IEICE Communications Express
Online ISSN : 2187-0136
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Showing 1-5 articles out of 5 articles from the selected issue
  • Yu-Ming Huang, Chin-Huai Shih, Hsiang-Pang Li, Hsie-Chia Chang
    Type: LETTER
    2018 Volume 7 Issue 8 Pages 291-296
    Published: 2018
    Released: August 01, 2018
    [Advance publication] Released: May 17, 2018
    JOURNALS FREE ACCESS

    Cooperative constructions of polar codes suitable to multi-channels (parallel channels) is presented in this paper. The constructions consist of several polar codes as mother codes and re-polarization processes, which unify all mother codes into one scheme. Based on our approach, any arbitrary length can be achieved by adjusting the number of processes.

    Moreover, a cooperative decoding algorithm for the unified scheme, which decodes all mother codes in parallel and spreads the decoding results within each mother code from itself to the others, is provided as well. Simulation results show that the FER of the proposed length-compatible scheme even outperforms a conventional polar code with limited length and similar rate.

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  • Shigenori Kinjo, Shuichi Ohno
    Type: LETTER
    2018 Volume 7 Issue 8 Pages 297-302
    Published: 2018
    Released: August 01, 2018
    [Advance publication] Released: May 30, 2018
    JOURNALS FREE ACCESS

    In this study, a simple and high performance precoding scheme for downlink multi-user MIMO (DL MU-MIMO) systems is investigated. Sorted QR decomposition algorithm is adapted for zero-forcing (ZF) Tomlinson-Harashima precoding (THP) with user-stream permutation in order to select a permutation pattern which maximizes a sum-rate of the DL MU-MIMO system. In addition, allocating unequal number of bits to each user-stream improves the DL performance of the ZF-THP in the MU-MIMO scenario. Numerical results show that the proposed ZF-THP scheme outperforms a conventional MMSE-THP scheme.

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  • Isamu Shitara, Takefumi Hiraguri, Kazuto Yano, Naoto Egashira, Tomoaki ...
    Type: LETTER
    2018 Volume 7 Issue 8 Pages 303-308
    Published: 2018
    Released: August 01, 2018
    [Advance publication] Released: June 06, 2018
    JOURNALS FREE ACCESS

    Recently, with the widespread use of wireless local area network (WLAN), many access points (APs) and stations (STAs) of WLAN are densely employed. Since the dense deployment of APs causes an overlapping basic service set (OBSS) environment which results in increased interference, the area spectral efficiency decreases. In this paper, in order to improve the area spectral efficiency under OBSS environment, we proposed a transmission power control scheme using an indicator issued from a neighbor AP. If the AP knows that the channel occupancy rate (COR) of OBSS is increasing by reporting from associated STAs, it issues an indicator, and other AP hearing the indicator change their transmission power accordingly. We evaluate the performance of the proposed scheme by computer simulation with different AP separations. Simulation results show the proposed scheme achieves high area spectral efficiency.

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  • Kyota Hattori, Masahiro Nakagawa, Masaru Katayama, Jun-ichi Kani
    Type: LETTER
    2018 Volume 7 Issue 8 Pages 309-314
    Published: 2018
    Released: August 01, 2018
    [Advance publication] Released: June 08, 2018
    JOURNALS FREE ACCESS

    Network virtualization technology such as cloud edges (CEs) will contribute to the cost-effective construction of carrier networks while maintaining saving of hardware and bandwidth resources. In this letter, we propose a future metro network architecture based on Next-Generation Passive Optical Network Stage 2 technologies to support CEs. This makes it possible to reduce the number of transmitters and receivers for the accommodation of both user traffic and traffic between CEs cost-effectively by sharing burst-mode transmitters and burst-mode receivers between CEs. We execute the preliminary evaluation of network capital expenditure with the proposed method by numerical simulation.

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