PURPOSE: To increase data collection efficiency at a base station by selecting either plural time not being superimposed based on the receiving time of a timing signal when the timing signal is received at a mobile station and transmitting data from a mobile station to the base station.

CONSTITUTION: When a press-to-talk switch 11 in the mobile station 1 is turned on and voice is inputted to a transmitter, a voice signal is added on a radio equipment 13 via a controller 12, and transmitted from an antenna 14. The signal is received at the base station 2 by a radio equipment 22 via an antenna 21, and voice output can be obtained from a speaker 24 via a controller 23. At this time, when a press-to-talk switch 25 is turned on and the voice is inputted to the transmitter, the voice signal is added on the radio equipment 22, and transmitted via the antenna 21. Then, at the mobile station 1, the signal is received from the antenna 14 as stated, and either the plural time not being superimposed is selected based on the receiving time of the timing signal, and the data is transmitted from the mobile station 1 to the base station 2.