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    Item type:Publication,
    Transmit diversity for TS-OFDM signal in higher time-varying fading channels
    (2017-11-03)
    Danchai, Anusan
    ;
    Reangsuntea, Arttapol
    ;
    Boonsrimuang, Pisit
    ;
    Reangsuntea, Pongsathorn
    ;
    Mori, Kazuo
    This paper proposes a channel estimation and equalization methods for a transmit diversity system of using time domain training sequence inserted orthogonal frequency division multiplexing (TS-OFDM) signal in higher time-varying fading channels. The salient feature of the proposed channel impulse response (CIR) estimation method for the transmit diversity system with a space frequency block coding is to employ a new design of training sequence (TS) signal which can reduce the leakage of power spectrum density (PSD) and keep higher CIR estimation accuracy. In the proposed equalization method, the estimated CIR at every sampling time and the known TS signals are employed at the receiver for removing the inter-symbol interference (ISI) caused in higher time-varying fading channels so as to employ the overlap and add (OLA) operation. This paper presents various simulation results to demonstrate the effectiveness of the proposed transmit diversity system as comparing with the conventional methods.
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    Item type:Publication,
    Low-complexity FDE method for TS-OFDM signal under higher time-varying channels
    (2016-09-06)
    Reangsuntea, Pongsathorn
    ;
    Mori, Kazuo
    ;
    Kobayashi, Hideo
    ;
    Reangsuntea, Arttapol
    ;
    Boonsrimuang, Pisit
    A losing of orthogonality among subcarriers in higher time-varying fading channels causes an inter-carrier interference (ICI) in orthogonal frequency division multiplexing (OFDM) signal which leads a fatal degradation both for the channel estimation accuracy and bit error rate (BER) performances. To solve this problem, this paper firstly proposes a channel estimation method with a new design of time domain training sequence (TS) of using a triangular window function which can achieve higher channel estimation accuracy with keeping lower leakage of power spectrum density (PSD) at the outside of OFDM allocated frequency bandwidth than the conventional TS signal. Secondly, this paper proposes a low-complexity frequency domain equalization (FDE) method which can achieve better BER performance than the conventional one-tap FDE method. The feature of proposed FDE method is to enable the reduction of complexity by using a Maclaurin's expansion algorithm in the inverse matrix calculation. This paper presents various computer simulation results to demonstrate the effectiveness of proposed FDE method as comparing with the conventional FDE methods.