Device and method

1. A base station, comprising:

circuitry configured to

dynamically change an uplink/downlink configuration of a time division duplex (TDD) carrier from one configuration among multiple configurations to another configuration among the multiple configurations; and

notify a terminal device of the changed uplink/downlink configuration and of an appropriate radio resource for device-to-device (D2D) communication for the changed uplink/downlink configuration, wherein

the changed uplink/downlink configuration includes at least a predetermined number of uplink subframes,

the circuitry notifies the terminal device of the appropriate radio resource for D2D communication for each of the multiple configurations,

the appropriate radio resource of a respective configuration includes at least one uplink subframe and a period, and

a number of uplink subframes included in the appropriate radio resource differs from a number of uplink subframes of the changed uplink/downlink configuration.

2. The base station according to claim 1 , wherein the appropriate radio resource for each of the multiple configurations is a radio resource of at least one uplink subframe common among the multiple configurations.

3. The base station according to claim 2 , wherein the appropriate radio resource is a periodic radio resource that is repeated at a period corresponding to a number of uplink subframes of the uplink/downlink configuration.

4. The base station according to claim 2 , wherein

when the uplink/downlink configuration is a first configuration, the appropriate radio resource is a radio resource of an uplink subframe of a first number and is a periodic radio resource that is repeated at a first period, and

when the uplink/downlink configuration is a second configuration, the appropriate radio resource is a radio resource of an uplink subframe of a second number that is less than the first number and is a periodic radio resource that is repeated at a second period shorter than the first period.

5. The base station according to claim 2 , wherein the circuitry is further configured to notify the terminal device of the appropriate radio resource when a number of uplink subframes of the uplink/downlink configuration is equal to or greater than a predetermined number.

6. The base station according to claim 5 , wherein the circuitry is further configured to notify the terminal device of the appropriate radio resource by reporting system information indicating the appropriate radio resource.

7. The base station according to claim 1 , wherein

the changed uplink/downlink configuration is a configuration including at least a predetermined number of uplink subframes, and

a number of uplink subframes included in the appropriate radio resource differs from the number of uplink subframes of the uplink/downlink configuration.

8. The base station according to claim 7 , wherein the appropriate radio resource is a periodic radio resource that is repeated at a period corresponding to a number of uplink subframes of the uplink/downlink configuration.

9. The base station according to claim 7 , wherein

when the uplink/downlink configuration is a first configuration, the appropriate radio resource is a radio resource of an uplink subframe of a first number and is a periodic radio resource that is repeated at a first period, and

when the uplink/downlink configuration is a second configuration, the appropriate radio resource is a radio resource of an uplink subframe of a second number that is less than the first number and is a periodic radio resource that is repeated at a second period shorter than the first period.

10. The base station according to claim 7 , wherein the circuitry is further configured to notify the terminal device of the appropriate radio resource when a number of uplink subframes of the uplink/downlink configuration is equal to or greater than a predetermined number.

11. The base station according to claim 1 , wherein the appropriate radio resource is a periodic radio resource that is repeated at a period corresponding to a number of uplink subframes of the uplink/downlink configuration.

12. The base station according to claim 1 , wherein

when the uplink/downlink configuration is a first configuration, the appropriate radio resource is a radio resource of an uplink subframe of a first number and is a periodic radio resource that is repeated at a first period, and

when the uplink/downlink configuration is a second configuration, the appropriate radio resource is a radio resource of an uplink subframe of a second number that is less than the first number and is a periodic radio resource that is repeated at a second period shorter than the first period.

13. The base station according to claim 1 , wherein the circuitry is further configured to notify the terminal device of the appropriate radio resource when a number of uplink subframes of the uplink/downlink configuration is equal to or greater than a predetermined number.

14. The base station according to claim 1 , wherein

the changed uplink/downlink configuration has two or more successive uplink subframes, and

the appropriate radio resource is included in the two or more successive uplink subframes of the changed uplink/downlink configuration, and

at least one uplink subframe of the two or more successive uplink subframes is not occupied by the appropriate radio resource.

15. The base station according to claim 14 , wherein the circuitry is further configured to notify the terminal device of the appropriate radio resource only when the changed uplink/downlink configuration includes two or more successive uplink subframes.

16. The base station according to claim 1 , wherein the circuitry is further configured to notify the terminal device of the appropriate radio resource by reporting system information indicating the appropriate radio resource.

17. A method, comprising:

dynamically changing, by circuitry, an uplink/downlink configuration of a time division duplex (TDD) from one configuration among multiple configurations to another configuration among the multiple configurations; and

notifying, by the circuitry, a terminal device of the changed uplink/downlink configuration and of an appropriate radio resource for device-to-device (D2D) communication for the changed uplink/downlink configuration, wherein

the changed uplink/downlink configuration includes at least a predetermined number of uplink subframes,

the circuitry notifies the terminal device of the appropriate radio resource for D2D communication for each of the multiple configurations,

the appropriate radio resource of a respective configuration includes at least one uplink subframe and a period, and

a number of uplink subframes included in the appropriate radio resource differs from a number of uplink subframes of the changed uplink/downlink configuration.

18. A terminal device, comprising:

circuitry configured to acquire information indicating an uplink/downlink configuration of a time division duplex (TDD) carrier that is dynamically changed by a base station from one configuration among multiple configurations to another configuration among the multiple configurations, and information indicating an appropriate radio resource for device-to-device (D2D) communication for the changed uplink/downlink configuration, wherein

the information indicating an appropriate radio resource for D2D communication for the changed uplink/downlink configuration includes information for each of the multiple configurations and the appropriate radio resource of a respective configuration includes at least one uplink subframe and a period,

the changed uplink/downlink configuration includes at least a predetermined number of uplink subframes,

the circuitry is further configured to control D2D communication using the appropriate radio resource of the respective configuration, and

a number of uplink subframes included in the appropriate radio resource differs from a number of uplink subframes of the changed uplink/downlink configuration.