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[Author] Duk-Kyu PARK(5hit)

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  • Performance Evaluation of Base Station Antenna Arrays Using Common Correlation Matrix for W-CDMA System under Multipath Fading Environment

    Duk-Kyu PARK  Yoshitaka HARA  Yukiyoshi KAMIO  

     
    PAPER

      Vol:
    E84-A No:12
      Page(s):
    3026-3034

    We analyzed the performance of adaptive array antennas with a RAKE receiver by employing a common correlation matrix of the sample matrix inversion (CCM-SMI) algorithm in a multipath Rayleigh fading environment for W-CDMA reverse link. A common correlation matrix is usually used to provide adaptive weights for multiple users and multiple delay paths and can be used in packet communications transmitted using frame units. The proposed CCM-SMI algorithm had a better BER and SINR for lower computational complexity compared with the conventional SMI algorithm, even when using a RAKE receiver in multipath Rayleigh fading environment.

  • A Dynamic Channel Assignment Strategy Using Information on Speed and Moving Direction for Micro Cellular Systems

    Kazunori OKADA  Duk-kyu PARK  Shigetoshi YOSHIMOTO  

     
    PAPER-Access, Network

      Vol:
    E79-B No:3
      Page(s):
    279-288

    The dynamic channel assignment (DCA) strategy proposed here uses information on the mobile station speed and direction of motion to reduce the number of forced call terminations and channel changes in micro cellular systems. This SMD (speed and moving direction) strategy is compared with the main DCA strategies by simulating a one-dimensional service area covering a road on which there are high-speed mobile stations (HSMSs) and low-speed mobile stations (LSMSs).The simulation results show that the SMD strategy has the best performance in terms of forced call termination and channel change. The performance difference between the SMD strategy and the other DCA strategies increases as cell size decreases and as HSMS speed increases. While the SMD strategy does not yield the best total call blocking rate, its total carried load is the best when cells are small and HSMS speed is high. Also, the SMD performance improves when the HSMS offered load is small and the LSMS offered load is large. Although the SMD strategy requires information on the speed and direction of each mobile station and it increases call blockings somewhat, it reduces the number of forced call terminations and channel changes considerably, which is important in micro cellular systems.

  • A Study on Distributed Control Dynamic Channel Assignment Strategies in Sector Cell Layout Systems

    Satoru FUKUMOTO  Kazunori OKADA  Duk-Kyu PARK  Shigetoshi YOSHIMOTO  Iwao SASASE  

     
    PAPER

      Vol:
    E79-A No:7
      Page(s):
    975-982

    In estimating the performances of Distributed control Dynamic Channel Assignment (DDCA) strategies in sector cell layout systems, we find that sector cell layout systems with DDCA achieved a large system capacity. Moreover, we also indicate the problem, which is the increase of occurrences of cochannel interference, raised by using DDCA in sector cell layout systems. The new channel assignment algorithm, which is called Channel Searching on Direction of Sector (CSDS), is proposed to cope with the problem. CSDS assigns nominal channels to each sector according to their direction so that the same frequency channel tends to be used in sectors having the same direction. We show, by simulations, that CSDS is an adequate algorithm for sector cell layout systems because it significantly improves performance on co-channel interference while only slightly decreasing system capacity.

  • Performance of Distributed Dynamic Channel Assignment in Cellular Systems

    Duk-Kyu PARK  Kazunori OKADA  

     
    PAPER

      Vol:
    E78-A No:7
      Page(s):
    838-844

    We compared--for the same propagation conditions and parameters--the performances of distributed dynamic channel assignment (DDCA) strategies and the performance of fixed channel assignment (FCA). This comparison quantitatively showed the effects of DDCA strategies in increasing spectrum efficiency. It also showed that using DDCA with transmitter power control (TPC) increases the system capacity to 3 4 times what it is with FCA and to 1.4 1.8 times what it is when using DDCA without TPC. We also evaluated the blocking rate and the interference probability for the inside of a cell and found that these are generally much higher close to the cell border than they are near the base station.

  • An Extended Pawula F-Function for MPSK Signal Vector Perturbed by Correlated Two-Dimensional Gaussian Noise

    Seungkeun PARK  Byeong-Gwon KANG  Duk-Kyu PARK  

     
    LETTER-Fundamental Theories for Communications

      Vol:
    E89-B No:11
      Page(s):
    3104-3107

    This letter presents an extended Pawula F-function for computing the error rate of generalized M-ary phase shift keying (MPSK) system in the presence of phase error, quadrature error, and I-Q gain mismatch over additive white Gaussian noise (AWGN) and fading channels. The extended Pawula F-function conditioned on an instantaneous fading carrier-to-noise ratio (CNR) is derived in the form of the Craig representation.