Author Search Result

[Author] Ken IGARASHI(4hit)

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  • Mobility-Aware TCP: Making Robust TCP against Segment Loss in Wireless Networks

    Ken IGARASHI  Masami YABUSAKI  

     
    PAPER

      Vol:
    E86-A No:7
      Page(s):
    1636-1644

    This paper proposes "Mobility-Aware TCP" to solve the problem that arises with New-Reno TCP if Post Registration Handover is used. In Mobility-Aware TCP, when the MT holds an unreturned ACK after handover, lost segments are retransmitted by Flow Control instead of Congestion Control. Therefore, the sender can retransmit segments without throttling the transmission rate. Moreover, if there is no ACK, the MT chooses retransmission schemes that can get higher throughput. Computer simulations compare Mobility-Aware TCP to New-Reno TCP with Post Registration Handover, and New-Reno TCP without Post Registration Handover. The simulations show that the proposal can maintain high throughput even in the face of high segment loss or long handover latency.

  • Care-of Prefix Routing for Moving Networks

    Toshihiro SUZUKI  Ken IGARASHI  Akira MIURA  Masami YABUSAKI  

     
    PAPER

      Vol:
    E88-B No:7
      Page(s):
    2756-2764

    In future, mobile terminals may be linked in various types of local network where the whole network is moving. Mobile networks will need to provide global connectivity to such moving networks and manage their mobility. A moving network consists of mobile terminals and a mobile router, which acts as the gateway to the mobile network. To manage the mobility of the moving network, it is important to minimize the packet overhead, to optimize routing, and to reduce the volume of handoff signals over the mobile network and air interface. This paper proposes a new routing mechanism using hierarchical mobile network prefix assignment, home agent concatenation, hierarchical address management, and hierarchical re-routing. In hierarchical mobile network prefix assignment, a mobile router is assigned a mobile network prefix, which is used as a prefix when allocating the location addresses of mobile terminals in the moving network, so allowing them to be managed in a hierarchical manner. Home agent concatenation limits the number of home agents which need to be updated during handoff by enabling one home agent hold information relating to others, while hierarchical address management minimizes the volume of handoff signals by managing the location addresses of all mobile terminals in a hierarchical manner. Hierarchical re-routing introduces a local anchor router in order to localize handoff and to optimize routing. Simulation results show that our proposed routing method is better than the conventional solutions in terms of efficiency of data transmission including data transmission delay, and handoff performance.

  • Handover with Proactive Anchor Router Relocation and Data Buffering

    Shin-ichi ISOBE  Atsushi IWASAKI  Ken IGARASHI  Masami YABUSAKI  

     
    PAPER-Mobility Management

      Vol:
    E87-B No:5
      Page(s):
    1193-1201

    This paper proposes "Handover with Proactive Anchor Router Relocation and Data Buffering" to suppress packet loss and packet miss-ordering during handover. To prevent packet miss-ordering, anchor router is proactively relocated to the optimal position before the mobile terminal performs handover. And, to eliminate packet loss during handover, anchor router buffers the packet only during handover. Moreover, anchor router assigns sequential numbers to the buffered packets to eliminate duplicate packet reception. Simulation results show that our proposal eliminates packet miss-ordering and duplicate reception while preventing packet loss.

  • Unicast Extension Multicast Protocol for Forwarding Entry Reduction and Source Mobility Support

    Ken IGARASHI  Harunobu FUKAZAWA  Masami YABUSAKI  

     
    PAPER-Mobility Management

      Vol:
    E87-B No:5
      Page(s):
    1202-1210

    IP multicast is seen as an efficient way of encouraging multimedia services such as Internet TV and Videoconferencing because it can deliver packets to multiple users while efficiently using network resources. Source Specific Multicast (SSM) is suggested as the IP multicast routing protocol and it can construct multicast trees efficiently. However it increases multicast forwarding table entries and fails to handle source mobility. This paper proposes the Unicast Extension Multicast Protocol (UMP) to solve these problems. In the protocol, only the routers that act as branching points keep multicast forwarding table entries, and packets are delivered between these routers using IP unicast. This prevents the multicast forwarding table entries from burdening other non-branch routers. Additionally, UMP supports source mobility by using the recursive join messages to prevent the creation of redundant paths while supporting source mobility.

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