Communication method of terminal and communication method of base station for direct communication link between terminals

A communication method of a base station for controlling a direct communication link between terminals, comprising:

• scheduling a first terminal by sending, from the base station, a first ranging command message to the first terminal using unicast transmission, so that the first terminal transmits a first ranging code;
• scheduling second terminals by sending, from the base station, a second ranging command message to the second terminals using broadcast transmission, so that the second terminals receive the first ranging code transmitted by the first terminal;
• and
• receiving first information from the second terminals, the first information including a quality measurement result of the first ranging code that is received by the second terminals from the first terminal,
• wherein the first and second ranging command messages are of a same format that includes a plurality of fields, including
• an action field indicating whether each ranging command message is for ranging code transmission or ranging code reception, the action field in the first ranging command message indicating the ranging code transmission, the action field in the second ranging command message indicating the ranging code reception, and
• a dedicated ranging code index that is an index identifying the first ranging code.