Patent ID: 8588828

Claim:
A mobile communication system configured to comprise a mobile terminal and a base station which performs radio communication with the mobile terminal, wherein the base station comprises: a first antenna including a first antenna element having a first polarization characteristic and a second antenna element having a second polarization characteristic orthogonal to the first polarization characteristic; a second antenna including a third antenna element having the first polarization characteristic and a fourth antenna element having the second polarization characteristic; first to fourth baseband signal converters which convert received signals received by the first to fourth antenna elements to baseband signals, respectively; a first antenna combining unit which weights the baseband signals converted by the first and second baseband signal converters by multiplying the baseband signals by first and second weight coefficients, respectively, and adds the weighted baseband signals to one another; a second antenna combining unit which weights the baseband signals converted by the third and fourth baseband signal converters by multiplying the baseband signals by the first and second weight coefficients, respectively, and adds the weighted baseband signals to one another; a third antenna combining unit which weights the baseband signals added by the first and second antenna combining units by multiplying the baseband signals by third and fourth weight coefficients, respectively, adds the weighted baseband signals to one another and outputs the result; a first signal processor which calculates, as the first and second weight coefficients, such first and second weight coefficients that the combined polarization of the received signals received by the antenna elements in the first and second antennas, respectively, are orthogonal to a polarization of an interfering signal existing in the same direction as a desired signal, by MMSE (Minimum Mean Square Error) using an already-known pilot signal, wherein the interference signal can be removed even if the interference signal exists in the same direction as a desired signal; and a second signal processor which calculates, as the third and fourth weight coefficients, such third and fourth weight coefficients that a null is formed in a direction different from the direction of the desired signal in directivity patterns of the first and second antennas and in which an interfering signal exists, by MMSE using an already-known pilot signal.