Method of handling device-to-device communication and communication device thereof

1. A method of handling device-to-device communication for a user equipment (UE) of a wireless communication system, the method comprising:

during a period of transmission of a first plurality of data blocks, periodically triggering at least one feedback request with a predetermined period;

transmitting a second plurality of data blocks after receiving at least one feedback, wherein the at least one feedback is transmitted by at least one other UE in response to the at least one feedback request; and

not transmitting the second plurality of data blocks when, after the first plurality of data blocks are completely transmitted, the UE determines that the UE does not receive any feedback in response to the at least one feedback request transmitted during the period of the transmission of the first plurality of data blocks, from the least one other UE.

2. The method of claim 1 , wherein the predetermined period for periodically triggering the at least one feedback request is configured by a network of the wireless communication system or predetermined by the UE.

3. The method of claim 1 , wherein the at least one feedback request and the at least one feedback are respectively comprised in a medium access control (MAC) packet data unit (PDU), a radio link control (RLC) unacknowledged mode (UM) PDU or a packet data convergence protocol (PDCP) PDU.

4. The method of claim 3 , wherein the at least one feedback request and the at least one feedback are a MAC control element in the MAC PDU, a field of or in data part of a header of the MAC PDU, the RLC UM PDU or the PDCP PDU.

5. A method of handling device-to-device communication for a user equipment (UE) of a wireless communication system, the method comprising:

triggering a feedback request every time after a first number of data blocks are transmitted;

transmitting a subsequent first number of data blocks after receiving at least one feedback, wherein the at least one feedback is transmitted by at least one other UE in response to the at least one feedback request; and

not transmitting the subsequent first number of data blocks when the UE determines that the UE does not receive any feedback in response to the at least one feedback request from the least one other UE.

6. The method of claim 5 , wherein the first number are configured by a network of the wireless communication system or predetermined by the UE.

7. The method of claim 5 , wherein the at least one feedback request and the at least one feedback are respectively comprised in a medium access control (MAC) packet data unit (PDU), a radio link control (RLC) unacknowledged mode (UM) PDU or a packet data convergence protocol (PDCP) PDU.

8. The method of claim 5 , wherein the at least one feedback request and the at least one feedback are a MAC control element in the MAC PDU, a field of or in data part of a header of the MAC PDU, the RLC UM PDU or the PDCP PDU.

9. A method of handling device-to-device communication for a user equipment (UE) of a wireless communication system, the method comprising:

transmitting a first plurality of data blocks; and

transmitting at least one transmission end indication when the first plurality of data blocks are completely transmitted;

wherein the at least one transmission end indication indicates that the UE determines not to transmit more data blocks, and at least one other UE stops monitoring a channel for receiving data blocks only when the at least one other UE receives the at least one transmission end indication.

10. The method of claim 9 , wherein after transmitting at least one transmission end indication, the UE receives a second plurality of data blocks from the other UE.

11. The method of claim 9 , wherein the transmission end indication is in the last data block of the first plurality of data blocks and is comprised in a medium access control (MAC) packet data unit (PDU), a radio link control (RLC) unacknowledged mode (UM) PDU or a packet data convergence protocol (PDCP) PDU.

12. The method of claim 11 , wherein the transmission end indication is a MAC control element in the MAC PDU or a field in a header of the MAC PDU, the RLC UM PDU or the PDCP PDU.