We Claim:
1. A communication system comprising a base station device and a communication terminal device capable of radio communication with the base station device,
wherein the base station device communicates with the communication terminal device using a self-contained subframe, the self-contained subframe including a downlink signal to be transmitted from the base station device to the communication terminal device, and an uplink signal to be transmitted from the communication terminal device to the base station device in response to the downlink signal,
the uplink signal has a structure including an uplink control signal indicating information for controlling transmission of the uplink signal, and uplink user data to be transmitted before and after the uplink control signal, and
the base station device notifies the communication terminal device of the structure of the uplink signal.
2. The communication system according to claim 1,
wherein the base station device predetermines scheduling for retransmission to retransmit the downlink signal, before performing initial transmission of the downlink signal.
3. The communication system according to claim 1 or 2,
wherein the uplink signal includes an uplink sounding reference signal, and the base station device sets, as control information, a period with which the user equipment device transmits the uplink sounding reference signal, and transmits the downlink signal including the control information to the user equipment device.