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[Author] Jong KIM(26hit)

21-26hit(26hit)

  • Energy-Aware Error Correction for QoS-Provisioning Real-Time Communications in Wireless Networks

    Kyong Hoon KIM  Wan Yeon LEE  Jong KIM  

     
    LETTER

      Vol:
    E91-A No:7
      Page(s):
    1682-1685

    A key issue in QoS-provisioning real-time wireless communications is to provide the QoS requirement with low energy consumption. In this paper, we propose an energy-efficient error correction scheme for real-time communications with QoS requirements in wireless networks. The QoS requirement of a message stream is modeled with (m, k) constraint, implying that at least m messages should be sent to a receiver during any window of k periods. The proposed scheme adaptively selects an error correcting code in an energy-efficient manner so that it maximizes the number of QoS provisionings per unit energy consumption.

  • Dynamic Two-Tier Cell Structure for Bandwidth Reservation of Handoffs in Cellular Networks

    Jae Keun PARK  Wan Yeon LEE  Sung Je HONG  Jong KIM  

     
    LETTER-Mobile Information Network

      Vol:
    E91-A No:10
      Page(s):
    3003-3005

    To satisfy both the bandwidth efficiency of low-speed mobile hosts (MHs) and seamless handoff of high-speed MHs in cellular networks, this paper proposes a reservation scheme which exploits a dynamic two-tier cell structure and the handoff probability. The dynamic two-tier cell structure determines the reservation and non-reservation zones according to the speed of MHs. The handoff probability is calculated using the moving speed and the direction of MHs.

  • Probabilistic Checkpointing

    Hyochang NAM  Jong KIM  Sung Je HONG  Sunggu LEE  

     
    PAPER-Fault Tolerance

      Vol:
    E85-D No:7
      Page(s):
    1093-1104

    For checkpointing to be practical, it has to introduce low overhead for the targeted application. As a means of reducing the overhead of checkpointing, this paper proposes a probabilistic checkpointing method, which uses block encoding to detect the modified memory area between two consecutive checkpoints. Since the proposed technique uses block encoding to detect the modified area, the possibility of aliasing exists in encoded words. However, this paper shows that the aliasing probability is near zero when an 8-byte encoded word is used. The performance of the proposed technique is analyzed and measured by using experiments. An analytic model which predicts the checkpointing overhead is first constructed. By using this model, the block size that produces the best performance for a given target program is estimated. In most cases, medium block sizes, i.e., 128 or 256 bytes, show the best performance. The proposed technique has also been implemented on Unix based systems, and its performance has been measured in real environments. According to the experimental results, the proposed technique reduces the overhead by 11.7% in the best case and increases the overhead by 0.5% in the worst case in comparison with page-based incremental checkpointing.

  • Hybrid Authentication and Key Distribution Scheme for Wireless Mobile Multi-Hop Networks

    Yong Lee   Goo-Yeon LEE  Hwa-Jong KIM  Choong-Kyo JEONG  

     
    LETTER-Network

      Vol:
    E92-B No:2
      Page(s):
    616-619

    In this letter, we propose a hybrid authentication algorithm to alleviate the latent security problems of mobile multi-hop networks. The proposed scheme uses centralized authentication when a node first joins the network, and uses distributed authentication for the hop-by-hop authentication among multi-hop nodes. We also analyze performance of the proposed scheme.

  • Efficient Compression Method for Cell Animation Video

    Byongseok MIN  Seungjong KIM  Mrinal MANDAL  Jechang JEONG  

     
    PAPER-Multimedia Systems for Communications" Multimedia Systems for Communications

      Vol:
    E88-B No:8
      Page(s):
    3443-3450

    Animation video is becoming very popular with the availability of low cost computing resources. The cell animation is a popular method, used for producing animation video. In order to efficiently encode these videos, conventional video codecs, such as AutoDesk Animation Pro FLC, Intel Indeo 5, and MPEG-4 can be used to achieve high compression. However, when cell animation videos are compressed at very low bit rate by these traditional codecs, objectionable artifacts, e.g., false color, blurred contours, and blocking artifact, are severely occurred. In this paper, we propose an efficient compression method for cell animation images. The proposed method employs hybrid coding scheme which includes intraframe and interframe coding modes. The intraframe mode consists of color quantization, adaptive differential pulse code modulation, forward classification, and Golomb-Rice coding. The interframe coding consists of block-based techniques and exploits the characteristics of motion. Simulation results show that the proposed method provides superior performance over AutoDesk Animation Pro FLC, MPEG-1, Intel Indeo 5, and MPEG-4 standards.

  • Crest Factor Reduction for Complex Multi-Carrier Signal Processing

    Young-Hwan YOU  Min-Goo KANG  Han-Jong KIM  Pan-Yuh JOO  Hyoung-Kyu SONG  

     
    LETTER-Digital Signal Processing

      Vol:
    E88-A No:1
      Page(s):
    378-380

    One of the main disadvantage of multi-carrier CDMA (MC-CDMA) signals is the high peak power of the transmitted signals which limits their applications. To account for this issue, we provide a simple signal processing for reducing the high crest factor (CF) of MC-CDMA signals. Using this modified MC-CDMA signal, the high CF due to Walsh spreading sequences can be mitigated without explicit side information and degradation in the detection performance.

21-26hit(26hit)

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