Transmission power control method and base station

A transmission power control method in a mobile communication system including a user apparatus and a base station, the transmission power control method enabling the base station to control transmission power of a discovery signal of the user apparatus, the transmission power control method comprising:

• a user apparatus number estimation step of estimating a number of the user apparatuses transmitting discovery signals by monitoring the discovery signals transmitted from the user apparatuses;
• a power class determination step of, by referring to power class setting information which associates the number of the user apparatuses transmitting the discover signals with a power class used for determining transmission power information of the discovery signal in the user apparatus, determining the power class associated with the number of the user apparatuses estimated in the user apparatus number estimation step;
• and
• a step of transmitting the power class determined in the power class determination step to the user apparatus.