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[Author] Chai-Keong TOH(4hit)

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  • GAHA and GAPA: Two Link-Level Approaches for Supporting Link Asymmetry in Mobile Ad Hoc Networks

    Dongkyun KIM  Chai-Keong TOH  Yanghee CHOI  

     
    PAPER-Terrestrial Radio Communications

      Vol:
    E86-B No:4
      Page(s):
    1297-1306

    Existing routing protocols for mobile ad hoc networks assume that all nodes have the same transmission range. In other words, the mobile ad hoc network has symmetric links, which means that two neighboring nodes A and B are within the transmission range of one another. However, since nodes consume battery power independently according to their computing and communication load, there exist asymmetric links, which means that node A is within node B's transmission range, but not vice versa. In this paper, two approaches are presented to support routing in the existence of asymmetric links: GAHA (GPS-based Hop-by-hop Acknowledgment) and GAPA (GPS-based Passive Acknowledgment) schemes. Both GAHA and GAPA can be applied to any routing protocols by utilizing GPS (Global Positioning System) location information. Simulation results reveal that both GAHA and GAPA protocols cope well in the presence of asymmetric wireless links and nodes' mobility.

  • Standardization Efforts & Future Research Issues for Wireless Sensors & Mobile Ad Hoc Networks

    Chai-Keong TOH  Petri MAHONEN  Mikko UUSITALO  

     
    INVITED PAPER

      Vol:
    E88-B No:9
      Page(s):
    3500-3507

    In this paper, we provide various perspectives related to wireless sensor and mobile ad hoc networking research. We reveal their commonalities and differences and suggest the need for participation from the computer science community, in addition to communications and protocols. In particular, we reveal the various issues that demand deeper investigation, collaborative research, and standardization. We introduced the aim, structure, objectives, and goals of the World Wireless Research Forum (WWRF) and highlight the activities conducted by the WWRF Working Group 3. Finally, we discuss the status of various standardization efforts and present new research issues and challenges.

  • Routing with Load-Balancing in Multi-Radio Wireless Mesh Networks

    Anh-Ngoc LE  Dong-Won KUM  You-Ze CHO  Chai-Keong TOH  

     
    PAPER

      Vol:
    E92-B No:3
      Page(s):
    700-708

    This paper addresses the interference and load imbalance problems in multi-radio infrastructure mesh networks where each mesh node is equipped with multiple radio interfaces and a subset of nodes serve as Internet gateways. To provide backbone support, it is necessary to reduce interference and balance load in Wireless Mesh Networks (WMNs). In this paper, we propose a new Load-Aware Routing Metric, called LARM, which captures the differences in transmission rates, packet loss ratio, intra/inter-flow interference and traffic load in multi-radio mesh networks. This metric is incorporated into the proposed load-balancing routing, called LBM, to provide load balancing for multi-radio mesh network. Simulation results show that LARM provides better performance compared to WCETT and hop-count routing metrics in LBM routing protocol.

  • FOREWORD

    Chai-Keong TOH  Kenichi MASE  Susumu YOSHIDA  

     
    FOREWORD

      Vol:
    E88-B No:9
      Page(s):
    3499-3499