A radio resource control method of controlling a radio resource for transmitting user data by a mobile station via an uplink, including: sending, from a radio base station, a signal indicative of a reduction of a maximum allowable transmission rate of the user data signaled to the mobile station connected to the radio base station, to a radio network controller; and controlling, at the radio network controller, the radio resource based on the reported signal indicative of the reduction of the maximum allowable transmission rate.