Abstract: A method of sidelink communications by a plurality of user equipment (UE) without the control of a base station in a wireless communication system is disclosed. In one embodiment, the UE being a scheduler end is configured to allocate the resources for initial/repeated transmissions and ACK/NACK messages, and also transmit information regarding the allocated resources to both the UEs being a transmitter end and a receiver end. In one embodiment, retransmission is performed when none of the scheduler and transmitter ends has received the ACK message sent by the receiver end, so as to minimize redundant retransmission in consideration of transmission reliability. In one embodiment, retransmission is performed when at least one of the scheduler and transmitters end has received the NACK message sent by the receiver end before the retransmission timer has reached to zero, so as to minimize transmission latency.

Abstract: A method of sidelink communications by a plurality of user equipment (UE) without the control of a base station in a wireless communication system is disclosed. In one embodiment, the UE being a scheduler end is configured to allocate the resources for initial/repeated transmissions and ACK/NACK messages, and also transmit information regarding the allocated resources to both the UEs being a transmitter end and a receiver end. In one embodiment, retransmission is performed when none of the scheduler and transmitter ends has received the ACK message sent by the receiver end, so as to minimize redundant retransmission in consideration of transmission reliability. In one embodiment, retransmission is performed when at least one of the scheduler and transmitters end has received the NACK message sent by the receiver end before the retransmission timer has reached to zero, so as to minimize transmission latency.