Patent ID: 8520611

Claim:
A communication system, comprising: a mobile station; and a base station comprising a resource allocator that allocates first control information to be transmitted to the mobile station to a unit resource in a first control channel for a basic resource unit, where M unit resources, M being an integer equal to or greater than two, in the first control channel through which the base station transmits the first control information to the mobile station, are defined as a basic resource, the basic resource being a unit for associating the first control information with a resource in a second control channel through which the mobile station transmits second control information to the base station, and a first control information transmitter that transmits said allocated first control information to the mobile station, wherein information on an association relationship between the first control information and an index of the resource in the second control channel is shared between the base station and the mobile station in advance, the information on the association relationship being obtained based on an index of the unit resource to which the first control information has been allocated and the number of M unit resources constituting the basic resource, the mobile station comprising a second control information transmitter that receives said first control information, obtains the index of the resource in the second control channel associated with the first control information from the information on the association relationship shared in advance, obtains the index of the unit resource to which the received first control information has been allocated, and transmits said second control information using the resource with the obtained index in the second control channel.