Provided are a method and a wireless device for transmitting a data packet in a wireless communication system. The wireless device engages in peer discovery with a receiver and monitors whether transmission (TX) scheduling information from a base station is received. A data packet is transmitted to the receiver on the basis of the TX scheduling information. The TX scheduling information comprises resource allocation information indicating resource allocation for transmitting the data packet, identification information indicating an identifier for the receiver; and information indicating whether the TX scheduling information is for TX scheduling or reception (RX) scheduling.