User apparatus, base station apparatus, and method in mobile communication system

A base station apparatus for receiving an uplink control signal from a user apparatus using a single carrier scheme, comprising:

• a transmission unit configured to transmit a downlink control signal and a downlink data signal;
• and
• a receiving unit configured to receive an uplink control signal including acknowledgement information indicating positive acknowledgement or negative acknowledgement for the downlink data signal,
• wherein, the receiving unit, in which a correspondence relationship that uniquely associates a resource of the downlink control signal with a resource to be used for the uplink control signal is defined, receives the uplink control signal in the resource that is specified according to the correspondence relationship based on a resource of the downlink control signal transmitted by the transmission unit, and
• wherein the receiving unit specifies a cyclic shift amount and a frequency band as the resource to be used for the uplink control signal, and receives the uplink control signal using the specified frequency band, the uplink control signal being generated by multiplying an orthogonal code sequence by the acknowledgment information, the orthogonal code sequence being cyclically rearranged with the specified cyclic shift amount.