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Department: search.filters.department.Department of Electrical and Electronics EngineeringSubject: search.filters.subject.Orthogonal frequency division multiplexing

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Now showing 1 - 4 of 4
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    Autoencoder-based enhanced joint delay-Doppler index modulation for OTFS modulation
    (Institute of Electrical and Electronics Engineers Inc., 2024) Department of Electrical and Electronics Engineering; Tek, Yusuf İslam; Başar, Ertuğrul; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering
    Orthogonal time frequency space (OTFS) provides highly effective performance in channels that exhibit both time and frequency variability. OTFS can fully leverage channel diversity by multiplexing data symbols on the whole delay-Doppler domain. However, improving the reliability of OTFS systems is essential to meet the rigid requirements of next-generation communication technologies. Addressing these challenges, we introduce a novel approach named autoencoder (AE)based enhanced joint delay-Doppler index modulation OTFS (AEE-JDDIM-OTFS). This strategy selectively activates either delay or Doppler resource bins within a subframe, utilizing multidimensional symbol vectors created by the AE to boost error performance. The capability of AE to generate symbols with increased squared minimum Euclidean distance (SMED) plays a crucial role in this enhancement. Computer simulation outcomes confirm that AEE-JDDIM-OTFS surpasses traditional OTFS and other comparative schemes in bit error rate performance. © 2024 IEEE.
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    Capacity analysis for joint radar-communication capable coherent MIMO radars
    (Elsevier, 2020) Department of Electrical and Electronics Engineering; Arık, Muharrem; Akan, Özgür Barış; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering
    Recently, huge attention is attracted to the concept of integrating communication and radar missions within the same platform. Joint Radar-Communications (JRC) system gives an important opportunity to reduce spectrum usage and product cost while doing concurrent operation, as target sensing via radar processing and establishing communication links. A JRC-capable coherent MIMO radar system have been proposed recently in the literature. Several methods are introduced to reach dual goal as a notable null level towards the direction of interest of the radar and MIMO radar waveform orthogonality. Due to the limitations originated form the JRC operation, communication channel may encounter unwanted amplitude variations. This unwanted modulation normally affects the communication performance by its nature, due to the fades on radiated signal amplitude towards the direction of communication. However, the effect of this unintentional modulation on communication channel is yet to be investigated. In this paper, the communication channel for JRC capable phase-coded coherent MIMO radars is analyzed and investigated under additive white Gaussian noise and Rayleigh/Rician fading conditions. Communication capacity is evaluated for each channel condition. The results reveal that, using the single-side limited null direction fixed waveform generation method displays the best capacity performance under all channel conditions.
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    Index modulation: from waveform design to reconfigurable intelligent surfaces
    (Springer Science and Business Media Deutschland Gmbh, 2024) Wen, Miaowen; Department of Electrical and Electronics Engineering; Doğukan, Ali Tuğberk; Başar, Ertuğrul; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering
    While the first 5G-Advanced standard is being developed step by step with certain advancements, wireless researchers have already begun exploring radical communication paradigms toward 6G wireless networks of 2030 and beyond. Within this context, index modulation (IM) technologies might provide spectrum- and energy-efficient solutions by utilizing the promising concept of indexing transmit entities. © 2024, The Author(s), under exclusive license to Springer Nature Switzerland AG.
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    PAPR reduction precoding for orthogonal time frequency space modulation
    (Institute of Electrical and Electronics Engineers Inc., 2023) Department of Electrical and Electronics Engineering; Tek, Yusuf İslam; Başar, Ertuğrul; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering
    Orthogonal time frequency space (OTFS) modulation is a promising technique for efficient data transmission in wireless communication systems, particularly in high-mobility scenarios. However, as in other multicarrier schemes, OTFS has one major drawback, high peak-to-average power ratio (PAPR), which can lead to signal distortion and performance degradation. There are various techniques to reduce the PAPR for multicarrier systems. One of these techniques is precoding. In multicarrier systems, precoders such as the Zadoff-Chu transform (ZCT), Walsh-Hadamard transform (WHT), and discrete cosine transform (DCT) were used for PAPR reduction. However, the effect of these precoders on OTFS has not been investigated yet for PAPR reduction. In this work, we propose these precoders to reduce the high PAPR of OTFS modulation. Computer simulation results show that using these transforms as precoder in OTFS leads to significant PAPR reduction with a small error performance compromise. © 2023 IEEE.