A mobile station includes an identifier selection unit selecting one identifier among identifiers supplied in advance when the mobile station initiates communications and a connection request signal generation unit generating a connection request signal including the identifier. A radio access network apparatus includes a response signal generation unit, in response to the connection request from the mobile station, generating a response signal including an identifier assigned by a radio access network system and information indicative of an uplink radio resource assigned for the mobile station and a transmission unit transmitting the response signal to the mobile station transmitting the connection request.