Base station, terminal, and wireless communication system, for license assisted access

1. A base station that performs wireless communication with a terminal using a shared band, the base station comprising:

a controller configured to generate a request signal for requesting data transmission of the terminal in the shared band and specifying a first transmission timing of the terminal; and

a transmitter configured to transmit to the terminal the request signal, wherein,

the request signal includes information used for specifying a second transmission timing, which is a next transmission timing when the terminal does not perform data transmission at the first transmission timing, and which is specified by an offset from a reference timing,

the controller is further configured to allocate, as a data transmission period from the reference timing, first time units of a plurality of continuous time units, the plurality of continuous time units including a second time unit that is not allocated as a data transmission period,

the first transmission timing is specified as a timing at one of the first time units, and

the first time units do not include the second transmission timing.

2. The base station according to claim 1 , wherein the reference timing corresponds to the first transmission timing.

3. The base station according to claim 1 , wherein the request signal includes time limit information indicating a time limit allowed to postpone the data transmission of the terminal.

4. The base station according to claim 1 , wherein

the controller controls performing the wireless communication with the terminal using the shared band and a licensed band.

5. The base station according to claim 1 , the first time units are continuous time units.

6. The base station according to claim 1 , wherein the information corresponds to the number of the first time units.

7. The base station according to claim 1 , wherein a plurality of continuous time units include a third time unit that is not allocated as a data transmission period and that is immediately before the first time units, and the second time unit is immediately after the first time units, and

the offset from the reference timing to the second transmission timing corresponds to the number of all of the first time units between the third time unit and the second time unit.

8. The base station according to claim 1 , wherein the controller is further configured to receive data at the second transmission timing, when the transmitter of the base station transmits to the terminal a permission signal at or after the first transmission timing.

9. The base station according to claim 1 , wherein the second transmission timing corresponds to the second time unit and is not included in the first time units.

10. A terminal that performs wireless communication with a base station using a shared band, the terminal comprising:

a receiver configured to receive a request signal for requesting data transmission of the terminal in the shared band and specifying a first transmission timing;

a controller configured to determine whether the shared band is idle or busy; and

a transmitter configured to perform, when the controller determines that the shared band is idle before the first transmission timing, data transmission to the base station in the shared band, wherein

the request signal includes information used for specifying a second transmission timing, which is a next transmission timing when the terminal does not perform data transmission at the first transmission timing, and which is specified by an offset from a reference timing,

first time units of a plurality of continuous time units are allocated as a data transmission period, the plurality of continuous time units including a second time unit that is not allocated as a data transmission period,

the first transmission timing is specified as a timing at one of the first time units,

the first time units do not include the second transmission timing, and

the transmitter transmits data to the base station at the second transmission timing, when the controller determines that the shared band is idle before the second transmission timing specified by the information.

11. The terminal according to claim 10 , wherein the reference timing corresponds to the first transmission timing.

12. The terminal according to claim 10 , wherein the request signal includes time limit information indicating a time limit allowed to postpone the data transmission of the terminal.

13. The terminal according to claim 10 , wherein

the controller controls performing the wireless communication with the base station using the shared band and a licensed band.

14. A wireless communication system comprising a base station and a terminal, wherein the base station and the terminal perform wireless communication using a shared band, wherein

the base station includes:

a first controller configured to generate a request signal for requesting data transmission of the terminal in the shared band and specifying a first transmission timing of the terminal; and

a first transmitter configured to transmit to the terminal the request signal, wherein

the request signal includes information used for specifying a second transmission timing, which is a next transmission timing when the terminal does not perform data transmission at the first transmission timing, and which is specified by an offset from a reference timing,

the first controller is further configured to allocate, as a data transmission period, first time units of a plurality of continuous time units, the plurality of continuous time units including a second time unit that is not allocated as a data transmission period,

the first transmission timing is specified as a timing at one of the first time units, and

the first time units do not include the second transmission timing; and

the terminal includes:

a receiver configured to receive the request signal;

a second controller configures to determine whether the shared band is idle or busy; and

a second transmitter configures to perform, when the second controller determines that the shared band is idle before the first transmission timing, data transmission to the base station in the shared band, wherein

the second transmitter transmits data to the base station at the second transmission timing, when the second controller determines that the shared band is idle before the second transmission timing specified by the information.