Method of device-to-device communication in wireless mobile communication system

A data transmission/reception method of a first device that performs data transmission to a second device through a first D2D link and data reception from the second device through a second D2D link, comprising:

• receiving release transmission assignment information of the first D2D link or release reception assignment information of the second D2D link from a base station in a first subframe;
• transmitting whether the release transmission assignment information or the release reception assignment information has been successfully received to the base station in a second subframe after a predetermined number (x) of subframes from the first subframe;
• and
• preferentially performing the transmission of whether the release transmission assignment information or the release reception assignment information has been successfully received when the second subframe collides with a subframe in which reception of the reception success or failure information from the second device for the data transmitted to the second device or transmission of the reception success or failure information for the data received from the second device is performed.

A data reception method of a first device for D2D communication, comprising:

• receiving subframe cycle information for initial transmission from a base station;
• receiving activation reception assignment information for the D2D communication from the base station in a first subframe;
• transmitting whether the activation reception assignment information has been successfully received to the base station in a second frame after a predetermined number (m) of subframes from the first subframe;
• and
• receiving initial transmission data from the second device based on the activation reception assignment information and subframe cycle information for the initial transmission.