Two-step search procedure for D2D communication

A method for operating a second user equipment (UE) performing device-to-device (D2D) communication, the method comprising:

• receiving, from a first UE, a discovery code and a multicast identifier (ID), through a discovery subframe, the discovery code acquired corresponding to an ID of an application program installed in the first UE;
• determining whether to receive additional information on the application program from the first UE based on the received discovery code;
• and
• when it is determined that reception of the additional information will take place, receiving the additional information using the multicast ID through a D2D multicast subframe.

A method for operating a discovery server, the method comprising:

• receiving, from a first user equipment (UE), an identifier (ID) of an application program for the first UE;
• determining a discovery code corresponding to the ID of the application program installed in the first UE;
• and
• transmitting, to the first UE, the discovery code and a multicast ID of the first UE,
• wherein the multicast ID of the first UE is used for transmitting additional information on the application program through a device-to-device (D2D) multicast subframe.

A first user equipment (UE) performing device-to-device (D2D) communication, the first UE comprising:

• a transceiver configured to transmit/receive a signal;
• and
• at least one processor configured to:
• acquire a discovery code corresponding to an identifier (ID) of an application program installed in the first UE,
• acquire a multicast ID to be used for transmitting additional discovery information on the application program,
• broadcast the discovery code and the multicast ID in a discovery subframe, and
• transmit, to a second UE, the additional information on the application program through a D2D multicast subframe using the multicast ID.

A second user equipment (UE) performing D2D (device-to-device) communication, the second UE comprising:

• a transceiver configured to transmit/receive a signal;
• and
• at least one processor configured to:
• receive, from a first UE, a discovery code and a multicast identifier (ID), through a discovery subframe, the discovery code acquired corresponding to an ID of an application program installed in the first UE,
• determine whether to receive additional information on the application program from the first UE based on the received discovery code, and
• when it is determined that reception of the additional information will take place, receive the additional information using the multicast ID through a D2D multicast subframe.

A discovery server comprising:

• a transceiver configured to transmit/receive a signal;
• and
• at least one processor configured to:
• receive, from a first user equipment (UE), an identifier (ID) of an application program for the first UE,
• determine a discovery code corresponding to the ID of the application program installed in the first UE, and
• transmit, to the first UE, the discovery code and a multicast ID of the first UE,
• wherein the multicast ID of the first UE is used for transmitting additional information on the application program through a device-to-device (D2D) multicast subframe.