Method for device to device communication in a wireless communication system and apparatus therefor

1. A method of performing device-to-device (D2D) communication in a wireless communication system, the method comprising:

communicating, by a first user equipment, with an existing connected user equipment currently connected with the first user equipment through at least one channel among a plurality of channels while hopping on a plurality of the channels based on a first channel hopping period and a first channel hopping sequence;

discovering, by the first user equipment, a second user equipment to newly connect with while hopping on the plurality of the channels based on a second channel hopping period and a second channel hopping sequence; and

performing, by the first user equipment, synchronization with the discovered second user equipment,

wherein the first channel hopping period is configured with identical time intervals for each of the plurality of the channels and

wherein one time interval among the configured time intervals is set equal to the second channel hopping period.

2. The method of claim 1 , wherein discovering the second user equipment to newly connect with comprises discovering the second user equipment by repeating a channel hopping twice based on the second channel hopping sequence during a double of the second channel hopping period.

3. The method of claim 1 , wherein the first channel hopping sequence of the first user equipment is different from the second channel hopping sequence of the first user equipment.

4. The method of claim 1 , wherein the first channel hopping sequence of the first user equipment is identical to the second channel hopping sequence of the first user equipment.

5. The method of claim 1 , wherein performing, by the first user equipment, the synchronization with the second user equipment further comprises transmitting, by the first user equipment, a connection request message to the second user equipment and receiving a connection response message in response to the connection request message from the second user equipment and wherein the connection request message comprises synchronization information of the first user equipment and channel hopping sequence information of the first user equipment.

6. The method of claim 1 , further comprising: performing, by the first user equipment, the synchronization with the second user equipment and performing, by the first user equipment, synchronization with the existing connected user equipment based on the synchronization matched with the second user equipment.

7. The method of claim 6 , further comprising: communicating, by the first user equipment, with the second user equipment and the existing connected user equipment after an elapse of a prescribed time since performing the synchronization with the second user equipment and the existing connected user equipment.

8. The method of claim 1 , wherein discovering, by the first user equipment, the second user equipment to newly connect with further comprises:

transmitting, by the first user equipment, a probe request message to the second user equipment; and

receiving, by the first user equipment, a probe response message in response to the probe request message from the second user equipment.

9. The method of claim 8 , wherein a scheme for the first user equipment to transmit the probe request message comprises one of unicast, multicast and broadcast.

10. The method of claim 1 , wherein the first channel hopping sequence of the first user equipment before discovering the second user equipment is different from a channel hopping sequence after performing the synchronization with the second user equipment.

11. The method of claim 1 , wherein the second user equipment performs the D2D communication with a user equipment other than the first user equipment.

12. A method of performing device-to-device (D2D) communication in a wireless communication system, comprising:

receiving, by a second user equipment, a probe request message from a first user equipment;

transmitting, by the second user equipment, a probe response message in response to the probe request message to the first user equipment; and

performing, by the second user equipment, synchronization with the first user equipment,

wherein the first user equipment communicates with an existing connected user equipment currently connected with the first user equipment through at least one channel among a plurality of channels while hopping on a plurality of the channels based on a first channel hopping sequence during a first channel hopping period,

wherein the first user equipment transmits the probe request message to the second user equipment while hopping on a plurality of the channels based on a second channel hopping period and a second channel hopping sequence,

wherein the first channel hopping is configured with identical time intervals for each of the plurality of the channels, and

wherein one time interval among the configured time intervals is set equal to the second channel hopping period.

13. A first user equipment performing device-to-device (D2D) communication in a wireless communication system, the first user equipment comprising:

a transceiver; and

a processor that:

controls the transceiver to communicate with an existing connected user equipment currently connected with the first user equipment through at least one channel among a plurality of channels while hopping on a plurality of the channels based on a first channel hopping period and a first channel hopping sequence, and

discovers a second user equipment to connect newly with while hopping on a plurality of the channels based on a second channel hopping period and a second channel hopping sequence, and match synchronization with the discovered second user equipment,

wherein the first channel hopping is configured with identical time intervals for each of the plurality of the channels, and

wherein one time interval among the configured time intervals is set equal to the second channel hopping period.