Patent ID: 8488534

Claim:
A base station used in a mobile communication system employing orthogonal frequency division multiplexing (OFDM) for downlink, comprising: a scheduler determining allocation of radio resources for each subframe such that one or more resource blocks are allocated to a selected one of user devices for communications; a control channel generating unit generating a control channel including common control information to be mapped to frequency components distributed across a system frequency band and specific control information to be mapped to the one or more resource blocks allocated to the selected one of the user devices; and a transmission signal generating unit generating a transmission signal by time-division-multiplexing the common control information and the specific control information according to scheduling information from the scheduler, wherein the common control information is transmitted every subframe as lower-layer control information and includes information units with a predetermined data size a number of which information units is less than or equal to a specified multiplicity, a format indicator representing one of preset options that indicates a number of symbols occupied by the common control information in a corresponding subframe, and information indicating a maximum number of the information units, the information indicating the maximum number of the information units being transmitted as a part of the common control information at a predetermined interval longer than or equal to one subframe.