A mobile station comprises a receiver and a processor. The receiver is configured to receive, from a base station, allocation information indicating one or a plurality of allocated resource block(s) of uplink which are consecutive in a frequency domain. The processor is configured to determine, based on the allocation information, one of the resources of downlink, to which an ACK or NACK signal is distributively mapped onto a plurality of resource elements in subcarrier groups. The subcarrier resources within subcarrier group are consecutive in frequency domain and nonconsecutive in the frequency domain among subcarrier groups.