Wireless communications system, base station, and terminal

1. A wireless communications system configured to perform wireless communication by using a first band dedicated to the system and a second band, the system comprising:

a base station configured to

detect an available carrier wave of the second band, wherein the second band is shared by the wireless communication system and another wireless communication system with a different base station from the base station,

control a detection interval of the available carrier wave or a detection period of the available carrier wave; and continuously transmit downlink user data in the second band during at least a portion of a remaining period of a first unit period, wherein

the downlink user data is scheduled to have a data length equal to a length of the portion of the remaining period, when detecting the available carrier wave of the second band in the first unit period, and

transmit in a second unit period subsequent to the first unit period, a control signal that permits the terminal to transmit uplink data to the base station in the second band, the base station transmitting the control signal in the first band to the terminal so as to perform the uplink data transmission; and

the terminal configured to transmit the uplink data, based on the control signal transmitted by the base station.

2. A base station of a wireless communications system configured to perform wireless communication by using a first band dedicated to the system and a second band, the base station comprising:

a memory; and

a processor coupled to the memory, the processor configured to:

detect an available carrier wave of the second band, wherein the second band is shared by the wireless communication system and another wireless communication system with a different base station from the base station;

control a detection interval of the available carrier wave or a detection period of the available carrier wave; and

continuously transmit downlink data of the second band during at least a portion of a remaining period of a first unit period, when detecting the available carrier wave of the second band in the first unit period, wherein

the downlink data is scheduled to have a data length equal to a length of the portion of the remaining period; and transmit in a second unit period subsequent to the first unit period, a control signal that permits the terminal to transmit uplink data to the base station in the second band, the base station transmitting the control signal in the first band to the terminal so as to perform the uplink data transmission.

3. A terminal of a wireless communications system configured to perform wireless communication by using a first band dedicated to the system and a second band, the terminal comprising:

a memory; and

a processor coupled to the memory, the processor configured to:

receive in the first band from a base station, a control signal that permits the terminal to transmit uplink data to the base station in the second band, when detecting an available carrier wave of the second band in a first unit period, the base station continuously transmitting downlink user data in the second band in at least a portion of a remaining period of the first unit period and transmits the control signal in a second unit period subsequent to the first unit period in the first band to the terminal so as to perform the uplink data transmission, wherein

the second band is shared by the wireless communication system and another wireless communication system with a different base station from the base station, and

the downlink user data is scheduled to have a data length equal to a length of the portion of the remaining period, the base station controlling a detection interval of the available carrier wave or a detection period of the available carrier wave; and

transmit uplink data of the data transmission, based on the control signal received from the base station.

4. A wireless communications system configured to perform wireless communication by using a first band dedicated to the system and a second band, the system comprising:

a base station configured to perform, when detecting an available carrier wave of the second band in a first unit period, downlink user data transmission in the second band from the base station to a terminal in at least a portion of a period remaining of the first unit period and a second unit period subsequent to the first unit period, wherein

the second band is shared by the wireless communication system and another wireless communication system with a different base station from the base station, and

the downlink user data is scheduled to have a data length equal to a length of the portion of the remaining period, the base station transmitting in the second unit period, a control signal indicating the downlink user transmission in at least the portion of the period, the base station controlling a detection interval of the available carrier wave or a detection period of the available carrier wave; and

the terminal configured to transmit uplink data in the second unit period, based on the control signal transmitted from the base station in the second unit period.

5. A base station of a wireless communications system configured to perform wireless communication by using a first band dedicated to the system and a second band, the base station comprising:

a memory; and

a processor coupled to the memory, the processor configured to:

detect an available carrier wave of the second band;

control a detection interval of the available carrier wave or a detection period of the available carrier wave; and

perform downlink user data transmission in the second band from the base station to a terminal in at least a portion of a period remaining of a first unit period and a second unit period subsequent to the first unit period, wherein

the second band is shared by the wireless communication system and another wireless communication system with a different base station from the base station, and

the downlink user data is scheduled to have a data length equal to a length of the portion of the remaining period, when detecting the available carrier wave of the second band in the first unit period; and

transmit in the second unit period, a control signal indicating the uplink data transmission in at least the portion of the period and the second unit period.

6. A terminal of a wireless communications system configured to perform wireless communication by using a first band dedicated to the system and a second band, the terminal comprising:

a memory; and

a processor coupled to the memory, the processor configured to:

receive downlink user data in at least a portion of a period and a second unit period based on a control signal transmitted from a base station in the second unit period, wherein

the second band is shared by the wireless communication system and another wireless communication system with a different base station from the base station, and

the control signal is received from the base station that, when detecting an available carrier wave of the second band in a first unit period, performs uplink data transmission in the second band from the base station to the terminal in at least a portion of a period remaining of the first unit period, and

the downlink user data is scheduled to have a data length equal to a length of the portion of the remaining period and a second unit period subsequent to the first unit period and transmits in the second unit period, the control signal that permits the terminal to transmit uplink data to the base station indicating data transmission in the second band and the control signal indicating the signal transmission in at least the portion of the period and the second unit period, the base station controlling a detection interval of the available carrier wave or a detection period of the available carrier wave.