Patent ID: 7054397

Claim:
A mobile communication system comprising a plurality of mobile stations and a base station, said base station comprising a plurality of antennas, a frequency shift portion, a combining portion, a receiving portion and a signal processing portion, wherein: each antenna receives radio waves transmitted by the mobile stations; the frequency shift portion shifts the received signals with a frequency corresponding to each of the antennas; the combining portion combines the signal, which is shifted in frequency, as a combining signal; the receiving portion converts the combining signal in frequency to make an intermediate frequency signal, and converts the intermediate frequency signal into a digital signal; and the signal processing portion comprises: spreading demodulation means which demodulates the digital signal with spreading by the use of a spreading code that is compensated frequency shift component corresponding to each of the antennas and which makes a demodulation signal at every antenna; judging means which specifies an arrival direction of each of the radio waves of the mobile stations on the basis of the demodulation signal and which produces the demodulation signal for each of the mobile stations; and fading compensation means which performs a RAKE combination from the demodulation signal for each of the mobile stations, wherein: the frequency shift portion comprises a plurality of amplifiers corresponding to the antennas, a plurality of mixers, and a plurality of oscillators; each amplifier amplifies a signal received at every antenna; each oscillator oscillates a frequency predetermined on the basis of a value corresponding to each of the antennas; and each mixer frequency-shifts the amplified signal with the oscillating signal.