IEICE Communications Express
Online ISSN : 2187-0136
ISSN-L : 2187-0136
Volume 9 , Issue 4
Showing 1-5 articles out of 5 articles from the selected issue
  • Ayumu Nakayama, Manabu Hagiwara
    Type: LETTER
    2020 Volume 9 Issue 4 Pages 100-104
    Published: 2020
    Released: April 01, 2020
    [Advance publication] Released: January 22, 2020
    JOURNALS FREE ACCESS

    A quantum error-correcting code for single deletion errors is provided. To the authors’ best knowledge, this is the first code for deletion errors.

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  • Akira Naka
    Type: LETTER
    2020 Volume 9 Issue 4 Pages 105-110
    Published: 2020
    Released: April 01, 2020
    [Advance publication] Released: January 27, 2020
    JOURNALS FREE ACCESS

    We numerically evaluate Achievable Information Rate (AIR) and Bit Error Rate (BER) performances of Probabilistic Amplitude Shaping (PAS), eight-dimensional modulation with Bit-Interleaved Coded Modulation Iterative Detection (BICM-ID), and conventional two-dimensional 16QAM (Quadrature Amplitude Modulation) for future high-speed optical communication systems. We confirm that end-to-end BER performances of three modulation formats are almost identical at a same transmission rate when the error correction is used once, and the iterative detection makes the performance of eight-dimensional modulation format better. Further, we verify the BER error-free conditions can be estimated by Normalized General Mutual Information (NGMI) for each modulation format.

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  • Keisuke Fujita
    Type: LETTER
    2020 Volume 9 Issue 4 Pages 111-116
    Published: 2020
    Released: April 01, 2020
    [Advance publication] Released: January 30, 2020
    JOURNALS FREE ACCESS

    This letter presents an effective Q factor formula for self-resonant spherical surface antennas. The self-resonant lossless Q factor and radiation efficiency calculated using spherical wave expansion provide an approximated expression for the effective Q factor. The resultant effective Q factor is larger than that of the infinitesimal loop antenna and smaller than that of the infinitesimal dipole antenna. Comparison of the result with the Q factor of spherical helix antennas has shown good agreement. A simple estimation formula can help design a small spherical helix antenna.

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  • Ryota Mizutani, Yukiko Shimbo, Hirofumi Suganuma, Hiromichi Tomeba, Ta ...
    Type: LETTER
    2020 Volume 9 Issue 4 Pages 117-122
    Published: 2020
    Released: April 01, 2020
    [Advance publication] Released: February 07, 2020
    JOURNALS FREE ACCESS

    This letter investigates the theoretical system capacity of multi-user multiple-input multiple-output (MU-MIMO) orthogonal frequency division multiplexing (OFDM) Tomlinson-Harashima precoding (THP) in the presence of terminal mobility. Considering that MU-MIMO THP has been adopted for OFDM-based mobile broadband systems, analyzing the effects of time-selective fading and the modulo loss peculiar to THP on system capacity is essential. In this study, we theoretically derive both the multi-user interference (MUI) and inter-carrier interference (ICI) resulting from terminal mobility and incorporate these into the modulo loss analysis based on the mod-Λ channel. The theoretical results obtained by the proposed analysis are compared with those of linear precoding, which demonstrates the applicability of THP to OFDM-based mobile broadband systems.

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