Communication device performing device-to-device communication and operating method thereof

A communication device performing device-to-device (D2D) communication, the communication device comprising:

• a memory configured to store programs related to selecting a communication mode;
• and
• a processor connected to the memory and configured to execute the programs to,
• perform a comparison operation using first information provided from an counterpart terminal of the D2D communication and second information stored in the communication device;
• and
• select one of cellular communication and the D2D communication as a communication mode with the counterpart terminal based on a result of the comparison operation.

An operating method of a communication device, the method comprising:

• preforming signaling at least one of periodically or non-periodically between at least one base station and a plurality of devices including the communication device;
• receiving a first message, the first message including resources of a direct link for device-to-device (D2D) communication from the base station;
• transmitting a channel information calculation message to at least one counterpart device from among the plurality of devices;
• receiving a second message from the counterpart device, the second message including first information from the counterpart device of the D2D communication, the first information being a value calculated using channel information of a downlink of cellular communication and channel information of the direct link;
• and
• selecting one of the cellular communication or the D2D communication as a communication mode with the counterpart device, based on channel information of an uplink of the cellular communication and the received first information.