Method for receiving synchronizing signals for direct communication between terminals in wireless communication system, and device for same

A user equipment (UE) for acquiring synchronization for device-to-device (D2D) communication in a wireless communication system, the UE comprising:

• a transceiver configured to transmit and receive a signal to and from a base station (BS), an external synchronization source different from the BS, or a counterpart UE of the D2D communication;
• and
• a processor connected to the transceiver,
• wherein the processor is configured to:
• control the transceiver to receive, from the BS, information on a synchronization type for the D2D communication, wherein the UE is in coverage of a cell related to the BS,
• acquire synchronization for the D2D communication using a synchronization source, based on the information on the synchronization type, and
• control the transceiver to transmit information on the synchronization source used by the UE to the BS,
• wherein the synchronization source is one of i) the cell related to the BS and ii) an external synchronization source different from the BS, and
• wherein, when the information on synchronization type is related to the BS, the cell is used as the synchronization source, and when the information on the synchronization type is related to the external synchronization source, the external synchronization source is used as the synchronization source.