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Yoshihiko KUWAHARA Yoshimitsu IKI Kazuo NAGAO Shuichi OBAYASHI Keishi MURAKAMI Akio SATO Shoichiro KAWAMURA Masaharu HATA
Multi-path propagation structure in the urban mobile communication environment of 25 GHz band has been measured by means of newly developed "multi-path propagation parameter measurement equipment," which is capable of estimating coupled DOA (Direction Of Arrival), TOA (Time Of Arrival) and relative field strength by super resolution techniques. Before measurement, basic performance of the equipment has been evaluated in the anechoic chamber in order to ascertain limitation on measurement. For practice and verification of outdoor propagation characteristics, basic data have been collected in a works where accurate buildings and road layout is known. Sub-sequently, data have been collected in the urban mobile communication environment and following characteristics have been confirmed. 1) DOA and TOA of wave reflected by the side of building almost follow the ray-trace. 2) Street trees make 25 GHz band wave attenuate. 3) There are such unusual cases that it is possible to communicate in spite of out of line-of-sight by multi-path propagation. 4) Narrow streets have very complicated propagation structures. Finally, technologies that should be developed for the high-speed digital mobile communication are proposed based on the measurement results.
Yasuo SUZUKI Tokihiko YOKOI Yoshimitsu IKI Eiji KAWAGUCHI Nobuo NAKAJIMA Koji ODA Ryoichi HIDAKA
In relation to the Software Defined Radio (SDR) concept, an experimental simulation system was developed. Likewise, verification tests were performed in order to validate the envisaged SDR certification processes including its development, certification, distribution, and software installation assuming the future possibility of exchanging the software in the field.
Tokihiko YOKOI Yoshimitsu IKI Jun HORIKOSHI Katsuji MIWA Yoshio KARASAWA Akira FUKUDA Jun-ichi TAKADA Yuichi KURODA Takayasu SHIOKAWA Yukitsuna FURUYA Shigenari SUZUKI Yasuhiro SENBA Yoshihide YAMADA Hiroshi HARADA Yasuo SUZUKI Kiyomichi ARAKI
It is expected that software receivers will be widely available for radio communication, broadcasting and radio monitoring applications because they are able to be equipped with multimode, multirate and multiband functions in a single hardware platform. This paper describes the basic techniques required for software receivers for both hardware and software. The evaluation items and methods were studied and some evaluations done with an experimental software receiver model fabricated for radio monitoring applications. Future concepts in radio communication, broadcasting and radio monitoring applications where software receivers are thought to be suitable, were studied, and problems for realization identified.