Nippon Telegraph and Telephone Corporation

Takeshi Onizawa

Tetsu Sakata

Masahiro Morikura

Masato Mizoguchi

Tomoaki Kumagai

A coherent detection system for multicarrier modulation system capable of accurate channel estimation even in severe environment with high thermal noise and deep multipath fading, has been found with simple structure and small circuit size. The present coherent detection system comprises a channel estimation circuit ( ) for estimating a channel attenuation of a preamble part of each subcarriers, an adaptive filter ( ) for smoothing estimated channel attenuation among subcarriers, a divider ( ) for coherent detection of a data part by dividing a receive vector by smoothed estimated channel attenuation for each subcarriers, and a characteristic extraction circuit ( ) for extracting characteristic value of each subcarriers. The adaptive filter ( ) is controlled depending upon characteristic value of each subcarriers measured by the characteristic extraction circuit ( ). A characteristic value may be amplitude, phase rotation, vector difference, modulation system, of each subcarriers, and/or combination of those values.

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Kanagawa, Japan

Tetsu Sakata