Mobile radio communication system having radio zones of sector configurations and antenna selecting method employed therein

摘要

A method of selecting sector antenna which is capable of reducing interference and improving the efficiency of utilization of frequencies is applied to a mobile radio communication system wherein a plurality of sector antennas whose half-power beam widths are different from basically used normal sector antennas are used so as to cover the same areas in an overlapping state. A radio base station located within a corresponding zone covers a plurality of sector cells using the sector antennas provided for each of the corresponding sector cells. Further, some of the radio base stations employ a way to cover partial area overlapping a normal sector cell with a narrow sector cell using a sector antenna whose half-power beam width is small. Each radio base station has a predetermined constant according to the half-power beam width. When a radio terminal requests a call origination, the corresponding radio base station selects an antenna whose sum of a received level of a signal sent from the radio terminal and the constant is largest among the assignable sector antennas.