To absorb jitters to transmit/receive data correctly.

When data is transmitted/ received wirelessly by frames for a predetermined length of period, a base station device 10, which allocates any one of multiple frame offsets to each communication channel and takes synchronization between a radio interface 50 and an ATM line 40 by using the multiple frame offsets resulting from sub-dividing the frame, allows cell jitter on the ATM line 40 for a period corresponding to predetermined units of a frame offset width. One frame offset can therefore be allocated to multiple communication channels, considering the attainable cell transmission bandwidth within the period corresponding to the tolerated jitter width so that fragment generation can be prevented.