Faculty Profiles - TOMISATO Shigeru

Papers - TOMISATO Shigeru

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An iterative peak power reduction method with adaptive intermediary over-sampling for wireless OFDMA systems Reviewed

Kazuhiko Fujimoto, Shigeru Tomisato, Masaharu Hata, and Hiromasa Fujii

電子情報通信学会論文誌EB E94-B ( 2 ) 576 - 579 2011.2

Experimental study of mobile propagation loss correction formula for a slope terrain area Reviewed

Takahiro Fujitani, Shigeru Tomisato, Masaharu Hata

IEEE Vehicular Technology Conference 2010

Authorship：Corresponding author Language：English Publishing type：Research paper (international conference proceedings)

Service area upgrading and expanding is expected in current and future cellular systems. Since residential areas on a hilly and/or slope terrain are spreading in the outskirts of cities in Japan, the correction for the urban mobile propagation loss formula becomes one of the important issues in radio link and cell layout designs in those areas, especially within 1km distance from a base station. This paper introduces an example of correction formula for the slope terrain area based on an experimental study of mobile path loss prediction. The result shows the path loss at the objective point can be estimated by the urban mobile path loss and the correction value according to the factor expressed by the elevation angle from the base station antenna top. Although the average slope angle is only used as a parameter in the conventional correction for the slope terrain area with at least 5 to 10km length, the result means it is not enough for the correction to the area within 1km distance from a base station. ©2010 IEEE.

DOI： 10.1109/VETECF.2010.5594354

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An Adaptive Soft Clipping Method for Spectrum Sharing OFDMA Systems Reviewed

Toshihisa Fujiwara, Shigeru Tomisato, Masaharu Hata, Hiromasa Fujii, Takahiro Asai, Yukihiko Okumura

2009 IEEE 20TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS 305 - 309 2009.9

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

This paper proposes an adaptive soft clipping method for spectrum sharing OFDMA systems. The proposed method controls in-band and out-of-band distortion power by changing the nonlinearity parameter of soft clipping. The simulation results show that the proposed method can control the distortion power by 10 dB for a practical power amplifier. The results also show that a low-peak OFDMA transmitter can be realize with reasonable computational complexity because iterative processing for peak power reduction is unnecessary.

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A clipping noise canceller for iterative clipping and filtering in wireless OFDMA systems with nonlinear distortion Reviewed

Yukari Mori, Shigeru Tomisato, Masaharu Hata, Hiromasa Fujii, Takahiro Asai, Yukihiko Okumura

2009.9

Experimental Study of BWA System Applied in an Intermediate and Mountainous Area Reviewed

Makoto Ono, Yukiji Mikamo, Keisuke Ohtou, Masaharu Hata, Shigeru Tomisato

TENCON 2009 - 2009 IEEE REGION 10 CONFERENCE, VOLS 1-4 1982 - + 2009.1

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

As one of the effective way to overcome the digital divide issue in the lightly populated area, the BWA (Broadband Wireless Access) system is expected and field trials have been conducted extensively in Japan. This paper introduces the results of BWA field experiments conducted in a typical intermediate and mountainous area in Japan. In the BWA network, WiMAX units are used as relay stations and R-LAN units are structuring the meshed network. The result shows that the study of effective frequency utilization is important to realize the multi-hop relaying. It is also suggested that the multiple channel transmission in the meshed network needs the topological node allocation study to reduce delay affects.

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Turbo receiver with SC/Simplified-MMSE (S-MMSE) type equalizer for MIMO channel signal transmission

Hiromasa Fujii, Shigeru Tomisato, Suda Hirohito

IEEE Vehicular Technology Conference 58 ( 1 ) 632 - 636 2003

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Institute of Electrical and Electronics Engineers Inc.

This paper proposes a novel turbo equalization method, called SC/Simplified-MMSE (S-MMSE), for multiple-input multiple-output (MIMO) channel signal transmission. Our method, which deals with residual inter sub stream interference as their average over a frame, achieves excellent error performance at small computational cost. We evaluate our method by link-level and system-level simulations. A complexity comparison is also presented.

DOI： 10.1109/vetecf.2003.1285094

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In-lab Real-time Experiment of Interference Canceller TCC Implemented with Field Programmable Gate Array Reviewed

MURATA Hidekazu, TSUKAMOTO Satoshi, TOMISATO Shigeru, MATSUMOTO Tadashi, YOSHIDA Susumu

The Transactions of the Institute of Electronics,Information and Communication Engineers B 84 ( 7 ) 1226 - 1232 2001.7

A space/time pre-equalization technique for down-link signal transmission in time-division-duplex (TDD) mobile multimedia communications

Shigeru Tomisato, Kazuhiko Fukawa, Tadashi Matsumoto

European Signal Processing Conference 1998- 1998

Language：English Publishing type：Research paper (international conference proceedings) Publisher：European Signal Processing Conference, EUSIPCO

This paper proposes a new spatial and temporal (S/T) pre-equalization technique for time-division-duplex (TDD) mobile multimedia communication systems. Base station (BS) employs an adaptive array antenna (AAA) and an adaptive decision feedback equalizer (DFE) for up-link signal reception. The weight vectors for the up-link AAA and DFE are also used for pre-equalization of signal to be transmitted. With the S/T pre-equalization at the transmitter, the needs for equalizers at mobile station (MS) can be eliminated. In order to evaluate performances of the proposed S/T pre-equalization scheme, this paper uses a detailed propagation model which looks into the mobile propagation mechanism more in detail than conventional multipath models. Performances of the proposed S/T pre-equalizer are then demonstrated through computer simulations. The results show that the proposed scheme is effective in reducing effects of both inter-symbol and cochannel interferences.

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Coherent hybrid DS-FFH CDMA with adaptive interference cancelling for cellular mobile communications

Shigeru Tomisato, Kazuhiko Fukawa, Hiroshi Suzuki

IEICE Transactions on Communications E77-B ( 5 ) 589 - 597 1994.5

Language：English Publishing type：Research paper (scientific journal) Publisher：Inst of Electronics, Inf & Commun Engineers of Japan

This paper proposes Coherent-HYBrid Direct-Sequence Fast-Frequency-Hopping (CHYB-DS-FFH) CDMA with Adaptive Interference Cancelling (AIC) for cellular mobile communications. The features of CHYB-DS-FFH are symbol-by-symbol frequency diversity and low chip-rate DS multiplexing
both of which are based on a coherent FFH modulation and demodulation scheme. The combination of coherent FFH, space diversity, and AIC is very effective for reducing the performance degradation due to interference. Computer simulations demonstrate BER performance of a 2 hop 500-kHz-interval frequency hopping system using (i) a linear canceller or (ii) a nonlinear canceller. Both systems employ the two branch space diversity reception of 10 kb/s QPSK with FFH over a 1 MHz system bandwidth. In quasi-static channels, the average BER performance is 10-2 with average Eb/No less than 8 dB. In dynamic fading channels under full interference conditions, CHYB-DS-FFH with the linear adaptive interference canceller realizes a BER of 10-2 at the average Eb/No of 15 dB with maximum Doppler frequency fD of 5 Hz, whereas CHYB-DS-FFH with the non-linear adaptive interference canceller achieves the same BER at the average Eb/No of 15 dB with fD equal to 30 Hz.

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