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Iterative based ML demodulation method for OFDM signal under higher mobile environments
(2015-07-01)
Reangsuntea, Pongsathorn
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Hourai, Mio
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Mori, Kazuo
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Boonsrimuang, Pisit
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Kobayashi, Hideo
Orthogonal Frequency Division Multiplexing (OFDM) signal would be damaged significantly by inter- carrier interference (ICI) in higher time-varying fading channels which leads fatal degradation of bit error rate (BER) performance due to the loss of orthogonality among subcarriers. To solve this problem, this paper proposes an iterative based maximum likelihood demodulation (MLD) method which can achieve better BER performance with lower computation complexity even in higher time-varying fading channels. The features of proposed method are to employ a time domain training sequence (TS) in the estimation of channel impulse response (CIR) instead of using pilot subcarriers in the frequency domain and to employ a time domain equalization (TDE) method with a maximum likelihood (ML) estimation instead of using a conventional frequency domain equalization (FDE) method. This paper also proposes a low-complexity iterative method for solving the simultaneous equations in the MLD method instead of using an inverse matrix calculation. This paper presents various simulation results in higher time-varying fading channels to demonstrate the effectiveness of proposed method as comparing with the conventional frequency domain equalization method.
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Iterative based time domain equalization method for OFDM signal under high mobile environments
(2014-01-23)
Reangsuntea, Pongsathorn
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Mori, Kazuo
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Kobayashi, Hideo
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Boonsrimuang, Pisit
A loss of subcarrier orthogonality in orthogonal frequency division multiplexing (OFDM) signal due to time-varying multipath fading channel causes an inter-carrier interference (ICI) which would lead fatal degradation of bit error rate (BER) performance. To solve this problem, this paper proposes a high accuracy time domain channel impulse response (CIR) estimation method and a time domain equalization (TDE) method of using estimated CIR at every sampling time in conjunction with a low-complexity iterative method instead of using an inverse matrix calculation. The salient feature of proposed method is to employ a time-domain training sequence (TS) for the estimation of CIR at every sampling time and low-complexity iterative method for solving the simultaneous equations which are required in the TDE method. This paper presents various simulation results to demonstrate the effectiveness of proposed TDE method as comparing with the conventional frequency domain equalization (FDE) method.
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Proposal of channel estimation method for bi-directional OFDM based ANC in higher time-varying fading channel
(2014-01-01)
Mata, Tanairat
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Naito, Katsuhiro
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Mori, Kazuo
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Boonsrimuang, Pisit
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Kobayashi, Hideo
Broadband Analog Network Coding (ANC) based on OFDM has been widely investigated to increase capacity of bi-directional relay communications. The broadband ANC based on OFDM technique is required to estimate channel frequency responses (CFRs) between both user terminals (UTs) and a relay station (RS) precisely so as to remove the self-information data from the received signal and to demodulate the other user's information data with frequency equalization. Many channel estimation methods have been proposed for the OFDM based broadband ANC. However bit error rate (BER) performance of these methods would be degraded relatively in higher time- varying fading channels due to the inaccurate estimation of CFR. To solve this problem, this paper proposes a CFR estimation method which can achieve better BER performance with keeping higher transmission efficiency even in higher time-varying fading channels. The salient features of proposed CFR estimation method are to enable the estimation of combined CFR at the UT for both channels between the UTs and RS by using scattered pilot subcarriers and to enable the demodulation of information data without feedback information of CFR estimated at the RS. This paper presents various simulation results in the higher time-varying fading channels to demonstrate the effectiveness of proposed CFR estimation method for the bi-directional OFDM based ANC.
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Proposal of STBC MIMO-OFDM for ITS systems
(2013-09-02)
Mata, Tanairat
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Naito, Katsuhiro
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Boonsrimuang, Pisit
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Mori, Kazuo
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Kobayashi, Hideo
Orthogonal Frequency Division Multiplexing (OFDM) is a popular technique in the wireless communication systems which can achieve high transmission data rate with high signal quality even in the multipath fading channel which is a typical operation condition under wireless communication systems. MIMO (Multi Input-Multi Output)-OFDM is also considered as a promising technique for realizing the future ITS services. In this paper, we propose a new road to vehicle communication system (RVC) for the ITS by using the STBC MIMO-OFDM technique which can achieve a high transmission data rate with high signal quality even under the high mobile ITS environments. © 2013 IEEE.
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Proposal of PAPR reduction method for OFDM signal by re-ordering of clusters
(2013-01-01)
Mata, Tanairat
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Naito, Katsuhiro
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Mori, Kazuo
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Kobayashi, Hideo
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Boonsrimuang, Pisit
One of the major disadvantages of OFDM technique is the high PAPR in the time domain signal. The larger PAPR signal would cause the fatal degradation of BER performance and un-desirable spectrum regrowth in the nonlinear channel. One of the promising PAPR reduction methods is the Partial Transmit Sequence (PTS) method which can achieve better PAPR performance with reasonable computation complexity. But the PTS method is required to inform the side information to the receiver for the correct demodulation of data information by using the separate channel. To solve the above problem, this paper proposes a new PAPR reduction method without requiring the separate channel. The salient feature of the proposed method is to reduce the PAPR performance by reordering of clusters in the frequency domain at the transmitter and reconstructing the clusters by using the cluster ID under embedded in the data information at the receiver. The proposed method can achieve almost the same PAPR performance and computation complexity as those for the PTS method without requiring the transmission of side information. This paper presents various computer simulation results to verify the effectiveness of the proposed method. © 2013 IEEE.
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Proposal of new PAPR reduction method for OFDM signal by using permutation sequences
(2012-05-09)
Boonsrimuang, Pornpawit
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Limwattanachai, Kanchana
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Boonsrimuang, Pisit
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Kobayashi, Hideo
Many PAPR reduction techniques for OFDM signal have been proposed up to today, which can be classified into two major methods as the distortion and distortion-less methods. The most of distortion-less methods show better PAPR performance without degradation of BER performance. This paper proposes a novel distortion-less PAPR reduction method which employs the permutation sequence in the frequency domain with embedded side information. The feature of proposed method is to achieve the better PAPR performance with very few side information for the correct demodulation of data information at the receiver. This paper presents various computer simulation results to verify the effectiveness of proposed method as comparing with the conventional OFDM method in the non-linear channel. © 2012 GIRI.
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Peak-to-average power ratio reduction method for OFDM signal by using permutation sequences
(2011-12-01)
Boonsrimuang, Pornpawit
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Kobayashi, Hideo
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Limwattanachai, Kanchana
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Boonsrimuang, Pisit
Many PAPR reduction techniques for OFDM signal have been proposed up to today, which can be classified into two major methods as the distortion and distortion-less methods. The most of distortion-less methods show better PAPR performance without degradation of BER performance. This paper proposes a novel distortion-less PAPR reduction method which employs the permutation sequence in the frequency domain with embedded side information. The feature of proposed method is to achieve the better PAPR performance with very few side information for the correct demodulation of data information at the receiver. This paper presents various computer simulation results to verify the effectiveness of proposed method as comparing with the conventional OFDM method in the non-linear channel. © 2011 IEEE.
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Proposal of improved PTS method for STBC MIMO-OFDM systems
(2010-01-01)
Mata, Tanairat
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Boonsrimuang, Pornpawit
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Boonsrimuang, Pisit
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Kobayashi, Hideo
This paper proposes a new Partial Transmit Sequence (PTS) method in conjunction with the concurrent algorithm for Space Time Block Code Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing (STBC MIMO-OFDM) systems. The feature of proposed PTS method is that each cluster is divided into two parts and these two parts employ the different weighting factors to achieve the better Peak to Average Power Ratio (PAPR) with keeping the same size of side information and almost the same size of computational complexity as that for the conventional concurrent PTS method. Copyright © 2010 The Institute of Electronics, Information and Communication Engineers.
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A new weighting factor with concurrent PAPR reduction algorithm for STBC MIMO-OFDM
(2009-12-01)
Mata, Tanairat
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Boonsrimuang, Pornpawit
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Boonsrimuang, Pisit
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Kobayashi, Hideo
Partial Transmit Sequences (PTS) method seems to be attractive for the reduction of Peak to Average Power Ratio (PAPR) in the Orthogonal Frequency Division Multiplexing (OFDM) system, since it can obtain better PAPR property by modifying OFDM signals without any degradation of BER performance. Meanwhile it also shows the potential capability to be utilized in MIMO-OFDM system with a concurrent PAPR reduction algorithm based on the property of orthogonal Space-Time Block Coded (STBC)[1]. On the other hand, the PTS method can improve the PAPR reduction performance very well as increasing the number of weighting factors and clusters. However, the size of side information proportionally increases as increasing the number of weighting factors or/and clutters, which are required to the receiver for recovering the original data. In this paper, we propose a new determination method for the weighting factor of PTS in conjunction with the concurrent [2] algorithm for the STBC MIMO-OFDM systems, which can improve the PAPR performance, computation complexity without any increasing of side information, and improve the BER (Bit Error Rate) performance. ©2009 IEEE.
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Proposal of simple PAPR reduction method for OFDM signal by using dummy sub-carriers
(2008-01-01)
Boonsrimuang, Pisit
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Mori, Kazuo
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Paungma, Tawil
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Kobayashi, Hideo
One of the disadvantages of using OFDM is the larger peak to averaged power ratio (PAPR) in its time domain signal as compared with the conventional single carrier modulation method. The larger PAPR signal would course the fatal degradation of bit error rate (BER) performance due to the inter-modulation noise occurring in the non-linear amplifier. To overcome this problem, this paper proposes a simple PAPR reduction method by using dummy sub-carriers, which can achieve the better PAPR performance with less computational complexity than the conventional method. This paper presents various computer simulation results to verify the effectiveness of proposed method as comparing with the conventional method in the non-linear channel. Copyright © 2008 The Institute of Electronics, Information and Communication Engineers.

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