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Dr. Yoshihisa Okumura (born 1926, in Isikawa Prefecture〔(【引用サイトリンク】title=NAE Website - Yoshihisa Okumura )〕) is a Japanese engineer, known for development of cellular telephone networks. His radio survey of signal strength as a function of distance as measured in drive tests in automobiles was critical to the system planning of mobile radio telephone systems. == Professional career == Okumura studied electrical engineering at the Kanazawa Institute of Technology from 1944 to 1947. Dr. Okumura began his professional career in 1950 with the Japanese National Telephone and Telegraph Corporation (NTT), where he collected radio propagation data in the 150 to 1920 MHz bands. These bands were later identified as appropriate for mobile phone systems (in no small part, because of the data collected by Okumura). Okumura's careful study in various topographical environments in metropolitan, suburban, rural and even mountainous regions at distances from 1 to 100 km was published in 1968.〔 Y. Okumura, ''Field strength and its variability in VHF and UHF land-mobile radio service'', Electrical Communication Laboratory, Vol 16, Number 9-10, 1968.〕 His 10-year survey included varying the height of the antennas from ground level to 10 meters which helps in planning radio coverage of mobile phone cell towers. Okumura's work was advanced in the International Radio Consultative Conference (CCIR) which recognized that this work was applicable to all countries contemplating mobile cellular phone systems. The curves he published have become known as the Okumura Model and were critical to identifying the 800 MHz band as an appropriate target for mobile phone operation. About 1970, Okumura was promoted to the directorship of the Mobile System Research Section of the Electrical Communication Laboratory (ECL) of NTT. His staff grew to about 20 individuals, who pioneered the early high capacity cellular phone systems. Okumura retired from the ECL in 1975 and joined Toshiba. In 1979 he became a professor in Kanazawa Institute of Technology, retiring in 2000 as professor emeritus. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Yoshihisa Okumura」の詳細全文を読む スポンサード リンク
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