Mobile communication system and mobile communication method

A processor of a radio terminal, the processor communicatively coupled to a memory and configured to:

• receive first information on radio resources for direct communication, from a base station by broadcast;
• receive second information on a threshold value from the base station;
• perform the direct communication by use of a radio resource autonomously selected among the radio resources;
• directly receive a radio signal from another radio terminal during performing the direct communication by use of the radio resources;
• compare received power of the radio signal with the threshold value of the second information;
• notify the base station of information on the received power in response to the received power larger than the threshold value;
• and
• not notify the base station of information on the received power in response to the received power being smaller than the threshold value.

A mobile communication method, comprising:

• transmitting, by a base station, first information on radio resources for direct communication by broadcast;
• receiving, by a radio terminal, the first information from the base station;
• transmitting, by the base station, second information on a threshold value from the base station;
• receiving, by the radio terminal, the second information from the base station;
• performing, by the radio terminal, the direct communication by use of a radio resource autonomously selected among the radio resources;
• directly receiving, by the radio terminal, a radio signal from another radio terminal during performing the direct communication by use of the radio resources;
• comparing, by the radio terminal, received power of the radio signal with a threshold value of the second information;
• notifying, by the radio terminal, the base station of information on the received power in response to the received power being larger than the threshold value;
• and
• not notifying, by the radio terminal, the base station of the information on the received power in response to the received power being smaller than the threshold value.