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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/6

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Department: search.filters.department.Department of Electrical and Electronics EngineeringSubject: search.filters.subject.Operations research and management science

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Now showing 1 - 5 of 5
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    PublicationOpen Access
    Joint transmit-and-receive antenna selection system for MIMO-NOMA with energy harvesting
    (Institute of Electrical and Electronics Engineers (IEEE), 2021) Department of Electrical and Electronics Engineering; Başar, Ertuğrul; Aldababsa, Mahmoud; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; 149116; N/A
    In this article, outage probability (OP) of a joint transmit-and-receive antenna selection (JTRAS) scheme is analyzed in multiple-input–multiple-output nonorthogonal multiple-access-based downlink energy harvesting (EH) relaying networks. In this dual-hop and amplify-and-forward relaying-based network, since the first and second hops are types of single-user and multiuser systems, respectively, the optimal JTRAS and suboptimal majority-based JTRAS schemes are employed in the first and second hops. The theoretical OP analysis is carried out over Nakagami-m fading channels in the cases of perfect and imperfect successive interference cancellation. An asymptotic OP expression is also obtained at a high signal-to-noise ratio regime. Finally, Monte Carlo simulations are performed to substantiate the accuracy of the theoretical analysis. It is shown that the optimal power splitting ratios at the EH relay are different for users and the users with good channel conditions have minimum optimal ratios.
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    PublicationOpen Access
    Reconfigurable intelligent surface-empowered MIMO systems
    (Institute of Electrical and Electronics Engineers (IEEE), 2021) Department of Electrical and Electronics Engineering; Başar, Ertuğrul; Khaleel, Aymen; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; 149116; N/A
    Reconfigurable intelligent surface (RIS)-assisted communications appear as a promising candidate for future wireless systems due to its attractive advantages in terms of implementation cost and end-to-end system performance. In this article, two new multiple-input multiple-output (MIMO) system designs using RISs are presented to enhance the performance and boost the spectral efficiency of state-of-the-art MIMO communication systems. Vertical Bell Labs layered space-time (VBLAST) and Alamouti's schemes have been considered in this article and RIS-based simple transceiver architectures are proposed. For the VBLAST-based new system, an RIS is used to enhance the performance of the nulling and canceling-based suboptimal detection procedure as well as to noticeably boost the spectral efficiency by conveying extra bits through the adjustment of the phases of the RIS elements. In addition, RIS elements have been utilized in order to redesign Alamouti's scheme with a single radio frequency signal generator at the transmitter side and to enhance its bit error rate (BER) performance. Monte Carlo simulations are provided to show the effectiveness of our system designs and it has been shown that they outperform the reference schemes in terms of BER performance and spectral efficiency.
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    PublicationOpen Access
    Flexible spatial modulation with transmit antenna selection for MIMO systems
    (Institute of Electrical and Electronics Engineers (IEEE), 2022) Department of Electrical and Electronics Engineering; Başar, Ertuğrul; Kurt, Mehmet Akif; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; 149116; N/A
    This article introduces flexible spatial modulation with transmit antenna selection (FSM-TAS) for future multiple-input multiple-output systems. In this scheme, the number of active antennas varies in each time interval depending on the incoming bits. After determining the number of active antennas, channel coefficients corresponding to each possible active antenna combination are added up. Then, a certain number of antenna combinations with largest gains is selected to apply spatial modulation (SM). For the proposed system, complexity and outage probability analyses are performed. In addition, it has been shown by Monte Carlo simulations that FSM-TAS provides better bit error rate performance than the benchmark enhanced SM with generalized antenna selection under the same spectral efficiency and the same number of transmitter and receiver antennas.
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    PublicationOpen Access
    Generalized code index modulation and spatial modulation for high rate and energy-efficient MIMO systems on Rayleigh block-fading channel
    (Institute of Electrical and Electronics Engineers (IEEE), 2021) Çögen, Fatih; Aydın, Erdoğan; Kabaoğlu, Nihat; İlhan, Hacı; Department of Electrical and Electronics Engineering; Başar, Ertuğrul; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; 149116
    In this article, a high data rate and energy-efficient multiple-input multiple-output transmission scheme is considered by combining two popular and rational modulation techniques: spatial modulation (SM) and code index modulation-spread spectrum (CIM-SS). Since in the considered system, called generalized CIM-SM (GCIM-SM), incoming information bits determine modulated symbols, activated transmit antenna indices as well as their corresponding spreading code indices, data bits are conveyed not only by modulated symbols but also by the indices of the active antenna and spreading codes. Hence, a GCIM-SM scheme accommodates faster data rates while spending less transmission power and possessing better error performance compared to the conventional direct sequence spread spectrum (DS-SS), SM, quadrature SM (QSM), and CIM-SS systems. The mathematical expressions of the GCIM-SM system for bit error rate, throughput, energy efficiency, and the system complexity are derived to analyze the overall system performance. Besides, it has been shown via computer simulations that the GCIM-SM system has lower transmission energy, faster data transmission rate, and better error performance than DS-SS, SM, QSM, and CIM-SS systems. Performance analysis of the considered system was performed on Rayleigh block-fading channels for quadrature amplitude modulation technique.
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    PublicationOpen Access
    Cooperative space shift keying media-based modulation with hybrid relaying
    (Institute of Electrical and Electronics Engineers (IEEE), 2020) Yarkın, Ferhat; Altunbaş, İbrahim; Department of Electrical and Electronics Engineering; Başar, Ertuğrul; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; 149116
    In this paper, we propose two novel cooperative space shift keying media-based modulation (SSK-MBM) schemes. In the first scheme, a multiantenna source communicates with multiple relays and the destination by applying SSK-MBM, i.e., by altering the activated antenna and the ON/OFF status of radio-frequency mirrors. Moreover, multiantenna relays have the capability of hybrid relaying, which means that the relays that correctly decode the source's signal take part in the transmission by applying the SSK-MBM technique; however, the relays that erroneously decode the source's signal amplify and forward their received signal to the destination. In the second scheme, we consider a novel cooperative SSK-MBM scheme with a hybrid relay selection in which a multiantenna source communicates with a selected relay and the destination by applying SSK-MBM. Error probability expressions for the proposed schemes are derived. Comprehensive computer simulations show that the derived analytical expressions are in agreement with the numerical results and show that the performance of hybrid relaying scheme is superior to that of the decode-and-forward as well as the amplify-and-forward techniques. It is shown that the proposed SSK-MBM systems outperform the conventional cooperative single-input multiple-output and spatial modulation systems for particularly high modulation orders and sufficient number of receive antennas at the destination.