WIRELESS COMMUNICATION SYSTEM, BASE STATION APPARATUS, MOBILE STATION APPARATUS, AND WIRELESS COMMUNICATION METHOD

摘要

A mobile station device (1) determines an uplink carrier component to which a physical downlink control channel through which the start of random access processing is ordered corresponds. Provided is a radio communication system in which a base station device (3) and a mobile station device (1) communicate with each other using a plurality of component carriers, wherein the base station device (3) is provided with a random access control unit (1012) that previously assigns a random access resource corresponding to a specific downlink component carrier by which the mobile station device (1) can start random access communication, and a transmission processing unit (111) that transmits control information indicating the start of the random access processing, and the mobile station device (1) is provided with a random access processing unit (2012) that starts the random access processing using the random access resource corresponding to the specific downlink component carrier, which is previously assigned by the base station device (3) when receiving the control information indicating the start of the random access processing.