| Co-Investigator(Kenkyū-buntansha) |
MIYAMOTO Shinichi Osaka University, Faculty of Engineering, Assistant Professor, 工学部, 助手 (50252614)
HARA Shinsuke Osaka University, Faculty of Engineering, Assistant Professor, 工学部, 助手 (80228618)
SAMPEI Seiichi Osaka University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (50252599)
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| Research Abstract |
This project targets the development of key technologies for the adaptive modulation systems as well as to study its applications to some practical wireless multimedia communication systems. In the adaptive modulation systems, modulation parameters, such as the modulatio scheme and sysmbol rate are controlled according to the propagation path conditions. Therefere, key for the adaptive modulation system is how to precisely estimate channel conditions for the transmitted signals under time varying propagation path conditions.
In 1995 fiscal year, we have developed key techniques necessary for the adaptive modulation system, such as the channel condition monitoring techniques and confirmed that modulation parameter control according to theestimated channel condition and modulation parameter estimation on the burst by burst basis are feasible with high accuracy. Moreover, it is confirmed that the adaptive modulation modem is feasible with relatively a simple hardware.
In 1996 fiscal year, we have conducted computer simulation of the adaptive modulation modem and confirmed that the adaptive modulation is very effective in achieving higher quality and higher bit rate transmission than the conventional QPSK systems, especially unde frequency selective fading conditions. Moreover, we have studied its applications to the practical wireless multimedia comunication systems, such as the circuit switching system and packet switching systems. As a result of computer simulation, system capacity for the adaptive modulation system was confirmed to be 3.5 times higher than the conventional QPSK systems. In the case of packet wsitching systems, throughput performance improvement due to the adaptive modulation technique was confirmed to be two times higher than the conventional QPSK systems.
With these results, we have concluded that the developed adaptive modulation techniques are very effective in achieving flexible and reliable future wireless multimedia communication systems.
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