To attain expansion of range by setting the delay time of a slot before or after the slot under communication over guard time when that slot is not used.

When communication is performed between a base station 10 and a terminal 13 in its ordinary area 11, the delay time is set corresponding to the distance but it is within the guard time as conventional techniques. When the terminal 13 tries to move out of the area 11 as shown by an arrow, in this case, the base station 10 monitors the condition of the slot before or after the slot for the communication of the terminal 13 and when that preceding or following slot is used, operation is performed as usual but when that preceding or following slot is not used, the setting value of delay time is set over the guard time so that communication can be continued.