Mobile communication system and mobile communication method

A mobile communication method, which is used in a mobile communication system including a plurality of radio base stations that communicate with a radio terminal,

• the plurality of radio base stations constituting a radio base station group including one anchor radio base station and non-anchor radio base stations other than the anchor radio base station, and the method comprising:
• a step A of transmitting, by the anchor radio base station, a control signal for adjusting a timing, at which the radio terminal transmits an uplink signal, to the radio terminal, in order to adjust a timing, at which the uplink signal is received from the radio terminal, to a desired timing,
• a step B of measuring, by the non-anchor radio base station, reception quality of an uplink signal received from the radio terminal,
• a step C of notifying, by the non-anchor radio base station, the anchor radio base station of the reception quality measured in the step B, and
• a step D of determining, by the anchor radio base station, whether or not to exclude the non-anchor radio base station from the radio base station group on the basis of the reception quality notified from the non-anchor radio base station.