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Author: search.filters.author.Miyanaga, Y.Has files: No

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    New papr reduction in ofdm systems by hybrid algorithm of pts and appr methods
    (2009-12-01)
    Pradabpet, C.
    ;
    Yoshizawa, S.
    ;
    Miyanaga, Y.
    ;
    Dejhan, K.
    In this paper, we propose a new peak to average power ratio (PAPR) reduction technique by a hybrid algorithm based on a partial transmit sequence (PTS) and adaptive peak power reduction (APPR) methods. This technique is used in a system based on orthogonal frequency division multiplexing (OFDM OFDM has orthogonally modulated sub-carriers which unexpectedly give large PAPR and tends to reduce the power efficiency of a RF amplifier. To reduce PAPR, the sequence of input data is rearranged by PTS for the reduction of PAPR and then fed to APPR process in the proposed system. The APPR method controls the peak level of the modulation signal by an adaptive algorithm. It reduces modulation signals over a predefined range. A proposed reduction method consists of these two methods and realizes both advantages at the same time. In simulation results, the proposed method shows the improvement on PAPR, PSD, and also the high performance on bit error rate of an OFDM system.
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    Searching phase optimize in PTS-APPR method by GA for PAPR reduction in OFDM-WLAN systems
    (2009-11-12)
    Pradabpet, C.
    ;
    Yoshizawa, S.
    ;
    Miyanaga, Y.
    ;
    Dejhan, K.
    In this paper, we propose a new PAPR reduction using the hybrid of a partial transmit sequences (PTS) and an adaptive peak power reduction (APPR) methods with genetic algorithm (GA). These methods are used in an Orthogonal Frequency Division Multiplexing (OFDM) system. The OFDM employs orthogonal sub-carriers for data modulation. These sub-carriers unexpectedly present a large Peak to Average Power Ratio (PAPR) in some cases. In order to reduce PAPR, the sequence of input data is rearranged by PTS. The APPR method is also used to controls the peak level of modulation signals by an adaptive algorithm. A proposed reduction method consists of these two methods and realizes both advantages at the same time. In order to make the optimum condition on PTS for PAPR reduction, a quite large calculation cost must be demanded and thus it is impossible to obtain the optimum PTS. In the proposed method by using genetic algorithm, the total calculation cost becomes drastically reduced. The parameter for simulation used standard WLAN in IEEE 802.11a system. In simulation results, the proposed method shows the improvement on PAPR and also reveals the high performance on bit error rate (BER) of an OFDM system. © 2009 IEEE.
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    A new PAPR reduction in OFDM-WLAN systems by hybrid algorithm of PTS and APPR methods
    (2007-12-01)
    Pradabpet, C.
    ;
    Yoshizawa, S.
    ;
    Miyanaga, Y.
    ;
    Dejhan, K.
    In this paper, we propose a new PAPR reduction technique by a hybrid algorithm based on a partial transmit sequence (PTS) and adaptive peak power reduction (APPR) methods. This technique is used in a system based on Orthogonal Frequency Division Multiplexing (OFDM). OFDM has many orthogonally modulated subcarriers which unexpectedly give a large peak to average power ratio (PAPR) and tends to reduce the power efficiency of a RF amplifier. A sequence of input data is rearranged by PTS for the reduction of PAPR and then fed to APPR process in the proposed system. The APPR method controls the peak level of the modulation signal by an adaptive algorithm. It reduces modulation signals over a predefined range. A proposed reduction method consists of these two methods and realizes both advantages at the same time. In simulation results, the proposed method shows the improvement on PAPR and also the high performance on bit error rate performance of an OFDM system. ©2007 IEEE.
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    A GHz analog multiplier for UWB communications
    (2007-12-01)
    Hidayat, R.
    ;
    Dejhan, K.
    ;
    Moungnoul, P.
    ;
    Miyanaga, Y.
    A gigahertz wideband analog multiplier is proposed. The multiplier based on the MOS cascade operation circuit. The inputs are in voltage mode and become in current mode after multiplication. The result shows that the multiplier can be applied for UWB communications. The circuit is based on 0.18 μm CMOS technology simulated using HSPICE with level 49. ©2007 IEEE.
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    Automatic indexing system for atmospheric laser radar data
    (2002-01-01)
    Lerkvaranyu, S.
    ;
    Miyanaga, Y.
    ;
    Dejhan, K.
    ;
    Cheevasuvit, F.
    ;
    Mizutani, K.
    The purpose of this paper is to design a new method for an automatic indexing system with unsupervised conditions. In this paper, the method of a self-organizing clustering network is adopted. It is used to classify and index a large amount of real atmospheric laser radar data. Initially, the parameters of each cluster will start with random initial values and are adapted with the algorithm. In this paper, six groups are clustered from the given data. It is also shown that some of these indicate quite important atmospheric condition characteristics.