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Indexed at: search.filters.indexed.WoSSubject: search.filters.subject.Orthogonal frequency division multiplexing

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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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    PublicationOpen Access
    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.