A first base station is configured to be connected with a second base station via an X2 interface. The first base station includes: a controller containing at least one processor and at least one memory, and configured to execute processes of transmitting a message, which includes a first identifier, coverage state information, and a second identifier, to the second base station before modifying a coverage of the first cell, the first identifier identifying the first cell, the coverage state information indicating that a state of the coverage after modification of the coverage, the second identifier identifying a second cell for compensating at least part of the coverage of the first cell; and modifying the coverage of the first cell after transmitting the message.