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[Author] Takahiro FUJITA(3hit)

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  • Online Combinatorial Optimization with Multiple Projections and Its Application to Scheduling Problem

    Takahiro FUJITA  Kohei HATANO  Shuji KIJIMA  Eiji TAKIMOTO  

     
    PAPER

      Vol:
    E101-A No:9
      Page(s):
    1334-1343

    We consider combinatorial online prediction problems and propose a new construction method of efficient algorithms for the problems. One of the previous approaches to the problem is to apply online prediction method, in which two external procedures the projection and the metarounding are assumed to be implemented. In this work, we generalize the projection to multiple projections. As an application of our framework, we show an algorithm for an online job scheduling problem with a single machine with precedence constraints.

  • An End-to-End Network Architecture for Supporting Mobility in Wide Area Wireless Networks

    Riaz INAYAT  Reiji AIBARA  Kouji NISHIMURA  Takahiro FUJITA  Kaori MAEDA  

     
    PAPER-Network

      Vol:
    E87-B No:6
      Page(s):
    1584-1593

    This paper presents a network architecture with a dual interface IP handoff technique that allows smooth node mobility without using any intermediate proxy. The proposed architecture is suitable for low bit-rate time sensitive real time applications, where payload tends to be short and packet header overhead is particularly significant. Connections are established as per permanent addresses of the nodes but are carried on by the IP layer according to the temporary addresses by address translation within the end hosts. The mapping information is maintained by database servers, which can be placed in the Internet in a distributed manner. We describe the architecture and show its mobile capabilities by prototype implementation and performance evaluation. Furthermore a dual-interface handoff suitable to the proposed architecture is also introduced. Preliminary results show that the proposed architecture has significantly low overheads. It is compatible with the existing infrastructure and works fine in both IPv4 and IPv6 environments. Analysis also shows that with dual-interface handoff it is possible to achieve seamless handoff without any packet loss by exploiting overlapping coverage area and speed of the mobile node. Handoff latency is reduced significantly as compare to MIPv6. We believe that with more powerful network interface card drivers our concept of dual interface handoff can be realized.

  • An Output Voltage Estimation and Regulation System Using Only the Primary-Side Electrical Parameters for Wireless Power Transfer Circuits

    Takahiro FUJITA  Kazuyuki WADA  Kawori SEKINE  

     
    PAPER

      Pubricized:
    2023/07/24
      Vol:
    E107-A No:1
      Page(s):
    16-24

    An output voltage estimation and regulation system for a wireless power transfer (WPT) circuit is proposed. Since the fluctuation of a coupling condition and/or a load may vary the voltage supplied with WPT resulting in a malfunction of wireless-powered devices, the output voltage regulation is needed. If the output voltage is regulated by a voltage regulator in a secondary side of the WPT circuit with fixed input power, the voltage regulator wastes the power to regulate the voltage. Therefore the output voltage regulation using a primary-side control, which adjusts the input power depending on the load and/or the coupling condition, is a promising approach for efficient regulation. In addition, it is desirable to eliminate feedback loop from the secondary side to the primary side from the viewpoint of reducing power dissipation and system complexity. The proposed system can estimate and regulate the output voltage independent of both the coupling and the load variation without the feedback loop. An usable range of the coupling coefficient and the load is improved compared to previous works. The validity of the proposed system is confirmed by the SPICE simulator.