics Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    In this paper, we propose a secure wireless communications system through a multiple input multiple output (MIMO) channel which includes a multiple antenna base station and multiple single antenna legitimate users that are overheard by a multiple antenna eavesdropper. By assuming that the eavesdropper's channel is unknown by the base station, an artificial noise beamforming is used to prevent this eavesdropper to decode legitimate users' message in the downlink. Additionally, the base station has only imperfect channel state information (CSI) of legitimate users which is the practically relevant case. Under the condition of imperfect CSI, a noise leakage on legitimate users' signal is occurred and it degrades the achievable average secrecy sum rate. In order to reduce this noise leakage, the semi-orthogonal selection having a rotated codebook is proposed to establish a secure communications link. We demonstrate the average secrecy sum rate results of the proposed algorithm for secure multiuser MIMO systems under imperfect CSI through extensive simulation results. (c) 2019 Elsevier B.V. All rights reserved.