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[Author] Kojiro ARAKI(3hit)

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  • Fiber-Oriented Wireless Systems for Intelligent Networks

    Kojiro ARAKI  Hiroyuki OHTSUKA  

     
    INVITED PAPER

      Vol:
    E79-B No:3
      Page(s):
    222-229

    This paper overviews fiber-oriented wireless communication systems, particularly in the area of microcell systems. The benefits of fiber-oriented wireless systems are discussed focusing on an application board scheme to facilitate new service deployment in light of intelligent networks. Dynamic range improvement technologies to remove interference are highlighted. Overall system performance is calculated for an economical FP-LD. Furthermore, effective modem use and a potential diversity technique are introduced. This strategy will play a role in realizing flexible fiber-optic subscriber networks.

  • Theoretical Analysis of Synergistic Effects Using Space Diversity Reception and Adaptive Equalization in Digital Radio Systems

    Kojiro ARAKI  Shozo KOMAKI  

     
    PAPER-Radio Communication

      Vol:
    E79-B No:4
      Page(s):
    569-577

    The synergistic effects obtained by adopting both space diversity reception and adaptive equalization play a very important role in circuit outage reduction. This paper quantitatively analyzes these synergistic effects when dispersive and flat fading occur simultaneously. Analytical results show that the synergistic effects are of the same magnitude as the adaptive equalizer improvement factor when only dispersive fading causes outage. The synergistic effects gradually disappear when noise is the predominant cause of outage.

  • BER Performance of Optically Controlled MESFETs as Photodetectors

    Tatsuya SHIMIZU  Hiroyuki OHTSUKA  Kojiro ARAKI  

     
    PAPER-Optomicrowave Devices

      Vol:
    E79-C No:1
      Page(s):
    46-51

    This paper presents the performance of optically controlled MESFETs as photodetectors. The optical performance characteristics such as optic-to-electric responsivity, and BER for a π/4-QPSK signal are experimentally investigated. Measurements are performed by using MMIC compatible MESFETs. Experimental results are also evaluated in comparison with calculated PIN-PD limit. Optic-to-electric responsivity has high gain at lower received optical powers. It is shown experimentally that MESFET photodetectors improve the permissible optical power by 6 dB compared to the PIN-PD limit. Optically controlled MESFETs will provide a novel receivers for fiber-optic systems.