PURPOSE: To attain high-speed digital signal transmission and to improve the transmission quality by using an asynchronous carrier having the same normal frequency in plural base stations and applying angular modulation to each carrier and transmitting the result with a digital base band signal of same information synchronizing the transmission timing and allowing a mobile station to apply diversity reception to transmitted radio wave.

CONSTITUTION: A carrier from carrier generators 13, 14 in base stations 11, 12 is subjected to angular modulation by the same digital base band signal at modulators 15, 16 and transmitted respectively from transmission antennas 17, 18. The digital base band signal is generated from a digital signal generator 19 in the base station 11, for example, and divided into two, the one is used as a modulation signal to the modulator 15 and the other is fed to the modulator 16 of the base station 12 through an inter-station transmission line 21 as a modulation signal. The radio waves transmitted from the transmission antennas 17, 18 pass through multiple transmission lines 23, 24 respectively signal and a mobile station 25 receives the transmitted radio wave in terms of diversity.