It is an object of the present invention, in a mobile communication system using the Enhanced Uplink, to maximize a capacity of a radio resource for use in a circuit switching channel, and to provide a data communication as a best effort service using an available radio resource. The present invention includes, in the mobile communication system, a step of measuring an enhanced noise rise within a predetermined frequency bandwidth, a step of measuring a total interference noise rise within the predetermined frequency bandwidth, and a step of determining whether or not to set a new channel within the predetermined frequency bandwidth based on the enhanced noise rise and the total interference noise rise in response to a setup request for the new channel from a mobile station UE.