Faculty Profiles - YAMAZATO Takaya

Papers - YAMAZATO Takaya

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Multi-antenna transmission scheme for convolutionally coded DS/CDMA system Reviewed

Ban K, Katayama M, Stark WE, Yamazato T, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E80A ( 12 ) page： 2437 - 2444 1997.12

A constant amplitude coding for orthogonal multi-code CDMA systems Reviewed

T Wada, T Yamazato, M Katayama, A Ogawa

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E80A ( 12 ) page： 2477 - 2484 1997.12

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

In this paper, we present orthogonal multi-code CDMA systems with the constant amplitude transmission. In general, the dynamic range of the amplitude of the transmitting signal is very large in the case of orthogonal multi-code CDMA systems. In order to realize the constant amplitude transmission for orthogonal multi-code CDMA systems, we propose a constant amplitude coding. First, we show the basic concept of the constant amplitude coding. And then, we show that the constant amplitude transmission can be realized by the combination of the conventional orthogonal multi-code CDMA and the constant amplitude coding. Finally, the effectiveness of the proposed method is evaluated in terms of the bit error rate performance and it is shown that the proposed method is robust to the non-linear distortion caused by a high power amplifier (HPA).

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A spread-spectrum system with dual processing gains designed for cyclic noise in power line communications Reviewed

H Niwa, O Oono, M Katayama, T Yamazato, A Ogawa, N Isaka

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E80A ( 12 ) page： 2526 - 2533 1997.12

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

We propose a spread-spectrum power line communication system considering the cyclic features of the noise in the lines. For this purpose, we model the noise as the sum of a time-invariant stationary process and two cyclostationary processes, i.e., cyclic continuous noise and cyclic impulsive noise. The proposed system employs two different countermeasures to each of these two classes of cyclic noise. For the cyclic continuous noise, it uses multiple-processing-gain spread spectrum technique: the smaller processing gains are assigned for the periods with lower instantaneous noise power and the larger ones for the periods of higher noise power, Considering the cyclic impulsive noise, convolutional coding with interleaving is applied. In order to analyze the performance improvement due to the employment of multiple processing gains, we introduce a simple model of the continuous noise. The overall performance is evaluated bu computer simulation with the actual noise wave-form measured in power lines.

Web of Science

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A simple transmit/receive antenna diversity for indoor DS/CDMA wireless communication systems Reviewed

K Ban, M Katayama, T Yamazato, A Ogawa

IEICE TRANSACTIONS ON COMMUNICATIONS Vol. E80B ( 12 ) page： 1790 - 1796 1997.12

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

This paper proposes a direct-sequence spread spectrum (DS/SS) communication system with a new diversity technique designed for indoor multi-path Fading channels where path diversity isn't available. In this system, the transmitter sends a same signal from multiple antennas at the same time with intentional time delays, which allows the receiver to distinguish and combine the signals from different antennas. We also consider the combination of this scheme with the conventional receiving antenna diversity for additional diversity gain. Furthermore, it is found that the use of the multiple transmitting antennas decreases the effect of the multiple access interference.

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An Initial Acquisition Method for M-ary Spread-Spectrum Signals Using Hadamard Code Sequences Reviewed

WADA Tadahiro, YAMAZATO Takaya, KATAYAMA Masaaki, OGAWA Akira

IEICE Trans. Fundamentals Vol. 80 ( 11 ) page： 2172 - 2179 1997.11

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

In this paper, we examine a new initial symbol acquisition method for M-ary spread-spectrum (M-ary/SS) signals that are affected by large carrier frequency offset. By the effect of the carrier frequency offset, preamble signal energy is dispersed to the undesired outputs. The proposed method is based on the collection of such dispersed signal energies by using reference patterns. The reference patterns are constructed by using the characteristic of Hadamard code sequences. The effectiveness of the proposed method is evaluated in terms of mean acquisition time.

CiNii Research

An initial acquisition method for M-ary spread-spectrum signals using Hadamard code sequences Reviewed

Wada T, Yamazato T, Katayama M, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E80A ( 11 ) page： 2172 - 2179 1997.11

An initial acquisition method for M-ary spread-spectrum signals using Hadamard code sequences Reviewed

T Wada, T Yamazato, M Katayama, A Ogawa

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E80A ( 11 ) page： 2172 - 2179 1997.11

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

Web of Science

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Performance Analysis of the CDMA Unslotted ALOHA Systems with Finite Population and Fixed Packet Length

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

1997 IEICE General Conference Vol. A-5-11 page： 112 1997.9

A Study on the Capacity of a Multi Processing-Gain SSMA System

L. Zhang, M. Katayama, T. Yamazato and A. Ogawa

Technical Report of IEICE Vol. SST97 ( 59 ) page： 19-24 1997.9

A study on the performance of CDMA ALOHA system under a cellular environment

Y. Asai, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST97 ( 57 ) page： 39275 1997.9

pi/2-shift BPSK - A modulation scheme robust to nonlinear amplification for CDMA mobile communications Reviewed

Kashyap K, Wada T, Katayama M, Yamazato T, Ogawa A

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES Vol. E80A ( 9 ) page： 1634 - 1639 1997.9

A Study on Wireless Transmission of MPEG Encoded Image Signals Using DS/SS Modulation

S. Makido, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. DSP97 ( 66 ) page： 37-42 1997.7

A Study on CDMA-Unslotted ALOHA with Data Packets Over CDMA Voice Signals

A. Sandouk, T. Sato, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SST97 ( 27 ) page： 43-48 1997.7

A Modeling of the Noise for Power Line Communication Systems

O. Ohno, M. Katayama, T. Yamazato, and A. Ogawa

Technical Report of IEICE Vol. DSP97 ( 61 ) page： 39275 1997.7

Prospective Performance of LEO Satellite Systems Employing Spread-Spectrum Techniques

A. Jamalipour, M. Katayama, T. Yamazato, and A. Ogawa

Technical Report of IEICE Vol. SST97 ( 18 ) page： 31-38 1997.6

Multi-Antenna Transmission Scheme for a Convolutionally Coded DS/CDMA System

K. Ban, M. Katayama, T. Yamazato, and A. Ogawa

Technical Report of IEICE Vol. SST97 ( 1 ) page： 39088 1997.6

A Study on Orthogonal Multi-Code CDMA Systems Using Constant Amplitude Coding

T. Wada, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. RCS97 ( 35 ) page： 19-24 1997.6

Influence of Multiple-Access Interference in a Multi Processing-Gain SSMA System

H. Hiraiwa, M. Katayama, T. Yamazato, and A. Ogawa

Technical Report of IEICE Vol. SST97 ( 2 ) page： 39275 1997.6

Simultaneous Acquisition of DS/SS Signals with Doppler Shift in Multi-LEO-Satellite Communication Systems

M. Ishizu, M. Katayama, T. Yamazato, and A. Ogawa

Technical Report of IEICE Vol. SANE97 ( 6 ) page： 35-40 1997.4

An Initial Acquisition Method for Observing Ecology of Sea Animals Using LEO Satellite

T. Tokuyasu, T. Yamazato, M. Katayama and A. Ogawa

Technical Report of IEICE Vol. SANE97 ( 8 ) page： 45-50 1997.4

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Papers - YAMAZATO Takaya