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[Author] Seung-Sik CHOI(3hit)

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  • Capacity Estimation of Forward Link in CDMA Systems Supporting High Data-Rate Service

    Seung-Sik CHOI  Dong-Ho CHO  

     
    PAPER-Wireless Communication Technology

      Vol:
    E84-B No:8
      Page(s):
    2170-2177

    The capacity analysis of CDMA forward link is required to allocate high data-rate users. To solve this problem, we analyze the capacity of the CDMA forward link based on optimum power control. In a multi-cell environment, the intracell interference and intercell interference are derived. To show the capacity impact of high data-rate users, we introduce a location dependent factor, which is the ratio of intercell interference to intracell interference. Considering the location dependent factor, we propose a coordinated allocation scheme that can be used to allocate high data-rate users in sectorized cells. As a result, we show the capacity impact of high data-rate users according to location variations. The outage probability can be decreased when the coordinated allocation scheme is applied.

  • Performance Analysis of NAV Based Contention Window in IEEE 802.11 LAN

    Seung-Sik CHOI  

     
    LETTER-Mobile Information Network and Personal Communications

      Vol:
    E97-A No:1
      Page(s):
    436-439

    In IEEE 802.11 standard, the contention window (CW) sizes are not efficient because it does not consider the system load. There has been several mechanisms to achieve the maximum throughput by the optimal CW. But some parameters such as the number of stations and system utilization are difficult to measure in WLAN systems. To solve this problem, we use the network allocation vector (NAV) which represents the transmission of other stations. This parameter can be used to measure the system load. Thus, the CW sizes can be estimated by the system load. In this paper, we derive the analytical model for the optimal CW sizes and the maximum throughput using the NAV and show the relationships between the CW sizes, the throughput and the NAV.

  • An Enhanced Route Recovery Protocol for Mobile Ad Hoc Networks

    Sangkyung KIM  Noyeul PARK  Changhwa KIM  Seung-sik CHOI  

     
    LETTER-Network

      Vol:
    E91-B No:2
      Page(s):
    597-600

    In case of link failures, many ad hoc routing protocols recover a route by employing source-initiated route re-discovery, but this approach can degrade system performance. Some use localized route recovery, which may yield non-optimal paths. Our proposal provides a mechanism that can enhance the overall routing performance by initiating route recovery at the destination node. We elucidate the effects through simulations including comparisons with AODV and AODV with local repair.