Faculty Profiles - YAMAZATO Takaya

Papers - YAMAZATO Takaya

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Performance analysis of multiple-route packet combining scheme for real-time communications in wireless multihop networks Reviewed

Hirayama Y, Nakagawa N, Okada H, Yamazato T, Katayama M

2004 IEEE 15TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOLS 1-4, PROCEEDINGS page： 140 - 144 2004

SNIR Analysis of Asynchronous MC-CDMA System in Frequency Selective Fading Channel Reviewed Open Access

H. Takeuchi, T. Yamazato, H. Okada, M. Katayama

IEICE Transaction on Fundamentals Vol. J86-A ( 12 ) page： 1426-1430 2003.12

SNIR Analysis of Asynchronous MC-CDMA System in Frequency Selective Fading Channel Reviewed Open Access

H. Takeuchi, T. Yamazato, H. Okada, M. Katayama

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. J86-A ( 12 ) page： 1426-1430 2003.10

Language：Japanese Publishing type：Research paper (scientific journal)

This paper presents the signal to noise plus interference ratio(SNIR) analysis of the asynchronous Multicarrier (MC)-CDMA system with multipath fading channel. We derive the SNIR of the MC-CDMA system and compared with that of the DS-CDMA. We found that the SNIR of the MC-CDMA is equal to that of the band-limited DS-CDMA system under the same bandwidth and the same spreading factor.

Open Access

Reducing Peak Power of Coded OFDM Systems with Multiple Symbol Mapping Reviewed Open Access

M. Harada, T. Yamazato, H. Okada, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. J86-A ( 10 ) page： 1058-1067 2003.10

Language：Japanese Publishing type：Research paper (scientific journal)

In this paper, we propose a novel coding scheme to reduce a peak envelope power (PEP) of convolutionally coded orthogonal frequency devision multiplex (OFDM) signals. In this system, convolutionally coded bits are mapped into symbol sequence. The symbol sequence have multiple symbols which are adjusted so as to show low PEP. Also, applying a set partition to the symbol sequence enable to enlarge an Euclidean distance between each sequence. We evaluate the performance of proposed system under the effect of nonlinear amplifier.

Open Access

Reducing Peak Power of Coded OFDM Systems with Multiple Symbol Mapping Reviewed Open Access

M. Harada, T. Yamazato, H. Okada, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals Vol. J86-A ( 10 ) page： 1058-1067 2003.10

基地局ダイバシチを用いたTCPによる無線インターネット接続に関する一検討

内藤克浩, 岡田啓, 山里敬也, 片山正昭

電子情報通信学会ネットワークシステム研究会 Vol. 103 ( 204 ) page： 31 - 36 2003.7

Performance Improvement for Coded OFDM Systems with Adaptive Interleaving in Frequency Selective Fading Channel Reviewed

M. Harada, T. Yamazato, H. Okada, M. Katayama, A. Ogawa

IEICE Transaction on Fundamentals of Electronics, Communications and Computer Sciences Vol. E86-A ( 6 ) page： 1541-1549 2003.6

Language：English Publishing type：Research paper (scientific journal)

In an attempt to improve the performance under frequency selective fading environment, we develope in this paper an orthogonal frequency division multiplex (OFDM) system in which adaptive interleaving is applied. The adaptive interleaving is a method that assigns symbols adaptively to the subcarriers in order to cope with frequency selective fading based on a channel state information (CSI) sent back from the reception end. The concept of adaptive interleaving is to maximize a free Euclidean distance in the limited interleave size. In this paper, we extend the method by an introduction of bit interleaving and multiple trellis coded modulation (MTCM). MTCM assigns two or more symbols to one trellis branch and shows good performance in frequency selective fading. If we could assign those set of symbols with an aid of the adaptive interleaving, the performance improvement can be expected. Another improvement method considered in this paper is the use of bit interleaving. The bit interleaving techniques randomize the effect of channel more efficiently compared to the case of symbols interleaving. Thus the further performance improvement is expected. One draw back is that since the interleaving process is done in bit level, bit interleaving can not be applied to TCM nor MTCM. In this paper, we mainly focus on adaptive bit and symbol interleaving and discuss the performance from the point of interleaving effect, and the error correcting code (convolutional code and MTCM).

Performance improvement for coded OFDM systems with adaptive interleaving in frequency selective fading channel Reviewed

Harada M, Yamazato T, Okada H, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E86A ( 6 ) page： 1541 - 1549 2003.6

Performance Improvement for Coded OFDM Systems with Adaptive Interleaving in Frequency Selective Fading Channel Reviewed

Harada M.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Vol. E86-A ( 6 ) page： 1541 - 1549 2003.6

Performance Improvement for Coded OFDM Systems with Adaptive Interleaving in Frequency Selective Fading Channel Reviewed

M. Harada, T. Yamazato, H. Okada, M. Katayama, A. Ogawa

IEICE Transactions on Fundamentals Vol. E86-A ( 6 ) page： 1541-1549 - 1549 2003.6

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In an attempt to improve the performance under frequency selective fading environment, we develop in this paper an orthogonal frequency division multiplex (OFDM) system in which adaptive interleaving is applied. The adaptive interleaving is a method that assigns symbols adaptively to the subcarriers in order to cope with frequency selective fading based on a channel state information (CSI) sent back from the reception end. The concept of adaptive interleaving is to maximize a free Euclidean distance in the limited interleave size. In this paper, we extend the method by an introduction of bit interleaving and multiple trellis coded modulation (MTCM). MTCM assigns two or more symbols to one trellis branch and shows good performance in frequency selective fading. If we could assign those set of symbols with an aid of the adaptive interleaving, the performance improvement can be expected. Another improvement method considered in this paper is the use of bit interleaving. The bit interleaving techniques randomize the effect of channel more efficiently compared to the case of symbols interleaving. Thus the further performance improvement is expected. One draw back is that since the interleaving process is done in bit level, bit interleaving can not be applied to TCM nor MTCM. In this paper, we mainly focus on adaptive bit and symbol interleaving and discuss the performance from the point of interleaving effect, and the error correcting code (convolutional code and MTCM).

CiNii Research

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A study on linear filtering in frequency domain for DS-CDMA systems Reviewed

TAKEUCHI Hiroshi, YAMAZATO Takaya, OKADA Hiraku, KATAYAMA Masaaki

Proceedings of the IEICE General Conference Vol. 2003 page： 154 2003.3

A Study on Turbo Soft-Decision Decoding for Hard-Detected Optical Communication signals Reviewed

ZHENG Chen, YAMAZATO Takaya, OKADA Hikaru, KATAYAMA Masaaki, OGAWA Akira

IEICE Trans. Communication, B Vol. 86 ( 3 ) page： 1022 - 1030 2003.3

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

We propose a method to realize soft-derision decoding for hard-detected signals. In this paper, a novel concept is introduced as "error-deleeled reliability." The method is very useful for optical fiber communications (OFC) as hard detection is the only detection method for the OFC systems. We demonstrate our proposed method using the turbo code in which soft information is required for decoding. As a result, the simulation shows slight difference in the range of moderate to high signal-to-noise ratio between the proposed decoding scheme and the conventional turbo decoding scheme. Moreover, the bit error rate of If 10^<〜11> can be achieved by serial concatenation of a ReedSolomon code and a turbo code for Q-factor lower than 8.0dB with a bandwidth expansion ratio of 33.3%.

CiNii Research

A Study on Turbo Soft-Decision Decoding for Hard Detected Optical Communication Signals Reviewed

C. Zheng, T. Yamazato, H. Okada, M. Katayama, A. Ogawa

IEICE Transactions on Communications Vol. E86-B ( 3 ) page： 1022-1030 2003.3

Language：English Publishing type：Research paper (scientific journal)

We propose a method to realize soft-decision decoding for hard-detected signals. In this paper, a novel concept is introduced as error-detected reliability. The method is very useful for optical fiber communications (OFC) as hard detection is the only detection method for the OFC systems. We demonstrate our proposed method using the turbo code in which soft information is required for decoding. As a result, the simulation shows slight difference in the range of moderate to high signal-to-noise ratio between the proposed decoding scheme and the conventional turbo decoding scheme. Moreover, the bit error rate of 10-11 can be achieved by serial concatenation of a Reed-Solomon code and a turbo code for Q-factor lower than 8.0 dB with a bandwidth expansion ratio of 33.3%.

Noise analysis on wide-band PLC with high sampling rate and long observation time Reviewed

Y. Hirayama, H. Okada, T. Yamazato and M. Katayama

7th International Symposium on Power-Line Communications and Its Applications page： 142-147 2003.3

Language：English

This manuscript reports the results of the measurement of wide-band PLC noise with high speed (50MHz) sampling and long (10.4s) observation duration. The measured noise is divided in frequency, and stochastic properties of the noise waveforms in each frequency bands, such as autocorrelations, probability density functions, and correlation coefficients between noise waveforms of different frequency bands are discussed. Cyclostationary features of the noise in each band is confirmed. It is found that the amplitude distribution in each band is different, and that Gaussian noise model is not a good approximation in higher frequency bands.

Soft-Decision Decoding of Low-Density Parity-Check Codes for Hard-Detected Optical Communication Signals Reviewed

C. Zheng, T. Yamazato, H. Okada, M. Katayama, A. Ogawa

IEICE Transactions on Communications Vol. E86-B ( 3 ) page： 1132-1135 2003.3

Language：English Publishing type：Research paper (scientific journal)

A soft-decision decoding scheme of low-density parity-check codes (LDPC) is proposed for hard-detected signals of optical fiber communication (OFC) systems. Based on the error detection, the proposed scheme converts the received hard-decision into soft reliability for the input of the LDPC decoder, and soft-decision decoding is performed. Simulation results under OFC channels are shown and superior performance is obtained by using the proposed decoding scheme of the LDPC codes.

A Study on Turbo Soft-Decision Decoding for Hard Detected Optical Communication Signals Reviewed

C. Zheng, T. Yamazato, H. Okada, M. Katayama, A. Ogawa

IEICE Transactions on Communications Vol. E86-B ( 3 ) page： 1022-1030 - 1135 2003.3

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

A soft-derision decoding scheme of low-density parity-check codes (LDPC) is proposed for hard-detected signals of optical fiber communication (OFC) systems. Based on the error detection, the proposed scheme converts the received hard-decision into soft reliability for the input of the LDPC decoder, and soft-decision decoding is performed. Simulation results under OFC channels are shown and superior performance is obtained by using the proposed decoding scheme of the LDPC codes.

CiNii Research

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A study on turbo soft-decision decoding for hard-detected optical communication signals Reviewed

Zheng C, Yamazato T, Okada H, Katayama M, Ogawa A

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E86B ( 3 ) page： 1022 - 1030 2003.3

A study on turbo soft-decision decoding for hard-detected optical communication signals Reviewed

Zheng C., Yamazato T., Okada H., Katayama M., Ogawa A.

IEICE Transactions on Communications Vol. E86-B ( 3 ) page： 1022 - 1030 2003.3

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：IEICE Transactions on Communications

We propose a method to realize soft-decision decoding for hard-detected signals. In this paper, a novel concept is introduced as "error-detected reliability." The method is very useful for optical fiber communications (OFC) as hard detection is the only detection method for the OFC systems. We demonstrate our proposed method using the turbo code in which soft information is required for decoding. As a result, the simulation shows slight difference in the range of moderate to high signal-to-noise ratio between the proposed decoding scheme and the conventional turbo decoding scheme. Moreover, the bit error rate of 10-11 can be achieved by serial concatenation of a Reed-Solomon code and a turbo code for Q-factor lower than 8.0 dB with a bandwidth expansion ratio of 33.3%.

Scopus

Soft-decision decoding of low-density parity-check codes for hard-detected optical communication signals Reviewed

Zheng C, Yamazato T, Okada H, Katayama M, Ogawa A

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E86B ( 3 ) page： 1132 - 1135 2003.3

Soft-decision decoding of low-density parity-check codes for hard-detected optical communication signals Reviewed

Zheng C.

IEICE Transactions on Communications Vol. E86-B ( 3 ) page： 1132 - 1135 2003.3

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Papers - YAMAZATO Takaya