Papers - Kohiyama, Kenji

２５６ＱＡＭマイクロ波無線中継方式

KOHIYAMA KENJI

電子情報通信学会誌 73 ( 8 ) 845-856 1990.08

Research paper (scientific journal), Joint Work

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ＮＴＴが実用化した４・５・６ＧＨｚ帯マイクロ波ディジタル無線中継方式について，開発のねらい，方式概要，主要技術などを総合的に報告した。本方式は世界で最初に２５６ＱＡＭという超多値変調を採用し，１中継器で４００Ｍｂｉｔ／ｓの大容量伝送を行うもので，従来のアナログＦＭ通信を超える周波数利用効率が達成率が達成できた。

ディジタル無線方式のビット誤り率分布とエラ-セコンド特性

こひやま けんじ

電子通信学会論文誌 B 69 ( 12 ) 1776-1786 1986.12

Research paper (scientific journal), Joint Work

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マルチパス・フェージング時における１６値ＱＡＭディジタル無線方式のビット誤り率分布をエラー発生要因，受信条件，伝搬路種類別に明らかにした。つぎに，それらの分布に対してエラー発生をポアソン生起と仮定して６４ｋｂ／ｓ系におけるＥＳ（エラーセコンド）値を推定した。

64/256QAMディジタルマイクロ波伝送方式(技術展望)

KOHIYAMA KENJI

電子通信学会誌 68 ( 8 ) 889-895 1986.08

Research paper (scientific journal), Joint Work

２５６ＱＡＭディジタルマイクロ波方式　Ｉ　　実現性に関する基礎検討

KOHIYAMA KENJI

電子通信学会技術研究報告 84 ( 1 ) 73-80（CSB84-71） 1984

Research paper (scientific journal), Joint Work

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既設のマイクロ波ルートに導入する条件のもとで，２５６ＱＡＭ方式の実現性に関 して検討した。まず，周波数利用効率の観点から，多値ＱＡＭ変調方式が優れていることを述べた。次に，フェージング伝搬路における２５６ＱＡＭ方式のクロック速度の上限を求め，マルチキャリア方式が有効であることを示した

An experiment in integrated digital satellite communications

Watanabe-Y　Kohiyama-K　　Inoue-M　　Matsumoto-M　Takaki-I

IEEE-Journal-on-Selected-Areas-in-Communications. Vol.SAC-1, No.1   143-152 1983.01

Research paper (scientific journal), Joint Work

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The experiment the authors conducted for integrated digital satellite communications is aimed at realising integrated services digital networks by satellite communication. The experiment was carried out in 1980 using the Japanese experimental communication satellite 'CS'. This experiment uses 30/20 GHz small earth stations and demand-assignment time-division　multiple-access (TDMA) systems. Communications between customer terminals, which contain video conferencing, high-speed facsimile communication,high-speed computer communication, and packet-switching signal transmission, were carried out through the experimental digital satellite link. This paper describes the configuration of the experimental　integrated digital satellite communications system and the experimental results of communications between customer terminals.

Advanced high capacity domestic satellite communications system

Iso-A　　Kohiyama-K　Odate-H　　Ishida-N

Acta-Astronautica. 10 ( 1 ) 43-49 1983.01

Research paper (scientific journal), Joint Work

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Describes a concept of multibeam high capacity transmission possible with a 30/20 GHz and 50/40 GHz domestic satellite communication system. The relationship between satellite antenna pointing accuracy and　multi-satellite interference are looked at.

Demand-assigned TDMA system for a digitally integrated services network

Watanabe-Y　Samejima-S　Kato-S　Kohiyama-K

Journal-of-Spacecraft-and-Rockets. 18 ( 2 ) 133-137 1981.03

Joint Work

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The demand-assigned time division multiple access (DAK-TDMA) system has remarkable advantages with regard to effective utilization ofsatellite traffic channels and network flexibility. The DA-TDMA system is one of key　technological developments for application to integrated services　satellite digital networks (ISSDN) which transmit digitally integrated　information signals between Earth stations. The experimental DA-TDMA system designed for an ISSDN experiment hasa 20 Mbps bit rate and operates　in a fully variable demand-assignment mode. The ISSDN experiment using the　Japanese 30/20 GHz band 'CS' satellite, which is planned as the first　stage of ISSDN study in Japan, is scheduled to start in 1980. The outline　of the DA-TDMA system and the ISSDN experimental plan are presented.

Demand assignment TDMA system for the integrated digital

Watanabe-Y　Kato-S　Inoue-T　Kohiyama-K

Japan-Telecommunications-Review. 23 ( 1 ) 73-77 1981.01

Research paper (scientific journal), Joint Work

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The demand assignment time division multiple access (DA-TDMA) system has remarkable advantages with regard to effective utilization of　satellite traffic channels and network flexibility. The DA-TDMA system is one of several key technological developments for application to　integrated digital satellite communications, which transmit digitally　integrated information signals between earth stations. The experimental　DA-TDMA system designed for a integrated digital satellite communication　experiment has a 20 Mbps bit rate and operates in a fully variable demand　assignment mode. This paper describes an outline of the DA-TDMA system and　the experimental plan.

Effects of diffusion-induced strain and dislocation on phosphorus diffusion into silicon

Matsumoto-S　Aoki-Y　Kohiyama-K　Niimi-T

Journal-of-the-Electrochemical-Society. 125 ( 1 ) 1840-1845 1978.11

Research paper (scientific journal), Joint Work

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The diffusion-induced strain and dislocation effects on the diffusion of phosphorus into silicon have been investigated. When phosphorus is diffused singly, the diffusion coefficient of phosphorus increases considerably at high concentrations. While, when phosphorus and germanium are diffusion simultaneously, fewer dislocations areobserved and the　diffusion-induced strain is compensated. In strain-compensated diffusion, concentration profiles of phosphorus agree well with the theoretical curves (erfc). It is shown that the enhancement of the diffusion　coefficient of phosphorus at high concentrations is attributed to the diffusion-induced strain. Besides, dislocations retard the diffusion front by absorbing excess vacancies, showing the opposite effect of strain.

Atmospheric optical communication system

Kobayashi-T　Kohiyama-K　Nishino-K

IEEE-Transactions-on-Communications. Vol.COM-25,No.12'   1508-1511 1977.12

Research paper (scientific journal), Joint Work

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The prototype atmospheric optical communication system has been developed, and various field tests have been carried out in Tokyo andNiigata. The system with a laser diode can transmit a 4-MHz color television signal or 120 telephone channels. This paper gives an outline description of system design based on field test results.

Radio-relay system for simultaneous transmission of telephone and video signals

Nishino-K　Kohiyama-K　　Kobayashi-T

Japan-Telecommunications-Review. 19 ( 1 ) 36-42 1977.01

Research paper (scientific journal), Joint Work

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The radio-relay system for simultaneous transmission of telephone and video signals has been developed to transmit 4 MHz color videosignal and　multiplexed telephone signals simultaneously via existing FDM microwave　transmission systems to which some equipments are added. The addedequipment are the circuit-connecting equipment which combines with and　separates into the multiplexed telephone signals and color video signal,　and the system switching equipment. This system has been used as the transmission system of a video conference system which started operation　from May 1976, and the satisfactory result is obtained. The system is　expected to play an importantrole as the video transmission system of the　video conference system, because it can be realized economically and　briefly by carrying out a few changes on the existing microwave　transmission system in the 5 GHz SF-E1 system, the 6 GHz SF-U3 system, the　11 GHz SF-T5 system and others.

20 G-400 M digital radio-relay system repeater

Kohiyama-K　Horikawa-I　Mommma-K　Yamamoto-H　Morita-K

Review-of-the-Electrical-Communication-Laboratories. 24 ( 7-8 ) 552-572 1976.07

Research paper (scientific journal), Joint Work

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Describes construction and performance of a 400 Mb/s 4-phase　shiftkeying repeater operating in the 20 GHz band. The repeater consistsof all solid-state devices such as transistors and IC's. Gunn diodes are used　for a transmitter local oscillator, and IMPATT diodes for a receiver local oscillator. A PIN diode is adopted as a switching diode for a 20 GHz band　direct phase-modulator. The 4-phase coherent detection circuit design method is developed with an intermediate frequency of 1.7 GHz. Expected　overall repeater error rate characteristics were satisfied, and an　extremely stable repeater was realized with less than 4 dB of equivalent　C/N degradation over the -10 degrees C to 45 degrees C temperature range.

20G―400M方式用送受信装置(20G―400M準ミリ波ディジタル伝送方式特集)

KOHIYAMA KENJI

電気通信研究所研究実用化報告 24 ( 10 ) 2169-2205 1975.10

Research paper (scientific journal), Joint Work

400-Mb/s QPSK repeater for 20-GHz digital radio-relay system

Yamamoto-H Kohiyama-K Morita-K

IEEE-Transactions-on-Microwave-Theory-and-Techniques. Vol.MTT-23, No.4   334-341 1975.04

Research paper (scientific journal), Joint Work

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The repeater is totally solid state for miniaturisation, high reliability and economy with the adoption of microwave IC's, monolithicIC's, and direct oscillation by Gunn diodes in the 20-GHz band. Themodulation and demodulation techniques of the repeater employ　QPSK,which has a theoretical advantage over FSK, DPSK, or ASK in error　rate performance, considering spectrum utilisation. The error rate performance is further improved by using a simple digital equalisation for　intersymbol interference. The error rate performance of thissystem was　measured. From the test results, it became evident that the equivalent carrier-to-noise ratio (C/N) degradation of error rate performance at a　10/sup -6/ error rate was about 5 dB under fixed temperature conditions　and that the equivalent C/N degradation due to a -10 degrees C to +45　degrees C temperature variation was only 1 dB.

Dynamic characterization of band reflection type cavity stabilizedGunn oscillator

Kohiyama-K　Momma-K

Electronics-and-Communications-in-Japan. 57 ( 9 ) 70-78 1974.09

Research paper (scientific journal), Joint Work

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Operation of a band reflection type cavity stabilized Gunn oscillator　is analyzed by considering its dynamic characteristics. The properties of　convenient for measurement and its coupling with a band reflection type　frequency stabilizing circuit is discussed. Reduction of the output power as a result of frequency stabilization is studied and it is found that the　power dissipated by a matched load is small. FM noise is measured and Rieke diagrams are constructed,thus providing a frame of reference for the　design theory of this type of Gunn oscillator.

Construction and overall performance of experimental 20 GHz digital radio repeater

Yamamoto-H　Kohiyama-K

Review-of-the-Electrical-Communication-Laboratories. 22 ( 7-8 ) 571-578 1974.07

Research paper (scientific journal), Joint Work

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A repeater capable of transmitting a 400 Mb/s digital signal in the 20 GHz band is described. The repeater is equipped with transistors and IC　for receiver mixer, IF amplifier, demodulator, and carrier recovery　circuit. Gunn diodes are used for transmitter and receiver local　oscillator and transmission power amplifier. For effectiveuse of the radio　frequency, q.p.s.k. is adopted as multi-level modulation, and coherent　detection as demodulation. The required transmission band can be limited by compensating for the intersymbol interference. Overall error rate　characteristics of the experimental repeater almost attain the predetermined goal, and an extremely stable repeater is realized with an　error rate degradation of 1 dB underambient temperature variations between　-10 degrees and +45 degrees C.

Experimental 20 GHz digital radio-relay system transmitter design and characteristics

Kohiyama-K　Omori-H　Momma-K　Yamamoto-H

Review-of-the-Electrical-Communication-Laboratories. 22 ( 7-8 ) 579-581 1974.07

Research paper (scientific journal), Joint Work

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The transmitter consists mainly of a 20 GHz band direct 4 PSK　modulator including a pulse shaper and a pulse amplifier, a band reflection type transmitting local oscillator using a 20 GHz Gunn diode　and an injection locked amplifier. It also has an alarm signal detection　circuit, FM modulator for sending supervision and control signal, and DC current stabilized power supply sources. Output power is19.0 dBm or more, when the temperature variation is from -10 degrees to +45 degrees C, maximum modulation phase error is 5 degrees or less, transmitting frequency variation is within +or-3 MHz and output power variation is +1.0　approximately -1.5dB.

Error rate performance of 20 GHz digital radio repeaters

Yamamoto-H　Kohiyama-K　Horikawa-I

Electronics-and-Communications-in-Japan. 57 ( 4 ) 86-93 1974.04

Research paper (scientific journal), Joint Work

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The Electrical Communication Laboratory has completed the　construction of the 20-GHz digital radio repeater. This paper discusses　itserror rate performance. The discussion centres on various causes　oferror rate degradation. The theoretical results derived using approximated equations are verified by the experiment. Overall performance of the experimental repeater is evaluated and the effectiveness of the　method of evaluating the performance is confirmed.

A new type of highly frequency stabilized self-oscillating converter using transferred-electron diodes

Kohiyama-K　　Shiota-H

Proceedings-of-the-IEEE. 60 ( 6 ) 739-740 1972.06

Research paper (scientific journal), Joint Work

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A new type of highly frequency stabilized self-oscillating up-convertor using transferred-electron diodes is described. Experiments　were made under the following conditions. Self-oscillating frequency(local　frequency), signal frequency (IF), and output frequency were20.1 GHz, 1.5 GHz and 18.6 GHz, respectively. The best result achieved was a maximum　power output of +14 dBm, a 3-dB bandwidth of 1 GHz, and a self-oscillating frequency stability of 1.2*10/sup -6// degrees C.

A new type of frequency-stabilized Gunn oscillator

Kohiyama-K　Momma-K

Proceedings-of-the-IEEE. 59 ( 10 ) 1532-1533 1971.10

Research paper (scientific journal), Joint Work

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A new type of frequency-stabilization method, for a Gunn oscillator consisting of a high-Q single-tuned oscillator circuit is described. The frequency stability of this stabilized oscillator was 5*10/sup 5/ over a temperature change from -10 to 60 degrees at 20.970 GHz. This result satisfies the requirement for a 20-GHz radio relay system.