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Subject: search.filters.subject.TS-OFDM

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    Time domain equalization method for TS-OFDM signal under higher mobile environments
    (2017-12-01)
    Reangsuntea, Pongsathorn
    ;
    Boonsrimuang, Pisit
    ;
    Mori, Kazuo
    ;
    Kobayashi, Hideo
    In higher time-varying fading channels, the signal quality of orthogonal frequency division multiplexing (OFDM) technique would be degraded relatively due to the occurrence of inter-carrier interference (ICI). To solve this problem, this paper firstly proposes a new design of time domain training sequence (TS) in the estimation of channel impulse response (CIR) for the TS-OFDM signal which can reduce the leakage of power spectrum density (PSD) at the outside of OFDM allocated frequency bandwidth with keeping higher CIR estimation accuracy. Secondly, this paper proposes a time domain equalization (TDE) method which can achieve better bit error rate (BER) performance with keeping lower computation complexity even in higher time-varying fading channels. The salient feature of the proposed TDE method is to employ a partial differentiation for the time domain CIR matrix for solving the maximum likelihood (ML) equation in which the time domain CIR matrix becomes a symmetric banded matrix. From this feature, a low-complexity parallel block inverse matrix algorithm can be employed in the calculation of inverse matrix in keeping the same accuracy as that of the direct inverse matrix calculation. This paper presents various computer simulation results to demonstrate the effectiveness of the proposed TDE method for the TS-OFDM signal as compared with conventional frequency domain equalization (FDE) methods under higher mobile environments.
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    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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    Low-complexity MMSE-FDE method for TS-OFDM signal under high mobile environments
    (2016-12-16)
    Reangsuntea, Pongsathorn
    ;
    Sanada, Kousuke
    ;
    Mori, Kazuo
    ;
    Kobayashi, Hideo
    ;
    Boonsrimuang, Pisit
    This paper proposes a minimum mean square error-frequency domain equalization (MMSE-FDE) method for training sequence inserted orthogonal frequency division multiplexing (TS-OFDM) signal under high mobile environments. The salient features of proposed method are to enable the acquisition of frequency diversity gain by using the enhanced CIR matrix and to enable the reduction of complexity by employing the fast algorithm for inverse matrix calculation. From the simulation results, this paper confirms that the proposed method can achieve better bit error rate (BER) performance than the conventional MMSE-FDE methods with keeping lower complexity.
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    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.