Connectivity supporting method for D2D communication and wireless device

1. A method for supporting connectivity of D2D (Device-to-Device) communication between a first wireless device and a second wireless device, the method performed by a third wireless device and comprising:

receiving first information on a first resource pool available for D2D communication from a base station;

transmitting the second information on a second resource pool to the first wireless device and the second wireless device,

wherein the second resource pool includes resources available for the D2D communication between the first wireless device and the second wireless device;

monitoring a D2D communication link between the first wireless device and the second wireless device;

receiving data from the first wireless device,

wherein the data is generated by the first wireless device and intended to be delivered to the second wireless device;

determining whether the D2D communication link between the first wireless device and the second wireless device is terminated based on a result of the monitoring; and

providing the data to the second wireless device when the D2D communication link is terminated and the data is received before the D2D communication link is terminated.

2. The method of claim 1 ,

wherein the third wireless device is located in a cell coverage extension area of the base station,

wherein the first wireless device and the second wireless device are out of the cell coverage extension area.

3. The method of claim 1 , wherein the first information is received repeatedly from the base station using a plurality of subframes.

4. The method of claim 1 , wherein the providing the data includes:

searching for a fourth wireless device adjacent to the second wireless device,

wherein the fourth wireless device has received the data before the D2D communication link between the first wireless device and the second wireless device is terminated; and

upon detection of the fourth wireless device, transmitting to the fourth wireless device, a control signal for instructing the fourth wireless device to transmit the data to the second wireless device.

5. The method of claim 1 , wherein the providing the data includes:

upon the second wireless device broadcasting a data request message, determining whether the data request message reaches a fourth wireless device containing the data; and

upon determination that the data request message does not reach the fourth wireless device, transmitting a power adjustment signal to the second wireless device to instruct the second wireless device to increase transmission power for the data request message.

6. The method of claim 1 , wherein the providing the data includes:

determining whether a fourth wireless device having the required data is located in an area where the first information cannot be received directly from the base station;

upon determination that the fourth wireless device is located in the area, updating the resource pool so that a D2D communication link is established between the second wireless device and the fourth wireless device; and

sending the updated resource pool to the second wireless device.

7. The method of claim 6 , further comprising:

reporting information on the updated resource pool to the base station.

8. The method of claim 1 , wherein the providing the data includes:

receiving support priorities for devices supporting the connectivity of the D2D communication from the second wireless device; and

upon determining, based on the received support priorities, that the third wireless device is to support the connectivity of the D2D communication, transmitting the data to the second wireless device.

9. The method of claim 1 , further comprising:

when a collision between scheduling assignments for the D2D communication between the first wireless device and the second wireless device is detected based on the result of the monitoring, reconstructing the resource pool so that the collision is prevented; and

transmitting the reconstructed resource pool to one of the first wireless device or the second wireless device.

10. The method of claim 9 , further comprising:

reporting information on the reconstructed resource pool to the base station.

11. A support device for supporting connectivity of D2D (Device-to-Device) communication between a first wireless device and a second wireless device, the support device comprising:

a transceiver; and

a processor operatively coupled to the transceiver and configured to control the transceiver, wherein the processor is further configured to:

control the transceiver to receive first information on a resource pool available for D2D communication from a base station;

control the transceiver to transmit the second information on the resource pool to the first wireless device and the second wireless device,

wherein the second resource pool includes resources available for the D2D communication between the first wireless device and the second wireless device;

monitor a D2D communication link between the first wireless device and the second wireless device;

control the transceiver to receive data from the first wireless device,

wherein the data is generated by the first wireless device and intended to be delivered to the second wireless device;

determine, whether the D2D communication link between the first wireless device and the second wireless device is terminated based on a result of the monitoring; and

control the transceiver to provide the data to the second wireless device when the D2D communication link is terminated and the data is received before the D2D communication link is terminated.

12. The support device of claim 11 ,

wherein the support device is located in a cell coverage extension area of the base station,

wherein the first wireless device and the second wireless device are out of the cell coverage extension area.

13. The support device of claim 11 ,

wherein the processor is further configured to search for a fourth wireless device adjacent to the second wireless device, the fourth wireless device being a device that has received the data before the D2D communication link between the first wireless device and the second wireless device is terminated; and

upon detection of the fourth wireless device, control the transceiver to transmit, to the fourth wireless device, a control signal instructing the fourth wireless device to transmit the data to the second wireless device.

14. The support device of claim 11 , wherein the processor is further configured to:

upon the second wireless device broadcasting a data request message, determine whether the data request message reaches a fourth wireless device containing the data; and

upon determination that the data request message does not reach the fourth wireless device, control the transceiver to transmit a power adjustment signal to the second wireless device to instruct the second wireless device to increase transmission power for the data request message.

15. The support device of claim 11 , wherein the processor is further configured to:

determine whether a fourth wireless device having the data is located in an area where the first information cannot be received directly from the base station;

upon determination that the fourth wireless device is located in the area, update the resource pool so that a D2D communication link is established between the second wireless device and the fourth wireless device; and

control the transceiver to transmit the updated resource pool to the second wireless device.

16. The support device of claim 15 , wherein the processor is further configured to control the transceiver to report information on the updated resource pool to the base station.

17. The support device of claim 11 , wherein the processor is further configured to:

control the transceiver to receive support priorities for devices supporting the connectivity of the D2D communication from the second wireless device; and

upon determining, based on the received support priorities, that the third wireless device is to support the connectivity of the D2D communication, control the transceiver to transmit the data to the second wireless device.

18. The support device of claim 11 , wherein the processor is further configured to:

when a collision between scheduling assignments for the D2D communication between the first wireless device and the second wireless device is detected based on the result of the monitoring, reconstruct the resource pool so that the collision is prevented; and

control the transceiver to transmit the reconstructed resource pool to one of the first wireless device or the second wireless device.

19. The support device of claim 18 , wherein the processor is further configured to control the transceiver to report information on the reconstructed resource pool to the base station.