Method and apparatus for adjusting device-to-device timing in wireless communication system

1. A method for adjusting, by a first group owner device of a first device-to-device (D2D) group, D2D timing in a wireless communication system, the method comprising:

detecting interference from a second D2D group;

transmitting a reference signal to all group member devices of the first D2D group;

receiving a D2D timing difference, which is calculated by a first group member device of the first D2D group, from the first group member device,

wherein the D2D timing difference is a timing difference between the reference signal transmitted from the first group owner device and a reference signal transmitted from a second group owner device;

adjusting D2D timing of the first D2D group to avoid the detected interference from the second D2D group, based on the received D2D timing difference; and

transmitting the adjusted D2D timing of the first D2D group to the all group member devices of the first D2D group,

wherein the first group owner device operates as an access router of the first D2D group, and the second group owner device operates as an access router of the second D2D group.

2. The method of claim 1 , wherein the interference from the second D2D group is detected by receiving a signal on the second D2D group.

3. The method of claim 2 , wherein the signal on the second D2D group includes information on D2D resources used by the second D2D group.

4. The method of claim 3 , wherein the D2D resources used by the second D2D group includes at least one of time resources or frequency resources used by the second D2D group.

5. The method of claim 1 , further comprising:

receiving a D2D timing difference calculated by a network, from the network.

6. The method of claim 1 , further comprising:

receiving, from the first group member device, measured quality of the reference signal transmitted from the second group owner device.

7. The method of claim 1 , further comprising:

receiving information on the second group owner device of the second D2D group.

8. The method of claim 7 , wherein the information on the second group owner device of the second D2D group includes at least one of a user equipment (UE) identity of the second group owner device of the second D2D group, D2D security information, or D2D-related code and sequence transmitted from the second group owner device of the second D2D group.

9. A first group owner device of a first device-to-device (D2D) group in a wireless communication system, the first device comprising:

a transceiver that transmits or receives a radio signal; and

a processor, coupled to the transceiver, that:

detects interference from a second D2D group,

controls the transceiver to transmit a reference signal to all group member devices of the first D2D group,

controls the transceiver to receive a D2D timing difference, which is calculated by a first group member device of the first D2D group, from the first group member device,

wherein the D2D timing difference is a timing difference between the reference signal transmitted from the first group owner device and a reference signal transmitted from a second group owner device,

adjusts D2D timing of the first D2D group to avoid the detected interference from the second D2D group, based on the received D2D timing difference, and

controls the transceiver to transmit the adjusted D2D timing of the first D2D group to the all group member devices of the first D2D group,

wherein the first group owner device operates as an access router of the first D2D group, and the second group owner device operates as an access router of the second D2D group.

10. The first device of claim 9 , wherein the interference from the second D2D group is detected by receiving a signal on the second D2D group.