To allow a plurality of base stations to earlier find out crosstalk of a control channel due to the effect of an obstacle where a control channel is set on a common control carrier.

A plurality of base stations 10-12 control communication respectively by a common control carrier to set communication for a plurality of mobile stations 101-121. Radio transmission reception sections 13, 14 alternately transmit/receive control and communication channels by the 4-channel multiplex TDMA/TDD system adopting the modulation demodulation system II/4-shift QPSK. A control section 18 senses a common control carrier for a prescribed period by a periodic scan program in a memory 21 to check crosstalk with a time slot of other base station and sets a control channel to an idle time slot on the occurrence of crosstalk. In comparison with a conventional system where a carrier is sensed when a station is open, the crosstalk of the control channel by a mobile body or the like is earlier found out. Furthermore, the same effect as reduction of a scan interval is obtained through time division scanning where a start time of periodic scanning by a plurality of base stations in the system is made different.