Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği

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

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COAR Access Rights: search.filters.coarAccessRights.open accessSubject: search.filters.subject.MIMO systems

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Now showing 1 - 5 of 5
  • Conference Object
    Citation - WoS: 1
    Citation - Scopus: 3
    Hybrid Beamforming for Secure Multiuser Mmwave Mimo Communications
    (Institute of Electrical and Electronics Engineers, 2020) Erdoğan, Oğulcan; Özbek, Berna; Busari, Sherif Adeshina; González, Jonathan
    Secure communication is critical in wireless networks as the networks are prone to eavesdropping from unintended nodes. To address this challenge, physical layer security (PLS) is being employed to combat information leakage. In this paper, we present the performance evaluations based on the secrecy rate and the secrecy outage probability for multiuser multiple-input multiple-output (MIMO) millimeter-wave (mmWave) communications by employing hybrid beamforming (HBF) at the base station, legitimate users and eavesdropper. Using a 3-dimensional mmWave channel model and uniform planar antenna arrays (UPA), we employ artificial noise (AN) beamforming to jam the channels of eavesdropper and to enhance the secrecy rate. The transmitter uses the minimum mean square error (MMSE) precoder to mitigate multiuser interference for the secure MIMO mmWave systems. It is shown that the overall system performance highly depends on the power allocation factor between AN and the signal of legitimate users. © 2020 IEEE.
  • Conference Object
    Citation - WoS: 1
    Citation - Scopus: 2
    Implementation of Pre-Fft Beamforming in Mimo-Ofdm
    (Institute of Electrical and Electronics Engineers Inc., 2016) Gökçeli, Selahattin; Uslu, Merve; Karabulut Kurt, Güneş; Özbek, Berna; Alakoca, Hakan; Durmaz, Mehmet Akif
    In this study, real-time software defined radio implementation of the point to point multiple input multiple output (MIMO) orthogonal frequency division multiplexing (OFDM) system using pre-fast Fourier transform (pre-FFT) beamforming technique in both the transmitter and the receiver is done for the first time in the literature. By taking benefit of the MIMO system's spatial multiplexing property, the performance of the implemented pre-FFT beamforming approach is demonstrated in terms of bit error rate and error vector magnitude measurements. As a result of the test results, the effect of the beamforming methods on the performance of communication systems are clearly observed.
  • Article
    Citation - WoS: 4
    Citation - Scopus: 5
    An Asymptotically Stable Robust Controller Formulation for a Class of Mimo Nonlinear Systems With Uncertain Dynamics
    (Taylor and Francis Ltd., 2016) Bıdıklı, Barış; Tatlıcıoğlu, Enver; Zergeroğlu, Erkan; Bayrak, Alper
    In this work, we present a novel continuous robust controller for a class of multi-input/multi-output nonlinear systems that contains unstructured uncertainties in their drift vectors and input matrices. The proposed controller compensates uncertainties in the system dynamics and achieves asymptotic tracking while requiring only the knowledge of the sign of the leading principal minors of the input gain matrix. A Lyapunov-based argument backed up with an integral inequality is applied to prove the asymptotic stability of the closed-loop system. Simulation results are presented to illustrate the viability of the proposed method.
  • Article
    Citation - WoS: 11
    Citation - Scopus: 11
    Design of an Experimental Twin-Rotor Multi-Input Multi-Output System
    (John Wiley and Sons Inc., 2015) Bayrak, Alper; Doğan, Fırat; Tatlıcıoğlu, Enver; Özdemirel, Barbaros
    Twin-rotor multi-input multi-output system (TRMS) is a popular experimental setup utilized mostly for development and evaluation of aerovehicle control algorithms. Motivated by its popularity, construction steps of a TRMS setup in an academic setting are presented in this paper. Specifically, design of mechanical and electronic hardware components and development of related computer software are described in detail. Preliminary experiment results are also presented to demonstrate the performance of the system. © 2015 Wiley Periodicals, Inc.
  • Conference Object
    Citation - WoS: 5
    Citation - Scopus: 5
    On Precoding Mimo-Fbmc With Imperfect Channel State Information at the Transmitter
    (Institute of Electrical and Electronics Engineers Inc., 2014) Le Ruyet, Didier; Zakaria, Rostom; Özbek, Berna
    This paper studies the impact of imperfect channel state information (CSI) due to limited feedback link on the performance of multi-user MIMO system using filter bank based multicarrier (FBMC) modulation. The system is composed of a transmitter performing Zero Forcing (ZF) precoding and single antenna receivers applying decoding techniques. Simulation-based results show that except when the number of users is less than the number of transmit antennas, the BER performance and capacity of FBMC and OFDM modulation are the same. These results are theoretically justified due to the distribution of the interfering terms. As in OFDM, depending on the number of interferers, for a given BER performance target, the required number of feedback bits per channel vector can be rather high. FBMC becomes attractive not only because it relaxes the synchronization with respect to OFDM, but also because it achieves the same performance results as OFDM for multiuser MIMO precoding even in the case of imperfect CSI at the transmitter. © 2014 IEEE.