A base station includes a memory; a processor configured to transmit a wireless signal to a wireless terminal and to receive a wireless signal from the wireless terminal; and a controller configured to, while a radio link between the wireless terminal and the base station is disconnected, and an upper-layer connection between the base station and an upper-layer node is maintained wherein the wireless terminal uses the upper-layer connection for communication through the base station, in response to an event that one of first setting information for setting the radio link and second setting information for setting the upper-layer connection is changed, transmit setting information having been changed among the first setting information and the second setting information to the wireless terminal through the processor.