Chamchoy, Monchai

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Chamchoy, Monchai
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monchai.ch@kmitl.ac.th

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    Characterization of in-home UWB channel with different antenna directivity
    (2004-12-01)
    Chamchoy, Monchai
    ;
    Promwong, Sathaporn
    ;
    Tangtisanon, Prakit
    ;
    Takada, Jun Ichi
    An ultra-wideband (OWE) channel characterization for a typical modern home environments is examined over a frequency range of 3 GHz to 11 GHz. A frequency domain based experiment combined with a dual polarization measurement procedure is performed for line-of-sight (LOS) and non line-of-sight (NLOS) environments. The double ridge horn antenna and the biconical antenna are used to investigate the dependence of the antenna directivity on the UWE channel. The characterization of the path loss exponent, n, and the time dispersion parameters such as the mean excess delay, τ̄, and the RMS delay spread, σ<inf>̄,</inf> are analyzed. Based on the experiment results, utilizing the high directivity antenna can reduce the effects of the multipath propagation on the UWE signal. © 2004IEEE.
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    Rayleigh performance of transmitter preceding based-multiuser detection for DS-CDMA over Rayleigh fading environments
    (2004-09-27)
    Changsuwan, Paitune
    ;
    Chamchoy, Monchai
    ;
    Rawiwan, Panarat
    ;
    Tangtisanon, Prakit
    This paper presents performance of joint transmitter preceding and multiuser detection at base station which improve the performance of DS/CDMA system. We considers a synchronous DS/CDMA system over Rayleigh fading environment, The transmitter preceding technique based on the channel decomposition is developed for several multiuser detection schemes (decorrelating, MMSE and parallel interference cancellation) which are employed to estimate the received signal. In addition, the performance of each multiuser detection is also presented to average bit error rate. Moreover, according to the result, it is found that the performance of the bit error rate and the near-far resistance are more effective than those of the receiver without the transmitter preceding technique. On the other hand, as the result, it is found that the performance of the bit error rate of the proposed system with diversity technique is more effective than those of the receiver without diversity combining.
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    Spatial correlation properties of multiantenna UWB systems for in-home scenarios
    (2004-12-01)
    Chamchoy, Monchai
    ;
    Promwong, Sathaporn
    ;
    Tangtisanon, Prakit
    ;
    Takada, Jun Ichi
    Ultra-wideband (UWB) communication has recently attracted great interest for short-range and high data rate wireless networks. Multi-antenna UWB transmissions, on the other hand, are considered as an effective technique to improve the link reliability and transmission rate. The bene. t of such systems can be drawn from the correlation independently. In this paper, the spatial correlation properties of the transmitter/receiver for the multiantenna UWB systems under line-of-sight (LOS) and non-line-of-sight (NLOS) conditions are presented. The synthesized antenna arrays are used to represent the multiple antennas at both ends. The correlation results show that the correlation decreases as the antenna separation distance increases for LOS scenario. In the case of NLOS environment, the correlation does not depend on such separation distance.