A base station includes a transmitter configured to transmit a downlink controlling formation to a user equipment, the downlink control information being generated based on an uplink allocation information indicating a first frequency block corresponding to a first plurality of subcarriers which are contiguous in frequency and a second frequency block corresponding to a second plurality of subcarriers which are contiguous in frequency, wherein at least a subcarrier, which is not indicated by the uplink allocation information, is located between the first frequency block and the second frequency block; and a receiver configured to receive a reference signal including a reference signal sequence having a sequence length corresponding to a first bandwidth which is a summation of a second bandwidth of the first frequency block and a third bandwidth of the second frequency block.