RADIO COMMUNICATION SYSTEM, BASE STATION APPARATUS, MOBILE STATION APPARATUS, RADIO COMMUNICATION METHOD, AND PROGRAM

摘要

A mobile station apparatus 2 is assigned multiple component carriers in an uplink and a downlink by a base station apparatus and communicates with the base station apparatus by using the component carriers. The mobile station apparatus 2 includes a downlink control channel detector 67 and a carrier component identifying unit 53a. The downlink control channel detector 67 detects a downlink control channel from multiple search spaces where to detect the downlink control channel. From the search space where the downlink control channel detected by the downlink control channel detector 67 is arranged, the carrier component identifying unit 53a identifies the component carriers controlled with downlink control information transmitted in the downlink control channel and addressed to the mobile station apparatus. This makes it possible to identify the component carrier controlled with the downlink control information (DCI) transmitted in the downlink control channel (PDCCH) without increasing the coding ratio of the downlink control channel (PDCCH).